Like a bat out of climate Hell:
Alaska and the Amazon are done
By Bruce Melton / The Rag Blog / February 2, 2011
I have been really busy lately with my new HD film about the pine beetle pandemic in the Rocky Mountains of North America. Current social and geopolitical issues however have allowed (demanded) that I take the time to remind everyone of the profound importance of climate change to the human species.
We know why Wisconsin, Tunisia, Egypt, Libya, Bahrain, Iran, (and the rest of us) are in such a mess. It is the same reason as why we were in such a mess in the U.S. in the 1960s, the 1920s, and the 1860s. Powerful groups of people then decided that “all” of us should behave the same way: “their” way. The result? Civil liberties are (were) disrupted, wars erupted.
“Things” however, need to be put into perspective. Because we as a society have refused to listen to our climate scientists for the last 30 years, Mother Nature is now in the driver’s seat. Our climate has changed. It has changed greatly, profoundly and irreversibly in time frames that matter to us humans. Impacts today are affecting societies around the world — all societies. Wars, drought, food shortages, extreme weather events including massive snowstorms and floods, all are being blamed in part or in whole on climate change.
The extreme ranges of the climate modeling projections — between 1.4 and 11.5 degrees of warming over the next century — have a meaning that has been utterly and completely lost on our society. The 1.4 degrees of warming was how much our climate would change in a perfect world where there were no messy feedback mechanisms and the entire spectrum of scientific guesses were correct.
The 11.5 degrees of warming included some of those messy feedback mechanisms, but climate scientists were quick to remind us, repeatedly, that there were unknown unknowns out there that they did not take into account. They also told us that some things, like dynamical ice sheet disintegration of the Greenland and Antarctic ice sheets were also not represented in the models because they were known unknowns. The scientists knew about them, but they did not know enough to make educated decisions, so they left them out.
Three decades of intensive scientific research, possibly more science than on any one issue ever, is now being radically realized in the physical world. Climate change is happening now. It is large and violent. It is happening at the upper limits of the science projections, which means it is happening sooner, faster, and with greater impacts than the “average” scenarios told us about.
Adaptation is simply too late for what has already happened. We cannot undo the vast amount of damage we are discovering. Adaptation was something viable for the low and middle ranges of the projections. These are not my words, but words that have been repeated over and over again.. But we as a society chose not to listen.
This is not to say that many individuals haven’t indeed heard what is being said. A significant portion of society certainly understands the seriousness of the situation that our scientists have been telling us about for decades; when will the rest of use listen? We have been warned that adaptation will only be possible if we act soon to limit warming to the low end of the projections. Remember? That was 20 years ago when Kyoto was created!
Beyond dangerous climate change:
An article in the prestigious Philosophical Transactions of the Royal Society (founded by King Charles II in 1660, the United Kingdom’s national academy of sciences) tells the story of exactly how critical the climate crisis has so rapidly become.
These researchers from the Universities of Manchester and East Anglia tell us that the 2 degrees C threshold to prevent dangerous climate change (3.6 degrees F above pre-industrial times, about 1.8 or 2.0 degrees F warmer than now), beyond which we can consider changes to be dangerous, should no longer be seen as such.
Because evidence shows very distinctly that our climate is changing at the very high end of the range of projections, faster and with greater impacts already occurring, this 2 degrees C threshold should be considered the tipping point beyond which “Extremely Dangerous Climate Change” (not my words, the scientists’ words) will take place. (1)
Another Article in Philosophical Transactions, by researchers whose alma maters include Oxford, the University of Arizona, and the Tyndall Center for Climate Research, reminds us that, “Most analysts would agree that the current state of [most of the] efforts to reduce greenhouse gases make the chances of keeping below 2 degrees C extremely slim.” (2)
We have all heard that the Amazon is a very important place when it comes to climate. We know that the Amazon is a global climate regulator that we cannot live without. It stores incredible amounts of carbon to help regulate the temperature of Earth. It generates rainfall and water. It cools the planet with its greenness and humidity.
One of the first things that our climate scientists recognized three decades ago was that the interior of continents would dry with warming and that this would mean bad things for the Amazon. But it also would mean bad things for the interior of other continental locations.
One thing that we did not know 30 years ago was how much carbon is stored in the northern forests of the world. The forests of the north, the boreal or taiga, hold nearly twice the amount of carbon as do the tropical forests of the world.
