From the BNL press release, some serious questions about climate sensitivity and aerosols.
Why Hasn’t Earth Warmed as Much as Expected?
New report on climate change explores the reasons
January 19, 2010 UPTON, NY – Planet Earth has warmed much less than expected during the industrial era based on current best estimates of Earth’s “climate sensitivity”—the amount of global temperature increase expected in response to a given rise in atmospheric concentrations of carbon dioxide (CO2). In a study to be published in the Journal of Climate, a publication of the American Meteorological Society (the early online release of the paper is available starting 19 January 2010; the link is given below), Stephen Schwartz, of Brookhaven National Laboratory, and colleagues examine the reasons for this discrepancy.
According to current best estimates of climate sensitivity, the amount of CO2 and other heat-trapping gases added to Earth’s atmosphere since humanity began burning fossil fuels on a significant scale during the industrial period would be expected to result in a mean global temperature rise of 3.8°F—well more than the 1.4°F increase that has been observed for this time span. Schwartz’s analysis attributes the reasons for this discrepancy to a possible mix of two major factors: 1) Earth’s climate may be less sensitive to rising greenhouse gases than currently assumed and/or 2) reflection of sunlight by haze particles in the atmosphere may be offsetting some of the expected warming.
“Because of present uncertainties in climate sensitivity and the enhanced reflectivity of haze particles,” said Schwartz, “it is impossible to accurately assign weights to the relative contributions of these two factors. This has major implications for understanding of Earth’s climate and how the world will meet its future energy needs.”
A third possible reason for the lower-than-expected increase of Earth’s temperature over the industrial period is the slow response of temperature to the warming influence of heat-trapping gases. “This is much like the lag time you experience when heating a pot of water on a stove,” said Schwartz. Based on calculations using measurements of the increase in ocean heat content over the past fifty years, however, this present study found the role of so-called thermal lag to be minor.
A key question facing policymakers is how much additional CO2 and other heat-trapping gases can be introduced into the atmosphere, beyond what is already present, without committing the planet to a dangerous level of human interference with the climate system. Many scientists and policymakers consider the threshold for such dangerous interference to be an increase in global temperature of 3.6°F above the preindustrial level, although no single threshold would encompass all effects.
The paper describes three scenarios: If Earth’s climate sensitivity is at the low end of current estimates as given by the Intergovernmental Panel on Climate Change, then the total maximum future emissions of heat-trapping gases so as not to exceed the 3.6° threshold would correspond to about 35 years of present annual emissions of CO2 from fossil-fuel combustion. A climate sensitivity at the present best estimate would mean that no more heat-trapping gases can be added to the atmosphere without committing the planet to exceeding the threshold. And if the sensitivity is at the high end of current estimates, present atmospheric concentrations of heat-trapping gases are such that the planet is already committed to warming that substantially exceeds the 3.6° threshold.
The authors emphasize the need to quantify the influences of haze particles to narrow the uncertainty in Earth’s climate sensitivity. This is much more difficult than quantifying the influences of the heat-trapping gases. Coauthor Robert Charlson of the University of Washington likens the focus on the heat trapping gases to “looking for the lost key under the lamppost.”
Schwartz observes that formulating energy policy with the present uncertainty in climate sensitivity is like navigating a large ship in perilous waters without charts. “We know we have to change the course of this ship, and we know the direction of the change, but we don’t know how much we need to change the course or how soon we have to do it.”
Schwartz and Charlson coauthored the paper with Ralph Kahn, NASA Goddard Space Flight Center in Maryland; John Ogren, NOAA Earth System Research Laboratory in Colorado; and Henning Rodhe, Stockholm University.
The early online release of the paper is available at AMS’s journals online site.
Founded in 1919, the AMS has a membership of more than 14,000 professionals, professors, students, and weather enthusiasts. AMS publishes nine atmospheric and related oceanic and hydrologic journals, sponsors multiple conferences annually, and directs numerous education and outreach programs and services. For more information see www.ametsoc.org.
