Tag: Global Science Report

What the New IPCC Global Warming Projections Should Have Looked Like

Global Science Report is a feature from the Center for the Study of Science, where we highlight one or two important new items in the scientific literature or the popular media. For broader and more technical perspectives, consult our monthly “Current Wisdom.”

The United Nations’ Intergovernmental Panel on Climate Change (IPCC) released its Fifth Assessment Report (AR5) last week to fanfare and stinging criticism.

Most of the criticism was aimed at the IPCC’s defense of climate models—models that the latest observations of the earth’s climate evolution show to be inaccurate, or at least are strongly indicative that is the case.

There are two prominent and undeniable examples of the models’ insufficiencies: 1) climate models overwhelmingly expected much more warming to have taken place over the past several decades than actually occurred; and 2) the sensitivity of the earth’s average temperature to increases in atmospheric greenhouse gas concentrations (such as carbon dioxide) averages some 60 percent greater in the IPCC’s climate models than it does in reality (according to a large and growing collection of evidence published in the scientific literature).

Had the IPCC addressed these model shortcomings head on, the flavor of their entire report would have been different. Instead of including projections for extreme climate changes as a result of continued human emissions of greenhouse gases resulting from our production of energy, the high-end projections would have featured relatively modest changes and the low-end projections would have been completely unremarkable.

Since changes in the earth’s temperature scale approximately linearly with a property known as the earth’s equilibrium climate sensitivity (how much the earth’s average surface temperature rises as a result of a doubling of the atmosphere’s carbon dioxide concentration), it is pretty straightforward to adjust the IPCC’s projections of future temperature change to bring them closer to what the latest science says the climate sensitivity is. That science suggests the equilibrium climate sensitivity probably lies between 1.5°C and 2.5°C (with an average value of 2.0°C), while the climate models used by the IPCC have climate sensitivities which range from 2.1°C to 4.7°C with an average value of 3.2°C.

To make the IPCC projections of the evolution of the earth’s average temperature better reflect the latest scientific estimates of the climate sensitivity, it is necessary to adjust them downward by about 30% at the low end, about 50% at the high end, and about 40% in the middle.

The figure below the jump shows what happens when we apply such a correction (note: we maintain some internal weather noise). The top panel shows the projections as portrayed by the IPCC in their just-released Fifth Assessment Report, and the lower panel shows what they pretty much would have looked like had the climate models better reflected the latest science. In other words, the lower panel is what the IPCC temperature projections should have looked like.

 

New IPCC Report Will Be Internally Inconsistent and Misleading

Global Science Report is a feature from the Center for the Study of Science, where we highlight one or two important new items in the scientific literature or the popular media. For broader and more technical perspectives, consult our monthly “Current Wisdom.”

The United Nation’s Intergovernmental Panel on Climate Change (IPCC) seems more intent on maintaining the crumbling “consensus” on anthropogenic global warming than on following climate science to its logical conclusion—a conclusion that increasingly suggests that human greenhouse gas emissions are less important in driving climate change than commonly held.

This fact is obvious from the embarrassing lack of internal inconsistency contained in the leaked versions of  the IPCC’s Fifth Assessment Report. The Summary for Policymakers, a succinct and brief document supposedly encapsulating what is in the entire 3,000-page report is supposed to be approved by closing time on Friday, at a meeting currently taking place in Stockholm.

In no place will this internal inconsistency be more obvious than in how the IPCC deals with the discrepancy between the observed effectiveness of greenhouse gases in warming the earth and this effectiveness calculated  by the climate models that the IPCC uses to project future climate change.

The warming effectiveness is known as the “climate sensitivity” and is the key parameter in how much the earth’s surface temperature rise as a result of the increasing atmospheric concentration of carbon dioxide and other greenhouse gases. Most all climate impacts are related to the climate sensitivity—the lower the climate sensitivity, the fewer the impacts.

One problem. Climate scientists don’t know what the value of the climate sensitivity really is.