In Alaska, as reported in Nature Geoscience in December, the boreal forest has changed from a carbon sink to a carbon source. The boreal forests spread across 4.2 billion acres in the furthest northern reaches of the world. Nearly one quarter of Earth’s land is covered by boreal forests. Alaska’s boreal forests are in trouble, and if the rest of the world’s boreal forests, with nearly twice the carbon as the world’s tropical forests, have not already behaved similarly to Alaska’s boreal, they soon will.
In the far north, because of warming that is two to four times greater than Earth’s average warming, forest fires have doubled since the 1960s. Not only this, but large fires have doubled in frequency as well. Warming is the cause. Warming means drought, even if rainfall is normal, a warmed climate evaporates more — a lot more. More importantly though, it is not just the trees that burn and release their carbon back to the atmosphere. The soils are burning too.
Northern forest soils are chock full of carbon. Because of the slow decomposition rate in the north country (which is ice- and snow-covered much of the year) organic material decomposes slowly. In addition, a great deal of the northern forest is underlain by melting permafrost.
This investigation, carried out by the University of Guelph in Ontario, the U.S. Geologic Survey, U.S. Forest Service, and the University of Maryland, looked at the predominant boreal forest type in Alaska, made up mostly of black spruce. This type of forest is struggling on the edge of survival in the far north. It is generally sparse, short, ragged, twisted, leaning, and gnarly. To compound the drying because of a longer warm season caused by climate change, permafrost is melting. Its water drains away and leaves soils even dryer.
Much of the melting permafrost is made of peat or peat-like material. Much of peat is made up of that wonderful matt of mosses and lichens that grows on the ground in the North. These peats only partially decompose when they die because they become entombed in ice before the decomposition process can complete and there they stay for thousands of years Once melted and dried, if fires do not release their carbon, decomposition does.
So we have several things going on here to cause the north, the great boreal forest, to change from a carbon sink to a carbon source — and a big carbon source at that. More fires are burning more trees. These trees are burned up and are not sequestering carbon. Late season fires, that burn deeper into peat rich soils because late in the season those soils are at their driest, have increased four fold since the 1960s, and more large fire are burning deeper into carbon rich peat soils that are no longer entombed in ice because the permafrost is melting. (3)
Billions of trees are dead in the Amazon — now:
From the University of Leeds in the United Kingdom, published in the journal Science this month: In 2005, the Amazon had a 100-year drought. An event like this is supposed to be a once in a hundred-year occurrence; more accurately, an event like this has a one percent change of occurring in any one given year. So the chance that the Amazon would have another such event five years later is quite low. Except during an abrupt climate change. Not only has it happened, but the 2010 drought was likely more than half again as extreme as the 2005 drought.
What has been projected in the models is happening now. Drought is rapidly increasing in the Amazon. The rain forest is dying off. A hundred year drought is not an easy thing to live through if you are a tree. The 2005 event was devastating to the Amazon forest. But the death of trees is just the beginning. What does this mean for the critical climate control system that is the Amazon rain forest? You know, the one that sequesters so much CO2 that it is indispensable?
The authors say: “Having two events of this magnitude in such close succession is extremely unusual, but is unfortunately consistent with those climate models that project a grim future for Amazonia.”
They also tell us that their analysis does not consider forest fires caused by the drought conditions. In an article in the U.K. Guardian, Lewis is quoted as saying the number of trees that died in the 2010 drought alone was “in the low billions of trees.”
These researchers from the University of Leeds in the UKL estimate that the 2010 drought will be responsible for 8 billion tons of CO2. The Amazon biosystem normally sequesters 1.5 billion tons of CO2 per year. Along with the 2005 drought, the Amazon forest was responsible for 13 to 14 billion tones of CO2 emissions, or will be over the next dozen or so years as the trees decay. Thirteen billion tons of CO2 is almost a decade’s worth of sequestration from one of the largest single sinks in the world. Thirteen billion tons is also two years worth of CO2 emissions from all of the U.S. Thirteen billion tons is 42 percent of mankind’s annual global CO2 emissions. (4)
From the Leeds University press release:
Two unusual and extreme droughts occurring within a decade may largely offset the carbon absorbed by intact Amazon forests during that time. If events like this happen more often, the Amazon rainforest would reach a point where it shifts from being a valuable carbon sink slowing climate change, to a major source of greenhouse gasses that could speed it up.
