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.
Recall our long essay series a few years (e.g., here) ago regarding the now-debunked “Hockey Stick” depiction of hemispheric and/or global temperatures. In 2001, the United Nations Intergovernmental Panel on Climate Change (IPCC) rolled out a depiction of temperatures over the past 1,000 years, and as seen below (Figure 1), the Medieval Warm Period and the Little Ice Age all but disappeared, and the warming rate of the most recent 100 years looked nothing short of incredible. The second plot below (Figure 2) comes from the most recent IPCC assessment, and note that (a) the plot is clearly labeled as “Northern Hemisphere,” (b) the recent warming looks less impressive, and (c) the Medieval Warm Period and the Little Ice Age periods are more prominent.
For more than 100 years, climate scientists have fully understood that if all else were held constant, an increase in the atmospheric concentration of carbon dioxide (CO2) would lead to an increase in the near-surface air temperatures. The problem becomes a lot more complicated in the real world when we consider that “all else” cannot be held constant and there are a lot more changes occurring at any one time than just the concentration of CO2. Once the temperature of the Earth starts inching upward, changes immediately occur to atmospheric moisture levels, cloud patterns, surface properties, and on and on. Some of these changes, like the additional moisture, amplify the warming and represent positive feedback mechanisms. Other consequences, like the development of more low clouds, would act to retard or even reverse the warming and represent negative feedbacks. Getting all the feedbacks correct is critical to predicting future conditions, and these feedbacks are simulated numerically in global climate general circulation models (GCMs). Herein lies a central component of the great debate — some GCMs predict relatively little warming for a doubling of CO2, and others predict substantial warming for the same change in atmospheric composition.
Over the past decade, considerable debate existed regarding the temperature history of the Earth on the time scale of millennia. If you followed our discussion on the subject, you know that one camp would like you believe that the highly-publicized warming of the planet over the past century is absolutely unprecedented over the past few thousand years. This group seems to fixate on the “hockey stick” representation of the temperature history of the past 1,000 years, and they hold on to the stick in spite of evidence to the contrary. Many others have argued based on proxy evidence throughout the world that the past few thousand years include a very warm period 1,000 years ago and a cold period 500 years ago; in their eyes, the warming of the past century is not at all unusual. These folks even go on to suggest that the Earth today may not be yet as warm as conditions 1,000 years ago, despite the 100 ppm increase in atmospheric carbon dioxide over the past century.
About a month ago, we ran a piece reflecting back on the behavior of the satellite-derived temperature history of the earth’s lower atmosphere for the past 10 years of so. We commented that the two major realizations of the temperature history of the lower atmosphere—one derived by researchers at the University of Alabama-Huntsville (UAH) and the other by researchers at Remote Sensing Systems (RSS)—seemed to be drifting apart in recent months. Well, it has since been determined that a slight computational error involving the data for 2007 had been introduced in the RSS routines, and this error has now been corrected (see here for more detail) so all is now well again in the world of satellite-derived global temperatures—or it is?
Yes and no.
The Arctic is melting, right? There is simply no questioning this pillar of the greenhouse scare, and images of ice melting, polar bears struggling, and indigenous people crying the blues are all part of any self-respecting presentation of global warming. Imagine a study published in a major journal showing that a location in the Arctic has “a trend of -0.3°C over the last 1,500 years.” Of course, you would never have learned of such a result had you not discovered World Climate Report.
(January 9, 2008: An important update has been added to the bottom of this post)
A couple of interesting items have come to light recently regarding the temperature of the earth’s lower atmosphere as measured by satellites. Here we run briefly run through some of them, in no particular order.
The U.K.’s Hadley Center has issued a forecast that 2008 will come in as one of the top 10 warmest years in its 150+ year record of global average temperature. While this forecast is about as risky as predicting that the next box of a dozen doughnuts you buy will contain twelve of the one-holed wonders, the press seems enthralled by it, as virtually all major news wires ran the story under with some variant of the headline “2008 to be among hottest years on record.”
Here’s a trivial question for geography buffs: What is the capital of Nunavut (pronounced ‘Noo-na-voot’)? If you know that the answer is Iqaluit (formerly Frobisher Bay), you win five stars. Of course, you are probably the only one in the room who has a clue about this place called Nunavut.
As seen in the map below (Figure 1), Nunavut is the largest and newest territory of Canada; it was separated officially from the Northwest Territories on April 1, 1999 via the Nunavut Act and the Nunavut Land Claims Agreement Act, though the actual boundaries were established in 1993. The creation of Nunavut resulted in the first major change to Canada’s map since the incorporation of the new province of Newfoundland and Labrador in 1949. Nunavut includes Ellesmere Island to the north, as well as the eastern and southern portions of Victoria Island in the west. Nunavut is both the least populated and the largest of the provinces and territories of Canada. It has a population of only 29,474 spread over an area the size of Western Europe. If Nunavut were a sovereign nation, it would be the least densely populated in the world: nearby Greenland, for example, has almost the same area and twice the population.
It’s that time of year again when we see headlines about 2007 being the mth warmest year on record over the past n years whether we are talking about the United States or the world as a whole. Reporters breathlessly reveal that the trend in temperatures is alarming and completely unprecedented over the eons of earth history. The buildup of greenhouse gases is immediately blamed, and we are all left to believe that the rising temperatures can only be explained by human emissions. Rarely does anyone seem to question the quality of the temperature data, and yet, articles appear regularly in the scientific literature showing that the near-surface air temperature measurements are fraught with errors, gaps, and any number of inhomogeneities.
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