From NASA Goddard/GISS: same-o, same-o
Paleoclimate Record Points Toward Potential Rapid Climate Changes
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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LazyTeenager says:
December 9, 2011 at 3:46 pm
Willis says
These guys can’t even tell a believable lie. It hasn’t warmed a tenth of a degree in the last decade, that’s nonsense.
————-
So Willis I take it that you want people to focus on the short term trend as a predictor of future trends rather than the more robust , (against short term noise) long term trend. Is that a valid interpretation of what you are saying?
Lazy Teenager:
Could you please tell us why we warmed from 1880 to approx 1950? There seems to be many varied ideas of why, but no definitive certainty. Maybe with your infinite knowledge you can elighten the rest of us humble folks. And then explain to us poor uneducated folks why the warming from the 1970’s to approx 2,000 is caused by co2 rather than the same force that caused the sharper level of warming from 1915-1945. I have many brain cells reserved just for your informative reply. Please don’t keep them waiting.
I love how all of the warming is at the polls just like their models predict. Of course there is no data there, just automatic estimates programmed in to show warming. We have left confirmation bias in the dust. Perhaps a new name in science for this kind of faux data. I suggest Hansenized as the term.
SteveE says:
December 9, 2011 at 3:03 am
“Could you yet me know what the Earth’s average global surface temperature anomaly was for the periods 2000 – 2010 and 1990 – 2000. ”
See the unadjusted rural data at RUTI:
http://hidethedecline.eu/pages/posts/ruti-global-land-temperatures-1880-2010-part-1-244.php
but frankly for 1990-2010 I would prefer satellite data
NASA as data provider
as a global warming reason:
HANSEN plus buddies man-made CO2 is an issue
Wattsupwiththat plus buddies man-made CO2 is not an issue
is the above scheme correct?
wermet says:
December 9, 2011 at 3:59 pm
I find the phrases “…has risen by .8 degrees Celsius since 1880…” and “increasing at a rate of about .1 degree Celsius per decade” to be written in bad form. As an engineer, I was taught to always include the leading zero before a decimal point to prevent confusion since many people will overlook this small mark. There is significantly less chance of misreading 0.8 versus .8. Plus, it emphasizes the zero and decimal point, which makes it look far less threatening. (Probably why Hansen and crew left it out in the first place).
===========
+1
Hansen makes it clear why his preferred CO2 level is 350 ppm. Paleo evidence shows that the Greenland and Antarctica ice sheets cannot be self-sustaining at higher values. Their melting, even if slow or non-steady, will lead to tens of meters of extra sea-level some time in the future. The only question is how quickly this will happen.
Jim, the CO2 level during the Eemian was 270-280 ppm way under Hensens 350 ppm.
The ice sheet melted at 280 ppm producing a 100 m higher sea level,
Since before 1750 we had 280 ppm as well and the sea level increases by 3 mm per year and not more…… even went down the past 2-3 years….
You see. there is no connection between CO2ppm and the sea level or else the present 392 ppm
would have produced a strong melt which is not the case — its all pure invention of Henson and has no base…..
Joachim, yes, the Ice Ages had even more ice due to the Canadian and European glaciers that resembled Greenland today. Sea level was 120 m lower during them. If Greenland and Antarctica melt there is 70 more meters available, just like that rise out of the ice ages. It has happened before, and can happen again. These areas remained frozen during the Eemian, so Hansen’s point is that at 400 ppm they can ‘t remain frozen.
Jim, I see you are a good-will person and that you are easily impressed by clever reasoning….
But: In paleoclimates, ice melt/temp rises are always preceding (cause) and the CO2-level increase was always following secondary (effect). Please read articles on evaluations of ice core drilling, Warmist authors always scramble for detecting one single paleo-timespan, where CO2 increases FIRST and melt as consequence……and then they feel so sorry that this time they
could not do it, maybe next time, the poor guys…..
….. The statistical time lag of CO2-increase after temp/melt iscrease is between 200 and 800 years….
As you said “It happended before and it could therefore happen again” which means temps first and CO2 afterwards, no change of “cause and effect” as Henson does, a sophisticated trick of rhetorics, known since the old Greeks…. please….JS
Jim D says:
December 10, 2011 at 2:01 pm
Joachim, yes, the Ice Ages had even more ice due to the Canadian and European glaciers that resembled Greenland today. Sea level was 120 m lower during them. If Greenland and Antarctica melt there is 70 more meters available, just like that rise out of the ice ages. It has happened before, and can happen again. These areas remained frozen during the Eemian, so Hansen’s point is that at 400 ppm they can ‘t remain frozen.
It is some 50° below zero in Antarctica, it isn’t going to melt at all for a few thousand years at the rate things were going before it stopped warming. Last time I looked, Antarctica had been gaining ice since we started measuring it.
