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This new study's findings indicate that increases in CO2 and other GHG won't produce as much warming of surface temperatures as had been previously thought.

25 November 2011

CO2 climate sensitivity 'overestimated'

Global temperatures could be less sensitive to changing atmospheric carbon dioxide (CO2) levels than previously thought, a study suggests.

By Jennifer Carpenter
Science reporter, BBC News

The researchers said people should still expect to see "drastic changes" in climate worldwide, but that the risk was a little less imminent.

The results are published in Science.

Previous climate models have tended to used meteorological measurements from the past 150 years to estimate the climate's sensitivity to rising CO2.

From these models, scientists find it difficult to narrow their projections down to a single figure with any certainty, and instead project a range of temperatures that they expect, given a doubling of atmospheric CO2 from pre-industrial levels.

The new analysis, which incorporates palaeoclimate data into existing models, attempts to project future temperatures with a little more certainty.

The authors stress the results do not mean threat from human-induced climate change should be treated any less seriously, explained palaeoclimatologist Antoni Rosell-Mele from the Autonomous University of Barcelona, who is a member of the team that came up with the new estimates.

While the situation we face may have less drastic surface temperature rises in store, it remains very serious problem for a variety of other detrimental effects stemming from the rise on CO2 and they remain undiminished. Not the least of these being the increasing acidification of the oceans as they continue to soak up more CO2 from the atmosphere.


World's oceans in peril

Climate change is causing our oceans to become increasingly acidic, threatening to alter life as we know it.

Dahr Jamail
22 Nov 2011

According to the Intergovernmental Panel on Climate Change, carbon emissions have already risen "far above even the bleak scenarios."

Oceans absorb 26 per cent (2.3bn metric tonnes) of the carbon human activities released into the atmosphere annually, according to a 2010 study published by Nature Geocience and The Global Carbon Project.

Unfortunately, global carbon emissions, rather than slowing down in order to stem climate change, are continuing to increase.

At a 2008 academic conference Exeter University scientist Kevin Anderson showed slides and graphs "representing the fumes that belch from chimneys, exhausts and jet engines, that should have bent in a rapid curve towards the ground, were heading for the ceiling instead".

He concluded it was "improbable" that we would be able to stop short of 650 ppm, even if rich countries adopted "draconian emissions reductions within a decade".

While we're not quite dropping into the fire yet the frying pan we're in still has quite a flame under it.

We can expect the climate deniers will try to distort the implications of this new study on surface temperatures. That's just what they do.

Originally posted to Lefty Coaster on Fri Nov 25, 2011 at 09:11 PM PST.

Also republished by DK GreenRoots and Climate Hawks.

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Comment Preferences

  •  Thanks for reading (23+ / 0-)

    Gasoline made from the tar sands gives a Toyota Prius the same impact on climate as a Hummer using gasoline made from oil. ~ Al Gore

    by Lefty Coaster on Fri Nov 25, 2011 at 09:06:40 PM PST

  •  OK. Warming of Surface Temp is What Fraction (4+ / 0-)

    of the array of planet responses?

    We are called to speak for the weak, for the voiceless, for victims of our nation and for those it calls enemy.... --ML King "Beyond Vietnam"

    by Gooserock on Fri Nov 25, 2011 at 09:17:11 PM PST

    •  Could you clarify you question? (1+ / 0-)
      Recommended by:

      I'm not sure what you're asking.

      Gasoline made from the tar sands gives a Toyota Prius the same impact on climate as a Hummer using gasoline made from oil. ~ Al Gore

      by Lefty Coaster on Fri Nov 25, 2011 at 09:25:53 PM PST

      [ Parent ]

      •  I think what he/she is saying (4+ / 0-)

        Is that a global increase in carbon dioxide may be manifested in several different ways, including effects such as:

        1.  Increased temperatures on the earth's surface

        2.  Increased temperatures in the shallow zones of the ocean

        3.  Decreased glacier/snow cover

        4.  Increased sea levels and submergence of near sea-level coastal lands, either long-term or associated with short-term storm surges

        5.  Changed vegetation extent and mix in various climatic zones

        6.  Changed albedo of the earth's surface associated with Nos. 3 and 5

        7.  Changed precipitation and rain storage patterns

        8.  Changed groundwater levels, lake levels, and river flow caused by No. 7

        9. Increased encroachment of salt water into coastal water supplies, caused by rising sea levels in association with No. 8.

