Global Warming—Not All It Is Made Out to Be
By Chip Knappenberger -- January 7, 2009In last Friday’s Wall Street Journal (Jan. 2, 2008), Science Journal editor Robert Lee Hotz reviewed the climate of 2008 and concluded that despite a relatively cool year, all signs were go for anthropogenic global warming proceeding at a rapid and destructive clip—perhaps even faster than climate models envisioned.
Hotz’s review was extremely selective, with the effect of keeping the specter of catastrophic global warming alive and well, in the face of mounting evidence that it has, in fact, become gravely ill.
A closer look at the recent behavior of global temperatures indicates that all is not well with climate-model projections of alarming climate change.
2008 added another year to a lengthening string in which the rate of global temperature rise has been far beneath model predictions showing that natural variability still plays a large role in everyday weather and climate. Man-made global warming has taken a back seat, at least temporarily, in driving climate.
The global average temperature in 2008 was ~0.2°F lower than it was in 2007 (the exact amount depends on whom you ask). Two-tenths of a degree may not sound like much, but consider that the best computer models constructed to mimic how our climate operates predict that as a result of our greenhouse gas emissions, the global average temperature ought to be rising at a rate of about 0.2°F every 5 years or so. A drop of two-tenths of a degree is a major step in the wrong direction.
Obviously, one year is too short a time to assess any climate trend or model. Natural variations in the earth’s weather/climate system are large enough to insure that global average temperatures do not smoothly step from one year to the next—even during “global warming.” So we must look over the longer term to get a better idea of what is going on.
Figure 1 shows the annual departures of the global temperature from the average value for the past three decades. (The data are from the University of East Anglia Climate Research Unit dataset). Clearly, over the past 30 years, global temperatures have risen overall. But, over the past 12 years, global temperatures haven’t budged. In the last six years, temperatures have actually fallen.
Figure 1. Global annual average surface temperature anomalies, 1977-2008 (data source: Climate Research Unit).
Much of this recent temperature behavior can be attributed to the timing of natural cycles and variations in the earth’s climate that are related to large-scale ocean and atmospheric circulation patterns in the Atlantic and Pacific oceans—phenomena such as the Atlantic Multidecadal Oscillation, the Pacific Decadal Oscillation, and the cycles of El Niño/La Niña cycles—and possibly to a small influence from solar variations. These natural influences can be tracked back in the climate record for hundreds of years and, as such, provide strong evidence that they are true components of the earth’s climate and not simply manifestations of recent anthropogenic global climate change.
Compare the observed temperature behavior (Figure 1) to the projections of future global surface temperatures made by climate models incorporating increases in the human emissions of greenhouse gases (Figure 2). Notice that the temperature projections made by climate models tend to rise steadily or in some cases accelerate a small amount with time during the first half of the 21st century—a condition opposite to recent observations.
Figure 2. Projections of global annual average surface temperature anomalies for the 21st century made by a collection of climate models run with a mid-range (SRES A1B) future emissions scenario. Each of the thin colored lines is a projection from a particular climate model, the thick black dotted line is the mean of all the models (source: IPCC, 2007).
What this all means is that climate models that are run with increasing concentrations of greenhouse gases are not replicating well the observed behavior of the earth’s temperature in recent years.
There are several possible reasons for this recent failure of the climate models. The first is that our scientific understanding of the workings of the earth’s climate system is incomplete. Important issues such as how clouds respond to changes in the earth’s temperature and human emissions are simply not well understood at this time. The second is that many processes are too complex to be thoroughly described in the models and/or operate at scales that are too small to be handled in climate models run on today’s best computers. In other words, existing computer power is not great enough to include all of the necessary details and therefore may be getting some things wrong. And third—in a sort of quasi-combination of the first two—a unique coincidence of “weather” events has occurred which has acted to offset much of the warming pressure from increasing greenhouse gas concentrations. However, models tell us that the likelihood of such an occurrence is growing exceedingly low as the string of years with a lack of global warming continues.
The net result of these combined problem areas is less-than-perfect models of our past and present climate (as evidenced by recent global temperature behavior) and unreliable projections of our climate to come. Instead of catastrophic climate changes involving rapid temperature increases, an accelerating sea-level rise, and a growing ferocity of hurricanes, we observe a slowing rate of global warming (as seen in Figure 1), a modest sea-level rise (e.g., Holgate, 2007), and hurricane behavior less related to global warming than to natural climate variations (e.g., Knutson et al., 2008). Other observed changes, such as increases in weather-related damages and destruction, are improperly attributed to changes in climate because they are thoroughly explained by increases in population and wealth (e.g., Pielke Jr., et al., 2008)—in other words, there are more material things getting in the way of naturally occurring storm systems.
When the data are fully examined, the specter of catastrophic climate change from our combustion of fossil fuels is not all that it is made out to be.
While coming years may or may not continue the cooling trend of the past several, they will almost assuredly continue to add to the growing evidence that our coming climate will likely be far less detrimental than the popular projections of it to which we are often exposed.
References:
Holgate, S. J., 2007. On the decadal rates of sea level change during the twentieth century. Geophysical Research Letters, 34, L01602, doi:10.1029/2006GL028492.
IPCC, 2007. Climate Change 2007: The Physical Science Basis, Working Group I Contribution to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge University Press, Cambridge, U.K., 996 pp.
Knutson, T., et al., 2008. Simulated reduction in Atlantic hurricane frequency under twenty-first-century warming conditions. Nature Geosciences, 1, 359 – 364.
