Posted on 12/09/2011 11:25:38 AM PST by Ernest_at_the_Beach
From NASA Goddard/GISS: same-o, same-o
Paleoclimate Record Points Toward Potential Rapid Climate Changes
The average global surface temperature of Earth has risen by .8 degrees Celsius since 1880, and is now increasing at a rate of about .1 degree Celsius per decade. This image shows how 2010 temperatures compare to average temperatures from a baseline period of 1951-1980, as analyzed by scientists at NASA’s Goddard Institute for Space Studies. Credit: NASA GISS
New research into the Earth’s paleoclimate history by NASA’s Goddard Institute for Space Studies director James E. Hansen suggests the potential for rapid climate changes this century, including multiple meters of sea level rise, if global warming is not abated.
By looking at how the Earth’s climate responded to past natural changes, Hansen sought insight into a fundamental question raised by ongoing human-caused climate change: “What is the dangerous level of global warming?” Some international leaders have suggested a goal of limiting warming to 2 degrees Celsius from pre-industrial times in order to avert catastrophic change. But Hansen said at a press briefing at a meeting of the American Geophysical Union in San Francisco on Tues, Dec. 6, that warming of 2 degrees Celsius would lead to drastic changes, such as significant ice sheet loss in Greenland and Antarctica.
Based on Hansen’s temperature analysis work at the Goddard Institute for Space Studies, the Earth’s average global surface temperature has already risen .8 degrees Celsius since 1880, and is now warming at a rate of more than .1 degree Celsius every decade. This warming is largely driven by increased greenhouse gases in the atmosphere, particularly carbon dioxide, emitted by the burning of fossil fuels at power plants, in cars and in industry. At the current rate of fossil fuel burning, the concentration of carbon dioxide in the atmosphere will have doubled from pre-industrial times by the middle of this century. A doubling of carbon dioxide would cause an eventual warming of several degrees, Hansen said.
In recent research, Hansen and co-author Makiko Sato, also of Goddard Institute for Space Studies, compared the climate of today, the Holocene, with previous similar “interglacial” epochs – periods when polar ice caps existed but the world was not dominated by glaciers. In studying cores drilled from both ice sheets and deep ocean sediments, Hansen found that global mean temperatures during the Eemian period, which began about 130,000 years ago and lasted about 15,000 years, were less than 1 degree Celsius warmer than today. If temperatures were to rise 2 degrees Celsius over pre-industrial times, global mean temperature would far exceed that of the Eemian, when sea level was four to six meters higher than today, Hansen said.
“The paleoclimate record reveals a more sensitive climate than thought, even as of a few years ago. Limiting human-caused warming to 2 degrees is not sufficient,” Hansen said. “It would be a prescription for disaster.”
Hansen focused much of his new work on how the polar regions and in particular the ice sheets of Antarctica and Greenland will react to a warming world.
Two degrees Celsius of warming would make Earth much warmer than during the Eemian, and would move Earth closer to Pliocene-like conditions, when sea level was in the range of 25 meters higher than today, Hansen said. In using Earth’s climate history to learn more about the level of sensitivity that governs our planet’s response to warming today, Hansen said the paleoclimate record suggests that every degree Celsius of global temperature rise will ultimately equate to 20 meters of sea level rise. However, that sea level increase due to ice sheet loss would be expected to occur over centuries, and large uncertainties remain in predicting how that ice loss would unfold.
Hansen notes that ice sheet disintegration will not be a linear process. This non-linear deterioration has already been seen in vulnerable places such as Pine Island Glacier in West Antarctica, where the rate of ice mass loss has continued accelerating over the past decade. Data from NASA’s Gravity Recovery and Climate Experiment (GRACE) satellite is already consistent with a rate of ice sheet mass loss in Greenland and West Antarctica that doubles every ten years. The GRACE record is too short to confirm this with great certainty; however, the trend in the past few years does not rule it out, Hansen said. This continued rate of ice loss could cause multiple meters of sea level rise by 2100, Hansen said.
Ice and ocean sediment cores from the polar regions indicate that temperatures at the poles during previous epochs – when sea level was tens of meters higher – is not too far removed from the temperatures Earth could reach this century on a “business as usual” trajectory.
“We don’t have a substantial cushion between today’s climate and dangerous warming,” Hansen said. “Earth is poised to experience strong amplifying feedbacks in response to moderate additional global warming.”
Detailed considerations of a new warming target and how to get there are beyond the scope of this research, Hansen said. But this research is consistent with Hansen’s earlier findings that carbon dioxide in the atmosphere would need to be rolled back from about 390 parts per million in the atmosphere today to 350 parts per million in order to stabilize the climate in the long term. While leaders continue to discuss a framework for reducing emissions, global carbon dioxide emissions have remained stable or increased in recent years.
Hansen and others noted that while the paleoclimate evidence paints a clear picture of what Earth’s earlier climate looked like, but that using it to predict precisely how the climate might change on much smaller timescales in response to human-induced rather than natural climate change remains difficult. But, Hansen noted, the Earth system is already showing signs of responding, even in the cases of “slow feedbacks” such as ice sheet changes.
The human-caused release of increased carbon dioxide into the atmosphere also presents climate scientists with something they’ve never seen in the 65 million year record of carbon dioxide levels – a drastic rate of increase that makes it difficult to predict how rapidly the Earth will respond. In periods when carbon dioxide has increased due to natural causes, the rate of increase averaged about .0001 parts per million per year – in other words, one hundred parts per million every million years. Fossil fuel burning is now causing carbon dioxide concentrations to increase at two parts per million per year.