        10. Consumption of the ocean's buffering capacity, potentially manifested by shifts in seawater pH

        11. Changes in viability of certain sea life that rely on pH-sensitive organisms as a food source somewhere along their food chain

        13. Changes in agricultural practices and food production in the temperate zones that feed the planet's people

        14. Accelerated extinction and shifts in ecological niches, possibly including ours

        15.  Need I go on?

        Of those, Nos. 1 and 2 may not necessarily be the most significant.

  •  I'll take whatever form of... (8+ / 0-)

    ...good news I can get.  But this info, while certainly welcome, doesn't change the general picture too much.

    On the other hand, just watch the deniers run with it!   Suddenly science will be acceptable again — for two or three days.

    Freedom isn't "on the march." Freedom dances.

    by WarrenS on Fri Nov 25, 2011 at 09:54:59 PM PST

    •  Hi Warren! Yep, me too. (7+ / 0-)

      What this means is a lower probability of human extinction during your kid's lifetime.  

      Yip-yip-hooray!, and all that.  

      The denialists can take the study and shove it up their bloated bottoms, because if they accept it, they have to accept the premise of anthropogenic climate change.  

      Realistically, the move toward climate mitigation will continue at the same pace as it always has, which is to say, too slow to save us if we were headed for +5 Celsius in our lifetimes, but perhaps fast enough to save us if we have more time.  

      My sense of things is that humans will "just squeak by," and the dieoff will be limited to approximately half our number, due to other limits being hit first, for example food & water.  Animals multiply up to their ecosystem's food limit and then die back to some number below that point.

      So rejoice!, the denialists won't touch this study, Ma Nature is giving us more time, and the probabilities favor squeaking by rather than going extinct.

      Let's talk this weekend, there's newz.  

      "Minus one vote for the Democrat" equals "plus one vote for the Republican." Arithmetic doesn't care about your feelings.

      by G2geek on Sat Nov 26, 2011 at 12:32:58 AM PST

      [ Parent ]

  •  Less global warming (3+ / 0-)
    Recommended by:
    Lefty Coaster, ozsea1, Creosote

    than which previous thought?

    The IPCC scenarios are underestimates by any measure you care to apply.  And as for at least one previous thought about the relation between CO2 levels and global warming:

    here it is, from Petit et al. -- the results of the ice core tests.  Seems pretty solid -- as CO2 levels multiply, temperatures add, so you can do the math yourself.  Are they saying now that those are all wrong?

    "But it ain't about who ya love, see it's all about do ya love," -Michael Franti

    by Cassiodorus on Fri Nov 25, 2011 at 10:00:04 PM PST

    •  Science is a top peer reviewed journal (3+ / 0-)
      Recommended by:
      Neuroptimalian, ORDem, ozsea1

      Gasoline made from the tar sands gives a Toyota Prius the same impact on climate as a Hummer using gasoline made from oil. ~ Al Gore

      by Lefty Coaster on Fri Nov 25, 2011 at 10:03:36 PM PST

      [ Parent ]

      •  Missing from the diary (1+ / 0-)
        Recommended by:

        Which scientists did the study? And what climate sensitivity did they come up with?

        •  Old: 3C, New: 2.7C (4+ / 0-)

          As I recall from other news outlets, the previous IPCC estimate was for values between 2 and 4.5C, with 3C being the most likely value. The new study gives a value around 2.7C as the most likely.

          So it's not much of a drop at all, and it's only one study. Don't get your hopes up too much.

          Also, that's a value for 'warming based on a doubling of CO2', and we're on track to generate much more than a doubling of CO2. So we may get the same amount of warming as predicted, but it'll be based on less sensitivity but more CO2.

          •  In the interest of accuracy the New = 2.3K (1+ / 0-)
            Recommended by:

            versus the prior prediction of 3K and probably more importantly the 66% probability range is reduced to 1.7K - 2.6K and the risk of more extreme responses which is low in the curent models seems to be much reduced in their current analysis.

            But I absolutely agree with you, only one study, I am definitely not getting my hopes up, but for our sake I do hope that they are right.  

    •  In those previous cycles it was actually increased (2+ / 0-)
      Recommended by:
      Lefty Coaster, G2geek

      temperature that drove the increased CO2, the situation we are now in the case is reversed, the increased CO2 is driving the temperature increase. That is part of the reason that predictions are so difficult, the only similar events that we can look at all occurred many millions of years ago but not during the less than half million that is depicted in the graph that you show.

      Check this IPCC link here.  

  •  I think this study is suspicious, especially since (5+ / 0-)

    it comes on the heels of the IEA report that we have five years before we encounter permanent damage to the environment.

    It smacks of studies funded by the Koch brothers to counter the overwhelming amount of information that we're seeing laid out by the international community of scientists.

