‘We Would All Like Climate Sensitivity To Be Lower But It Isn’t’ Says Lead Scientist Of New Study

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"‘We Would All Like Climate Sensitivity To Be Lower But It Isn’t’ Says Lead Scientist Of New Study"

It would be good news if the climate’s sensitivity to carbon pollution were on the low side. No, that wouldn’t save us from catastrophic global warming — 7°F warming or higher — if we stay anywhere near our current emissions path (as I explain here).

But a low sensitivity would mean that aggressive action to reduce CO2 emissions starting now would have a modestly higher chance of keeping total warming below 4°F and averting the worst impacts. That’s the point of New Scientist‘s article, “A second chance to save the climate” on a new sensitivity study in Nature Geoscience:

“If we are lucky and the climate sensitivity is at the low end, and we have a strong agreement in 2015, then I think we stand a chance to limit climate change to 2 °C,” says Corinne Le Quéré of the Tyndall Centre for Climate Change Research in Norwich, UK. “But there’s a lot of ifs.”

If this new study is accurate, then near-term surface warming might be less than expected. But as the lead author Oxford’s Dr. Alexander Otto told the BBC, “We would all like climate sensitivity to be lower but it isn’t.”

The researchers say the difference between the lower short-term estimate and the more consistent long-term picture can be explained by the fact that the heat from the last decade has been absorbed into and is being stored by the world’s oceans.

Recent studies make clear the ocean is warming quite fast, as (see “Global Warming Has Accelerated In Past 15 Years, New Study Of Oceans Confirms” and here). If, as many climatologists believe, some of that ocean heat is released to the surface in the next decade or two, that would reverse the recent slowdown in the rate of surface warming.

Also, many other recent studies find that the climate is more sensitive than we expected:

Indeed, the new study does little to eliminate the confusion about sensitivity. The media continue to conflate and confuse climate sensitivity with how much warming will we subject our children and countless future generations to (see here and below).

Another related source of confusion is conflating “climate sensitivity” — which generally refers to the change in the global surface temperatures (absent major feedbacks) — with how sensitive the climate itself is to changes in temperature.

For instance, our climate models wildly underestimate what’s happening in the Arctic right now:

Arctic sea ice is melting much, much faster than even the best climate models had projected (actual observations in red). The reason is most likely unmodeled amplifying feedbacks. The image (from Climate Crocks via Arctic Sea Ice Blog) comes from a 2007 GRL research paper by Stroeve et al.

And considerable recent research suggests that our climate in turn is much more sensitive to Arctic ice loss than we ever thought:

Finally, since the media keep misreporting the issue, here once again are the four factors that determine how much warming we are going to inflict on future generations:

  1. The so-called “equilibrium climate sensitivity” – the sensitivity of the climate to fast feedbacks like sea ice and water vapor. The ECS, which is typically the focus of modeling studies like the new one discussed above, is how much warming you get if we suddenly adopt a super-aggressive effort to cut carbon pollution and only double CO2 emissions to 560 ppm — and there are no major “slow” feedbacks.  We know the fast feedbacks, like water vapor, are strong by themselves (see Study: Water-vapor feedback is “strong and positive,” so we face “warming of several degrees Celsius” and Skeptical Science piece here).
  2. The actual CO2 concentration level we hit, which on our current emissions path is far, far beyond 550 ppm (see U.S. media largely ignores latest warning from climate scientists: “Recent observations confirm … the worst-case IPCC scenario trajectories are being realised” — 1000 ppm).
  3. The real-world slower (decade-scale) feedbacks, such as tundra melt (see “Carbon Feedback From Thawing Permafrost Will Likely Add 0.4°F – 1.5°F To Total Global Warming By 2100“).
  4. Where they live — since people who live in the mid-latitudes (like most Americans) are projected to warm considerably more than the global average.

The Intergovernmental Panel on Climate Change concluded in 2007 that equilibrium climate sensitivity was in the range of 2.0-4.5C. The new study has a similar range, 0.9-5.0C.

Actual warming this century on our current emissions path is all but certain to be catastrophic, even if ECS is closer to 2°C than 3°C or more.

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18 Responses to ‘We Would All Like Climate Sensitivity To Be Lower But It Isn’t’ Says Lead Scientist Of New Study

  1. Raul M. says:

    We would all like the repair costs of extreme weather to be lower and a tie to fossil fuels between FEMA funding and a fossil fuel luxury tax might show interest in the costs of disaster weather events. What does it mean to take a stand on the realities of funding for FEMA? People and agencies seem to need FEMA’s help.
    Anthropogenic realities?

    • Raul M. says:

      Of course, a raising scale that reflects the cost of repairs to storm damage would price fossil fuels in real time reflection to the damage inflicted by flooding,drought, winds, hail stones and the list of damages goes on. As the damages mount over time the luxury tax would raise the funds necessary to repairs.

      • Raul M. says:

        A fossil fuel luxury tax that pays for FEMA weather disaster could pass a voter referendum with the funds available to the area that has passed the luxury tax?

        • Raul M. says:

          And because people decide to rebuild in the same locations there is infrastructure needed and hence the need for a fossil fuel luxury tax.