These two massive carbon sinks, the boreal forests of the North, and the Amazon, representing the majority of carbon sinks on land and about a quarter of Earth’s carbon sinks, were not even dreamed of flipping so soon.
Like a bat out of climate Hell:
Climate scientists have been telling us since the turn of the 21st century that climate change is worse than they thought; that their models were conservative, climate was changing faster than they understood, the changes were greater than they projected. They have been telling us that the impacts were (are) more severe, longer lasting, and even permanent on time scales that matter to humans.
They have been telling us that Earth’s environmental systems are at risk, that the functioning of our planet, that functionality that fostered complex human society, would forever change, in time frames that mattered to the human race. They have been telling us that the time frame is getting shorter too, and that it matters now to our generation, the current generation, not to our children’s or our grandchildren’s generations.
They have been telling us that insect infestations would be greater on a warmer planet. The forests of the world are in a shambles because of warming. Just in the Rocky Mountains of North America, 64 million acres are dead or dying from the attack of a native bark beetle.
The mountain pine beetle is out of control because its only enemy is extreme cold. The extremes of cold required to kill the beetle have disappeared in the Rockies because of warming that is greater than twice the world average. This outbreak is 20 times larger than anything ever before, is still underway, and is in fact out of control. Forest professionals say that they see no reason why the attack will not entirely circumnavigate the North American continent, to the Atlantic Ocean and the Gulf of Mexico. (5)
Greenland melt and ice discharge have more than tripled since the 1990s. (6) Antarctica was not supposed to begin losing ice until 2100, but has now caught up with Greenland. (7) Arctic sea ice is melting 70 years ahead of schedule. (8) Carbon dioxide emissions are rising faster than the long-term average for the last 610 million years, since plants colonized land. (9) Current CO2 atmospheric concentrations are as high as any time in the last 15 million years. (10) Global temperature is within one degree C of being as high as it has been in 1.35 million years. (11)
The last time it was as warm as it will be by mid century, sea level was 70 feet higher. The last time it was as warm as it will be by 2100, even with serious and aggressive greenhouse gas emission reductions, sea level was 200 feet higher. (12) CO2 emissions are rising faster than the IPCC worst-case scenario. (13) The last time Arctic sea ice was absent from the Arctic was 14 million years ago. (14)
Sea level was virtually static for most of the last 2,000 years, but now is rising 20 to 25 times faster than it was during most of the 19th and 20th centuries, at 3.4 to 3.7 mm per year. (15) When sea level rise reaches 7 mm per year, our barrier islands and coastal wetlands will disappear irreversibly. (16)
Sea level jumped 10 feet in a century or maybe 50 years or less during the last interglacial warm period 121,000 years ago, because of the collapse of the West Antarctic Ice Sheet, when Earth was within 1 degree C of being as warm as it is today. (17) Warming ocean currents in the Antarctic are melting the underside of the exposed part of the West Antarctic Ice Sheet so alarmingly fast (say the scientists) that it has allowed cryologists (ice scientists) to speculate that the a current collapse may already be underway. (18)
Seventy-five percent of complex Caribbean reefs were destroyed over the last 20 years by warmer waters and higher acidity and 2010 saw the worst bleaching events across the world that have ever been recorded. (19)
Methane venting from vast storage of Pleistocene deposits in the Arctic Ocean north of Siberia, frozen during the last 3 million years of ice ages, has now reached a level that is equal to all other methane venting from all of Earth’s oceans combined. (20)
Primary productivity in our oceans has declined 40% since 1950. (21) The life of carbon dioxide in our atmosphere has increased significantly because of warming. About half of CO2 will stay in our skies for 300 years. Half of the remaining will stay there for 10,000 years and the other half will stay there forever, or hundreds of millions of years, whichever comes first. (22)
The Proceedings of the National Academy of Sciences of the United States of America, in an article published in April of 2010, says that 97 to 98 percent of climate scientists consider the tenets of the IPCC to be valid. Of the 2 to 3 percent that do not, 80 percent have published fewer than 20 papers on climate change, whereas in the 97 to 98 percent group only 10 percent have published fewer than 20 papers. (23)
Climate scientists, economists and sociologists have been telling us that climate change would create wars across the world over oil, water, and food. They have been telling us that environmental systems would fail, breadbaskets would change to deserts, that sea level rise would displace hundreds of millions, that anarchy would rein. They have been telling us that economies would collapse, social systems would no longer function, and that the basics of society would fail. That’s the good news.
