There is a new paper (in press in the journal Geophysical Research Letters) that presents a lesson that we all should keep in mind—results based on reconstructions of climate phenomena that are based on once or twice removed “proxy” indicators, may not be as reliable as they appear (or as they are presented) to be. If this brings hockey sticks and salacious emails to mind, you are not alone.

“Proxies” are putative indicators of climate for which there are no direct measurements. Tree rings, for example, are wider when the summer is wet and not too hot. The actual “explained variance” between them and, say, annual temperature is complex to derive and not all that high. The same is true for most other types of proxies (e.g., corals, ice cores, lake sediments, stalagmites, boreholes, etc.). Therefore, the uncertainties in using proxies to “reconstruct” some aspect of the climate are typically large (certainly larger than typically portrayed) and making (robust) conclusions from such analyses becomes a bit tricky. Such problems are among the reasons that many people jumped all over Michael Mann’s infamous “hockey stick” reconstruction of climate, which claims to accurately represent annual temperatures on a year-to-year basis back some 1000 years. Lesson: be very careful with proxy climate data.

Today’s example involves wildfire occurrence in the western U.S., and the climate patterns that may influence it.

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As we have covered in previous essays, global warming alarmists insist that the southwestern United States is getting drier and will get substantially drier in the future due to the buildup of greenhouse gases. They bolster their claims by results from a relatively large number of articles in the professional scientific literature and countless comments in various UN IPCC reports. Throw in pictures of declining water levels at Lake Mead, some fountains in Las Vegas and golf courses in Phoenix, and just like magic, a scary scenario is produced.

As with virtually every other element of the climate change issue, the literature produces some surprises, and the drought in the Southwest claim runs up against some interesting realities. The latest article on this subject appears in a recent issue of the Journal of Geophysical Research and once again, the results are at odds with the popular perception of increased drought in the Southwest.

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In recognition of the recent discovery of the world’s largest beaver dam, we take a look into the activities of past beavers to see what they may be able to tell us about previous climate changes, and we speculate on the impacts that on-going climate changes may be having on the likes and dislikes of current beavers.

World’s largest beaver dam in found in Northern Alberta, Canada.

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One of the ongoing debates in the climate change world involves the popular prediction of more droughts, longer droughts, and droughts of greater intensity. The underpinnings of this prediction are easy to follow, so this is definitely a strong pillar in the climate alarmist camp. As the temperature increases, potential evapotranspiration (PET) will certainly increase. There are many equations describing the relationship between PET and temperature, and they all indeed show PET would increase should the temperature increase. The physics here is solid. So if PET increases, actual evaporation will increase in areas with even a small amount of soil moisture, and in the absence of some compensating increase in rainfall, soil moisture will be depleted. The combination of increasing temperatures and decreasing precipitation should all but guarantee the place will become drier thereby yielding the increase in drought duration, intensity, and frequency. There is always a drought somewhere on the planet to point to as evidence that this is really happening, will likely get worse in the future, and all the rest. We’ve all heard it a million times … “If we don’t act know, ______ will happen” (fill in the blank, but today, we will focus on droughts).

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If you really want to hit a home run with a global warming story, manage to link climate change to the beloved rainforest of the Amazon. The rainforest there is considered by many to be the “lungs of the planet,” the rainforest surely contains a cure for any ailment imaginable, all species in the place are critical to the existence of life on the Earth, and the people of the Amazon are surely the most knowledgeable group on the planet regarding how to care for Mother Earth.

The global warming alarmists have taken full advantage of the Amazon and they are very quick to suggest that the Amazon ecosystem is extremely sensitive to climate change. Furthermore, not only can climate change impact the Amazon, but global climate itself is strongly linked to the state of the Amazon rainforest.

But, as usual, there is more to this story than meets to eye (or, rather, the press).

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We are sure you have heard that global warming is causing more frequent and intense droughts throughout the world. Right? The claim is easy to make – higher temperatures increase evaporation rates, soil moisture is depleted, and drought conditions result. Indeed the Technical Summary of the most recent IPCC assessment includes “More intense and longer droughts have been observed over wider areas, particularly in the tropics and subtropics since the 1970s. While there are many different measures of drought, many studies use precipitation changes together with temperature. Increased drying due to higher temperatures and decreased land precipitation have contributed to these changes”. Further, they write “Although precipitation has increased in many areas of the globe, the area under drought has also increased. Drought duration and intensity has also increased. While regional droughts have occurred in the past, the widespread spatial extent of current droughts is broadly consistent with expected changes in the hydrologic cycle under warming. Water vapour increases with increasing global temperature, due to increased evaporation where surface moisture is available, and this tends to increase precipitation. However, increased continental temperatures are expected to lead to greater evaporation and drying, which is particularly important in dry regions where surface moisture is limited.” The bottom line in the table below from the IPCC’s Technical Summary leaves little doubt that the IPCC thinks that droughts have become more frequent, they have been caused in some part by humans, and they will become more frequent in the decades to come.