    Even the first sentence of the blurb is a little suspect:

    Assessing impacts of future anthropogenic carbon emissions is currently impeded by uncertainties in our knowledge of equilibrium climate sensitivity to atmospheric carbon dioxide doubling.

    That sounds very much like the language that is being used by climate change deniers.

    Also, in the current edition of Science you find this:

    An international scientific assessment finds for the first time that human activity has indeed driven not just climate change but also increases in some extreme weather and climate events around the world in recent decades. And those and likely other weather extremes will worsen in coming decades as greenhouse gases mount, the report finds.

    Even that article contained this sentence:

    But uncertainties are rife in the still-emerging field of extreme events.

    I wonder if they are feeling the same type of pressure that the conservatives are applying to the the Discovery Channel?

    •  Doesn't look like a climate denier (4+ / 0-)
      Recommended by:
      ORDem, erush1345, G2geek, Creosote
      College of Oceanic and Atmospheric Sciences, Oregon State University, Corvallis, OR 97331–5503, USA.
      2Woodrow Wilson School of Public and International Affairs, Princeton University, NJ 08544, USA.
      3Department of Earth and Planetary Sciences, Harvard University, Cambridge, MA 02138, USA.
      4Department of Earth and Atmospheric Sciences, Cornell University, Ithaca, NY 14850, USA.
      5Department of Geosciences, Oregon State University, Corvallis, OR 97331, USA.
      6Department of Geography, University of Oregon, Eugene, OR 97403, USA.
      7ICREA and Institute of Environmental Science and Technology, Universitat Autònoma de Barcelona, Bellaterra, Spain.

      Gasoline made from the tar sands gives a Toyota Prius the same impact on climate as a Hummer using gasoline made from oil. ~ Al Gore

      by Lefty Coaster on Fri Nov 25, 2011 at 10:49:30 PM PST

      [ Parent ]

    •  There are "uncertainties in our knowledge" is just (7+ / 0-)

      a plain statement of truth and I think it is a bit much to suggest that the study is suspicious. I am not a climate scientist but I know they are constantly trying to fine tune the climate models that have been developed, that's what they do. And with further information the models will continue to be refined, this study is just one step along the way.

      But yes, climate change deniers use the rubric of science to sow doubt and we do need to be on guard against that, but to preemptively question a study because the result goes against your thinking is not the way to do it.

      I am sure other climate scientists will be weighing in on this report in the upcoming days and weeks and I think it would be wise to wait and hear the various comments and criticisms before forming a judgment.


      •  I haven't drawn a definite conclusion, yet, but (2+ / 0-)
        Recommended by:
        ORDem, Creosote

        I am seeing a lot of credible environmentalists countering their assumptions...I just read an article by Robert Kennedy, Jr. discussing the increased efforts that are being made by climate deniers (sponsored by the oil companies) to discredit environmentalists.  

    •  This is Science (2+ / 0-)
      Recommended by:
      Lefty Coaster, ORDem

      It isn't sham or poorly done. It is scientific. No pressure there--if any, in the other direction.

      Remember, Murdoch bought National Geographic.

      Quidquid latine dictum sit, altum viditur.

      by MrMichaelMT on Sat Nov 26, 2011 at 03:46:36 AM PST

      [ Parent ]

  •  I thought that the data showed temperatures (4+ / 0-)
    Recommended by:
    G2geek, ozsea1, marsanges, Curt Matlock

    rising faster than the IPCC 'mean' predictions up to this point and this study seems to indicate that should not be the case.

    Anyway, I am guessing that this report will be scrutinized pretty carefully by the climate science community and as I stated above in my reply to praenomen, I will try not to prejudge but wait to hear the arguments.

  •  Decieving Title (1+ / 0-)
    Recommended by:

    This is not about overestimates or underestimates, this is about adjustments to models as more data comes in.  You should change your title to something less dramatic to describe that Science published an article that tweaks the climate change rate.  

    Your central point should remain that the issue is still out there, the main conclusions stand, but the feedback loop central to all science is voting that the rate assumptions may need to change a bit.    Your point at the end leads straight to this conclusion, especially the cite to 650 ppm.

  •  Your diary is a bit more fair and balanced than (2+ / 0-)
    Recommended by:
    ORDem, millwood

    what will spew from Fox News.

    The community of fools might be small were it not such an accomplished proselytizer.

    by ZedMont on Sat Nov 26, 2011 at 02:43:31 AM PST

  •  The headline is deceptive--as will be reporting (2+ / 0-)
    Recommended by:
    diffrntdrummr, Sylv

    There are a range of estimates in good scientific literature, and this study simply lands on a lower band in that range. Of course, you are correct in assuming that Faux will celebrate the headline, not the facts.

