P
pixelsmith
Guest
You emit methane daily and therefore are contributing to the accelerating climate change. What are you going to do about it?
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How Silly is Climate Change Denial?
- Thread starter Angel of Ioren
- Start date
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P
pixelsmith
Guest
I am serious tony.
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pixelsmith
Guest
I can't cut my miles. I don't let my car warm up in the morning anymore tho.
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Tyger
Paranormal Adept
Evidence, please, to support this claim. Be specific. There is science that indicates that humans are very much involved. Argue the point: How are humans not involved?
Upon what do you base this assertion? Again, science indicates that it very much is, and that is why we are in something of a bind. Argue the point: What convinces you that it is 'not accelerating'?
It's not solely about 'the planet'. The planet will go on. Humans exist within narrow parameters - those parameters shift too fast, and humans, as well as a great deal of the biosphere, will not be able to adapt to the changes. That is clear. We are watching it happen even now with the biosphere.
Tyger
Paranormal Adept
Tony B.
Paranormal Adept
So am I. End of discussion.
Tyger
Paranormal Adept
Pixel, you decided to come on another thread I started whose purpose is not to debate climate change. This is the thread for your debate. There are scads of threads debating this point. Keep your comments on the right thread in the relevant conversation, please.
You're a joke, Pixel. I haven't been beaten up. You have been behaving like a bully, for sure - but I would't say you've landed any punches. Alls you've been doing is laying bare your ignorance, I'm sorry to say. 
To each his own.
And now you begin your strange, twisted ad hominems. Trouble is, with every word you reveal how little you understand how science works. I supplied the Steven Schneider lecture because he was discussing at what point should science drive policy. An important point. One he was particularly in a position to explain, given his curriculum vitae.
Nasty.
How was he 'hypocritical'? How was he a 'con man'? How was he 'bought-and-paid-for? By whom? Why is he a "scientist" and not a scientist? (Keep in mind that he had a dual PhD - one in plasma physics - what is your PhD in?) Explain your reasoning. If your reasoning is summed up in the previous paragraph - that basically as an investigator he shifted his views over time - it sounds like you seriously don't understand science. I would like you to name one scientist who has not shifted their views over time when new evidence presents itself.
This is the man who you are pitifully mocking - it is so clear you haven't a clue how science works.
Stephen Schneider - Wikipedia, the free encyclopedia
TEXT: "Stephen Henry Schneider (February 11, 1945 – July 19, 2010) was Professor of Environmental Biology and Global Change at Stanford University, a Co-Director at the Center for Environment Science and Policy of theFreeman Spogli Institute for International Studies and a Senior Fellow in the Stanford Woods Institute for the Environment. Schneider served as a consultant to federal agencies and White House staff in the Richard Nixon,Jimmy Carter, Ronald Reagan, George H. W. Bush, Bill Clinton, George W. Bush and Barack Obama administrations.
"His research included modeling of the atmosphere, climate change, and the effect of global climate change on biological systems. Schneider was the founder and editor of the journal Climatic Change and authored or co-authored over 450 scientific papers and other publications. He was a Coordinating Lead Author in Working Group II IPCC TAR and was engaged as a co-anchor of the Key Vulnerabilities Cross-Cutting Theme for the Fourth Assessment Report (AR4) at the time of his death. During the 1980s, Schneider emerged as a leading public advocate of sharp reductions of greenhouse gas emissions to combat global warming. In 2006 Professor Schneider was an Adelaide Thinker in Residence advising the South Australian Government of Premier Mike Rann on climate change and renewable energy policies. In ten years South Australia went from zero to 31% of its electricity generation coming from renewables.
"An annual award for outstanding climate science communication was created in Schneider's honor after his death.
"Schneider grew up in Long Island, New York. He studied engineering at Columbia University, receiving his bachelor's degree in mechanical engineering in 1966. In 1971, he earned a Ph.D. in mechanical engineering and plasma physics. Schneider studied the role of greenhouse gases and suspended particulate material on climate as a postdoctoral fellow at NASA's Goddard Institute for Space Studies.
"In 1971, Schneider was second author on a Science paper with S. I. Rasool titled "Atmospheric Carbon Dioxide and Aerosols: Effects of Large Increases on Global Climate" (Science 173, 138–141). This paper used a one-dimensional radiative transfer model to examine the competing effects of cooling from aerosols and warming from CO2. The paper concluded: "However, it is projected that man's potential to pollute will increase 6 to 8-fold in the next 50 years. If this increased rate of injection... should raise the present background opacity by a factor of 4, our calculations suggest a decrease in global temperature by as much as 3.5 °C. Such a large decrease in the average temperature of Earth, sustained over a period of few years, is believed to be sufficient to trigger an ice age. However, by that time, nuclear power may have largely replaced fossil fuels as a means of energy production."
"Carbon dioxide was predicted to have only a minor role. However, the model was very simple and the calculation of the CO2 effect was lower than other estimates by a factor of about three, as noted in a footnote to the paper.
"The story made headlines in the New York Times. Shortly afterwards, Schneider became aware that he had overestimated the cooling effect of aerosols, and underestimated the warming effect of CO2 by a factor of about three. He had mistakenly assumed that measurements of air particles he had taken near the source of pollution applied worldwide. He also found that much of the effect was due to natural aerosols which would not be affected by human activities, so the cooling effect of changes in industrial pollution would be much less than he had calculated. Having found that recalculation showed that global warming was the more likely outcome, he published a retraction of his earlier findings in 1974.
"In a 1976 book The Genesis Strategy he discusses both long-term warming due to carbon dioxide and short-term cooling due to aerosols, and advocated for adopting policies that are resilient to future changes in climate."
You're a joke, Pixel. I haven't been beaten up. You have been behaving like a bully, for sure - but I would't say you've landed any punches. Alls you've been doing is laying bare your ignorance, I'm sorry to say. To each his own.How? (Though it's not 'my' science, you know.)
Really? Explain. Be specific. (I'm curious how much you really do know about scientific methodology.)
What are the details of the belief system? Be specific, please.
Man-made? Are there other kinds?
All of them? Explain how all the (man-made) climate models are all wrong. Be specific.
And now you begin your strange, twisted ad hominems. Trouble is, with every word you reveal how little you understand how science works. I supplied the Steven Schneider lecture because he was discussing at what point should science drive policy. An important point. One he was particularly in a position to explain, given his curriculum vitae.
What is wrong with you, Pixel? A man dies and you use his death to push your point?
Nasty.'My' point? I am very curious - what did you think was 'my' point in posting his lecture?
How was he 'hypocritical'? How was he a 'con man'? How was he 'bought-and-paid-for? By whom? Why is he a "scientist" and not a scientist? (Keep in mind that he had a dual PhD - one in plasma physics - what is your PhD in?) Explain your reasoning. If your reasoning is summed up in the previous paragraph - that basically as an investigator he shifted his views over time - it sounds like you seriously don't understand science. I would like you to name one scientist who has not shifted their views over time when new evidence presents itself.
This is the man who you are pitifully mocking - it is so clear you haven't a clue how science works.
Stephen Schneider - Wikipedia, the free encyclopedia
TEXT: "Stephen Henry Schneider (February 11, 1945 – July 19, 2010) was Professor of Environmental Biology and Global Change at Stanford University, a Co-Director at the Center for Environment Science and Policy of theFreeman Spogli Institute for International Studies and a Senior Fellow in the Stanford Woods Institute for the Environment. Schneider served as a consultant to federal agencies and White House staff in the Richard Nixon,Jimmy Carter, Ronald Reagan, George H. W. Bush, Bill Clinton, George W. Bush and Barack Obama administrations.