          • Raul M. says:

            Needed signatures on a plan to add a penny per gallon of gas to pay for disaster relief. With the size of storms maybe it will need to rise to a nickel per gallon of gas.

  2. prokaryotes says:

    “Our understanding of sensitivity is based on the Earth’s history, not on climate models, and we have good data on how the Earth responded in the past when carbon dioxide changed. So there is no reason to change the forecast for the long term.” – James Hansen http://www.guardian.co.uk/environment/2013/may/17/global-warming-not-stalled-climate

  3. prokaryotes says:

    Polar vortex moves deepest current

    The system is very sensitive to the weather over the seas east and west of Greenland, said Reichler. A few tenths of degrees cooling more or less will make the difference between sinking or not. And that climatological Achilles’ heel is one of the factors that make it possible that events about 30 kilometers higher have an influence on it.

    Reversing the polar vortex affects currents

    “Another reason is that changes in the stratosphere seem to happen on very long time scales, there’s a decadal rhythm to it”, Reichler says.

    Those changes reduce the strength of the prevailing westerly winds over Greenland, and with that the transport of cold air from North America. That, in turn, will decrease the rate of cooling of the ocean water. http://www.cosmosmagazine.com/news/polar-vortex-moves-deepest-current/

    • prokaryotes says:

      The Winter the Polar Vortex Collapsed

      The polar vortex was persistently weak from November 2012 through March 2013. At the peak of winter, in mid-January, the polar vortex was split in two by a massive sudden stratospheric warming. Instead of a vortex, very high surface pressure built under a dome of sinking over the north pole. Astonishingly, high pressure over the pole extended from the surface to the mid-stratosphere from late November to mid-March.

      High pressure over the pole pushed the weakened jet stream south over Siberia causing brutally cold weather in north-east Asia. Record smashing snow storms formed off the east coast of the U.S. when the blocked jet stream collided Arctic air with Gulf Stream moisture.

      Paradoxically, this bizarre winter may be tied to the loss of Arctic sea ice. Even more paradoxically, the “Global warming Stopped in 1998″ claim touted by climate skeptics may be linked to this winter’s bizarre weather. http://www.dailykos.com/story/2013/03/22/1195793/-The-Winter-the-Polar-Vortex-Collapsed

  4. Jeffi says:

    Joe – Have you read Rep. Lamar Smith’s opinion piece in the Washington Post today? He has about every denialists’ talking point starting with the supposed fact that global temperatures held steady over last 15 years according to University of East Anglia’s Climate Research Unit. His link to charts for the Northern Hemisphere, Southern Hemisphere and Globally to me show steady increase over the last 15 years and not holding steady as Rep. Smith says. Rep. Smith has a link to a State Dept. study and says the XL pipeline will create 40,000+ US jobs. I looked at the State Dept. link and I can’t find any mention of 40,000+ jobs. I’m sure Rep. Smith’s opinion piece does what is intended and that is to confuse the confused even more.

  5. Joan Savage says:

    Major volcanic eruptions cool the ocean at both 0-300m and 0-700m depths (Balmaseda et al. (2013) Figure 1). I was surprised at a ‘quick’ response for the deeper measurements.

    What would be prudent to realize is that we would need a triple Pinatubo (1991) to negate the ocean temperature rise between Pinatubo circa 1992 and 2009.
    Maybe if we measured the consequences of global warming in terms of the volcanic eruptions that would be ‘needed’ to countervale against it, instead of the somewhat abstract “sensitivity,” more people would get the picture.

    • BillD says:

      Joan–Aren’t the effect of volcanoes temporary anyway? After an extreme volcanic event, the temperature would be cooler for a couple of years but it would then go back to where it was without the volcano effect.

      • Joan Savage says:

        Yes. That’s the inference.

        How many major volcanoes over how many years would it take.. (sounds like a Dylan song refrain) to bring the average ocean temperature back down to say 1913, when we still had an Arctic.

        Pinatubo (1991) was estimated at 20 mT sulfur dioxide while Tambora (1815) released 22mT sulfur dioxide, with a following “Year with no Summer” in 1816, so that should tell us that increased CO2 is masking the full effect of volcanoes.
        The Toba super-eruption in Sumatra was thought to cause immediate loss of life from ash over continents, followed by a global winter that lasted about 10 years, and possibly accelerated a Pleistocene ice expansion.
        I think that leads to the real point. Abrupt reversal of CO2 driven warming by volcanic eruptions would be of such a magnitude that the direct destruction from the volcanoes would be at a nearly unimaginable scale.

        Metaphorically, we have no brakes to use. We must take our feet off the accelerators, downshift, and steer very very carefully.

  6. rollin says:

    The climate sensitivity is becoming a less important point as the ice and snow cover decrease in the northern and arctic regions.

    Albedo changes alone can double the radiative forcings very quickly. Weather and ecological changes will be dramatic.

  7. Peter Shepherd says:

    I like Joe’s common-sense statement:
    “If, as many climatologists believe, some of that ocean heat is released to the surface in the next decade or two, that would reverse the recent slowdown in the rate of surface warming.”? but would like to see references to oceanographers/climatologists who concur.

    While there may be some uncertainty on timing, the “what goes up/in must come down/out” must hold true for OHC.