Heat vs. Cold Related Mortality; More Evidence on Solar Influences

by William Yeatman on October 10, 2000

in Science

Heat vs. Cold Related Mortality

More evidence has come in showing that cold weather is deadlier than hot weather. A new study in the British Medical Journal (September 16, 2000) analyzed temperature-related mortality statistics in Europe to determine the effects of changing temperatures on mortality rates.

The researchers determined the 3 degree C band of temperature in each region that they studied with the lowest mortality rate and then compared the mortality rates from this baseline band with temperatures above and below the baseline.

They found two things of significance. First, “Heat related mortality occurs at higher temperatures in hotter regions than in cold regions of Europe and does not account for significantly more deaths in hotter areas,” and that, “People in cold regions of Europe protect themselves better from cold stress at a given level of outdoor cold.” So, “Populations in Europe have adjusted successfully to mean summer temperatures ranging from 13.5 degrees C to 24.1 degrees C, and can be expected to adjust to global warming predicted for the next half century with little sustained increase in heat related mortality.”

Second, there are many more cold-related deaths than heat-related deaths in Europe. “Mean annual heat related mortalities were 304 in North Finland, 445 in Athens, and 40 in London. Cold related mortalities were 2457, 2533, and 3129 respectively.” The researchers argue that, “Our data suggest that any increases in mortality due to increased temperatures would be outweighed by much larger short term declines in cold related mortalities.”

More Evidence on Solar Influences

New research is making a strong case that solar variability is a major factor in global warming. Using satellite and other data, researchers have determined that the suns impact on global warming may be much larger than previously thought. According to the Vancouver Sun (September 25, 2000), “The new studies say that the main reason is a solar-energy surge and a particularly big increase in ultraviolet (UV) light. This has coincided with a doubling in strength of the suns magnetic field.”

Paal Brekke, the deputy project scientist for the European Space Agencys Solar and Heliospheric Observatory (Soho) satellite, said that this could change the way we approach global warming policies. “Taxing carbon-based fuels may be good for other reasons, but our evidence suggests it will not be much help in keeping the Earth cool,” he said.

The new findings were a subject of debate at a recent conference entitled, “The Solar Cycle and Terrestrial Climate,” which took place on Tenerife (Canary Islands). Mike Lockwood, of the Rutherford Appleton Laboratory, believes that the sun played a significant role in the past but that now greenhouse gases are more important. “I have doubts about how low some people want to keep the solar contribution,” he said. “Over the whole of the last century, Id say it was perhaps about 40-50 percent of the total. But the important point is that most of that was in the first 50 years. From 1970 to now the main influence has been human activity, and thats rather scary.”

Brekke said, “The Sun may explain up to 20 percent of global warming over the last 30 years, if you look only at irradiance. But if you include other, indirect effects, including cosmic rays and their influence on cloud cover, that percentage could rise. The pattern of systematic change in the global climate over recorded history seems to follow the observed changes in cosmic ray flux. It is consistent with the explanation that a low flux corresponds to fewer clouds and a warming climate, and vice versa.”

Dr. Joanna Haigh of Imperial College, in London, added that the Soho data show that changes in UV radiation, which contributes to ozone creation (a potential greenhouse gas), are larger than once thought. “How much the ozone responds, and where it changes, is crucial,” she said. “In the upper stratosphere, about 50 km up, an increase in ozone will have a cooling effect. But about 20 km above the Earth, more ozone will act like other greenhouse gases, trapping infrared radiation and enhancing warming. I think its very unlikely anyway that the response of ozone to solar UV will be as dramatic as some reports have claimed.”

The IPCC report, according to Dr. Mike Hume, executive director of the Tyndall Centre for Climate Change Research, is very guarded on the subject. “It allows both a substantial role for the Sun, and an inconsequential one,” he said. “All the evidence suggests that its greenhouse rather than solar forcing thats the problem, but the IPCC leaves the door open. It is this range of uncertainties that makes future predictions so difficult.”

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