Not because the calculation is complicated—just take how much the global average temperature has changed over some longish time period (a couple of decades or longer) and divide by much energy was used to force that change.

More IPCC Misdirection: Its Dodgy Sea Level-Rise Assessment

Global Science Report is a weekly feature from the Center for the Study of Science, where we highlight one or two important new items in the scientific literature or the popular media. For broader and more technical perspectives, consult our monthly “Current Wisdom.”

 

The UN’s Intergovernmental Panel on Climate Change (IPCC) is set to release its Fifth Assessment Report (AR5) of the physical science of climate change at the conclusion on its editorial meeting in Stockholm scheduled from September 23-26th.

A version of its Summary for Policymakers (SPM)—perhaps the most influential portion of the report as it is the widest read—has been “leaked” to generate media interest in the upcoming release. It certainly has, but perhaps not in the manner intended. The leaked SPM has revealed a document so flawed and removed from current science that it has been described as not only being  “obsolete on the day that it is released, but that it will be dead wrong as well” (okay, we wrote that).

Examples already abound as to the problems evident in the leaked SPM. Here we add another—this one having to do with the recent rate of sea level rise.

In the Summary for Policymakers section of its Fourth Assessment Report (published in 2007) the IPCC had this to say about the rate of sea level rise:

Global average sea level rose at an average rate of 1.8 [1.3 to 2.3] mm per year over 1961-2003. The rate was faster over 1993 to 2003: about 3.1 [2.4 to 3.8] mm per year. Whether the faster rate for 1993 to 2003 reflects decadal variability or an increase in the longer-term trend is unclear.

Since then, we have highlighted numerous findings in the scientific literature that present strong evidence that the increase in the rate of sea level rise since 1993 is largely not an increase in the longer-term trend (or at least not from human-caused climate change which is the IPCC’s implication) and that the short-term rate of sea level rise has been slowing, and returning back towards the long-term average.

But the IPCC’s heart remains hardened.

The IPCC Is Pretty Much Dead Wrong

Global Science Report is a weekly feature from the Center for the Study of Science, where we highlight one or two important new items in the scientific literature or the popular media. For broader and more technical perspectives, consult our monthly “Current Wisdom.”

As the U.N.’s Intergovernmental Panel on Climate Change (IPCC) nears completion of its Fifth Assessment Report, it is becoming obvious that not only is the report going to obsolete on the day that it is released, but that it will be dead wrong as well.

We have discussed the implications of the IPCC’s failure to adequately ingest new literature—a failure that results partially from the cumbersome IPCC process and partly because the IPCC doesn’t want to include some findings that run counter to its storylines. The major implication being, of course, that the IPCC reports mislead policymakers around the world, which has a trickle-down effect on all of us who are subject to any resulting policies.

In our post on Monday, we noted the following passage from the “leaked” Summary for Policymakers of the upcoming Fifth Assessment Report:

[Climate] Models do not generally reproduce the observed reduction in surface warming trend over the last 10–15 years. There is medium confidence that this difference between models and observations is to a substantial degree caused by unpredictable climate variability, with possible contributions from inadequacies in the solar, volcanic, and aerosol forcings used by the models and, in some models, from too strong a response to increasing greenhouse-gas forcing. [italics in original]

We were generally pleased to see the IPCC admit that climate models are largely failing to capture the rate of rise (or lack thereof) of the global average surface temperature observed over the past 10-15 years. As we pointed out on Monday, we had written as much ourselves a few years ago.

But, the IPCC went way wrong in this paragraph in which they stated:

There is very high confidence that climate models reproduce the observed large-scale patterns and multi-decadal trends in surface temperature, especially since the mid-20th century. [italics in original]

No, they don’t.

Peer-reviewed or Not, the IPCC Accepts Our Conclusion

At the end of this month, the UN’s Intergovernmental Panel on Climate Change (IPCC) is scheduled to release the physical science basis of it Fifth Assessment Report on climate change. Between now and then, the final wording of its highly visible and influential Summary for Policymakers (SPM) will be hashed out in a meeting in Stockholm. The current draft version of the SPM has been “leaked” in order to drum up some media attention for the upcoming meeting/report.