"His research included modeling of the atmosphere, climate change, and the effect of global climate change on biological systems. Schneider was the founder and editor of the journal Climatic Change and authored or co-authored over 450 scientific papers and other publications. He was a Coordinating Lead Author in Working Group II IPCC TAR and was engaged as a co-anchor of the Key Vulnerabilities Cross-Cutting Theme for the Fourth Assessment Report (AR4) at the time of his death. During the 1980s, Schneider emerged as a leading public advocate of sharp reductions of greenhouse gas emissions to combat global warming. In 2006 Professor Schneider was an Adelaide Thinker in Residence advising the South Australian Government of Premier Mike Rann on climate change and renewable energy policies. In ten years South Australia went from zero to 31% of its electricity generation coming from renewables.
"An annual award for outstanding climate science communication was created in Schneider's honor after his death.
"Schneider grew up in Long Island, New York. He studied engineering at Columbia University, receiving his bachelor's degree in mechanical engineering in 1966. In 1971, he earned a Ph.D. in mechanical engineering and plasma physics. Schneider studied the role of greenhouse gases and suspended particulate material on climate as a postdoctoral fellow at NASA's Goddard Institute for Space Studies.
"In 1971, Schneider was second author on a Science paper with S. I. Rasool titled "Atmospheric Carbon Dioxide and Aerosols: Effects of Large Increases on Global Climate" (Science 173, 138–141). This paper used a one-dimensional radiative transfer model to examine the competing effects of cooling from aerosols and warming from CO2. The paper concluded: "However, it is projected that man's potential to pollute will increase 6 to 8-fold in the next 50 years. If this increased rate of injection... should raise the present background opacity by a factor of 4, our calculations suggest a decrease in global temperature by as much as 3.5 °C. Such a large decrease in the average temperature of Earth, sustained over a period of few years, is believed to be sufficient to trigger an ice age. However, by that time, nuclear power may have largely replaced fossil fuels as a means of energy production."
"Carbon dioxide was predicted to have only a minor role. However, the model was very simple and the calculation of the CO2 effect was lower than other estimates by a factor of about three, as noted in a footnote to the paper.
"The story made headlines in the New York Times. Shortly afterwards, Schneider became aware that he had overestimated the cooling effect of aerosols, and underestimated the warming effect of CO2 by a factor of about three. He had mistakenly assumed that measurements of air particles he had taken near the source of pollution applied worldwide. He also found that much of the effect was due to natural aerosols which would not be affected by human activities, so the cooling effect of changes in industrial pollution would be much less than he had calculated. Having found that recalculation showed that global warming was the more likely outcome, he published a retraction of his earlier findings in 1974.
"In a 1976 book The Genesis Strategy he discusses both long-term warming due to carbon dioxide and short-term cooling due to aerosols, and advocated for adopting policies that are resilient to future changes in climate."
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Burnt State
Paranormal Adept
well, many have tried before you and failed and you are now taking the smart path, trust me.
Tyger
Paranormal Adept
Manxman, you have a problem reading text. That's all I can surmise. I know you are presenting the text you are because you think it's relevant. It isn't.
Figure it out for yourself. Don't look to have it all spoon-fed to you. There is no way around it - you must read the science first-hand. I can't help you. That goes double for Pixel, but I think he's a lost cause. He's doing what he is doing on the thread to be perverse. He repeats himself endlessly - and never enters into real dialog. (He has latched onto one factoid about polar bears and can't let it go). He's a troll, pure and simple, and you have become one, too.
As others have stated - no one really has time for this. I don't. I still intend to post what interests me but you make a huge mistake if you think I am in conversation with you after this evening. I am not. Nor am I in conversation with Pixel after this evening. I'm sure you both will continue digging your holes ever deeper.
You both are impressive if only for the sweeping nature of your (clueless) ignorance.
Ignore is on.
Figure it out for yourself. Don't look to have it all spoon-fed to you. There is no way around it - you must read the science first-hand. I can't help you. That goes double for Pixel, but I think he's a lost cause. He's doing what he is doing on the thread to be perverse. He repeats himself endlessly - and never enters into real dialog. (He has latched onto one factoid about polar bears and can't let it go). He's a troll, pure and simple, and you have become one, too.
As others have stated - no one really has time for this. I don't. I still intend to post what interests me but you make a huge mistake if you think I am in conversation with you after this evening. I am not. Nor am I in conversation with Pixel after this evening. I'm sure you both will continue digging your holes ever deeper.
You both are impressive if only for the sweeping nature of your (clueless) ignorance.
Ignore is on.
Funny this guy.
posts a few wise cracks, then cites an article to sweep us away.
Article about 2 students discovering against mainstream thinking that warming creates more microbal action and increased co2 emissions from the soil.
Therefore counter argueing pixel's 'warming is good mantra.
And then flouncing because he hasnt been answered the way he wanted.
However his own referenced cite has plenty of peer reviewed papers/articles on there.
So heres the science tony, conducted by scientists and peer reviewed by their profession, and whose papers are accepted by all as the final word.
And this is where your 2 kids get it wrong, the bolded.
The physiology of microbes living underground could determine the amount of carbon dioxide emitted from soil on a warmer Earth, according to a study recently published online in Nature Geoscience.
Researchers at UC Irvine, Colorado State University and the Yale School of Forestry & Environmental Studies found that as global temperatures increase, microbes in soil become less efficient over time at converting carbon in soil into carbon dioxide, a key contributor to climate warming.
Microbes, in the form of bacteria and fungi, use carbon for energy to breathe, or respire, and to grow in size and in number. A model developed by the researchers shows microbes exhaling carbon dioxide furiously for a short period of time in a warmer environment, leaving less carbon to grow on. As warmer temperatures are maintained, the less efficient use of carbon by the microbes causes them to decrease in number, eventually resulting in less carbon dioxide being emitted into the atmosphere.
"Microbes aren't the destructive agents of global warming that scientists had previously believed," said Steven Allison, assistant professor of ecology & evolutionary biology at UCI and lead author on the study. "Microbes function like humans: They take in carbon-based fuel and breathe out carbon dioxide. They are the engines that drive carbon cycling in soil. In a balanced environment, plants store carbon in the soil and microbes use that carbon to grow. The microbes then produce enzymes that convert soil carbon into atmospheric carbon dioxide."
The study, "Soil-Carbon Response to Warming Dependent on Microbial Physiology," contradicts the results of older models that assume microbes will continue to spew ever-increasing amounts of carbon dioxide into the atmosphere as the climate continues to warm. The new simulations suggest that if microbial efficiency declines in a warmer world, carbon dioxide emissions will fall back to pre-warming levels, a pattern seen in field experiments.
Soil microbes produce less atmospheric CO<sub>2</sub> than expected with climate warming -- ScienceDaily
posts a few wise cracks, then cites an article to sweep us away.
Article about 2 students discovering against mainstream thinking that warming creates more microbal action and increased co2 emissions from the soil.
Therefore counter argueing pixel's 'warming is good mantra.
And then flouncing because he hasnt been answered the way he wanted.
However his own referenced cite has plenty of peer reviewed papers/articles on there.
So heres the science tony, conducted by scientists and peer reviewed by their profession, and whose papers are accepted by all as the final word.
And this is where your 2 kids get it wrong, the bolded.
The physiology of microbes living underground could determine the amount of carbon dioxide emitted from soil on a warmer Earth, according to a study recently published online in Nature Geoscience.
Researchers at UC Irvine, Colorado State University and the Yale School of Forestry & Environmental Studies found that as global temperatures increase, microbes in soil become less efficient over time at converting carbon in soil into carbon dioxide, a key contributor to climate warming.
Microbes, in the form of bacteria and fungi, use carbon for energy to breathe, or respire, and to grow in size and in number. A model developed by the researchers shows microbes exhaling carbon dioxide furiously for a short period of time in a warmer environment, leaving less carbon to grow on. As warmer temperatures are maintained, the less efficient use of carbon by the microbes causes them to decrease in number, eventually resulting in less carbon dioxide being emitted into the atmosphere.
"Microbes aren't the destructive agents of global warming that scientists had previously believed," said Steven Allison, assistant professor of ecology & evolutionary biology at UCI and lead author on the study. "Microbes function like humans: They take in carbon-based fuel and breathe out carbon dioxide. They are the engines that drive carbon cycling in soil. In a balanced environment, plants store carbon in the soil and microbes use that carbon to grow. The microbes then produce enzymes that convert soil carbon into atmospheric carbon dioxide."
