Update: the IPCC edifice is crumbling, see The state of climate science: ‘fluxed up’
See also Willis’ article One Step Forward, Two Steps Back, and Lomborg: climate models are running way too hot
This post will be a sticky for awhile, new posts will appear below it. – Anthony
Dialing Back the Alarm on Climate Change
A forthcoming report points lowers estimates on global warming
by Dr. Matt Ridley
Later this month, a long-awaited event that last happened in 2007 will recur. Like a returning comet, it will be taken to portend ominous happenings. I refer to the Intergovernmental Panel on Climate Change’s (IPCC) “fifth assessment report,” part of which will be published on Sept. 27.
There have already been leaks from this 31-page document, which summarizes 1,914 pages of scientific discussion, but thanks to a senior climate scientist, I have had a glimpse of the key prediction at the heart of the document. The big news is that, for the first time since these reports started coming out in 1990, the new one dials back the alarm. It states that the temperature rise we can expect as a result of man-made emissions of carbon dioxide is lower than the IPPC thought in 2007.
Admittedly, the change is small, and because of changing definitions, it is not easy to compare the two reports, but retreat it is. It is significant because it points to the very real possibility that, over the next several generations, the overall effect of climate change will be positive for humankind and the planet.
Specifically, the draft report says that “equilibrium climate sensitivity” (ECS)—eventual warming induced by a doubling of carbon dioxide in the atmosphere, which takes hundreds of years to occur—is “extremely likely” to be above 1 degree Celsius (1.8 degrees Fahrenheit), “likely” to be above 1.5 degrees Celsius (2.4 degrees Fahrenheit) and “very likely” to be below 6 degrees Celsius (10.8 Fahrenheit). In 2007, the IPPC said it was “likely” to be above 2 degrees Celsius and “very likely” to be above 1.5 degrees, with no upper limit. Since “extremely” and “very” have specific and different statistical meanings here, comparison is difficult.
Still, the downward movement since 2007 is clear, especially at the bottom of the “likely” range. The most probable value (3 degrees Celsius last time) is for some reason not stated this time.
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Most experts believe that warming of less than 2 degrees Celsius from preindustrial levels will result in no net economic and ecological damage. Therefore, the new report is effectively saying (based on the middle of the range of the IPCC’s emissions scenarios) that there is a better than 50-50 chance that by 2083, the benefits of climate change will still outweigh the harm.
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Above are excerpts of an article Dr. Ridley has written for the Wall Street Journal, who kindly provided WUWT with a copy.
Read the entire story here
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Bill Illis says:
September 14, 2013 at 8:53 am
For those interested in water vapor feedback numbers, here is the latest data up to August 2013.
The IPCC climate models are over-estimating water vapor by quite a bit so far. They have it an increase of 6.0% right now (and 22% by 2100) while last month, it was just 0.9% above average.
http://s23.postimg.org/qme9cxx4r/PCWV_IPCCAR5_Aug_2013.png
That is because (temps aren’t increasing as fast as predicted of course but also that) the ENSO is by far the biggest driver of water vapor levels. Water vapor lags 3 months behind the ENSO (like temperatures do which is not surprising).
http://s22.postimg.org/j48hjy7bl/ENSO_PCWV48_Aug_2013.png
But there is a well-known theory, Clausius-Clapeyron, that predicts a 7.0% increase in water vapor per 1.0C increase in temperatures and this is directly built into all the climate models. Clausius- Clapeyron is not entirely wrong, its just that the real Earth decides to use a slightly lower value of 4.6% instead (somehow tied in to the ENSO).
http://s22.postimg.org/exwtw3mhd/PCWV_vs_RSS_UAH_Temps_Aug_2013.png
This might say water vapor is indeed a positive feedback, but if you run the numbers at 4.6% rather than 7.0%, the CO2 doubling sensitivity falls to 2.0C per doubling (and then put clouds at zero net feedback rather than positive and the CO2 doubling sensitivity falls to 1.5C – that’s my number and it seems to pop out close to that number no matter how many different ways I look at it).
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Bill,
I did some numbers a while back and fed them into a 1-d absorption model. H2o is resjponsible for about 2x the absorption of co2 and is between two and 3x the power absorption when it comes to a doubling of the amount. One can come up with a simple number sensitivity for warming per W/m^2 increase based upon the current values we see and on the fact that there is a 33 deg C warming due to them. That value is 0.22 deg C rise per W/m^2. That indicates co2 without the h2o would accomplish 0.8 deg C rise for a doubling. If one assumes a 2 deg C rise in temperature thenone needs an additional 1.2 deg C due to ‘feedbacks’ with h2o being the major – acording to the experts. That means an additional 5.5 W/m^2 would be needed to achieve the 2 deg C rise that would cause the roughly 14% h2o vapor increase. This 5.5 W/m^2 is closer to a full doubling of h2o vapr, not a meager 14% increase. Hence 2 deg C could not be realized bya doubling of co2 and an h2o vapor increase of 14% or less. While 2 deg C may get close (just maybe) the outageous 4 and higher deg C per doubling shows the needed W/m^2 feedback increases get worse and worse with no where to get them from.
Beta Blocker says:
September 16, 2013 at 7:51 am
A thirty to fifty year trend of statistically significant cooling occurring in the face of continuously rising CO2 emissions will be needed before the Climate Science Industrial Complex admits that something might be wrong with their basic CO2-controls-climate narrative.//////////////////////////////////////////////////
We already do…it’s called the 1940s thru the 1970s…
Stopped reading at ” The shaded envelopes are the multimodel averages ±2 x s(t), where s(t) is the “between model” SD of the 20 (ALL+8.5) and 16 (NAT) ensemble-mean anomaly time series. To ”
This is a sort of measurement of precision.
There is no component of bias.
Most errors are a combination of precision and bias.
Why do so many ‘climate’ people make so elementary an error?
richardscourtney says:
September 16, 2013 at 4:10 am
tobyglyn:
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I see that neither of the Australian media links are allowing comments for this article. I believe that this is a new tactic with certain news outlets. The BBC stopped comments on climate change articles. The sceptics always seem to win the debate and they are pissed about that.
No comments→no readership→no income ☻