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2-Degree Global Warming Limit Is Called a “Prescription for Disaster”

The views expressed are those of the author and are not necessarily those of Scientific American.

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SAN FRANCISCO—A mantra that has driven global negotiations on carbon dioxide emissions for years has been that policy-makers must prevent warming of more than two degrees Celsius to prevent apocalyptic climate outcomes. And, two degrees has been a point of no return, a limit directly or indirectly agreed to by negotiators at international climate talks.

James Hansen, director of the NASA Goddard Institute for Space Studies in New York, whose data since the 1980s has been central to setting that benchmark, said today that two degrees is too much.

New, extensive study of the paleoclimate record going back 50 million years by Hansen and others now shows that the two-degree target for global temperature rise “is a prescription for disaster,” Hansen said here at a news conference during the American Geophysical Union meeting.

Hansen came to that conclusion after reviewing average and extreme perturbations in the paleoclimate record that have been more thoroughly documented in the past few years. The record shows that 50 million years ago, Earth was free of ice, and sea level was 70 meters higher on average than it is today. Both phenomena resulted from natural variations in mean temperatures due to slight changes in the sun’s output and Earth’s orbit over geological time scales. Rising temperatures today, over far shorter time scales in which neither the sun nor the orbit are factors, are caused primarily by higher levels of CO2 and other greenhouse gases in the atmosphere.

Atmospheric carbon dioxide levels before the industrial revolution were about 280 parts per million on average. They have been rising ever since, and today are about 397 ppm. A level of 450 ppm has generally been associated with an average global temperature rise of two degrees C. However, the latest analysis shows that a level of 450 ppm is enough to melt a significant portion of the world’s ice, because feedback mechanisms kick in; melting ice hastens the melting of even more ice, for example, and thawing permafrost emits methane that accelerates warming, prompting permafrost to thaw even more.

If the number reaches 560 ppm, a doubling of preindustrial values, sea level globally could rise 25 meters, according to Eelco Rohling, professor of ocean and climate change at University of Southampton in the U.K., who presented data at the AGU meeting with Hansen. Many large cities worldwide lie at that elevation or lower. The two scientists agreed that if nations continue to emit CO2 at current rates, the world could reach 560 ppm by 2100.

The paleoclimate record also shows that 560 ppm would be enough to melt all the ice in the Arctic, and later the Antarctic. Rohling said that once the Antarctic melts, sea levels would rise by 60 to 70 meters. “If governments keep going the way they are going,” Hansen added, “the planet will reach an ice-free state.”

Hansen concluded with a message to negotiators at the current climate talks in Durban, South Africa. If the world begins reducing CO2 emissions by 6 percent a year starting in 2012, Hansen said, atmospheric levels can return to the “safe” level of 350 ppm that he and others have long called for. “If the world waits until 2020 to begin,” he noted, “it will need to reduce CO2 by 15 percent a year to reach 350 ppm. We are out of time.”

Photo of James Hansen courtesy World Development Movement

Mark Fischetti About the Author: Mark Fischetti is a senior editor at Scientific American who covers energy, environment and sustainability issues. Follow on Twitter @markfischetti.

The views expressed are those of the author and are not necessarily those of Scientific American.

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  1. 1. RTreadgold 10:00 pm 12/6/2011

    You say:

    “If the number reaches 560 ppm, a doubling of preindustrial values, sea level globally could rise 25 meters”

    The paleoclimate record also shows that 560 ppm would be enough to melt all the ice in the Arctic

    These two assertions are incredible. Would you mind citing your sources, please? Thank you.

    Richard Treadgold,
    Climate Conversation Group

    Link to this
  2. 2. ccfeldt 8:17 am 12/7/2011

    I believe the 560ppm figure might have been taken from this paper:
    though that study seems to focus on the Greenland ice-sheet.

    Link to this
  3. 3. SuperString 8:49 am 12/7/2011

    Fifty millions years ago; that would have been at the beginning of the Eocene epoch, right after a paleothermal maximum solar event. Well and good, but the same sources DO say that carbon dioxide levels were 700-900 ppm, with a million year-long max of 2000 ppm. Along with this were massive amounts of methane due to outgassing from swamps, wetlands, and all the other abundance of flora that existed as a result of the co-2 levels. World-wide wetlands, triple-canopy forests, temperate polar regions, savannahs in the southern hemisphere; along with some of the most abundant and diverse animal populations seen in the geo-history of this planet. Yep, sounds like doom and gloom to me.