Among many interesting statements in the draft SPM, this one particularly caught our eye:

[Climate] Models do not generally reproduce the observed reduction in surface warming trend over the last 10–15 years. There is medium confidence that this difference between models and observations is to a substantial degree caused by unpredictable climate variability, with possible contributions from inadequacies in the solar, volcanic, and aerosol forcings used by the models and, in some models, from too strong a response to increasing greenhouse-gas forcing. [italics in original, bold added by us]

We found this interesting because back in 2010, we, along with several co-authors, wrote a paper titled “Assessing the consistency between short-term global temperature trends in observations and climate model projections.” In that paper, we demonstrated  that climate models do not generally reproduce the observed reduction in surface warming trend over the last 10-15 years. We also wrote that this was the result of some combination of inadequacies in the evolution of anthropogenic forcing (including aerosols), natural variability (both that which is captured and that which is insufficiently handled by climate models), as well as the strong possibility that climate models were producing too much warming for a given amount of greenhouse gas emissions.

Specifically, we wrote:

Helping Out the Times

Global Science Report is a weekly feature from the Center for the Study of Science, where we highlight one or two important new items in the scientific literature or the popular media. For broader and more technical perspectives, consult our monthly “Current Wisdom.”

Let us see if we can help New York Times’ global warming reporter Justin Gillis out.

In his article yesterday about the upcoming Fifth Assessment Report of the U.N.’s Intergovernmental Panel on Climate Change (IPCC), Gillis laments that the IPCC seems to be tamping down some of the more alarmist scenarios when it comes to the projected rate of rise of global temperatures and sea level.

Concerning projections of sea level rise, Gillis bemoans that the IPCC looks like (the final version of the Summary for Policymakers of the new report isn’t scheduled for release until the end of the this month at the conclusion of an IPCC editorial meeting in Stockholm) it will discount the “outlier” estimates that the rise this century will exceed five feet. Gillis writes “The drafters of the report went with the lower numbers, choosing to treat the outlier science as not very credible.”

When it comes to how fast the global average temperature is projected to rise, Gillis rues the possibility that the IPCC will lower its assessed value of the climate sensitivity, writing “In this case, the drafters of the report lowered the bottom end in a range of temperatures for how much the earth could warm, treating the outlier science as credible.”

The Tenuous Link between Stronger Winter Storms and Global Warming Becomes Even Weaker

Global Science Report is a weekly feature from the Center for the Study of Science, where we highlight one or two important new items in the scientific literature or the popular media. For broader and more technical perspectives, consult our monthly “Current Wisdom.”

Come the cold season, whenever there is some type of strong storm system near the U.S. Eastern Seaboard—be it a Nor’easter, a blizzard, or ex-hurricane Sandy—you don’t have to look very hard to find someone who will tell you that this weather is “consistent with” expectations of climate change resulting from human greenhouse gas emissions. The worse the storm, the more “consistent” it becomes.

The complete collection of climate science describes just how complex the physical processes are governing such storm systems. Teasing out any anthropogenic influence, including even the direction of any influence, is darn near impossible. Claims to the contrary are usually based on a highly selective assessment of the science or the data.

A case in point:

The latest en vogue explanation linking human greenhouse gas emissions to strong winter-season East Coast storms involves changes in the characteristics of the jet stream—a river of fast moving air in the atmosphere that influences both the strength and the forward speed of extratropical storm systems. A prominent (in the media, anyway) research study last year by Rutgers’s Jennifer Francis and University of Wisconsin’s Stephen Vavrus suggests that the declining temperature difference between the Arctic and the lower latitudes (adding greenhouse gases into the atmosphere warms colder, drier regions more so than warmer, wetter ones—with the notable exception of Antarctica) has led to changes in the jet stream which result in slower moving, and potentially stronger East Coast winter storm systems.