“Humans have overwhelmed the natural, slow changes that occur on geologic timescales,” Hansen said.
Patrick Lynch
NASA’s Earth Science News Team
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Chinese 2,485 year tree ring study shows natural cycles control climate, temps may cool til 2068
[ In short, we are in a sort of “drought”. Interesting that Hansen did say we were about 1 degree C short of the temperature achieved in the last interglacial (the 10,000 year long warm period between each 100,000 year long period of glaciation). ]
Never let the facts get in the way of a vested agenda....
Yeah, for most of the last 300 million years Earth has had Ice Free polar regions. So Wouldn’t both caps melting be a “return to normalcy”? That is of course ignoring the fact the planet is a dynamic system and there is such thing as “climate normalcy”
Well actually the SHAPE of the continents has a lot more to do with WHY we have ice caps vs trace atmospehric gasses.
The south pole has a land mass that covers the entire south polar region, and the north pole is pretty much a sea that is surrounded by landmasses. Both regions are thermically isolated and this is what prevents warm air/water from warming these areas up. Water moves more heat since it is more dense, so while the north cap may melt it will take a LOT more to melt the Southern Cap as it is isolated from the water flow.
Continenetial drift has moved them into this configuration in the last 60 million years, this is most likely why we have been having polar intiated “ice ages” since then.
If the continent of antarctica didn’t exist and there was a southern ocean in it’s place it would most likely be ice free or mostly ice free and there would be less restriction to water flow than the northern hemisphere has.
[ What a load of crap. I told a girl last night, who was screaming about saving trees, not to worry. The trees will get together and grow chainsaw proof bark. ]
Natural Selection Baby!
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DirkH says:
“Humans have overwhelmed the natural, slow changes that occur on geologic timescales,” Hansen said.
But “natural variability” has overwhelmed the alleged AGW during the last 15 years, according to other CAGW proponents; I would suggest that the CAGW movement now splinters into warring factions.
[ And thinly veiled in the message, man is the problem, so fewer men is the solution.
Centralized government is the most efficient means to fewer men. Hundreds of millions of fewer men. Billions of fewer men. ]
How many people as a percentage of population have died from “Death by Government” from 1901-2000 vs. 1801-1900 ?
I would say the percentage should be a higher number for the last 100 years than the previous one.
Elrich would love a World Government that ran on a policy of “Death by Government” and use his flimsy science to justify it.
[ “Humans have overwhelmed the natural, slow changes that occur on geologic timescales,” Hansen said.
Great! If we have such power, kindly demonstrate by stopping continental drift. ]
That affects climate more than a minute trace gas in the atmosphere.
[ Antarctica appears to have had a half billion years stuck at the bottom. There’s a mountain range there that may be that old and it’s encased. It’s currently under a 2 mile deep ice cap, but those mountains were glacier capped for a very long time and are nice and sharp, just like they were brand new. ]
Hmm, I always thought it drifted around with the others....
Of course there are so many theories on the past positions of continents, they only know where they used to fit together and not exactly WHERE they were in relation Long/Lat...
http://en.wikipedia.org/wiki/Antarctica#Geological_history_and_paleontology
I had previously scheduled that for next Tuesday, but then I thought, “Well, if I do that, California will be a less interesting place to live,” so I decided to just let things like continental drift and the climate just happen the way they always have.
Let me get this straight. The fact that the last interglacial maximum was warmer than this one and that sea levels were higher then somehow proves Hansen’s AGW theory? Really? Being colder this time is somehow warmer???
Am I making myself clear,
or shall I turn up the volume?"
Hansen has to be fired.
He is no longer a scientist.
He has become a member of a religious cult - a belief system - and a zealous evangelical for that set of beliefs.
He needs to be replaced by a true scientist who is skeptical enough to question every side of an issue and to admit, as Hansen does not, that, in some areas of science, what we know is far less than what there is to know and therefor our knowledge base is insufficient for making far flung predictions - as is the case with the earth’s climate and its cycles.
I wonder how many glass fulls of benzene Hansen drinks per day. The guy is beyond mental help.
UAH Update for January 2011: Global Temperatures in Freefall
Hansen would rather have us ruled by China ( Dr. James Hansen of NASA )
Hansen: US Democracy Not Competent To Deal With Global Warming Calls on China to “Save Humanity”
Hansen is a lying ass liberal! Anytime anybody trots out some NASA earth photo-map, SAR or other spectrum map of the earth, I ask where are the shots from Mt. Pinatubo in the Philipines? It released more crap into the atmosphere than ALL of humanity combined.
God is silently chuckling at the arrogance of man (at least some of them) for thinking their trifling endeavors have an impact on the massive scale of HIS earth....just chuckling...
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Wherever paleo-climate studies have looked – on a regional basis – Antarctica, Greenland, Tibet – you find 2-3 degree Celsius changes with a beat-frequency of about 1000 years – some of these rises are very steep (Greenland) – within decades – and this is quite normal throughout ice-ages and interglacials. This probably translates to a global 0.5-1 degree shift.
The current warm period is expected on this frequency and not at all unusual in rate of change or amplitude – despite the presence of higher levels of CO2 and other greenhouse gases. Hansen has consistently misinterpreted the natural signal – as confirmation of his models and calculations of ‘sensitivity’ to carbon dioxide. If, as many of us calculate from the real world evidence of radiation flux measurements, CO2 can account for no more than 20-25% of the warming, then future temperatures will be determined by the natural cycle – and many paleo-climate experts think this will turn downward (see Liu’s work on Tibet featured in an earlier thread).
What is so annoying is the way that the left-liberal-green press only ever report Hansen’s opinions thus inflating the carbon currency bubble.