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  4. 4. sault 9:47 am 12/7/2011

    Re SuperSting:

    That climate was brought about by slow natural forcings over millions of years. The animals and plants around then had plenty of time to adapt. We are heading towards that climate in the space of a few hundred years. This is on the order of 10,000x FASTER than natural climate change. Animals cannot adapt that fast. Whole ecosystems will crash, leaving room for opportunists like vermin and jellyfish. To top it all off, we’ll be losing millions of acres of arable land every year or so, all while having to feed 9 billion people or more. All while having to move our cities inland and accommodating the millions of climate refugees that will be dispersing from the growing uninhabitable areas. What we’re seeing in Somalia is a peek into this dreadful future.

    Or, we could put a modest price on carbon and save money by not wasting so much energy. We can install clean energy and not burden our environment with other pollutants that accompany CO2. We can adopt a lifestyle and transportation system that’s sustainable in the 21st Century and tell Saudi Arabia where they can shove their imported oil. We can employ millions to all the work required while we hand a hankercheif to the Koch Brothers as their 19th Century Energy technology becomes glaringly obsolete.

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  5. 5. Dredd 10:50 am 12/7/2011

    Judging by the impact on import / export numbers in the U.S., as a result of the recent recession (which brought consumption down notably), the catastrophe that a 5 meter (~21 ft.) rise in ocean level would bring would cripple some aspects of civilization. That would mean lower population via death and lower consumption via worldwide depression.

    And if that was not too late, perhaps a wising up of those who give good speeches but have no follow up.

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  6. 6. bigbopper 11:14 am 12/7/2011

    I do not believe anything significant will be done about reducing worldwide greenhouse gas emissions until we’re well into a worst-case scenario and it becomes abundantly clear to everyone that the consequences of continued inaction will far outweigh the costs of reducing greenhouse gas emissions. Of course, the folly of this is that at that point added to the costs of reducing greenhouse gas emissions there will be enormous costs of mitigating the effects of marked global warming.

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  7. 7. yarberry 1:46 pm 12/7/2011

    Bigbopper you are right on. Just listen to the candidates discuss (read deny) climate change. It almost seems to be expected and acceptable to bash science and scientists as being the new ‘commies’.
    I check under my bed every night to make sure there are no climate scientists hiding there.

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  8. 8. 2:41 pm 12/7/2011

    The disaster doom & gloom predictions fail to take into consideration that during Earth’s warmer periods life actually was much more abundant. These apocalyptic climate predictions remind me of other doom&gloom predictions such as the obescity problem in the USA is killing us all off even though our life expectancies are actually still rising. One of the mediating factors IS the humans are adaptible enough to overcome the rising sea levels by moving upsteam and able to desalinate water with new and more effiecient power sources to counteract the adversities.

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  9. 9. yarberry 3:13 pm 12/7/2011

    Humans are adaptable, more so than many species. And life will go on as in the past when CO2 levels were higher and the climate was warm. Our dinosaur friends did quite well for over 160 million years. What is not so readily adaptable are our societies.
    Increased shortage of water, food and resources has the potential to strain our already delicate balance between human groups and their environments. We can already see the beginnings to control water having an impact in many areas. The future of Himalayan water will impact billions of people.

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  10. 10. priddseren 4:07 pm 12/7/2011

    It is almost amusing how you warmists pick and choose data then so called reasons why it is not the same today. 50 million years ago, why there. Why not 56 million years ago when the PETM occured, which was the reason the ice melted. Also the 560 PPM, that was what the CO2 levels were before the PETM, the PETM jumped to over 1500 ppm and it slowly decreased. The antartic ice sheets did not even return until around 35 million years ago and life had to slowly adapt to an ice age coming not global warming.

    My favorite is of course how it was all natural back then and somehow nothing natural is occuring now. Nope, the sun doesn’t go to solar maximums anymore, that was just long ago. Methane being released back then was just swamps and volcanoes but nope, not today.

    And even back then there is still NO evidence CO2 causes the global warming you people claim. At worst, it is a minor contributor and appears to increase AFTER warming occurs. Watervapor and methane alone can account for any warming and certainly more than CO2 can produce.

    Plus and this is the best part, there was more CO2 in the atmosphere for millions of years longer than the lower CO2 levels of today and what has existed since the last ice age.