The latest discoveries show in terrifying detail that we are straddling the worst-case scenario modeled so far. But things are not going as we thought. Our society generally has the understanding that we can easily conquer climate change through green behavior. The changes we have been told would happen assume that our society will aggressively reduce our collective carbon footprints and by so doing, impacts would fall along the lower end of the range of damages.
Adaptation is a familiar part of the discussion. We can all adapt to different situations easily enough. It all seems so plausible. But earth systems have already been impacted, and as most of us have previously understood, according to the projections, these things were supposed to happen generations in the future.
What have we learned from climate scientists?
Every time (or uncomfortably often) that climate change specialists across this great planet tell us something about climate change, those things turn out to be understatements. They end up being conservative. The results end up being more extreme, they happen sooner with greater impacts, and with more unexpected surprises: bad surprises.
So really: What have we learned from climate scientists?
Climate change has destroyed the functionality of two of the greatest carbon sinks on the planet, generations ahead of what we understood to be the schedule. The additional carbon added to the atmosphere every year caused by the destruction of the forest carbon sinks, in a feedback loop of planetary scale, is larger than the annual greenhouse gas emissions from the United States.
The minimum target warming of 2 degrees C, that we thought we were shooting for to prevent dangerous climate change, is now out of reach. And most important, as a society we have dismally failed to act soon enough to limit impacts to the low end of the spectrum.
Despair or act?
If most of us jump off of a cliff right now, maybe we can bring our greenhouse gas emissions under control. Or maybe there is a better way to fix our climate. The challenge we face is no greater than challenges our society has faced before. An extremely controversial example that illustrates this point well is the means by which we ended World War II.
Hypothetical knowledge concerning the atomic bomb was available to scientists long before WWII. It took a very large amount of effort to bring this hypothetical knowledge into existence, but it was a task deemed worthy because of the great risks perceived at the time.
Climate scientists understood the risks and impacts of climate change literally decades ago. It is now becoming apparent that the current impacts reveal the risks from climate change may be far greater than those posed by world domination by oppressive leadership. Extremely Dangerous Climate Change is real. We cannot put the forests back together again in time frames that matter, but we may be able to prevent what will inevitably be greater impacts.
The solutions to fix climate change exist in academia already, as they did with the solutions to fix WW II prior to the war. All we need are a few “Manhattan Projects” to realize these solutions. And like the atomic bomb, it is inevitable that such great leaps in scientific knowledge will prove highly valuable to our society. Not so much like the actual bomb itself; it was the great advances in our society allowed by the greater understanding of atomic physics that was so enlightening.
[Bruce Melton is a registered professional engineer, environmental researcher, trained outreach specialist, and environmental filmmaker. He has been translating and interpreting scholarly science publications for two decades. His main mission is filming and reporting on the impacts of climate changes happening now, unknown to the greater portion of society. Austin, Texas is his home. His writing and films are on his website.]
Please read some of these yourselves. Most of them are not that difficult to comprehend, although there are always a few that are difficult. Reading these findings in the academic journals themselves lends an enormous amount of credibility to the issue. There is also an enormous amount of information that is included in these findings that is not included in my writing. Fascinating is a poor descriptor for these discoveries, and the volume of new and almost completely never heard of knowledge coming from our climate science community today, that is so, so little picked up in the popular media, is simply astounding.
1) Extremely Dangerous Climate Change beyond 2 degrees C … Anderson and Bows, Beyond dangerous climate change: emission scenarios for a new world, Philosophical Transactions of the Royal Society, December, 2010.
2) Extremely slim chance of holding to 2 degrees C … New et. al., Four degrees and beyond: the potential for a global temperature increase of four degrees and its implications, Philosophical Transactions of the Royal Society, December, 2010.
3) The boreal forest in Alaska has changed from carbon source to sink … Turetsky, et. al., Recent acceleration of biomass burning and carbon losses in Alaskan forests and peatlands, Nature Geosciences, December 2010.
Kasischke and Turetsky, Recent changes in the fire regime across the NA boreal region – spatial and temporal patterns of burning across Canada and Alaska, Geophysical Research Letters, May 2006.
Zhuang et. al., Net Emissions of CH4 and CO2 in Alaska – Implications for the regions greenhouse gas budget, Ecological Applications, Volume 17, 2007.