Research at Brookhaven was funded by the U.S. Department of Energy Office of Science.
h/t to WUWT commenter “Don S”
“The authors emphasize the need to quantify the influences of haze particles to narrow the uncertainty in Earth’s climate sensitivity. This is much more difficult than quantifying the influences of the heat-trapping gases.”
In that case, they haven’t got a chance in H-E-double MM charts of ever doing it, as evidenced by the actual on-going quantification – Nope, not quite finished yet.
The published paper;
http://pubs.giss.nasa.gov/docs/2008/2008_Baranov_etal.pdf
Additional info on same project;
https://kb.osu.edu/dspace/handle/1811/38228
https://kb.osu.edu/dspace/handle/1811/31409
I will point out that the people performing the actual measurements are not normally quite as certain of things as are the people who statistically bend, fold, staple, mutilate, and otherwise torture the resulting data. If you skip to the conclusion of the paper, you will see that the absorption coefficients for the water vapor continuum in one of the hallowed “window” regions need increased by an order of magnitude based on this recent research. If you check the HITRAN database website, you will find one of the researchers on this project, W. J. Lafferty, listed as a contributor. I mention this because HITRAN is used by some (probably most or all) for the line-by-line radiative transfer codes (which Gavin seems to be fond of). These are used as part of the basis for the assumptions of the efficacy of CO2, et. al., as GHG’s, and for assumptions regarding the effects of increasing concentrations of CO2 and radiative forcing with GCM’s, as well as assumptions regarding the amount of IR going through those atmospheric “windows”. This brings us back to the reason the water vapor coefficients were low in the first place; they came from what is referred to as the continuum CKD model, which is semi-empirical because some data was known, but not enough high-resolution data was available at the time it was developed, and the data was interpolated and in filled and otherwise tortured using assumptions based on what was “known” at the time, so it is a model, never the less. So we have models built on models. Nice.
I would also mention that not only are the correct values for the water vapor continuum still not completely defined, its very origin is contentious. So much for settled science. Research is also now starting to focus on collecting more empirical data for collision-induced absorption, for instance N2-H2O, etc.
Could you guys do me a favor and keep that last bit quiet? You know, that whole collision-induced absorption thingy. I mean, what’s a couple of orders of magnitude? I’m pretty sure we don’t want the “deniers” getting a hold of another wrench to throw into the gears of our models.
Have a nice day.
:
It seems that the arctic has taken a nose dive, in contrast to last year the same time. Some 13 degrees cooler in less than a month.
REPLY: I have been monitoring this, while the magnitude of the current temperature is not unusual compared to previous years, the steepness of the drop is noteworthy, but it’s not news yet. If it gets to 235K then maybe it will be. – Anthony
” anna v (21:42:10) :
It seems that the arctic has taken a nose dive, in contrast to last year the same time. Some 13 degrees cooler in less than a month.”
But over at Nansen, the blue curve for 2009 still climbs at a lower angle than the red curve for 2010. At JAXA (difficult to see) it seems the other way around. Might be the satellite, might be the smoothing.
Alexej Buergin (02:28:07) :
Well, sea ice extent takes some time to respond to temperature.
I think what probably has happened is that the wind patterns changed, and the cold air remains in the arctic instead of blowing down to lower latitudes. I like that :).
Why haven’t my predicated Lotto numbers matched the actual winning numbers?
Clearly there is a fault with the machine that draws the actual numbers.
Actually merited a blurb in USA Today! http://blogs.usatoday.com/sciencefair/2010/01/earth-may-be-less-sensitive-to-greenhouse-gases-than-thought.html
How about that!
I don’t think anyone really knows the true temp of planet Earth to even make a decent judgement. Also, because there’s a lot of missed temp data due to a drastically reduced number of very cold Siberian weather outposts and the effects of urban heat on other data collection, there just might not be any warming to explain.