Monday, December 17, 2012

Leaked IPCC Draft Report: Recent Warming Is Manmade, Cloud Feedback Is Positive, Inaction Is Suicidal

Ultra-conservative report still concludes sea level rise could reach 6 inches a decade by century's end! Deniers duped by leaker's blunder.

Figure SPM.6.a. Warming in two IPCC scenarios reveals humanity's choice. With aggressive action to reduce greenhouse gas emissions (RCP 2.6 with 443 ppm of CO2 in 2100), warming is modest and adaptation is plausible. With continued inaction (RCP 8.5 with 936 ppm in 2100), warming is a catastrophic and unmanageable 10°F over much of Earth's habited and arable land - and more than 15°F over the Arctic. This projection ignores many key amplifying feedbacks, such as the release of permafrost carbon, which would likely lead to far greater warming.

The draft 2013 Fifth Assessment report of the Intergovernmental Panel on Climate Change leaked this week makes clear inaction on climate change would be devastating to modern civilization. The report finds that the human fingerprint on climate has grown more obvious, concluding "it is virtually certain" the energy imbalance that causes global warming "is caused by human activities, primarily by the increase in CO2 concentrations. There is very high confidence that natural forcing contributes only a small fraction to this imbalance."

Yes, I know, the easily-duped deniers and their media stooges have reported the opposite is true, that solar forcing has been a significant driver of recent warming, but the deniers are as likely to be right as the flat earthers. The only question is why anyone still listens to them. I'll repost a debunking of their nonsense below.

The draft Summary for Policymakers (the only thing 99% of people will ever read) finds:

It is extremely likely [">95% probability"] that human activities have caused more than half of the observed increase in global average surface temperature since the 1950s. There is high confidence ["About 8 out of 10 chance"] that this has caused large-scale changes in the ocean, in the cryosphere, and in sea level in the second half of the 20th century. Some extreme events have changed as a result of anthropogenic influence.

That multiply-hedged morass is pretty much the mildest statement that could possibly be made. A December 2011 study found it's "Extremely Likely That at Least 74% of Observed Warming Since 1950″ was manmade; it's highly likely all of it was (see Figure 1 below).

For me, the leaked draft, which has not yet been peer reviewed - and thus still has time to be watered down yet more - underscores how pointless the IPCC has become. Like the 4th assessment before it, this ultra-conservative and instantly obsolete report ignores the latest science - see "Fifth Assessment Report Will Ignore Crucial Permafrost Carbon Feedback!" Note that including the permafrost feedback would probably make the RCP8.5 scenario in the top figure as much as 1.5°F warmer!

And like the AR4, the AR5 scenarios low-ball future impacts - "Arctic sea ice area is projected to decrease by 28% for September" for the 2016-2035 period vs. 1986-2005. Seriously IPCC, a 28% drop is the scenario your touting? In fact, as we have reported, many experts warn of "Near Ice-Free Arctic In Summer" in a decade if recent ice volume trends continue.

Even so, the uber-conservative AR5 draft makes clear to anyone who reads between the lines that inaction would be suicidal for humanity, with devastating warming and sea level rise that could hit a half a foot a decade by 2100. How precisely does one adapt to that?

Indeed, the report guts the one remaining myth of those who downplay future impacts, that clouds would act as a negative (or weakening) feedback. It finds:

The net radiative feedback due to all cloud types is likely positive.

But the report fails to clearly spell out what the recent science says about inaction - for that you might try "An Illustrated Guide to the Science of Global Warming Impacts" or the recentWorld Bank report, which warned "A 4°C [7°F] World Can, And Must, Be Avoided" To Avert "Devastating" Impacts.

So I can't see why AR5 would motivate anyone to act more than AR4 and thus I see little real-world value in the entire effort - see my November 2007 post, "Absolute MUST Read IPCC Report: Debate over, further delay fatal, action not costly"! Plus ça change, plus c'est la même chose.

Once again, the authors twist themselves in pretzels to over-hedge every statement with their precise (but inaccurate!) terminology. And so we learn in the draft Summary for Policymakers (SPM):

It is very likely that the Arctic sea ice cover will continue to shrink and thin in the course of the 21st century as global temperature rises.

No, really, it is "very likely" - "> 90% probability" - which I guess means, what, that the IPCC seriously thinks there is an up to 10% chance Arctic sea ice cover will stop shrinking and thinning???