The study, "Soil-Carbon Response to Warming Dependent on Microbial Physiology," contradicts the results of older models that assume microbes will continue to spew ever-increasing amounts of carbon dioxide into the atmosphere as the climate continues to warm. The new simulations suggest that if microbial efficiency declines in a warmer world, carbon dioxide emissions will fall back to pre-warming levels, a pattern seen in field experiments.
Soil microbes produce less atmospheric CO<sub>2</sub> than expected with climate warming -- ScienceDaily
How many more do you think there are on that site refuting your 2 students article, scientists i mean.
Symbiotic fungi inhabiting plant roots have major impact on atmospheric carbon, scientists say -- ScienceDaily
Microscopic fungi that live in plants' roots play a major role in the storage and release of carbon from the soil into the atmosphere, according to a University of Texas at Austin researcher and his colleagues at Boston University and the Smithsonian Tropical Research Institute. The role of these fungi is currently unaccounted for in global climate models.
Some types of symbiotic fungi can lead to 70 percent more carbon stored in the soil.
"Natural fluxes of carbon between the land and atmosphere are enormous and play a crucial role in regulating the concentration of carbon dioxide in the atmosphere and, in turn, Earth's climate," said Colin Averill, lead author on the study and graduate student in the College of Natural Sciences at UT Austin. "This analysis clearly establishes that the different types of symbiotic fungi that colonize plant roots exert major control on the global carbon cycle, which has not been fully appreciated or demonstrated until now."
"This research is not only relevant to models and predictions of future concentrations of atmospheric greenhouse gases, but also challenges the core foundation in modern biogeochemistry that climate exerts major control over soil carbon pools," added Adrien Finzi, co-investigator and professor of biology at Boston University.
Averill, Finzi and Benjamin Turner, a scientist at the Smithsonian Tropical Research Institute, published their research this week in Nature.
Soil contains more carbon than both the atmosphere and vegetation combined, so predictions about future climate depend on a solid understanding of how carbon cycles between the land and air.
Plants remove carbon from the atmosphere during photosynthesis in the form of carbon dioxide. Eventually the plant dies, sheds leaves, or loses a branch or two, and that carbon is added to the soil. The carbon remains locked away in the soil until the remains of the plant decompose, when soil-dwelling microbes feast on the dead plant matter and other organic detritus. That releases carbon back into the air.
One of the limits that both the plants and the soil-dwelling microbes share is the availability of nitrogen, an essential nutrient for all life. Most plants have a symbiotic relationship with mycorrhizal fungi, which help extract nitrogen and nutrients from the soil and make that nitrogen available for the plants to use. Recent studies have suggested that plants and their fungi compete with the soil microbes for the nitrogen available in the soil and that this competition reduces decomposition in the soil.
There are two major types of the symbiotic fungi, ecto- and ericoid mycorrhizal (EEM) fungi and arbuscular mycorrhizal (AM) fungi. EEM fungi produce nitrogen-degrading enzymes, which allows them to extract more nitrogen from the soil than the AM fungi extract.
Examining data from across the globe, Averill and his colleagues found that where plants partner with EEM fungi, the soil contains 70 percent more carbon per unit of nitrogen than in locales where AM fungi are the norm.
The EEM fungi allow the plants to compete with the microbes for available nitrogen, thus reducing the amount of decomposition and lowering the amount of carbon released back into the atmosphere.
Symbiotic fungi inhabiting plant roots have major impact on atmospheric carbon, scientists say -- ScienceDaily
Microscopic fungi that live in plants' roots play a major role in the storage and release of carbon from the soil into the atmosphere, according to a University of Texas at Austin researcher and his colleagues at Boston University and the Smithsonian Tropical Research Institute. The role of these fungi is currently unaccounted for in global climate models.
Some types of symbiotic fungi can lead to 70 percent more carbon stored in the soil.
"Natural fluxes of carbon between the land and atmosphere are enormous and play a crucial role in regulating the concentration of carbon dioxide in the atmosphere and, in turn, Earth's climate," said Colin Averill, lead author on the study and graduate student in the College of Natural Sciences at UT Austin. "This analysis clearly establishes that the different types of symbiotic fungi that colonize plant roots exert major control on the global carbon cycle, which has not been fully appreciated or demonstrated until now."
"This research is not only relevant to models and predictions of future concentrations of atmospheric greenhouse gases, but also challenges the core foundation in modern biogeochemistry that climate exerts major control over soil carbon pools," added Adrien Finzi, co-investigator and professor of biology at Boston University.
Averill, Finzi and Benjamin Turner, a scientist at the Smithsonian Tropical Research Institute, published their research this week in Nature.
Soil contains more carbon than both the atmosphere and vegetation combined, so predictions about future climate depend on a solid understanding of how carbon cycles between the land and air.
Plants remove carbon from the atmosphere during photosynthesis in the form of carbon dioxide. Eventually the plant dies, sheds leaves, or loses a branch or two, and that carbon is added to the soil. The carbon remains locked away in the soil until the remains of the plant decompose, when soil-dwelling microbes feast on the dead plant matter and other organic detritus. That releases carbon back into the air.
One of the limits that both the plants and the soil-dwelling microbes share is the availability of nitrogen, an essential nutrient for all life. Most plants have a symbiotic relationship with mycorrhizal fungi, which help extract nitrogen and nutrients from the soil and make that nitrogen available for the plants to use. Recent studies have suggested that plants and their fungi compete with the soil microbes for the nitrogen available in the soil and that this competition reduces decomposition in the soil.
There are two major types of the symbiotic fungi, ecto- and ericoid mycorrhizal (EEM) fungi and arbuscular mycorrhizal (AM) fungi. EEM fungi produce nitrogen-degrading enzymes, which allows them to extract more nitrogen from the soil than the AM fungi extract.
Examining data from across the globe, Averill and his colleagues found that where plants partner with EEM fungi, the soil contains 70 percent more carbon per unit of nitrogen than in locales where AM fungi are the norm.
The EEM fungi allow the plants to compete with the microbes for available nitrogen, thus reducing the amount of decomposition and lowering the amount of carbon released back into the atmosphere.
Tony B.
Paranormal Adept
Amen, brother. I should have stayed away from the wild-eyed and clueless, but NO, I had to come here and post something. Waste of my biology minor.
We can medicate crazy, but there ain't no cure for willfully stupid.
P
pixelsmith
Guest
Some day you hypocritical alarmists will figure out the con you have fallen for.
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flipper
Paranormal Adept
Here is the latest film on geo engineering (from Italy)
An older one
This is a podcast. The first part is about nuclear plants. The second part is about geo engineering. I really liked this podcast and found it very informative. Choose January 16:
Global Research News Hour – CKUW 95.9 FM
Global Research News Hour – CKUW 95.9 FM
Pair of new studies show how various forms of human activity, driven by a flawed economic system and vast consumption, is laying waste to Earth's natural systems
Humanity's rapacious growth and accelerated energy needs over the last generation—particularly fed by an economic system that demands increasing levels of consumption and inputs of natural resources—are fast driving planetary systems towards their breaking point, according to a new pair of related studies.
Prepared by researchers at the Stockholm Resilience Centre, the first study looks specifically at how "four of nine planetary boundaries have now been crossed as a result of human activity." Published in the journal Science* on Thursday, the 18 researchers involved with compiling evidence for the report—titled 'Planetary Boundaries 2.0'—found that when it comes to climate change, species extinction and biodiversity loss, deforestation and other land-system changes, and altered biogeochemical cycles (such as changes to how key organic compounds like phosphorus and nitrogen are operating in the environment), the degradation that has already take place is driving the Earth System, as a whole, into a new state of imbalance.
"Transgressing a boundary increases the risk that human activities could inadvertently drive the Earth System into a much less hospitable state, damaging efforts to reduce poverty and leading to a deterioration of human well-being in many parts of the world, including wealthy countries," said Professor Will Steffen, a researcher at the Centre and the Australian National University, Canberra, who was lead author for both studies.