    It would appear that we are far below normal CO2 concentrations and temperature for the millions of years of planetary existence with life on it and we are NOT any higher than past interglacial warming periods.

    So is a 2 degree rise a problem. No. The climate models, your only evidence, were wrong. We did not warm in the last decade as predicted. Since the planet had life when everything was a lot warmer and with more CO2 then where is the problem? the planet also removed naturally all the past natural increases of CO2, which were far higher and life continued with no problem.

    Now if you want to claim the planet is warming because 7 billion people are heating their homes, cooking food, running car engines, making producs, like steel, and etc… This is a theory worth looking at because this is a source of heat for the atmosphere and it is a more likely cause of this so called unnatural warming that CO2 is. At least this is a source of heat that is real and can be tested. Unlike Co2, when tested in a lab, doesnt actually trap all that much heat and its heat trapping as concetration of CO2 grows is not linear.

    Of course none of this article matters because the first false data in it is the so called “normal global average temperature”. Sorry, you warmists do not know what that number should be. You are purely guessing and considering you measure about 1000th of a percent of the total atmostphere, you could not possibly calculate what it is because you dont have enough information.

    Let me know when you people have something real we can work with. Until real comes…

    It is still useful to cut ALL polution. Unlike CO2, cars, factories and industrial life and 7 billion people produce many different toxins and polutants all of which have a highly detrimental effect on the planet and unlike CO2, can actually be proven to have that negative effect.

    Cars, why not go all hybrid or all electric? I guess you liberals dont want to give up your classic cars or gas engines either.

    How about self production of electricty made mandatory for everyone where Nukes, hydro, thermal, solar or wind power are not commercially available? Just moving off “the Grid” would be a massive savings of fuel, not to mention eliminating coal and oil as a fuel for electricty production. Oh that’s right you warmists dont want to actually solve a problem, you want an excuse to carbon tax everyone for monetary gain.

    I for one hope this is delayed not because I want polution, anyone who claims “deniers” are polluters are simply idiots, it is you environmentalists come up with solutions that both incredibly expensive, far more than the cost of keeping the polution and dealing with it OR worse, your solutions are more damaging than the problem.
    Take CFL lights, thanks you you idiots, we now have super expensive unreliable lights that must be replaced more often than incandecent bulbs(sorry residental use is not the same as an office building) and you have successfuly spread a known toxin, mercury, everywhere. In about a decade, we will hear stories on how a water table was contaminated by the mercury in landfills put there by CFLs. When all you fools had to do was wait a few years and LEDs could have been the replacement. Morons.

    By the time you people are done, you will have released some “fuel” you invent that doesn’t release CO2, but it will release something worse and you will have 6 other new chemicals released to deal with the toxic side effects of the previous fixes and the original “fuel” that we will end up with nice clean air with NO CO2 in it at all, thanks to carbon sequestering, so plants will be dying and all life will be suffering maladies from all of your so called fixes to the CO2 problem.

    Yeah, sounds like I am exagerating, except this is exactly the mentality you people have and it is pervasive in everything we do. Then to top it all of, this insanity you warmists will create, I will have to pay for. No thanks, I would rather have a balmy north pole than the toxins and who knows what else you warmists will do in the effort to “stop” natural warming.

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  11. 11. blue7053 5:50 pm 12/7/2011

    “These two assertions are incredible. Would you mind citing your sources, please? Thank you.”

    “If the number reaches 560 ppm, a doubling of preindustrial values, sea level globally could rise 25 meters, according to Eelco Rohling, professor of ocean and climate change at University of Southampton in the U.K., who presented data at the AGU meeting with Hansen.”


    When I came back from Viet Nam, I began to apply the Forrester Curves to Peak Oil, Global Warming, Capitalism, etc. As a way of keeping me occupied and out of trouble, it wasn’t 100% but it has gotten me out of the present debate.

    The data presents itself for scientific consideration and therefore, a solution. The fact is, it’s a political problem and the American Populace doesn’t know how to deal with those.

    Rather than 2006 as the tipping point, the figure I came up with was 1988


    For ‘political problem’ read:
    10. priddseren
    4:07 pm 12/7/2011

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  12. 12. SuperString 6:12 pm 12/7/2011

    I am not disputing that the rapid onset of warming on a global scale will not have insurmountable effects on some, if not most, human societies. Neither am I suggesting that the world will be a paradise for humanity if and when the planet returns to an ice-free condition. Nor am I purporting that human populations will be unaffected by climatic change.