Regarding Antarctica, before 35 million years ago it did not have permanent ice, and the global CO2 level and temperature were not much higher than now. For sure the Arctic summer sea ice will go first, followed by Greenland’s glacier, but that leads the way for a warmer earth due to the albedo change that finally lets Antarctica’s glaciers go. It is a series of tipping points over a few centuries.
Shame that Hansen missed his flight on Voyager 1.
Notice they don’t mention the dirty dark secret ? Geo engineering with extremely dangerous chemicals all over the west including AUSTRALIA , these people are nuts , Barium and aluminum oxide are very dangerous to everything .
What disgusts me MOST about Hansen’s INSANE remarks…is that he is doing that on a salary paid for by the TAXPAYER.
Who the HELL does he think he is?
Chris
Norfolk, VA, USA
Matt G says:
The bottom layers of the glacier are lost eventually forever via icebergs and extreme pressure at the bottom forming super cooled liquid water.
Greenland can only support so much ice because it is limited in land mass and the rest is lost especially via icebergs.
The Greenland cores were taken from the ice cap, not a glacier. As a result, calving into the sea is not an issue. Some of the cores are actually taken in valleys. Also, since there are longer cores in Antarctica, the argument that the pressure forms water is nonsense.
Evidence shows that the most Greenland ice was still there despite only 200m+ found in the ice cores
Actually, it was only 14 meters thick at the end of the Eemian .. in the valleys. It appears that the mountains were mostly ice free. Granted, this 14 meter layer is highly compressed today. However, it is not clear where the missing mass (thickness) went. By the way, there is another layer of ice and organic material below the Eemian layer. The weird part is that there is at least a 100,000 year discontinuity at that level (which I interpret to mean that all the previous ice was lost from melting). The organic material is not from an arctic environment and many species can not be identified.
You mention a sea level anomaly. I agree. Maybe ice was melting somewhere else as it was being added to Greenland. At any rate, in my opinion, the data does not support any of the accepted theories that I have seen.
Jim D,
Antarctica glaciated over 33.6 million years ago when CO2 was 1,400 ppm (use the real data rather than what James Hansen tries to change it to). It didn’t fall for another 2 million years after the initial glaciation. Global temperatures fell 2.0C even though CO2 did not change at all.
Greenland started having significant glaciers about 8 million years ago (mainly at high altitude in the northern sector) and then did not fully glaciate over until probably about 1 million years ago.
Technically, southern Greeland is too far south to have glaciers (same latitude as Sweden). It is only because the ice cap has built up to 3 kms high in the north-central area (and was 4 kms high in the last ice age) so that it has flowed south and the thermal inertia of all that ice next to it has kept it glaciated.
If this interglacial lasts for another 2 or 3 thousand years, the glaciers in the southern third of Greenland will be gone. It just takes a long period of time to melt out all that thermal inertia.
In the long interglacial, 400,000 years ago, the southern third of Greenland melted out and small trees even grew there. That interglacial was not particularly warm, about the same as today, but it was the longest one in the last 2.5 million years and the ice eventually melted out. There is NO evidence this occurred in any other interglacial. It should be noted that the current interglacial is similar to the one at 400,000 years in that the Milankovitch Cycles take a long time to put us back into glacial conditions, they are not regular (the current interglacial may last another 50,000 years or even 130,000 years).
Bill Illis, I have seen no one claim 1400 ppm only 35 million years ago. CO2 dropped gradually from about 1000 ppm 100 million years ago to nearer 500 ppm at the time Antarctica formed its ice cap. Yes Greenland could be hard to melt, but it is only the last of the northern glaciers, and the others went quickly after the last ice age with the warming that occurred then which has helped by the albedo feedback.
Joachim, you have to look at more distant paleoclimate to see that CO2 levels were declining naturally over the last couple of hundred million years, and this led to a cooling in the global temperature which finally enabled Antarctica to form and later the ice ages to start.
Jim D says:
“…CO2 levels were declining naturally over the last couple of hundred million years, and this led to a cooling in the global temperature which finally enabled Antarctica to form and later the ice ages to start.”
That’s not even wrong, that’s just cherry-picking a spurious correlation to arrive at a false cause and effect. CO2 levels have been high going into Ice Ages, and very low during warmer periods than the natural one we’re in now.
CO2 rises and declines follow temperature rises and declines on all time scales, from months to hundreds of millennia. Whatever effect CO2 has is negligible, and can be completely disregarded for all practical purposes.
Smokey, you need to explain why CO2 was dropping over the last 100 million years. It was natural sequestration in the soil and limestones. What resulted from that drop was a cooling temperature. This is standard knowledge in paleoclimate. Yes, it goes against the mantra of temperature always leads CO2 that is often used by skeptics who don’t think it can go the other way.
Sorry, Jim, either you are a 8th grader or a troll….