Observations and analysis of drought make clear it is already intensifying in many key regions thanks to global warming - see "NOAA Bombshell: Human-Caused Climate Change Already a Major Factor in More Frequent Mediterranean Droughts" and "Study: Global warming is driving increased frequency of extreme wet or dry summer weather in southeast, so droughts and deluges are likely to get worse." But all AR5 can muster up for the probability of future "increases in frequency and/or intensity of drought" is "Likely [> 66% probability] in some regions" - which I guess means the IPCC thinks there is 1 in 3 chance it won't happen anywhere! How could that be with the kind of warming we will see in the RCP8.5 scenario, which, it must be added is really just business as usual emissions and far from the worst-case?

This failure to warn the public and policymakers echoes the great failing of their 2011 extreme weather report (see "Blockbuster IPCC Chart Hints at Dust-Bowlification, But Report Is Mostly Silent on Warming's Gravest Threat to Humanity").

In it most extreme scenario, RCP8.5 - about 936 ppm of CO2 in 2100 (not a worst-case in the real world because of permafrost and other feedbacks) - sea level rise in 2100 is only about 2 feet. That assumes you can figure out what this means: "The contributions from ice sheet dynamical change and anthropogenic land water storage are treated as independent of scenario, since scenario dependence cannot be evaluated on the basis of existing literature, and as having uniform probability distributions, uncorrelated with the magnitude of global climate change." Clarity ain't the IPCC's strong suit.

In any case, most climate scientists expect considerably higher sea level rise, especially if we don't act. That's what the recent literature says - see "Sea levels may rise 3 times faster than IPCC estimated, could hit 6 feet by 2100" and "JPL bombshell: Polar ice sheet mass loss is speeding up, on pace for 1 foot sea level rise by 2050."

Finally, if you read the denier blogs or columnists - and if so, you have no one to blame but yourself - you've probably heard something about how the IPCC finds cosmic rays are a major climate driver. In fact, the SPM finds:

Cosmic rays enhance aerosol nucleation and cloud condensation nuclei production in the free troposphere, but there is high confidence that the effect is too weak to have any significant climatic influence during a solar cycle or over the last century.

For debunkings of the latest denier spin, see here and here and especially here, which has an interview with the lead author of the key draft chapter.

Below I'm reposting a Skeptical Science piece on the subject.

IPCC Draft Report Leaked, Shows Global Warming is NOT Due to the Sun

Posted on 14 December 2012 by dana1981

Alec Rawls, an occasional guest poster on the climate contrarian blog WattsUpWithThat who signed up to review the upcoming Intergovernmental Panel on Climate Change (IPCC) Fifth Assessment Report (as anyone can), has "leaked" a draft version of the report and declared that it "contains game-changing admission of enhanced solar forcing." This assertion was then repeated by James Delingpole at The Telegraph (with some added colorful language), and probably on many other climate contrarian blogs.

If the IPCC was to report that the sun is a significant player in the current rapid global warming, that would indeed be major news, because the body of peer-reviewed scientific literature and data clearly show that the sun has made little if any contribution to the observed global warming over the past 50+ years (Figure 1).

contributors 50

Figure 1: Percent contributions of greenhouse gases (GHGs), sulfur dioxide (SO2), the sun, volcanoes, and El Niño Southern Oscillation (ENSO) to the observed global surface warming over the past 50-65 years according to Tett et al. 2000 (T00, dark blue), Meehl et al. 2004 (M04, red), Stone et al. 2007 (S07, green), Lean and Rind 2008 (LR08, purple), Huber and Knutti 2011 (HK11, light blue), Gillett et al. 2012 (G12, orange), and Wigley and Santer 2012 (WS12, dark green).

So why would the latest IPCC report contradict these studies when its purpose is to summarize the latest and greatest scientific research? The answer is simple - it doesn't. Rawls has completely misrepresented the IPCC report.

Cosmic Source of Confusion

The supposedly "game-changing admission" from the IPCC report is this:

"Many empirical relationships have been reported between GCR [galactic cosmic rays] or cosmogenic isotope archives and some aspects of the climate system...The forcing from changes in total solar irradiance alone does not seem to account for these observations, implying the existence of an amplifying mechanism such as the hypothesized GCR-cloud link."

This statement refers to a hypothesis of Henrik Svensmark from the Danish National Space Institute, who has proposed that galactic cosmic rays (GCRs) could exert significant influence over global temperatures. The GCR hypothesis suggests that when they reach Earth, GCRs (high-energy charged particles originating from somewhere in our galaxy) are capable of "seeding" clouds; thus at times when a lot of GCRs are reaching the Earth's surface, more clouds will form. Clouds generally have a cooling effect on the Earth's temperature, because they reflect sunlight.