Kurz et. al., Mountain pine beetle and forest carbon feedback to climate change Nature April 2008. http://www.macroecology.ca/spatial/kurz.pdf
4) The Amazon Droughts … Lewis et. al., The 2010 Amazon Drought, Science, February 2011
Press Release: http://www.leeds.ac.uk/news/article/1466/
Guardian Article http://www.guardian.co.uk/environment/2011/feb/03/tree-deaths-amazon-climate
Phillips, et. al., Drought Sensitivity of the Amazon Rainforest, Science 323, 1344-1347 (2009). http://www.sciencemag.org/content/323/5919/1344.abstract Marengo, J. A., et al. The Drought of Amazonia in 2005, Journal of Climate, 21, 495-516. Link
5) Rocky Mountain pine beetle pandemic … British Columbia Ministry of Forests Mines and Lands. http://www.for.gov.bc.ca/hfp/mountain_pine_beetle/facts.htm The Rockies have seen more than twice the average global warming… Hotter and Drier: The West’s Changed Climate, Rocky Mountain Climate Organization, February, 2008. http://www.rockymountainclimate.org/website pictures/Hotter and Drier.pdf Spread across the continent… Risk assessment of the threat of mountain pine beetle to Canada’s boreal and eastern pine forests, Canadian Forest Service, 2008. http://dsp-psd.pwgsc.gc.ca/collection_2009/nrcan/Fo143-2-417E.pdf Massive simultaneous outbreaks… Jesse A. Logan and James A. Powell, “Ecological Consequences of Climate Change Altered Forest Insect Disturbance Regimes, USDA Rocky Mountain Research Station, 2005. http://www.usu.edu/beetle/documents/Logan-Powell2005.pdf
6) Greenland’s ice melt discharge has more than tripled … Velicogna, Increasing rates of ice mass loss from the Greenland and Antarctic ice sheets revealed by GRACE, Geophysical Research Letters, October 2009. Link.
Rignot, et. al., Change in the Velocity structure of the Greenland Ice Sheet, Science, February 2006. http://www.sciencemag.org/content/311/5763/986.full (free registration required)
IPCC, 2001: Climate Change 2001: Synthesis Report. A Contribution of Working Groups I, II, and III to the Third Assessment Report of the Intergovernmental Panel on Climate Change [Watson, R.T. and the Core Writing Team (eds.)]. Cambridge University Press, Cambridge, United Kingdom, and New York, NY, USA, 398 pp. See page 9 to start with. http://www.grida.no/climate/ipcc_tar/vol4/english/pdf/spm.pdf
7) Antarctica was not supposed to begin losing ice until 2100 – has now caught up with Greenland … IPCC, 2001: Climate Change 2001: Synthesis Report. A Contribution of Working Groups I, II, and III to the Third Assessment Report of the Intergovernmental Panel on Climate Change [Watson, R.T. and the Core Writing Team (eds.)]. Cambridge University Press, Cambridge, United Kingdom, and New York, NY, USA, 398 pp. see page 9 top start with. Velicogna, Increasing rates of ice mass loss from the Greenland and Antarctic ice sheets revealed by GRACE, Geophysical Research Letters, October 2009. Link.
8) Arctic Sea Ice Crash … Haas et. al., Reduced ice thickness in Arctic Transpolar Drift favors rapid ice retreat, Geophysical Research Letters, Sept 2008.