Please come up with a paleoclimatic measurement graph which shows that CO2 leads in the drop and temps will drop afterwards….this is no standard climate knowledge but pure AGW fairytale or
nonsense as of Henson….prove the link or give it up and dont confuse our Smokey…..
Jim D says:
December 11, 2011 at 9:37 am
Bill Illis, I have seen no one claim 1400 ppm only 35 million years ago. CO2 dropped gradually from about 1000 ppm 100 million years ago to nearer 500 ppm at the time Antarctica formed its ice cap
——————————
Sorry, someone has misinformed you about historical CO2 levels.
Joachim, I would suggest you read about or watch the video by a leading paleoclimatologist, Richard Alley of Penn State. The idea of a rock-weathering thermostat is described, where warmer climates remove CO2 from the atmosphere, thus cooling them towards cold climates, and then volcanoes warm it up again. I recommend the video because he is an entertaining speaker.
http://thinkprogress.org/romm/2009/12/21/205242/agu-richard-alley-explains-biggest-control-knob-carbon-dioxide-in-earths-climate-history/
Jim, the last try before I say its hopeless…..
By staying on the scientific level….. we must not take your suggestions of “Watching videos”
about “Ideas”….. as you say……this is only American type of entertainment….
We need a graph showing 1. CO2-content together with 2. Temps/Ice melting and then we can
see the correlation and what comes first……
This first Ice melting/temp change comes first due to “Orbital Forcing” i.e. changes in the Earth’s orbit with reduce/enlage at specific orbit sections the orbit… leading to higher/lower/changing RF…. the change in CO2-content comes afterwards with take off/slow down in the biosphere and organic content decomposition after x number of years…
Show the link of the Graph, there should be many since your convolution of cause and effect is
as you say “standard paleo knowledge…”
Jim D says:
“What resulted from that drop was a cooling temperature. This is standard knowledge in paleoclimate.” Nonsense. As Joachim says, prove it or give it up. Temperatures have been rising and declining, through Ice Ages and warming, irrespective of CO2 – which is now extremely low. The biosphere is starved of CO2, and any increase is beneficial.
As we can see from the paleo record, temperatures during the Holocene have trended downward. This has occurred while CO2 remained relatively unchanged, falsifying your unsupportable conjecture that declining temperatures are the result of declining CO2. That is demonstrable nonsense. And temperatures have not risen over the past decade and a half as CO2 has risen, showing that any putative warming due to CO2 is negligible at best.
Cooling temperatures do not result from declining CO2 as you claim; changes in CO2 follow changes in temperature, not vice-versa. Since you link to the anti-science propaganda blog thinkprogress, run by the execrable alarmist Joe Romm, it is no wonder that you have such mistaken beliefs. Search the WUWT archives for “CO2”, and get a real science education.
Smokey, you should watch Richard Alley’s talk that I linked above, which was an invited AGU science talk from 2009. This is an annual meeting of geoscientists in San Francisco and it is independent of Romm. You are just showing Greenland temperatures which are a poor substitute for global ones. Please explain where you think Alley is wrong. He is clearly an expert in this field and worth listening to rather than relying on skeptic blogs written by marine biologists and petroleum engineers. Yes, he makes fun of one skeptic letter that tried to victimize him, but you can ignore that as a cheap shot, if you want. It was an easy target for ridicule, and the audience appreciated it. Pay attention to the science and how it fits together.
Jim D says:
“Pay attention to the science and how it fits together.” Yet you ignore the evidence I provided that shows something different than your beliefs. As for Alley, I’ve followed his papers. His earlier ones are credible; his recent comments, not so much. He’d rather be petted by the clique than stick to his earlier findings.
Same for ‘just Greenland temperatures’; both hemispheres show strong simultaneous correlation in ΔT, indicating that the changes were global.
Give up on alarmist blogs, they cherry-pick and misrepresent because they have an agenda. Use the WUWT search function if you want to learn some honest climate science.
Smokey, thanks for trying, but I prefer to be guided by Alley’s experience. His charts are also more convincing than yours, and you haven’t even addressed the period before the ice ages which is where CO2 leads temperature. His long-term paleoclimate theory is just more complete.
Jim D,
Post a chart showing that CO2 leads temperature. Like this chart of the past 400,000+ years, and which clearly shows that in every change, temperature leads CO2 both up and down. Effect cannot precede cause, therefore CO2 is a function of temperature change, not a forcing.
Use the handy WUWT search function to get up to speed on this settled science.
Smokey, if you even watched what Alley said about the ice ages you would know every agrees that temperature led CO2 then because there was other forcing. He possibly even showed the same chart. In fact his prod at the skeptic’s letter was that he had made the same argument as you, which is that because sometimes temperature leads, CO2 never can. If CO2 drops or rises first, temperature has to follow. This is the point. It comes from radiation physics.