In addition to the four boundaries that have already been crossed, the study looked at five other ways in which the planetary systems are under assault by human activity. They include: stratospheric ozone depletion; ocean acidification; freshwater use; atmospheric aerosol loading (microscopic particles in the atmosphere that affect climate and living organisms); and the introduction of novel entities into ecosystems (e.g. organic pollutants, radioactive materials, nanomaterials, and micro-plastics).
And the whole climate has been changing for millions of years argument has to be weighed against this factor
"It is difficult to overestimate the scale and speed of change. In a single lifetime humanity has become a geological force at the planetary-scale," said Steffen, who also led the Acceleration study.
The conclusion that the world's dominant economic model—a globalized form of neoliberal capitalism, largely based on international trade and fueled by extracting and consuming natural resources—is the driving force behind planetary destruction will not come as a shock, but the model's detailed description of how this has worked since the middle of the 20th century makes a more substantial case than many previous attempts.
That Was Easy: In Just 60 Years, Neoliberal Capitalism Has Nearly Broken Planet Earth | Common Dreams | Breaking News & Views for the Progressive Community
"It’s clear the economic system is driving us towards an unsustainable future and people of my daughter’s generation will find it increasingly hard to survive. History has shown that civilisations have risen, stuck to their core values and then collapsed because they didn’t change. That’s where we are today." —Prof. Will Steffen
In an interview with the Guardian, Steffen spoke clearly about the overall impacts of the two new studies as he sounded the alarm over humanity's trajectory. "People say the world is robust and that’s true, there will be life on Earth, but the Earth won’t be robust for us," he said. "Some people say we can adapt due to technology, but that’s a belief system, it’s not based on fact. There is no convincing evidence that a large mammal, with a core body temperature of 37C, will be able to evolve that quickly. Insects can, but humans can’t and that’s a problem."
Humanity's rapacious growth and accelerated energy needs over the last generation—particularly fed by an economic system that demands increasing levels of consumption and inputs of natural resources—are fast driving planetary systems towards their breaking point, according to a new pair of related studies.
Prepared by researchers at the Stockholm Resilience Centre, the first study looks specifically at how "four of nine planetary boundaries have now been crossed as a result of human activity." Published in the journal Science* on Thursday, the 18 researchers involved with compiling evidence for the report—titled 'Planetary Boundaries 2.0'—found that when it comes to climate change, species extinction and biodiversity loss, deforestation and other land-system changes, and altered biogeochemical cycles (such as changes to how key organic compounds like phosphorus and nitrogen are operating in the environment), the degradation that has already take place is driving the Earth System, as a whole, into a new state of imbalance.
"Transgressing a boundary increases the risk that human activities could inadvertently drive the Earth System into a much less hospitable state, damaging efforts to reduce poverty and leading to a deterioration of human well-being in many parts of the world, including wealthy countries," said Professor Will Steffen, a researcher at the Centre and the Australian National University, Canberra, who was lead author for both studies.
In addition to the four boundaries that have already been crossed, the study looked at five other ways in which the planetary systems are under assault by human activity. They include: stratospheric ozone depletion; ocean acidification; freshwater use; atmospheric aerosol loading (microscopic particles in the atmosphere that affect climate and living organisms); and the introduction of novel entities into ecosystems (e.g. organic pollutants, radioactive materials, nanomaterials, and micro-plastics).
And the whole climate has been changing for millions of years argument has to be weighed against this factor
"It is difficult to overestimate the scale and speed of change. In a single lifetime humanity has become a geological force at the planetary-scale," said Steffen, who also led the Acceleration study.
The conclusion that the world's dominant economic model—a globalized form of neoliberal capitalism, largely based on international trade and fueled by extracting and consuming natural resources—is the driving force behind planetary destruction will not come as a shock, but the model's detailed description of how this has worked since the middle of the 20th century makes a more substantial case than many previous attempts.
That Was Easy: In Just 60 Years, Neoliberal Capitalism Has Nearly Broken Planet Earth | Common Dreams | Breaking News & Views for the Progressive Community
"It’s clear the economic system is driving us towards an unsustainable future and people of my daughter’s generation will find it increasingly hard to survive. History has shown that civilisations have risen, stuck to their core values and then collapsed because they didn’t change. That’s where we are today." —Prof. Will Steffen
In an interview with the Guardian, Steffen spoke clearly about the overall impacts of the two new studies as he sounded the alarm over humanity's trajectory. "People say the world is robust and that’s true, there will be life on Earth, but the Earth won’t be robust for us," he said. "Some people say we can adapt due to technology, but that’s a belief system, it’s not based on fact. There is no convincing evidence that a large mammal, with a core body temperature of 37C, will be able to evolve that quickly. Insects can, but humans can’t and that’s a problem."
More thinly covered over-crowding hype mike.
Google 'record crop yields 2014'
Heres some other science opinion, the paper attached to this summary, is up for peer review, all the experiments and code are all open source to be tested, and their results falsified if possible, thats how open science works, its not secret compartmentalised need to know basis..
Gonna have a go mike ?.
.
Temperature proxies
In this essay, we will briefly summarise the analysis in our Global temperature changes of the last millennium paper, which we have submitted for peer review at the Open Peer Review Journal.
In this paper, we reviewed the so-called “multi-proxy” studies which attempt to estimate how global temperatures have varied over the last 1000 years. Such studies cannot use thermometer records, as thermometers did not exist 1000 years ago. Instead, the studies rely on the use of temperature “proxies”, such as tree rings and lake sediments.
All of the studies we analysed reported at least three distinct climatic periods over the last millennium – two warm periods (the “Medieval Warm Period” and the “Current Warm Period”) and an intervening cool period (the “Little Ice Age”). However, there was a lot of disagreement between the different studies as to how these periods related to each other.
Some of the studies suggested that the Current Warm Period is dramatically warmer than the earlier warm period, which has led many people to believe that recent global warming is man-made (and due to CO2). However, other studies suggest that the Current Warm Period and the Medieval Warm Period were both comparable. Since the Medieval Warm Period predates the Industrial Revolution, it could not have been due to man-made global warming, and so presumably was a natural phenomenon.
If natural global warming caused a warm Medieval Warm Period, then perhaps much (or all) of the recent global warming was also a natural phenomenon, i.e., not man-made global warming! Alternatively we could say that the warmer the Medieval Warm Period was, the less “unusual” the Current Warm Period is. For this reason, the debate over the Medieval Warm Period has become intrinsically linked with the man-made global warming debate.
Unfortunately, we found a large number of very serious flaws in almost all of the studies. Some of these flaws could be easily overcome, if they were recognised by the scientific community. Others are more challenging, and would probably require a lot of careful and considered discussion, if they are to ever be resolved. As a result, the multiproxy studies might not be as reliable as currently thought. If this is the case, then, despite all the suggestions of pre-19th century cool and warm periods, we still can’t reliably compare temperatures before the thermometer era to current temperatures.
.
Google 'record crop yields 2014'
Heres some other science opinion, the paper attached to this summary, is up for peer review, all the experiments and code are all open source to be tested, and their results falsified if possible, thats how open science works, its not secret compartmentalised need to know basis..
Gonna have a go mike ?.
.
Temperature proxies
In this essay, we will briefly summarise the analysis in our Global temperature changes of the last millennium paper, which we have submitted for peer review at the Open Peer Review Journal.
In this paper, we reviewed the so-called “multi-proxy” studies which attempt to estimate how global temperatures have varied over the last 1000 years. Such studies cannot use thermometer records, as thermometers did not exist 1000 years ago. Instead, the studies rely on the use of temperature “proxies”, such as tree rings and lake sediments.
All of the studies we analysed reported at least three distinct climatic periods over the last millennium – two warm periods (the “Medieval Warm Period” and the “Current Warm Period”) and an intervening cool period (the “Little Ice Age”). However, there was a lot of disagreement between the different studies as to how these periods related to each other.