    What I am saying is that when using past climatic conditions as gleaned from the geologic record in order to support a scientific/societal agenda, scientists have a moral responsibility to present ALL the facts that said records yield. The Eocene DID have extremely elevated levels of atmospheric CO2 and methane. Animal and plant life DID flourish in all latitudes of the globe. Man-made influences on the environments cannot have the sudden or disastrous effects of, say, the Deccan or Siberian magma traps. Poor us, but the Earth will recover. By the way, the jury is still out on the orbital perturbation theory.

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  13. 13. Cervenec 8:47 pm 12/7/2011

    Here is an interesting note.
    The Conservatives will fall over themselves worried about and spreading the next Doomsday prediction spouted by some quack with fake credentials.
    Yet those same Conservatives will denounce scientific evidence warning our way of life must change in order that we save the planet for future generations.
    It makes sense when you consider their belief in God requires no scientific evidence either.

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  14. 14. Cervenec 9:17 pm 12/7/2011

    @priddseren: Aside from being a blowhard, I think you have completely missed the point of the article. You focused too much on your own bias to even relate any of your ridiculous comments to the theme of the article.
    It doesn’t matter if it’s 50 or 60 or 56 million years ago. What matters is that the changes today are occurring so fast, global climate change (aka global warming) can only be attributed to humans and civilization.
    It doesn’t matter how many parts per million, it matters that the difference is significant, and it is occurring rapidly. More rapidly than we may be able to counter. We definitely cannot evolve fast enough.
    Even if we could adapt, many of our food sources will succumb which could lead to a worldwide famine.
    The earth doesn’t have near the active volcanoes today that it had 50 million years ago. Let’s assume there was prolific life 50 million years ago with high CO2 levels in the atmosphere. All of that life had millenia to adapt to those changes. All current species of animal and plant, on the other hand, have adapted to live in a lower rate of CO2 in the atmosphere. A change of 50% in such a short period of time will be devastating to nearly all life on Earth.
    Most of your dialogue is simply prose replete with numbers and your own misguided misanthropic views of how science works. You have no tests, no experiments to back up your wild assertions. You saw a number and you threw it out hoping it would stick to something.
    It sounds like you have no science background whatsoever, but you like to look things up. You don’t try to understand, you’re just looking for numbers to support your beliefs. You accuse the scientists, who have little to gain monetarily, of doing exactly what you’re doing.
    Hopefully, I have provided a little insight to others as to how people like you operate. The scientists are trying to inform us, to warn us. You, on the other hand, are intentionally trying to misinform people. I can’t be sure why, but I would guess money is behind it. After all, you concluded your rambling with “I will have to pay for it. No thanks.”

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  15. 15. jayjacobus 10:03 pm 12/7/2011

    If I am going to reach a scientific conclusion I need data that I can trust. This would be my own data or data from an unbiased source.

    If the data shows a pattern, I need to understand the pattern. I should not trend data that has a discontinuity in it. I should understand the discontinuity first. (Are all measurements one the same way?)

    Next I will need to do my own analysis. If I rely on other people’s analysis, they may have a bias.

    I cannot scientifically rely on someone else’s analysis. That would be putting faith in a particular scientist and faith is for holy men, not scientists.

    What happened to acid rain? Was that a contrived disaster? Or is that not pertainent in light of global warning?

    Is the hole in the ozone layer gone?

    Environmental issues seem to have a short term, then they fade away and are replaced by another issue.

    Who should I have faith in: the environmentalists or the naysayers?

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  16. 16. Dr. Strangelove 4:22 am 12/8/2011

    “The paleoclimate record also shows that 560 ppm would be enough to melt all the ice in the Arctic, and later the Antarctic. Rohling said that once the Antarctic melts, sea levels would rise by 60 to 70 meters.”

    Unfortunately that’s cherry picking data. It’s not that simple. Paleoclimate record also shows that at 560 ppm and 4,000 ppm, temperature could be as low as 12C, an ice age. Climate change is complicated.

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  17. 17. 1:05 pm 12/8/2011

    Presuming climate change/global warming is real & irreversable, I keep waiting for the experts to factor in the stopping of the “conveyor belt” that carries warm southern water north & then returns with cold water to the south. My understanding of the belts’ movement is that if this occurred, the northern hemisphere would plunge into an ice age. Stay cool, or warm as your beliefs dictate.