So the hypothesis goes like this: high solar activity means a strong solar magnetic field, which deflects more GCRs away from Earth, which means less cloud formation, which means less sunlight is reflected away from Earth, which means more warming. This GCR-caused warming would amplify the warming already being caused by increased solar activity. Conversely, cooling from decreased solar activity would hypothetically be amplified by more GCRs on Earth, more clouds, more reflected sunlight, and thus more cooling.

It's important to note that so far virtually all scientific research on GCRs has shown that they are not effective at seeding clouds and thus have very little influence over the Earth's temperature. In fact, as Zeke Hausfather has noted, the leaked IPCC report specifically states this:

"...there is medium evidence and high agreement that the cosmic ray-ionization mechanism is too weak to influence global concentrations of [cloud condensation nuclei] or their change over the last century or during a solar cycle in any climatically significant way."

But more importantly in this context, even if GCRs did influence global temperature, they would currently be having a cooling effect.

Solar Activity is Down, Greenhouse Gases are Up

Rawls also provides the following quote from the IPCC report (emphasis added):

"There is very high confidence that natural forcing is a small fraction of the anthropogenic forcing. In particular, over the past three decades (since 1980), robust evidence from satellite observations of the TSI [total solar irradiance] and volcanic aerosols demonstrate a near-zero (-0.04 W m-2) change in the natural forcing compared to the anthropogenic AF increase of ~1.0 ± 0.3 W m-2."

The term "radiative forcing" refers to a global energy imbalance on Earth, which may be caused by various effects like changes in the greenhouse effect or solar activity. A positive forcing will result in warming temperatures, while a negative forcing will result in cooling.

Here the IPCC is saying that since 1980, the sun and volcanoes have combined to cause a slightly negative global energy imbalance, which means they have had a slight cooling influence on global temperatures over the past three decades. Indeed, solar activity has decreased a bit over that timeframe (Figure 2).

Figure 2: Global temperature (red, NASA GISS) and Total solar irradiance (blue, 1880 to 1978 from Solanki, 1979 to 2009 from PMOD), with 11-year running averages.

As we would expect, lower solar activity including a weaker solar magnetic field has translated into a slight increase in GCR flux on Earth (Figure 3). Note that on the left-hand axis of Figure 3, GCR counts decrease going up the axis in order to show the relationship with temperature, since fewer GCRs hypothetically means fewer clouds, less reflected sunlight, and higher temperatures.

cosmic rays vs temps

Figure 3: Global average surface temperature (red, NASA GISS) vs. GCR flux on Earth (blue, Krivova & Solanki 2003), with 11-year running averages.

So, if GCRs really do amplify the solar influence on global temperatures, since 1980 they are amplifying a cooling effect. In fact, GCRs reaching Earth recently hit record high levels (Figure 4), yet temperatures are still way up.

Figure 4: Record cosmic ray flux observed in 2009 by the Advanced Composition Explorer (NASA)

Physical Reality Intrudes on Rawls

Rawls has argued to the contrary by claiming that the climate is still responding to the increase in solar activity from the early 20th century, and that GCRs are amplifying that solar warming from over 60 years ago. This argument is simply physically wrong. As Figure 2 illustrates, when solar activity rises, temperatures follow suit very soon thereafter. In fact, during the mid-20th century, solar activity and global surface temperatures both flattened out. Are we to believe that the planet suddenly began responding to the pre-1950 solar activity increase in 1975-2012, after not warming 1940-1975? The argument makes no physical sense.

On top of that, the hypothetical GCR process is a relatively rapid one. Cloud formation from GCR seeding should occur within days, and clouds have very short lifetimes. For GCRs to have a warming effect, solar activity must be increasing right now. It is not, in fact solar activity has been essentially flat and slightly declining in recent decades. Changes in solar activity from 60+ years ago have no bearing whatsoever on GCRs today.

IPCC Shows Global Warming is NOT Solar

To sum up,

  • The leaked IPCC report states that there may be some connection between GCRs and some aspects of the climate system.
  • However, the report is also consistent with the body of scientific literature in stating that research indicates GCRs are not effective at seeding clouds and have very little influence on global temperatures.
  • Solar activity has been nearly flat and slightly decreasing in recent decades, meaning that if GCRs do amplify solar influences on climate, they are amplifying a cooling effect.

The body of peer-reviewed scientific literature is very clear: human greenhouse gas emissions, not solar activity or galactic cosmic rays, are causing global warming. The leaked IPCC report is entirely consistent with this conclusion. In fact, in attempting to argue to the contrary, Rawls has scored an own goal by showing that if anything, GCRs are currently amplifying a solar cooling effect.



http://thinkprogress.org/climate/2012/12/16/1334921/leaked-ipcc-draft-