Some of the studies suggested that the Current Warm Period is dramatically warmer than the earlier warm period, which has led many people to believe that recent global warming is man-made (and due to CO2). However, other studies suggest that the Current Warm Period and the Medieval Warm Period were both comparable. Since the Medieval Warm Period predates the Industrial Revolution, it could not have been due to man-made global warming, and so presumably was a natural phenomenon.
If natural global warming caused a warm Medieval Warm Period, then perhaps much (or all) of the recent global warming was also a natural phenomenon, i.e., not man-made global warming! Alternatively we could say that the warmer the Medieval Warm Period was, the less “unusual” the Current Warm Period is. For this reason, the debate over the Medieval Warm Period has become intrinsically linked with the man-made global warming debate.
Unfortunately, we found a large number of very serious flaws in almost all of the studies. Some of these flaws could be easily overcome, if they were recognised by the scientific community. Others are more challenging, and would probably require a lot of careful and considered discussion, if they are to ever be resolved. As a result, the multiproxy studies might not be as reliable as currently thought. If this is the case, then, despite all the suggestions of pre-19th century cool and warm periods, we still can’t reliably compare temperatures before the thermometer era to current temperatures.
.
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1. Introduction
In several of our papers on global temperature trends, we used datasets of weather station records to look at how global temperatures have changed since the late-19th century. However, what were temperatures like before the late-19th century? Unfortunately, there were not many weather stations then. And indeed, thermometers were only invented in the 16th and 17th centuries, while the Fahrenheit and Celsius scales were only proposed in the 18th century. So, thermometer records cannot directly tell us about temperatures before then.
To overcome this problem, a lot of researchers have tried to find different “temperature proxies” which could provide longer estimates. A temperature proxy is anything whose properties might have changed over the centuries whenever it got colder or warmer. For instance, a tree might grow faster during warm summers than during cold summers. So, the thickness of the tree rings in each year could be used as a proxy for local summer temperatures. Various proxies have been proposed over the years, such as lake sediments and ice cores, as well as tree ring widths.
Although these proxies are not actually temperature measurements, “paleoclimatologists” (scientists who study the climate of the past) hope that by comparing their proxy record to a local thermometer record, they can “calibrate” their proxy in the period where they both overlap. They then hope they can use their calibrated proxy record to approximate the local temperature changes over a much longer period than they could with the short thermometer record.
For example, in the video clip below, Peter Brown from Rocky Mountain Tree Ring Research describes how tree ring widths can be used to study climate:
In recent decades, a number of groups have tried combining sets of these proxy records together to construct long-term estimates of global temperature change over the last millennium or so. Because these studies combine multiple proxies from around the world, they are often referred to as “multi-proxy global temperature estimates”.
In our “Global temperature changes of the last millennium” paper, we reviewed these estimates, discussed the assumptions and approximations they made, and attempted to assess what they tell us about the global temperature trends of the last millennium. In this essay, we will summarise our main findings. But, if you are interested in learning more about temperature proxy studies, we provide a much more detailed review and discussion in the paper itself (Provide link!!!).
2. The “hockey stick graph”
One of the most prominent of the multi-proxy temperature estimates was a two-part study by three researchers: Mann, Bradley & Hughes. Their two papers were Mann et al., 1998 (Abstract; Google Scholar access) and Mann et al., 1999 (Abstract; Google Scholar access).
Mann, Bradley & Hughes, 1999's estimates of northern hemisphere temperatures for the last millennium. Click on image to enlarge.
These two papers (often called “MBH98” and “MBH99” respectively, after the authors’ initials and the year of publication) suggested a dramatic conclusion. Their study claimed that from 1000-1900 AD, the world (or at least the Northern Hemisphere) had been gradually cooling. But, suddenly, at the start of the 20th century, a period of rapid global warming began. The graph from the studies became known as the “hockey stick graph”, because it looked a bit like an ice hockey stick, lying on its flat (see the Figure on the right/above).
The Mann et al. studies seemed to vindicate those who had been claiming that the recent global warming was unusual and “man-made”. As a result, it received a lot of publicity, and featured heavily in the IPCC’s 3rd Assessment Report (2001) and Al Gore’s popular “An Inconvenient Truth” film (although it was mistakenly labelled as “Dr. Thompson’s Thermometer”).
Still, despite its initial popularity, subsequent analysis revealed a number of serious flaws in the studies (see our paper for a review). So, its dramatic conclusion is probably unreliable. However, its lead author, Prof. Michael Mann, has strenuously objected to any criticism of his papers, even co-founding a popular climate blog, Realclimate.org, and writing a book, to counter criticism. He believes that his critics are part of a global conspiracy to suppress his findings:
3. Other millennial temperature studies
Nonetheless, there have actually been quite a few other proxy-based global temperature estimates covering the 1000 years. Including the Mann et al. studies, we found 17 studies (20 estimates):
Also, for visual clarity, in this essay, we will only plot the 31-year running means of these estimates. See our paper for a discussion of the pros/cons of this approach.
All 20 of these proxy-based estimates have important similarities. They all have identified at least three climatically distinct periods: two relatively warm periods – the “Current Warm Period” (c. 1900 AD on) and the “Medieval Warm Period” (c. 800-1200 AD), and a relatively cool period – the “Little Ice Age” (c. 1500-1850 AD). The main disagreement is over how these three periods compare to each other.
The multiproxy studies which suggest that the Current Warm Period is unusual, compared to the rest of the millennium. Click on image to enlarge.
A few studies suggest that the Current Warm Period is much warmer than the Medieval Warm Period, i.e., the “hockey stick” studies.
These studies have been very popular amongst those claiming that the recent global warming is due to man-made global warming, and therefore very unusual.
Multiproxy studies which suggest Current Warm Period is warmer than the Medieval Warm Period. Click on image to enlarge.
Other studies agree that the Current Warm Period is a bit warmer, but suggest that the Medieval Warm Period was also quite warm.
These studies don’t rule out the possibility that the recent warming is unusual or that some of it is man-made. But, they do suggest that there is a lot of natural temperature variability over timescales of centuries. They don’t imply that recent temperatures are unusually warm, just that the recent warm period is warmer than the last similar warm period.
Multiproxy studies which suggest Medieval Warm Period was at least as warm as the Current Warm Period. Click on image to enlarge.
Finally, several studies suggest that the Medieval Warm Period was just as warm as (if not warmer than) the Current Warm Period.
Again, these studies don’t rule out the possibility that man-made global warming could have been occurring recently. But, they do suggest that temperatures naturally vary quite substantially from century to century. So, if man-made global warming were occurring, it should not be confused with the natural global warming since the Little Ice Age.
In summary, all of the studies seem to agree that there has been considerable global warming since at least the 19th century. Instead, the main disagreement seems to be over how “unusual” the recent global warming was. This disagreement ties into the debate over man-made global warming, because if the Current Warm Period is not that unusual, then man-made global warming could be either (1) superimposed over considerable “natural global warming” or (2) non-existent (in which case global warming would have nothing to do with our “carbon footprint”).
Still, if that was all that was left to be resolved, then we could actually be quite satisfied with the progress that has been made. Sure, there is still bitter disagreement over the the magnitudes of the warming and cooling periods, but at least everyone agrees on whether different periods were warming or cooling.
Unfortunately, things are not even that simple…
The first problem is that the proxy-based global temperature estimates do not actually agree with the thermometer-based estimates very well.
The thermometer-based estimates only cover a century or so, so if the proxy-based estimates do not even agree with the weather stations during the short period in which both records overlap, how confident can we be in the proxy records for longer periods, such as the last millennium?
We found two substantial disagreements between the proxy-based and the thermometer-based estimates.
4. The divergence problem
Graph illustrating the differences between the CRUTEM3 thermometer-based estimate (thick black line) and various proxy-based estimates (other lines) of temperatures over the 20th century. Click on image to enlarge.