Pielke Jr., R. A., et al., 2008. Normalized hurricane damages in the United States: 1900-2005. Natural Hazards Review, 9, 29-42.
[…] none too soon given recent developments. As Chip Knappenberger shows in a post today, scary alarmist scenarios that have driven Pew since its founding in 1998 (the year global […]
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http://scienceandpublicpolicy.org/originals/pew_center_science_brief.html
Nice blog guys. I don’t have anywhere the knowledge of energy and climate change that you all do, but I am indeed interested. I was wondering… could you put up a post on what you hope gets accomplished (vs. what might realistically happen) at the meeting in Copenhagen later this year to discuss the Kyoto Protocol? I’d appreciate a good expert opinion. Thanks!
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Hi there! I love the blog, but had a few critical comments about this post:
http://libertarian-left.blogspot.com/2009/01/properly-framing-skepticism-reply-to.html
Keep writing; I’ll keep reading!
Thanks for dropping by my site!
I think perhaps I misinterpreted the statement you made in your post. When you said “they will almost assuredly add to the growing evidence,” I read that as saying, “they will strengthen the case made by the growing evidence.” If so, then I think my criticism stands; the issues you cited don’t weigh in either direction with regard to the strength of the case made by the growing evidence.
But it now occurs to me that you may have meant that phrase in the sense of “they will add another, separate dimension to the case made by the growing evidence.” That is, that the case made by the growing evidence can be paired effectively with the notion that competing hypotheses are unreliable. If that’s what you meant, then I apologize for the misunderstanding and withdraw my criticism.
Parallel conversations are fun!:
http://libertarian-left.blogspot.com/2009/01/properly-framing-skepticism-reply-to.html?showComment=1232564940000#c349298708875060720
over the past 12 years, global temperatures haven’t budged. In the last six years, temperatures have actually fallen.
Chip, last March you told me that you and Pat are “attempting to publish a piece in Eos demonstrating that the idea that global warming “stopped” 10 years ago is nonsense. “ How’s that piece coming?
Much of this recent temperature behavior can be attributed to the timing of natural cycles and variations in the earth’s climate that are related to large-scale ocean and atmospheric circulation patterns in the Atlantic and Pacific oceans
On first glance this is unobjectionable, but here’s quite a bit of imprecision here, which leaves your intention rather vague (particularly as you note that “we must look over the longer term to get a better idea of what is going on”). What do you mean by “much” and “this recent”? Are you referring to 2001 on, or the past century? An unsophisticated reader could conclude that you think that GHGs and albedo-altering soot had no real effect on climate.
climate models that are run with increasing concentrations of greenhouse gases are not replicating well the observed behavior of the earth’s temperature in recent years.
My understanding is that climate models are intended to provide long-term projections based on guesses on GHGs and other inputs, not to forecast, much less “replicate”, weather over a few years. Or did I miss something?
The net result of these combined problem areas is less-than-perfect models of our past and present climate (as evidenced by recent global temperature behavior) and unreliable projections of our climate to come.
Agreed. But this provides no basis for comfort, much less a conclusion that “the specter of catastrophic climate change from our combustion of fossil fuels is not all that it is made out to be” – unless, that is, you have some particularly egregious short-term alarmism in mind that you care to point to.
While coming years may or may not continue the cooling trend of the past several, they will almost assuredly continue to add to the growing evidence that our coming climate will likely be far less detrimental than the popular projections of it to which we are often exposed.
“Almost assuredly”? There’s nothing in your post that provides any basis for predicting the future. Even with the current plateau and recent decline, temps remain well above what they were in the 80s and 90s, and a strong el Nino could easily ratchet temps up again, as we saw from 1996 to 1998.
If you feel so confident, perhaps you and Pat should move from the paid punditry business to the insurance business where, if you’re right and can find investors willing to back you, you can easily strike it rich and put folks like Munich Re and Lloyds out of business?
Danny,
Thanks for your thoughtful comments over at your blog site. In a single, rather limited piece, there is only so much I can go into and thus could not discuss the full nature of climate change. However, despite the limited content, I do not believe that I made the error of logic that you claim I did (and in any case, I didn’t mean to).
I quote you as saying “I believe that Knappenberger has mistaken the absence of evidence to be the evidence of absence” and yet in my article, as you quote, I state “they will almost assuredly continue to add to the growing evidence that our coming climate will likely be far less detrimental than the popular projections.” In other words, there is growing evidence that future climate change will not be as detrimental as often portrayed—so, in fact, I have no absence of evidence—it is just that discussing it all was not the intent of this particular article.
If you would like to see more about the large and growing amount of evidence that global warming is not proceeding along alarmist lines, I invite you to visit the website World Climate Report, where we have been discussing climate change issues for many years and where you will find myriad evidence that a close look at the science reveals a picture that is not nearly as scary as much of the press makes it out to be.
Thanks again for your interest in the topic and your readership!
-Chip
Danny,
Thanks again.
I meant that a relative flat temperature history in recent years is another piece of evidence that global warming is not looking to be catastrophic. Add this the modest sea level trends, most up-to-date research on hurricanes that doesn’t finger global warming, increasing trends in agricultural yields, declining human sensitivity to heat waves, etc., etc., (all documented at World Climate Report) and you start to build a pretty solid case that while there is an anthropogenic warming pressure on global climate, that the manifest changes won’t be, in net, terrible–especially if you are able to adapt—an ability for which we have shown a certain propensity.
-Chip