Maslowski, Ebb and Flow Arctic Sea Ice, Challenges, Arctic Regions Supercomputing Center, April 2008. http://www.arsc.edu/challenges/2008/ice_cover.html
Maslowski, Fresh Nor Conference in NUUK, August 2009. http://www.dmi.dk/dmi/handout_freshnor_4.pdf
Stroeve, et. al., Arctic Sea Ice Extent: Decline Faster than Forecast, American Geophysical Letters, 2007. http://www.ualberta.ca/~eec/Stroeve2007.pdf
October 2010, National Snow and Ice Data Center. http://nsidc.org/arcticseaicenews/2010/100410.html
9) CO2 is changing 14,000 times faster than the long-term average for the last 610,000 million years … Zeebe, Richard E., and Ken Caldeira. Close mass balance of long-term carbon fluxes from ice-core CO2 and ocean chemistry records. Nature Geoscience, Advance Online Publication, April 27, 2008. Press Release: http://www.hawaii.edu/news/article.php?aId=2272
10) CO2 concentration is as high any time in 15 million years … Tripati, et. al., Coupling of CO2 and Ice Sheet Stability Over Major Climate Transitions of the Last 20 million years, Science Express October 8, 2009. http://www.sciencemag.org/content/326/5958/1394.full
11) Average Earth temperature within 1 degree C of being the warmest in 1.35 million years… Hansen, et. al. Global temperature change, Proceedings of the National Academy of Sciences, September, 2006. http://www.pnas.org/content/103/39/14288.full
12) With temperatures similar to what we expect by mid century, sea level was 70 feet higher … Hansen, Scientific Reticence and Sea Level Rise, Environmental Research Letters, April – June 2007 http://iopscience.iop.org/1748-9326/2/2/024002/fulltext
13) CO2 emissions are worse than the worst-case scenario developed by the IPCC … Synthesis Report, Climate Change, Global Risks, Challenges and Decisions, Climate Change Congress, International Alliance of Research Universities, University of Copenhagen, March 2009. http://climatecongress.ku.dk/pdf/synthesisreport, Raupach, et. al., Global and regional drivers of accelerating CO2 emissions, PNAS, April 2007.
14) Arctic Sea Ice has not been absent in 14 million years … Darby, Arctic perennial ice cover over the last 14 million years, Paleoceanography, February 2008. Link.
Perovich and Richter-Menge, Loss of Sea Ice in the Arctic, Annual Review of Marine Science, October 2008. Link.
15) Sea level rise is greater than 20 times faster than it was for most of the 19th and 20th Centuries … Rahmstorf, A semi empirical approach to projecting sea level rise, Science, January 2007. http://www.sciencemag.org/content/315/5810/368.full Church and White, A 20th century acceleration in global sea-level rise, Geophysical Research Letters, 2006. Link Church et. al., Ice and Sea Level Change, Australia’s Commonwealth Scientific and Industrial Research Organization (CSIRO, NASA) 2007. Link
16) Barrier island and coastal wetland regeneration threshold of 7 mm per year…US Geological Survey, Environmental Protection Agency, National Oceanic And Atmospheric Administration and Department of Transportation Report, U.S. Climate Change Science Program Coastal Sensitivity to Sea Level Rise: A Focus on the Mid-Atlantic Region, November 2009. http://www.climatescience.gov/Library/sap/sap4-1/final-report/
17) Sea level rise of over 10 feet in a century or maybe less than fifty years … Blanchon, et. al., Rapid sea level rise and reef back stepping at the close of the last interglacial highstand, Nature, April 2009. http://www.springerlink.com/content/3371754158280v84/fulltext.pdf
18) Collapse of the West Antarctic Ice Sheet may already be underway … Katz and Worster, Stability of ice sheet grounding lines, Proceedings of the Royal Society, January 2010. http://rspa.royalsocietypublishing.org/content/466/2118/1597.full
19) Eighty percent of the complex coral reefs of the Caribbean are dead … Paddack, et. al., Recent Region-wide Declines in Caribbean Reef Fish Abundance, Current Biology, April 2009. Link
20) Methane venting in the Arctic Ocean north of Siberia equals all methane venting from the world’s oceans combined … National Science Foundation: Methane Releases From Arctic Shelf May Be Much Larger and Faster Than Anticipated http://www.nsf.gov/news/news_summ.jsp?cntn_id=116532 Study: Arctic seabed methane stores destabilizing, venting University of Alaska Fairbanks. http://www.uaf.edu/files/news/a_news/20100303192545.html Shakhova, et. al., Extensive methane venting to the atmosphere from sediments of the East Siberian Arctic Shelf, Science, March 2010. http://www.sciencemag.org/cgi/content/abstract/327/5970/1246
21) Primary productivity declined 40% since 1950… Boyce et. al., Global Phytoplankton decline over the past century, Nature, July 2010. Press Release: Phytoplankton in retreat, Dalhouse University.
22) Greenhouse gases stay in our skies for 300 years … Archer, Fate of fossil fuel CO2 in geologic time, Journal of Geophysical Research, vol. 110, 2005. Link
23) Among climate scientists, 97 to 98 percent support the tenets of the IPCC … Anderegg, et. al., Expert Credibility in climate change, PNAS April 2010. http://www.pnas.org/content/107/27/12107.full