One noticeable disagreement is that most proxy-based estimates suggest the warmest temperatures in the 20th century were in the early-to-mid-20th century. In contrast, thermometer-based estimates (e.g., the Climate Research Unit’s “CRUTEM3″) suggest that there has been almost continuous global warming since the late-19th century. This can be seen in the figure on the right/above, where the thick black line shows the thermometer-based estimates and the other lines show various proxy-based estimates.
Perhaps part of the problem is that more than half of the proxy-based estimates finish before 1980. But, regardless, all except two (Mann & Jones, 2003 and Mann et al., 2008 “CPS” – see Supplementary Information for our paper here) reach a warm peak by the 1940s-50s at the latest. They then show cooling until they finish.
This disagreement between proxies and thermometers has become known as the “divergence problem”. It was originally thought to be limited to tree-ring proxies from high latitude regions in the Northern Hemisphere. But, we found that it occurs for most of the proxy-based global temperature estimates.
In any case, the problem has important implications for man-made global warming theory:
By the way, the divergence problem received some discussion during the “Climategate” controversy, when it transpired that some prominent climate researchers had deliberately hidden the end part of the proxy estimates in some of their presentations, so that the divergence problem wouldn’t be seen. This was very unscientific as Prof. Richard Muller explains in the following extract from a presentation in September 2010:
5. The convergence problem
Graph illustrating the differences between thermometer-based estimates (thick black line = CRUTEM3, thick red line = Central Europe Temperature) and various proxy-based estimates (other lines) of temperatures over the 19th century. Click on image to enlarge.
In the 19th century, the proxy-based estimates seem to have the opposite problem. Unfortunately, there are very few thermometer records which stretch back far into the 19th century and most of them are from around the same area (i.e., Europe). Nonetheless, of those records which do exist, many suggest a cooling trend during the 19th century. In contrast, many of the proxy-based estimates suggest a warming trend for the 19th century (i.e., warming from the “Little Ice Age”). As you can see from the figure on the right/above, it is only towards the end of the 19th century that both types of estimates converge.
So, while there is a divergence problem for the 20th century, there is also a “convergence problem” for the 19th century.
Why is there such disagreement between the thermometer and proxy estimates? Well, supporters of the claim that recent temperatures are “unusual” and at least partly due to “man-made global warming” have suggested that:
As we mentioned earlier, in several of our papers we have identified a number of serious biases in the thermometer-based estimates. So, our work would suggest that much of the divergence problem could be explained by problems with the thermometers. Perhaps, the same also applies to the convergence problem.
However, there are also a number of serious problems with the proxies. So, maybe there are problems with both sets of estimates. In our paper, we discuss several of the potential proxy problems. For brevity, we’ll just discuss two here…
The “convergence problem” is less pronounced in some of the estimates we haven’t shown here, e.g., Mann et al., 1999 or Loehle, 2007 (see the Supplementary Information of our paper for the complete set – Provide link!). But, it should be noted that some estimates, e.g., Mann et al., 1999, actually use long European thermometer records as “temperature proxies”! So, this may explain some of the reduction in the problem.
6. Inconsistency between proxies
One serious problem is that different proxy records suggest quite different temperature trends – even for the same area. Indeed, even proxy records from the same data can be different, depending on how the data is processed.
Comparison between two different versions of the Polar Urals proxy dataset. Notice how the strong 'Medieval Warm Period' around 1000 A.D. in the Esper et al. version contradicts the 'Medieval Cold Period' of the Briffa et al., version. Solid black lines represent the 31-year running means.
For instance, the two proxy records in the figure on the left/above are different versions of the same “Polar Urals” tree ring data in Siberia.
In the Esper et al., 2002 version, the Medieval Warm Period seems to have been warmer than the Current Warm Period. Indeed, it also appears to have been warmer in the 14th and 15th centuries. But, the Briffa et al., 1995 version suggests the exact opposite.
This leads to a very difficult problem. If a researcher chooses to use the Esper version then it will make the Medieval Warm Period seem warmer than the Current Warm Period. But, if they choose to use the Briffa version, it will make the Medieval Warm Period seem colder than the Current Warm Period!
Both of the versions have their own problems, so some researchers might prefer one over the other. But, it is surprisingly unclear which of the versions best represents local temperature trends in the Polar Urals region. Indeed, it is quite likely that neither of them are accurate temperature estimates!
In our paper, we discuss several other examples where different proxies suggest different temperature trends for the same area. By choosing one proxy record instead of another one, a researcher can radically alter their temperature estimates. This means that proxy selection is a very subjective process.
This lack of consistency between individual temperature proxies, even in the same area, raises serious questions about the reliability of the global estimates.
7. Overlap in proxies used
Because there are only a small number of proxy series whose records cover the last millennium, some proxy series end up being re-used in different proxy-based estimates.
Two sets of proxies have been particularly controversial – the Yamal chronology and tree ring proxies constructed from bristlecone/foxtail pines in western U.S.
Both sets have particularly unusual “hockey stick”-like trends. And, in both cases, there are a number of reasons to doubt that their trends genuinely represent temperature trends (see our paper for a review).
But, between them, they are used by 14 of the 17 studies!
In some studies, the unusual trends of these series may not overly influence the overall estimates, e.g., Moberg et al., 2005 “detrended” their tree-ring series before using them. But, the fact that they are used so frequently unnecessarily raises doubts about the reliability of the estimates.
Table. The use of the Yamal chronology or bristlecone/foxtail pine proxies by the different estimates:
Study # proxies Bristlecone/foxtail pines Yamal chronology
Jones et al., 1998 17
Mann et al., 1999 12 Yes
Briffa, 2000 15
Yes
Crowley, 2000 15 Yes
Esper et al., 2002 14 Yes
Mann & Jones, 2003 13 Yes Yes
Moberg et al., 2005 18 Yes Yes
D’Arrigo et al., 2006 19
Yes
Hegerl et al., 2007 14 Yes Yes
Juckes et al., 2007 13 Yes
Loehle, 2007 18
Mann et al., 2008 1209 Yes
Ljungqvist, 2010 30
McShane & Wyner, 2011 1209 Yes
Christiansen & Ljungqvist, 2011 40 Yes Yes
Christiansen & Ljungqvist, 2012 32 Yes Yes
Shi et al., 2013 45 Yes Yes
8. Conclusions
If the current proxy-based estimates are in any way reliable, then it suggests that global temperatures vary significantly from century to century. They also suggest that the 20th century was warmer than the centuries immediately before it (the “Little Ice Age”). However, there is still disagreement over whether a warm period around 1000 years ago (the “Medieval Warm Period”) was similar, warmer or cooler than the “Current Warm Period”.
In our papers studying weather station records, we found that global temperatures have alternated between relatively cool and relatively warm periods roughly every 30/40 years since at least the late 19th century. If the proxy-based estimates are correct, then this semi-periodic behaviour probably needs to be superimposed onto longer term multi-centennial temperature changes.
However, there are a number of reasons to question the reliability of the proxy-based estimates. If they are unreliable, then the large temperature variability from century to century they imply might be wrong.
In several of our papers on global temperature trends, we used datasets of weather station records to look at how global temperatures have changed since the late-19th century. However, what were temperatures like before the late-19th century? Unfortunately, there were not many weather stations then. And indeed, thermometers were only invented in the 16th and 17th centuries, while the Fahrenheit and Celsius scales were only proposed in the 18th century. So, thermometer records cannot directly tell us about temperatures before then.
To overcome this problem, a lot of researchers have tried to find different “temperature proxies” which could provide longer estimates. A temperature proxy is anything whose properties might have changed over the centuries whenever it got colder or warmer. For instance, a tree might grow faster during warm summers than during cold summers. So, the thickness of the tree rings in each year could be used as a proxy for local summer temperatures. Various proxies have been proposed over the years, such as lake sediments and ice cores, as well as tree ring widths.
Although these proxies are not actually temperature measurements, “paleoclimatologists” (scientists who study the climate of the past) hope that by comparing their proxy record to a local thermometer record, they can “calibrate” their proxy in the period where they both overlap. They then hope they can use their calibrated proxy record to approximate the local temperature changes over a much longer period than they could with the short thermometer record.