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  18. 18. DSchoon 1:09 pm 12/8/2011

    Yes, climate change is complicated and those who promote it are using lots of claims of what “will happen”, when they should be saying “could or might happen”. Most are speculating about speculations that are mostly based on other speculations? That’s a scientifically dangerous road! We know much less than we pretend to know about what’s happening with the environment, e.g. global warming.

    Why are supposedly impartial global warming scientists allowing blatant media exaggerations and wild speculations to become the rule? The facts are, nobody is sure about what is going on and everybody is guessing and many of the most vocal have political agendas.

    As a scientist, I am very concerned that scientists studying global warming are being pressured by the media and fear-based advocacy groups to allow blatant exaggerations to trump the truth.

    The facts are, nobody knows, even those who say they do! We must stop the exaggerations and politically motivated rhetoric, or we’ll likely to end up following the wrong path and could make matters much worse. For example, those who are now considering geo-engineering technology to reverse global warming is who we should fear the most!

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  19. 19. Gomby007 2:47 pm 12/8/2011

    When I read comments like those of priddseren, all I want to do is explode out of rage.

    Scenario #1:
    priddseren is right, 98% of the scientists screaming out the top of their lungs that we are heading for shit are wrong.

    Consequence, if we aim at fixing the CO2 and pollution problems:
    Our children will inherit a healthier, cleaner world.

    Scenario #2:
    priddseren is wrong, 98% of the scientists screaming out the top of their lungs that we are heading for shit are right.

    Consequence, if we DON’T aim at fixing the CO2 and pollution problems:
    Our children will inherit a world of, well, pretty much Hell and a whole lot of suffering.


    Ok, so priddseren, now that we’re playing russian roulette with our children’s lives, are you ready to be the one pulling the trigger?

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  20. 20. yarberry 5:34 pm 12/8/2011

    Well I was a ‘warmist’, but this mornings I needed to put on my down parka, the heavy blue one, so it was cold. Then I realized that the climate isn’t warming it is getting colder. When I go home I plan to check with my neighbors and see it they also needed to wear parkas (peer review).
    I will update later and let you know how the science is coming along.
    Yes it is time to quit this attack on real science and take responsibility for our actions. It is our children and grandchildren that will need to deal with the mess.

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  21. 21. KiwiBuzz 5:59 pm 12/8/2011

    If the sea level was going to rise at this rapid rate, it should have started by now. But what had really happened is that over the last few years, the sea level has declined. This is showing clearly by the satellite record.

    On top of that, Hansen assumes that carbon dioxide will cause global warming which will cause the ice to melt. Global warming has stopped for the last 10 to 15 years and even the IPCC says it will not restart for 20 or 30 years. Which is near enough to saying that they haven’t got a clue.

    Hansen has made a huge amount of money out of his scare mongering. So why should anyone believe what he says?

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  22. 22. Sleepership 6:42 pm 12/8/2011

    The PETM was from ‘natural forcings’ over a short geologic period- relatively speaking- under 20,000 years- when temperatures spiked over 5-6 degrees C.

    Those ‘forcings’ where mostly from ‘tectonic’ events- volcanoes and continental shift- primarily in the Tethys Sea- a long time area of river deposits of carbon in that body of water- now called the Indian ocean.

    India was moving north toward the Asian continent at a high rate of speed. Large amounts of C02 where drawn into the atmosphere- which later melted Methane calthrates in shallow sea beds.

    C02 has been estimated at around 1100ppm. After India merged with Asia- the ‘spike’ in C02 ceased- but the planet continued to warm through the early Eocene.

    Finally around 45 million years ago- the planet began to cool- though it was still much warmer then today. Finally around 35 million years ago, CO2 dropped to around 450ppm, and Antarctica began to glaciate. There was another spike in C02 around 27 million years ago- and that ice melted again.

    Since that last spike in C02 and temperatures, the planet has cooled.

    C02 today is being introduced into the atmosphere at a rate of 10,000 times that of the PETM, or the End Permian.

    Hansen thus far has been very accurate with his analysis. C02 was last this high 15-20 million years ago (near 400ppm) at this level sustained- global temperatures where 5-7 degrees higher, sea levels 75 feet higher- with no ice in Greenland or the arctic year round.


