November 15, 2006

Stalagmite Story

Do stalagmites grow from the ceiling or the floor of cave? Time is up – they grow from the floor of caves (stalactites grow from the ceiling), but the key is that they grow over long periods of time. Some stalagmites are thousands of years old and if they are in just the right type of cave, they can preserve a signal of temperature and precipitation levels over the time they grew.

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October 26, 2006

Relief for Africa

Droughts and/or floods – blame global warming, right? Time and Newsweek are all too quick to blame either one on global warming, Al Gore’s movie certainly gave us vivid images of both severe droughts and severe floods, and to this day, ongoing drought in the Southwest is blamed on global warming in some circles. The Summary for Policymakers in most recent (2001) Intergovernmental Panel on Climate Change (IPCC) Report claims “In the mid- and high latitudes of the Northern Hemisphere over the latter half of the 20th century, it is likely that there has been a 2 to 4% increase in the frequency of heavy precipitation events.” Also, IPCC notes “Over the 20th century (1900 to 1995), there were relatively small increases in global land areas experiencing severe drought or severe wetness.” However, IPCC claims “In some regions, such as parts of Asia and Africa, the frequency and intensity of droughts have been observed to increase in recent decades.” In the main body of the document, we find in Southern Africa “significant decreases in precipitation being observed since the late 1970s.”

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October 24, 2006

For Peat’s Sake: Warmer is Better

Imagine your dog digging a hole in the backyard, and somehow, you then have an intricate story to tell about the climate history of human civilization. This is somewhat the case from an article published recently in the journal (we doubt you read regularly) Palaeogeography, Palaeoclimatology, Palaeoecology. In the global change fraternity, it is referred to as “Palaeo.”

A team of scientists from China’s State Key Laboratory of Loess and Quaternary Geology and the State Key Laboratory of Environmental Geochemistry turned their attention to a peat bog at Hongyuan in central China; they extracted a 5 meter core from the peat that contained a climate signal of the past 6,000 years. The grasses that built the peat over the centuries preserved an oxygen 18 isotope (d18O) signal over the entire 6,000 year period. The team of Xu, Hong, Lin, Zhu, Hong, and Jiang note that “For plants using precipitation as source water, the isotopic signals of precipitation can be modulated and recorded into plant cellulose through series of plant physiological processes. Since both the relative humidity and the amount of precipitation vary mildly, the oxygen/hydrogen isotopic fractionations during the plant physiological processes should be relatively constant. Therefore, the variation of d18O in plant cellulose should mainly reflect that of the precipitation. Because source water of the grass in the studying peat land is predominantly meteoric water, the d18O of peat cellulose should be quantitatively correlated to that of the precipitation, and thereby to air temperature.” More simply, the peat can tell us about the temperature over the past 6,000 years.

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October 23, 2006

Tropical Seas Sink Hockey Stick

Defending the “Hockey Stick” depiction of hemispheric or global temperature for the past 1,000 years just got a lot tougher. The “Hockey Stick” curiously wipes out the “Medieval Warm Period” of 1,000 years ago and the “Little Ice Age” that began 450 years ago and ended around 1900. We are supposed to look at the blade of the stick and conclude that the warming of the past 100 years is completely unlike anything seen for at least 1,000 years. It comes as no surprise that the “Hockey Stick” is prominently presented in many of the documents of the Intergovernmental Panel on Climate Change (IPCC). Defenders of the “Hockey Stick” make claims that the Medieval Warm Period and Little Ice Age were confined to the mid-to-high latitudes of the Northern Hemisphere and not felt throughout the rest of the world. This always seemed odd to us at World Climate Report given that variations of solar output seem to explain the higher temperatures 1,000 years ago and the colder temperatures of the Little Ice Age.

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October 20, 2006

Diatom Diatribe

If you have followed World Climate Report over the past few years, you are aware that we have taken countless swings at the “Hockey Stick” depiction of planetary temperature. The “Stick” is popular with the global warming crowd for it wipes out the “Medieval Warm Period” of 1,000 years ago and the “Little Ice Age” that began 450 years ago and thankfully ended around 1900. The “Stick” makes the warming of the 20th century look incredible, disturbing, and completely unmatched over the past 1,000 years. The only explanation for the recent warming must be the dreaded buildup of greenhouse gases.

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October 17, 2006

Another Swipe at the Hockey Stick

We have covered the “Hockey Stick” controversy many times at World Climate Report, but an article appeared recently in the Proceedings of the National Academy of Sciences that further buries the “Hockey Stick” depiction of planetary temperature.

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May 25, 2006

More Evidence of Arctic Warmth (a long time ago)

There are a lot of folks running around shouting that recent Arctic warming is, to use a favorite alarmist word, “unprecedented”—which means, to them at least, that we are approaching “dangerous” levels of climate change. It seems a bit odd to equate “unprecedented” with “dangerous,” since the former implies something that is novel, while the latter implies something that is known. So, for instance, since we know that for a good 90% of the past 400,000 years the earth was locked into ice age conditions, it would seem that a “precedented” cooling would be perceived to be far more “dangerous” than an “unprecedented” warming, wouldn’t it? But we digress.

In any case, how close to being “unprecedentedly” warm are we in our northerly latitudes? (We focus here on the Arctic because the Antarctic has been cooling for the past several decades, so that pretty much eliminates temperatures there from being unprecedented).

The answer, not very.

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December 9, 2005

Natural Warming Larger Than Thought?

Below are some observations found in a couple of recent journal articles that have received little attention—hmm, we wonder why?

The first observation was made by a team of paleoclimatologists led by Jan Esper in a viewpoint paper entitled “Climate: past ranges and future changes,” published in Quaternary Science Reviews. Esper and colleagues examined the amplitude of the temperature variations that have been reported for earth’s temperature during the past millennium. These include studies from the by-now familiar names of Mann, Moberg, Jones, Esper and Briffa.
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March 24, 2005

Reviewer Comments: Extracting a Climate Signal from 169 Glacier Records

A new paper that is soon to appear in the print version of Science magazine reconstructs the temperature history of the earth for the past 400 years using data gathered from 169 glaciers from around the world. Problems with this publication again lead us to wonder what is happening to the peer-review process at our major scientific journals. Here, we offer our comments, had we been one of the reviewers of the paper.
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March 3, 2005

Hockey Stick, 1998-2005, R.I.P.

The “hockey stick” representation of the temperature behavior of the past 1,000 years is broken, dead. Although already reeling from earlier analyses aimed at its midsection, the knockout punch was just delivered by Nature magazine. Thus the end of this palooka: that the climate of the past millennium was marked by about 900 years of nothing and then 100 years of dramatic temperature rise caused by people. The saga of the “hockey stick” will be remembered as a remarkable lesson in how fanaticism can temporarily blind a large part of the scientific community and allow unproven results to become “mainstream” thought overnight.
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