For example, in the video clip below, Peter Brown from Rocky Mountain Tree Ring Research describes how tree ring widths can be used to study climate:
In recent decades, a number of groups have tried combining sets of these proxy records together to construct long-term estimates of global temperature change over the last millennium or so. Because these studies combine multiple proxies from around the world, they are often referred to as “multi-proxy global temperature estimates”.
In our “Global temperature changes of the last millennium” paper, we reviewed these estimates, discussed the assumptions and approximations they made, and attempted to assess what they tell us about the global temperature trends of the last millennium. In this essay, we will summarise our main findings. But, if you are interested in learning more about temperature proxy studies, we provide a much more detailed review and discussion in the paper itself (Provide link!!!).
2. The “hockey stick graph”
One of the most prominent of the multi-proxy temperature estimates was a two-part study by three researchers: Mann, Bradley & Hughes. Their two papers were Mann et al., 1998 (Abstract; Google Scholar access) and Mann et al., 1999 (Abstract; Google Scholar access).
Mann, Bradley & Hughes, 1999's estimates of northern hemisphere temperatures for the last millennium. Click on image to enlarge.
These two papers (often called “MBH98” and “MBH99” respectively, after the authors’ initials and the year of publication) suggested a dramatic conclusion. Their study claimed that from 1000-1900 AD, the world (or at least the Northern Hemisphere) had been gradually cooling. But, suddenly, at the start of the 20th century, a period of rapid global warming began. The graph from the studies became known as the “hockey stick graph”, because it looked a bit like an ice hockey stick, lying on its flat (see the Figure on the right/above).
The Mann et al. studies seemed to vindicate those who had been claiming that the recent global warming was unusual and “man-made”. As a result, it received a lot of publicity, and featured heavily in the IPCC’s 3rd Assessment Report (2001) and Al Gore’s popular “An Inconvenient Truth” film (although it was mistakenly labelled as “Dr. Thompson’s Thermometer”).
Still, despite its initial popularity, subsequent analysis revealed a number of serious flaws in the studies (see our paper for a review). So, its dramatic conclusion is probably unreliable. However, its lead author, Prof. Michael Mann, has strenuously objected to any criticism of his papers, even co-founding a popular climate blog, Realclimate.org, and writing a book, to counter criticism. He believes that his critics are part of a global conspiracy to suppress his findings:
3. Other millennial temperature studies
Nonetheless, there have actually been quite a few other proxy-based global temperature estimates covering the 1000 years. Including the Mann et al. studies, we found 17 studies (20 estimates):
- Jones et al., 1998 (Abstract; Google Scholar access)
- Mann et al., 1999 (Abstract; Google Scholar access)
- Briffa, 2000 (Abstract; Google Scholar access)
- Crowley, 2000 (Abstract; Google Scholar access)
- Esper et al., 2002 (Abstract; Google Scholar access)
- Mann & Jones, 2003 (Abstract; Google Scholar access)
- Moberg et al., 2005 (Abstract; Google Scholar access)
- D’Arrigo et al., 2006 – “RCS” (Abstract; Google Scholar access)
- Hegerl et al., 2007 – “long” (Open access)
- Juckes et al., 2007 – “union” (Open access)
- Loehle, 2007 (Abstract; pdf available here)
- Mann et al., 2008 – they did two estimates: “CPS” and “EIV” (Open access)
- Ljungqvist, 2010 (Abstract; Google Scholar access)
- McShane & Wyner, 2011 (Abstract; Google Scholar access)
- Christiansen & Ljungqvist, 2011 (Open access)
- Christiansen & Ljungqvist, 2012 (Open access)
- Shi et al., 2013 – they did three estimates: “PC10+AR2″, “CPS” and “EIV” (Abstract; Google Scholar access)
Also, for visual clarity, in this essay, we will only plot the 31-year running means of these estimates. See our paper for a discussion of the pros/cons of this approach.
All 20 of these proxy-based estimates have important similarities. They all have identified at least three climatically distinct periods: two relatively warm periods – the “Current Warm Period” (c. 1900 AD on) and the “Medieval Warm Period” (c. 800-1200 AD), and a relatively cool period – the “Little Ice Age” (c. 1500-1850 AD). The main disagreement is over how these three periods compare to each other.
The multiproxy studies which suggest that the Current Warm Period is unusual, compared to the rest of the millennium. Click on image to enlarge.
A few studies suggest that the Current Warm Period is much warmer than the Medieval Warm Period, i.e., the “hockey stick” studies.
These studies have been very popular amongst those claiming that the recent global warming is due to man-made global warming, and therefore very unusual.
Multiproxy studies which suggest Current Warm Period is warmer than the Medieval Warm Period. Click on image to enlarge.
Other studies agree that the Current Warm Period is a bit warmer, but suggest that the Medieval Warm Period was also quite warm.
These studies don’t rule out the possibility that the recent warming is unusual or that some of it is man-made. But, they do suggest that there is a lot of natural temperature variability over timescales of centuries. They don’t imply that recent temperatures are unusually warm, just that the recent warm period is warmer than the last similar warm period.
Multiproxy studies which suggest Medieval Warm Period was at least as warm as the Current Warm Period. Click on image to enlarge.
Finally, several studies suggest that the Medieval Warm Period was just as warm as (if not warmer than) the Current Warm Period.
Again, these studies don’t rule out the possibility that man-made global warming could have been occurring recently. But, they do suggest that temperatures naturally vary quite substantially from century to century. So, if man-made global warming were occurring, it should not be confused with the natural global warming since the Little Ice Age.
In summary, all of the studies seem to agree that there has been considerable global warming since at least the 19th century. Instead, the main disagreement seems to be over how “unusual” the recent global warming was. This disagreement ties into the debate over man-made global warming, because if the Current Warm Period is not that unusual, then man-made global warming could be either (1) superimposed over considerable “natural global warming” or (2) non-existent (in which case global warming would have nothing to do with our “carbon footprint”).
Still, if that was all that was left to be resolved, then we could actually be quite satisfied with the progress that has been made. Sure, there is still bitter disagreement over the the magnitudes of the warming and cooling periods, but at least everyone agrees on whether different periods were warming or cooling.
Unfortunately, things are not even that simple…
The first problem is that the proxy-based global temperature estimates do not actually agree with the thermometer-based estimates very well.
The thermometer-based estimates only cover a century or so, so if the proxy-based estimates do not even agree with the weather stations during the short period in which both records overlap, how confident can we be in the proxy records for longer periods, such as the last millennium?
We found two substantial disagreements between the proxy-based and the thermometer-based estimates.
4. The divergence problem
Graph illustrating the differences between the CRUTEM3 thermometer-based estimate (thick black line) and various proxy-based estimates (other lines) of temperatures over the 20th century. Click on image to enlarge.
One noticeable disagreement is that most proxy-based estimates suggest the warmest temperatures in the 20th century were in the early-to-mid-20th century. In contrast, thermometer-based estimates (e.g., the Climate Research Unit’s “CRUTEM3″) suggest that there has been almost continuous global warming since the late-19th century. This can be seen in the figure on the right/above, where the thick black line shows the thermometer-based estimates and the other lines show various proxy-based estimates.
Perhaps part of the problem is that more than half of the proxy-based estimates finish before 1980. But, regardless, all except two (Mann & Jones, 2003 and Mann et al., 2008 “CPS” – see Supplementary Information for our paper here) reach a warm peak by the 1940s-50s at the latest. They then show cooling until they finish.
This disagreement between proxies and thermometers has become known as the “divergence problem”. It was originally thought to be limited to tree-ring proxies from high latitude regions in the Northern Hemisphere. But, we found that it occurs for most of the proxy-based global temperature estimates.
In any case, the problem has important implications for man-made global warming theory:
- If the problem lies with the proxies, then how do we know they wouldn’t have had similar problems in other centuries? For instance, if they are underestimating current temperatures, then maybe they also underestimated temperatures in the Medieval Warm Period.