    On a business as usual track we will see 450ppm by 2033- we will see 650ppm by 2050. And could easily see 800ppm by centuries end.

    Hansen has been eerily and uncannily very precise thus far-

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  23. 23. Gomby007 9:40 am 12/9/2011

    KiwiBuzz: Maybe you should research what you claim instead of cherry picking what you want to hear.

    NASA Satellites Detect Pothole on Road to Higher Seas:

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  24. 24. Gomby007 9:49 am 12/9/2011

    “But for those who might argue that these data show us entering a long-term period of decline in global sea level, Willis cautions that sea level drops such as this one cannot last, and over the long-run, the trend remains solidly up. Water flows downhill, and the extra rain will eventually find its way back to the sea. When it does, global sea level will rise again.” (article linked above)

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  25. 25. Jim Baird 12:28 pm 12/10/2011

    Mr. Hansen’s analysis is based an analogy of conditions millions of years ago. It seems to me the way to address the problem is with another analogy; Nature’s response to a warming planet, the hurricane.

    Hurricanes are atmospheric heat pipes which can release between 50 to 200 Terawatts of heat energy, 3 to 12 times the total primary energy used annually on the planet.

    Clearly if we could harness this source mankind’s problems related to energy and the environment would be over.

    GWMM OTEC accomplishes that with small – 1 meter in diameter – inverted, ammonia, hurricanes which convert the same heat source powering the larger storms – warm ocean water – and a heat sink of about 4oC – to productive work and electrical energy.

    With enough of these we can not only safely energize the planet, we can eliminate carbon emissions, increase carbon dioxide absorption (cooler water absorbs more CO2), cool the oceans and prevent potential extinction events due to clathrate breakdown or thermal runaway caused by warming amplification from increased atmospheric moisture.

    Fission or fusion, as Mr. Hansen prefers, on the other hand create twice as much waste heat as energy and most of this will end up in the ocean, exacerbating the sea level problem.

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  26. 26. KeefeAndAmanda 3:15 pm 12/10/2011

    priddseren4:07 pm 12/7/2011 wrote:

    “And even back then there is still NO evidence CO2 causes the global warming you people claim. At worst, it is a minor contributor and appears to increase AFTER warming occurs. Watervapor and methane alone can account for any warming and certainly more than CO2 can produce”

    Whether you know it or not, you skeptics say that since CO2 forcing is minor at most, essentially all the recent warming has been natural in that essentially only less reflected light from the sun has caused all or almost all of the recent warming. That is, whether you know it or not, the claims of Svensmark and Spencer et al. with respect to cosmic rays or oceans or clouds ultimately reduce to the claim that essentially only less reflected light from the sun has caused most all of the recent warming.

    However, your position has been falsified by the laws of physics:

    There is a book that is partially available online as a Google e-book “Solar activity and earth’s climate” by Rasmus E. Benestad, who obtained a Ph.D in physics from Atmospheric, Oceanic & Planetary Physics at Oxford University. Go to page 176. We read, “Any mechanism involving the albedo implies strongest response in the daytime temperature. Observations, on the other hand, suggest a reduction in the diurnal temperature range where the night-time temperature has increased more than the daytime temperature (Houghton et al., 2001). According to Svensmark’s hypothesis, the warming is due to the reduction in Earth’s albedo (reflected light), and therefore a long-term reduction in the low-level planetary cloud cover appears to be inconsistent with the observations.”

    That is, what Benestad says above is simply a polite way of saying that the reduction in the global diurnal temperature range where the global night-time temperature has increased more than the global daytime temperature strongly falsifies the hypothesis that essentially
    only less reflected light has caused all or almost all of the recent warming.

    That is, if the CO2 forcing with H2O amplification greenhouse gas activity is as weak as you deniers claim and the warming is mostly just reflected light, then there is nothing to keep enough heat from escaping out into space at night globally to avoid a global diurnal temperature range increase such that the global daytime temperature increases faster than the global nighttime temperature. But the opposite has been happening.

    And note that this falsification of the claim that essentially only less reflected light has caused all or almost all of the recent warming is a strong falsification. That is, even though a constant global diurnal temperature range would suffice to falsify the claim, a decreasing global diurnal temperature range strongly falsifies it. And depending on its rate of decline and on whether this rate of decline is changing and how it is changing, one could argue that this falsification is not just strong but very strong or even very, very strong.