A major article on global-scale drought has appeared recently in the Journal of Climate by drought experts from Princeton University and the University of Washington; the work was supported by the U.S. Department of Energy the National Oceanic and Atmospheric Administration. We saw an interesting sentence in their abstract as Sheffield et al. wrote “Globally, the mid-1950s showed the highest drought activity and the mid-1970s to mid-1980s the lowest activity.” That does not seem consistent with the story coming from the IPCC.

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Of the many pillars that support the alarmist view of global warming is that droughts will increase in many parts of the world. This prediction is fairly straightforward, for if temperatures increase, potential evapotranspiration (ETo) should increase as well. If precipitation stays the same in the future and ETo increases with higher temperatures, the area would see a reduction in soil moisture and a trend toward drought. Of course should precipitation be reduced while ETo rates increase, the trend toward drought could be severe. In the ultimate alarmist view, ETo increase and extreme precipitation increases, and the area would then see an increase in both floods and droughts. We have heard it all before and we have covered these topics in many essays, but the beat goes on and on.

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In nearly every presentation on global warming, we hear that floods and droughts will be more severe as the temperature rises. Believe it or not, and who would not believe it given thousands of websites on the issue, there are many scientists who believe the opposite. We have covered these topics in many previous essays, and a recent article in Quaternary Science Reviews reinforces our skeptical viewpoint.

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In the Wednesday December 5th, 2007 issue of the New York Times appeared a story by Felicity Barringer titled “Precipitation Across U.S. Intensifies Over 50 Years.” In it, Ms. Barringer reports on a new study released by an organization called Environment America that she described as “a national group that advocates new laws and policies to mitigate the effects of climate change.” The focus of the Environment America report was on the results of an analysis they performed examining trends in “extreme” precipitation frequency across the United States (apparently Environment America has spread these results to their arms in individual states, Environment Colorado, Environment California… you get the idea). The research was funded by the Pew Charitable Trusts. As Ms. Barringer reported, Environment America concluded that “Across the United States, the number of severe rainfalls and heavy snows has grown significantly in the last half-century, with the greatest increases in New England and the Middle Atlantic region” and, of course, that this was just as predicted to occur from global warming. Lest you think that more precipitation is a good thing, Environment America is quick to warn that “An increase in the frequency of storms delivering large amounts of rain or snow does not necessarily mean more water will be available” and that “[w]hile it may seem like a paradox, scientists expect that extreme downpours will be punctuated by longer periods of relative dryness, increasing the risk of drought.”

That the New York Times chose to highlight the Environment America report is interesting for a number of reasons, among them: 1) the report did not appear in the scientific literature (rather it was released by an environmental organization), 2) a day prior to the Times article, a paper was published in the peer-reviewed scientific literature which concluded that “extreme” precipitation was increasing across the United States (but no mention of it was made by Ms. Barringer), and 3) a paper published in the peer-reviewed scientific literature back in 2004, also described increases in “extreme” precipitation events across the United States, but also cautioned that based upon the nature of precipitation, increases in precipitation amounts are virtually always accompanied by apparent increases in “extreme” precipitation events and thus singling out “extreme” precipitation events without discussing overall precipitation trends is alarmist by its very nature. Oh, we forgot to mention, that the two papers in the scientific literature that found increases in extreme precipitation across the U.S. included among their co-authors some folks often deemed industry-funded global warming skeptics (Brommer, Cerveny, Balling, 2007; Michaels, Knappenberger, Frauenfeld, Davis, 2004). Perhaps our papers didn’t warrant coverage in the Times because we failed to include breathless prose about how global warming was to blame, or perhaps because we failed to outline steps that should be taken to reduce carbon dioxide emissions, or maybe we didn’t time the release of our papers to coincide with a major international meeting on climate change (although one of them was published by chance this week). Or maybe, it was that pointing out that the basic findings by some global warming “skeptics” closely matched that from “concerned” environmental organizations would take all the fun out of vilifying the skeptics, so it was best to simply ignore them to avoid the awkwardness altogether.

A closer look at the Environment America paper clearly shows it to be the inferior of the three papers—at least if scientific significance is the standard by which it is judged. If global warming alarmism is deemed the most important attribute, well, then there is no contest.

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According to 1,000s of websites trumpeting the horrors of global warming, we find countless claims that the ongoing build-up of greenhouse gases is causing droughts and floods all over the world. Hardly a week goes by nowadays without a front page news story about some weather or climate calamity occurring somewhere on the planet, and global warming is repeatedly claimed to be the cause. Turn the radio to NPR for an hour or so, and you will certainly be told how the failure of the United States to sign the Kyoto Protocol has caused some disastrous flood or drought.

Several articles have been published recently allowing us to catch a glimpse of centuries of climate variations in China, and as we have seen in hundreds of other similar studies, nothing all that unusual has been happening lately. The first of these recent articles will soon appear in Climate Dynamics and was written by the team of Shen, Wang, Hao, and Gong of the Atmospheric Sciences Research Center of the State University of New York. They note that “In recent decades, eastern China has suffered increased droughts in its north and increased floods in its south. The studies of climate models suggested that this trend could probably be attributed to the climate effects of black carbon aerosols and human-induced land cover changes”. Holy smokes – black carbon and land use? Shen et al. apparently haven’t been listening to enough NPR for surely drought and floods in China are related to global warming!

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