    Quidquid latine dictum sit, altum viditur.

    by MrMichaelMT on Sat Nov 26, 2011 at 03:45:34 AM PST

  •  Deceptive title? Fox blather? Doesn't matter (1+ / 0-)
    Recommended by:

    We are already too far gone. It makes little difference at this point what the denialists say, what the Fox loons spew, how the Koch-funded nutcases misuse this new study.

    Lookit. This shows a 10% tweak but no change to the big picture. No news there. This is basically another study showing the same things as virtually all the other legitimate studies.

    And what they all show, especially lately, is that we are too far gone. We are entering into a world of hurt. We might have been able to do something to mitigate this fifty years ago, or twenty, but now? No. It's too late to stop drastic change to the planet.

    If we get right on it and modify, well, most everything about what we do and how we do it, right away, humans just might not go extinct, and take most of our other co-inhabitant species with us. We'll "merely" trash our ecosystem to within an inch of its life, and our species to within an inch of ours too. Most other species too.

    But that's the best case scenario. And given the abysmally slow rate at which we're moving away from the technologies with which we've caused this, that scenario is highly unlikely.

    I will continue to work hard toward that best case scenario. Because, what other choice to honest caring people have? Hey, we might just pull it off. But it's clear to me that even in that best case scenario, in the best possible circumstances, we are utterly, utterly screwed.

  •  Also missing from the diary; (0+ / 0-)

    results of a thorough investigation of these scientist's bank accounts; secret, offshore, etc; for evidence of deposits by the World Oil Consortium?

    I read it may be possible to play 18 holes at the North Pole in about 25 years!  Does this mean another delay?

    apparently due to ancient hardware and the transition to dk4 I can't recc tip jars or comments any longer so in lieu of the 'standard nod' you'll see a variety of replies until this gets fixed or becomes a mighty big fucking pain in the ass

    by oopsaDaisy on Sat Nov 26, 2011 at 07:46:27 AM PST

  •  This is one climate projection among many (1+ / 0-)
    Recommended by:
    Calamity Jean

    I don't know that this particular projection overturns other projections. Let's not leap to conclusion here.

  •  Misleading. See Joe Romm (0+ / 0-)

    Joe Romm posted an extensive analysis of this paper in his blog (try It confirmed my sense that the analysis was legitimate, that it had serious limitations that called the definiteness of its conclusions into question, and that people reading the summary would get a completely false impression of its effect on climate change projections. And sure enough, the blog post and the comments show that most folks don't have a strong enough sense of what they're talking about, just a vague hope that "maybe things won't quite be as bad" or a vague sense that "I'm suspicious of the source."

    To summarize some of the things that Joe Romm is saying:

    1.  It's unlikely that this finding (that doubling carbon in the atmosphere, on its own, will raise temps 2.3 degrees centigrade, not 3 degrees centigrade, as previously thought) will hold up.  Other ways to measure parallel data consistently show 3 degrees or higher.

    2.  Even if it does hold up, the actual effect in our world of doubling present carbon in the atmosphere from 390 ppm to 780 ppm is most likely to be a rise in temps of 6 degrees or higher. The study looked at a Milankovitch-cycle warming from glacial maximum to now, which corresponds to a glacial minimum in the cycle. Warming beyond this involves big changes to "albedo" and other side effects that don't happen when you're going from "cold" to "warm". Moreover, uniquely, we are driving the process far faster than ever before with our emissions, so that other "long-term follow-on effects" become far more powerful in the short term, such as massive methane/carbon releases from peat, permafrost, and methane clathrates in the Siberian Seas.  The latter are not yet adequately included in almost all climate models, and the fact that other aspects of the process (like melting of Arctic sea ice) are happening far faster than predicted, are not included in these models either.

    3. Noting that "the risk [of drastic changes in climate] is a little less imminent" is misleading if not inaccurate. What they appear to be trying to say is that the climate change due to carbon emissions in the atmosphere itself over the next 40 years may be reduced by half a degree, so the risks of added impacts from, say, temperatures rising by 3 degrees over the next 40 years as opposed to 2.5 degrees are slightly less.  But remember, even if they are completely right, "drastic" changes in climate are imminent by almost anyone's definition.  And, as noted before, pick any time period and the difference between an x degree temperature rise and one that is only 90% as much (the overall temp difference, not just the one due directly to more carbon in the atmosphere) in its effect on you is really not going to be obvious.

    There's a good reason that the authors say that the "threat from human-caused climate change should [not] be treated less seriously" due to their study. That's because the study says zero about that threat.

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