    How do you skeptics deal with the fact of the falsification of your denials of what real peer-reviewed climate science has to say on greenhouse gas activity? You deal with it in two ways: You either ignore it and/or you try to use *local* phenomena to try to refute fact about *global* phenomena. That is, on the latter point, you try to use the fact that there has been an increase in the diurnal temperature range in some *local* climates to try to argue against the fact that the *global* diurnal temperature range has decreased. But since this is all about *global* climate and not about the climate of only your cherry-picked parts of the planet, this attempt to argue against fact is just an embarrassment to you skeptics who try this.

    By the way, if you try to say that increased water in the atmosphere by itself with no or almost no forcing from non-condensing greenhouse gases like CO2 will save the day for your denial of what real peer-reviewed climate science says about these non-condensing greenhouse gases, then consider this: Your equations in physics providing the calculations that fit reality on this one are where? Answer: Nowhere. (Note: Everyone in the skeptic community who does not try to confront this problem in some meaningful way (like Svensmark) know full well that they cannot even begin to make the numbers work to their favor on this one – they know that without non-condensing greenhouse gas forcers, H2O by itself cannot keep the planet from becoming much colder, and so rather than embarrass themselves trying to make the numbers work to their favor they elect to just ignore this problem when confronted with it.)

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  27. 27. isoptera 12:51 am 01/20/2012

    It is a fallacy that gas prices are high. Gas is probably selling for one quarter what it would cost to make it out of limestone. It is stupid to be using our petroleum for trivial purposes such as keeping warm or surface transportation. It should be confined to making lubricating oil and plastic or aerial transportation. Burning oil is like burning your furniture to keep warm.
    A moratorium had been imposed on ocean drilling, It is not ocean drilling that should be stopped, it is terrestrial drilling and even pumping. Ocean wells are too easy to sabotage in a war. So it is poor policy to suck our terrestrial oil dry during peacetime. Of course we should have floating steel barriers standing by in the case of Gulf oil. It is insane to allow oil to flow out across the ocean unimpeded.
    Everyone is stressing excessive use of fossil fuels as causing a green house affect on climate. However, that is the least of our problems. Sucking our petroleum reserves dry, even our oil shale, will have disastrous consequences in the future on our economy (USA) and our security, especially military security. We should use foreign fuel as much as possible. If we lose our freedom to the likes of Hitler, Osama Bin Ladin, or Stalin it will not make any difference what the temperature outside is. Life will not be worth living anyway.
    Increase in atmospheric carbon dioxide is undoubtedly increasing climate warmth somewhat. However I suspect that at least as great an affect on warmth is the baring of soil by increase in annual crop acreage, roads, buildings, grazing, and desertification currently. You may see an article that briefly discusses this and gives some solutions in more detail in .

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  28. 28. GluonSpring 12:55 am 04/18/2012

    We’re not going to cut CO2 emissions by 6% per year, much less 15% per year. Not this year, not the next, not this decade. We simply aren’t. It seems childish and completely ignorant of human psychology to think that we will (a psychology that is as real and as stubborn as any facts about the climate). Idealism of this sort won’t solve this problem. If this catastrophe is as imminent and certain as Hansen and others believe, I strongly suggest that they stop living in a dream world of imaginary human rationality and start investing serious energy into other ways we might avert or deal with this disaster. Geoengineering is a bad word among climate scientists, I know (though one wonders where their confidence in their models goes when geoengineering comes up?). Someone needs to think about it, though, because we’re not going to take a painful cure until we experience symptoms of the disease.

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  29. 29. lystrosaurian 11:34 pm 08/17/2012

    1. Rising 2ppm/yr, CO2 would reach 560 ppm by 2100. However, the rate has been accelerating, so it will go at a rate higher, such as 3 or 4ppm/yr. We should expect to see CO2 to be around 665 to 755.
    2. Kilometer wide plumes of methane are already coming from the floor of the East Siberian Sea. Methane is 100 times more powerful GHG than CO2 in stable concentration.
    3. The worst warming event occurred at the Permian-Triassic extinction event. The seas became anoxic, and 95% of life died. The Lystrosaurus was the dominant vertebrate life, accounting for over half of the vertebrate biomass.
    4. North Caroline has outlawed global warming. So, no worries.
    5. The US should change its bird symbol from the bald eagle that flies high and sees far, to the ostrich that buries its head in the ground, and sees nothing.

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