A few weeks ago, over at the blog MasterResource.org, WCR’s Chip Knappenberger took a look at just how confident one should be regarding the amount of warming that anthropogenic greenhouse gas (GHG) emissions have caused since the mid-20th century.

The IPCC claims that it is “very likely” that “most” of the warming since then has been the result of human GHG emissions. In IPCC parlance, “very likely” means with a greater than 90% likelihood. The EPA parrots the IPCC’s claim in the Technical Support Document for their Endangerment Finding (TSD, p. 2):

Most of the observed increase in global average temperatures since the mid-20th century is very likely due to the observed increase in anthropogenic GHG [greenhouse gas] concentrations.

But, in his MasterResource.org article, Knappenberger shows that this statement is not supported by recent findings in the scientific literature—findings that have appeared in the literature subsequent to the publication of the IPCC’s statement. He concluded that the IPCC’s statement—especially the likelihood designation—should be re-evaluated in light of what we know now.

In some sense, however, Knappenberger’s analysis did not go far enough. While he used middle-of-the-road estimates for the warming influence of some non-GHG factors, in some cases he was being too conservative—like when it comes to the non-climatic influences on local thermometers—and, further, he failed to include a potential impact from solar changes.

So here, we take Knappenberger’s analysis a bit further, and show that it is easy to demonstrate, using the contents of the peer-reviewed scientific literature, that anthropogenic GHG emissions could be responsible for less than one-third of the warming in the extant global temperature records.

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Ben Santer has an article over at RealClimate defending himself against some claims made recently by Fred Pearce in a series of articles Pearce did for the U.K.’s Guardian in recent weeks.

In particular, Santer discusses a 1996 paper that he (and colleagues) published in Nature magazine in which they reported to have identified a human fingerprint on global temperature change. Well, actually, in his RealClimate article Santer primarily discusses his Response to a Comment that WCR’s Patrick Michaels and Chip Knappenberger published in Nature that pointed out that had Santer et al. used the full observational period of record available at the time they published their original paper (instead of a truncated one), that Santer et al.’s statements “about the strength of the evidence for human alteration of the lower tropospheric climate must be tempered.”

In Santer’s RealClimate piece, he claims that in his Response to our Comment, that he “demonstrated that this criticism was simply wrong.” And that “[u]se of a longer record of atmospheric temperature change strengthened rather than weakened the evidence for a human fingerprint.”

At RealClimate, Santer provided this link to his Response to our Comments. Here, for completeness’s sake, we provide a link to our Comment.

We invite you to read them both and see for yourself.

Personally, we are incredulous that Santer maintains, even to this day, that had they used the full period of available record—which he admits would have shown a decline in the correlation between models and observations—that this somehow “strengthened rather than weakened the evidence for a human fingerprint.”

We can only wonder what he would have concluded had the full dataset of observations maintained or strengthened his original correlation! Somehow we doubt that had the updated data strengthened the correlation between models and observations, that Santer would have come out and declared this as evidence the human fingerprint was fading.

(There is lots more regarding this issue (and others discussed by Santer in his RealClimate article) that resides in our back pages. To investigate for yourself, use our ‘back issues’ search function and enter “Santer”)

Back at the end of October, we gave you all a preview of what how the U.S. average annual temperature was shaping up for 2009. At the time we postulated that we were headed for another pretty normal temperature year (on the heels of 2008’s pretty normal temperatures). Now, after the 3rd warmest November on record was followed by the 14th coldest December, the final numbers for 2009 are in and we were pretty much right on the button.

The annual average temperature for the U.S. in 2009 was 53.13°F, just a smidgen above the long-term (1901-2000) average. This now marks two years in a row in which the U.S. annual average temperature has returned back to normal after its recent 10-yr stint in the much above normal category.

Now we await 2010.

It shouldn’t take too much longer before we can come to the determination that the 1998-2007 warm period was more a part of natural variability than a sign of anthropogenic climate change.

Figure 1. U.S. annual average temperature, 1895-2009 (source: National Climatic Data Center)

A new paper that is soon to appear in the journal Geophysical Research Letters finds that across the U.S. daily record high temperatures are being set at about twice the frequency of daily record low temperatures and that this ratio—number of record highs to the number of record lows, has been growing larger over the past 50 years.

The popular press seems to be particularly taken with this finding, although headline proclamations fail to disclose important details of the actual findings reported by the National Center for Atmospheric Research’s (NCAR) Gerald Meehl and colleagues.