- If the problem lies with the thermometer records, then this suggests that the thermometer records have exaggerated recent temperature trends. It also would suggest that it was warmer in the earlier 20th century than it is now, even though CO2 concentrations are much higher now.
By the way, the divergence problem received some discussion during the “Climategate” controversy, when it transpired that some prominent climate researchers had deliberately hidden the end part of the proxy estimates in some of their presentations, so that the divergence problem wouldn’t be seen. This was very unscientific as Prof. Richard Muller explains in the following extract from a presentation in September 2010:
5. The convergence problem
Graph illustrating the differences between thermometer-based estimates (thick black line = CRUTEM3, thick red line = Central Europe Temperature) and various proxy-based estimates (other lines) of temperatures over the 19th century. Click on image to enlarge.
In the 19th century, the proxy-based estimates seem to have the opposite problem. Unfortunately, there are very few thermometer records which stretch back far into the 19th century and most of them are from around the same area (i.e., Europe). Nonetheless, of those records which do exist, many suggest a cooling trend during the 19th century. In contrast, many of the proxy-based estimates suggest a warming trend for the 19th century (i.e., warming from the “Little Ice Age”). As you can see from the figure on the right/above, it is only towards the end of the 19th century that both types of estimates converge.
So, while there is a divergence problem for the 20th century, there is also a “convergence problem” for the 19th century.
Why is there such disagreement between the thermometer and proxy estimates? Well, supporters of the claim that recent temperatures are “unusual” and at least partly due to “man-made global warming” have suggested that:
- The divergence problem is due to problems with the proxies, e.g., D’Arrigo et al., 2008 (Abstract; Google Scholar access), while,
- The convergence problem is due to problems with the thermometers, e.g., Böhm et al., 2010 (Abstract; Google Scholar access).
As we mentioned earlier, in several of our papers we have identified a number of serious biases in the thermometer-based estimates. So, our work would suggest that much of the divergence problem could be explained by problems with the thermometers. Perhaps, the same also applies to the convergence problem.
However, there are also a number of serious problems with the proxies. So, maybe there are problems with both sets of estimates. In our paper, we discuss several of the potential proxy problems. For brevity, we’ll just discuss two here…
The “convergence problem” is less pronounced in some of the estimates we haven’t shown here, e.g., Mann et al., 1999 or Loehle, 2007 (see the Supplementary Information of our paper for the complete set – Provide link!). But, it should be noted that some estimates, e.g., Mann et al., 1999, actually use long European thermometer records as “temperature proxies”! So, this may explain some of the reduction in the problem.
6. Inconsistency between proxies
One serious problem is that different proxy records suggest quite different temperature trends – even for the same area. Indeed, even proxy records from the same data can be different, depending on how the data is processed.
Comparison between two different versions of the Polar Urals proxy dataset. Notice how the strong 'Medieval Warm Period' around 1000 A.D. in the Esper et al. version contradicts the 'Medieval Cold Period' of the Briffa et al., version. Solid black lines represent the 31-year running means.
For instance, the two proxy records in the figure on the left/above are different versions of the same “Polar Urals” tree ring data in Siberia.
In the Esper et al., 2002 version, the Medieval Warm Period seems to have been warmer than the Current Warm Period. Indeed, it also appears to have been warmer in the 14th and 15th centuries. But, the Briffa et al., 1995 version suggests the exact opposite.
This leads to a very difficult problem. If a researcher chooses to use the Esper version then it will make the Medieval Warm Period seem warmer than the Current Warm Period. But, if they choose to use the Briffa version, it will make the Medieval Warm Period seem colder than the Current Warm Period!
Both of the versions have their own problems, so some researchers might prefer one over the other. But, it is surprisingly unclear which of the versions best represents local temperature trends in the Polar Urals region. Indeed, it is quite likely that neither of them are accurate temperature estimates!
In our paper, we discuss several other examples where different proxies suggest different temperature trends for the same area. By choosing one proxy record instead of another one, a researcher can radically alter their temperature estimates. This means that proxy selection is a very subjective process.
This lack of consistency between individual temperature proxies, even in the same area, raises serious questions about the reliability of the global estimates.
7. Overlap in proxies used
Because there are only a small number of proxy series whose records cover the last millennium, some proxy series end up being re-used in different proxy-based estimates.
Two sets of proxies have been particularly controversial – the Yamal chronology and tree ring proxies constructed from bristlecone/foxtail pines in western U.S.
Both sets have particularly unusual “hockey stick”-like trends. And, in both cases, there are a number of reasons to doubt that their trends genuinely represent temperature trends (see our paper for a review).
But, between them, they are used by 14 of the 17 studies!
In some studies, the unusual trends of these series may not overly influence the overall estimates, e.g., Moberg et al., 2005 “detrended” their tree-ring series before using them. But, the fact that they are used so frequently unnecessarily raises doubts about the reliability of the estimates.
Table. The use of the Yamal chronology or bristlecone/foxtail pine proxies by the different estimates:
Study # proxies Bristlecone/foxtail pines Yamal chronology
Jones et al., 1998 17
Mann et al., 1999 12 Yes
Briffa, 2000 15
Yes
Crowley, 2000 15 Yes
Esper et al., 2002 14 Yes
Mann & Jones, 2003 13 Yes Yes
Moberg et al., 2005 18 Yes Yes
D’Arrigo et al., 2006 19
Yes
Hegerl et al., 2007 14 Yes Yes
Juckes et al., 2007 13 Yes
Loehle, 2007 18
Mann et al., 2008 1209 Yes
Ljungqvist, 2010 30
McShane & Wyner, 2011 1209 Yes
Christiansen & Ljungqvist, 2011 40 Yes Yes
Christiansen & Ljungqvist, 2012 32 Yes Yes
Shi et al., 2013 45 Yes Yes
8. Conclusions
If the current proxy-based estimates are in any way reliable, then it suggests that global temperatures vary significantly from century to century. They also suggest that the 20th century was warmer than the centuries immediately before it (the “Little Ice Age”). However, there is still disagreement over whether a warm period around 1000 years ago (the “Medieval Warm Period”) was similar, warmer or cooler than the “Current Warm Period”.
In our papers studying weather station records, we found that global temperatures have alternated between relatively cool and relatively warm periods roughly every 30/40 years since at least the late 19th century. If the proxy-based estimates are correct, then this semi-periodic behaviour probably needs to be superimposed onto longer term multi-centennial temperature changes.
However, there are a number of reasons to question the reliability of the proxy-based estimates. If they are unreliable, then the large temperature variability from century to century they imply might be wrong.
The first comprehensive study of its kind has determined that ocean life is facing mass extinction from human activity
We’ve known for a while that achieving sustainability would be impossible with our lifestyles. Although the majority of Earth is covered in water we are vastly reliant on, many of our practices are causing unprecedented damage to marine biology: coral reef damage, resource mining, fish farming, construction work, chemical pollution, the depletion of bio resources, unintended species migration, global warming, military drills – to name just a few.
One of the key conclusions is that the oceans had until now largely evaded the damage we had caused to terrestrial life, seeing as we’re after all a terrestrial species. But after 1800, when industrialization hit, land extinction sped up and the stage was set for irreversible water damage, which is now mirroring the situation.
Mass extinction for Earth’s oceans probable, comprehensive study says — RT News
We’ve known for a while that achieving sustainability would be impossible with our lifestyles. Although the majority of Earth is covered in water we are vastly reliant on, many of our practices are causing unprecedented damage to marine biology: coral reef damage, resource mining, fish farming, construction work, chemical pollution, the depletion of bio resources, unintended species migration, global warming, military drills – to name just a few.
One of the key conclusions is that the oceans had until now largely evaded the damage we had caused to terrestrial life, seeing as we’re after all a terrestrial species. But after 1800, when industrialization hit, land extinction sped up and the stage was set for irreversible water damage, which is now mirroring the situation.
Mass extinction for Earth’s oceans probable, comprehensive study says — RT News