Although you can hardly blame the press, because the NCAR press release did much to lead them down this muddy path.

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Early last January, when the final 2008 numbers were in for the U.S. annual average temperature, we ran an article titled “U.S. Temperatures 2008: Back to the Future?” in which we noted that “The temperature in 2008 dropped back down to the range that characterized most of the 20th century.”

2009 seems to be following in 2008’s footsteps.

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This is an interesting headline.

We thought the debate is over global warming.

Apparently, not.

Last week, a poll by the Pew Center for the People and the Press showed that there has been an erosion of the percentage of American’s who think that the earth is heating up.

And now, the AP’s Seth Borenstein is out there trying to find out whether or not the earth is cooling!

How things have changed during the past 10 years.

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There is a bit of press covering a just-published paper that concludes that the current climate and ecological conditions in a remote lake along the north shore of Canada’s Baffin Island are unique within the past 200,000 years—and anthropogenic global warming is the root cause. Which of course, spells t-r-o-u-b-l-e.

Somehow, that temperatures there were several degrees higher than present for a good third of the past 10,000 years and that there has been virtually no temperature trend in the area during past 50 years—the time usually associated with the greatest amount of human-caused “global warming”—was conveniently downplayed or ignored.

Go figure.

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For another look at how the results of the latest work by Kyle Swanson and Anastasios Tsonis—which show, among other things, that the earth’s climate most likely shifted into a state which could result in a slowed rate of global warming lasting for another decade or so—are impacting the processes (both scientific and political) of climate change, see this piece over at MasterResource.org.

“Has the climate recently shifted?” is the title of a just-published paper in Geophysical Research Letters by researchers Kyle Swanson and Anastasios Tsonis from the University of Wisconsin-Milwaukee. Their examination of this topic was undoubtedly prompted by the recent behavior of global temperature which shows that the rate of warming has dramatically slowed during the past 7-12 years.

Updating a methodology that they had previously developed and used to identify several changes in the climate state that occurred during the 20th century, Swanson and Tsonis examined the temperature data from recent years to see if another state change had taken place:

Here, a new and improved means to quantify the coupling between climate modes confirms that another synchronization of these modes, followed by an increase in coupling occurred in 2001/02. This suggests that a break in the global mean temperature trend from the consistent warming over the 1976/77–2001/02 period may have occurred.

In other words, the authors think that they have identified another in a string of break points that signal a change in the general state of the earth’s climate.

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The data are just in from the National Climatic Data Center and they show that for the year 2008, the average temperature across the United States (lower 48 States) was 1.34ºF lower than last year, and a mere one-quarter of a degree above the long-term 1901-2000 average. The temperature in 2008 dropped back down to the range that characterized most of the 20th century.

Figure 1 shows the U.S. temperature history from 1895 to 2008. Notice the unusual grouping of warm years that have occurred since the 1998 El Niño. Once the 1998 El Niño elevated the temperatures across the country, they never seemed to return to where they were before. Proponents of catastrophic global warming liked to claim that is was our own doing through the burning of fossil fuels, but others were more inclined to scratch their heads at the odd nature of the record and wait to see what happened next.

Figure 1. U.S. average annual temperature history 1895-2008 (source: National Climatic Data Center, http://climvis.ncdc.noaa.gov/cgi-bin/cag3/hr-display3.pl)

You see, prior to 1998, there was little of note in the long-term U.S. temperature record. Temperatures fluctuated a bit from year to year, but the long-term trend was slight and driven by the cold string of years in the late 19th and early 20th century rather than by any warmth at the end of the record. In fact, from the period 1930 through 1997, the annual average temperature actually declined a hair—despite the on-going build-up of atmospheric greenhouse gas concentrations. The only suggestion that “global warming” had involved the U.S. was to be found in the post-1997 period—a period unusual in that the temperatures went up and stayed up at near-record levels year after year. It was not so much that temperatures continued to climb after 1998, but just that they never fell. This grouping of warm years nearly doubled the apparent overall warming trend in U.S. temperatures (starting in 1895) from 0.07ºF/dedade (ending in 1997) to 0.13ºF/decade (ending in 2007). And with this doubling of the warming trend came the big push for emissions restrictions.

But now, 2008 comes along and has broken this warm stranglehold. Perhaps this is an indication that the conditions responsible for the unusual string of warm years have broken down—and maybe they weren’t a sudden apparition of anthropogenic global warming after all.

Only time will tell for sure. But, at least for now, things seem like they have returned to a more “normal” state of being.