Roanoke Times
Copyright (c) 1995, Landmark Communications, Inc.
DATE: TUESDAY, March 14, 1995 TAG: 9503140088
SECTION: EDITORIAL PAGE: A5 EDITION: METRO
SOURCE: NORMAN MACDONALD AND JOSEPH SOBEL
DATELINE: LENGTH: Long
The new scientific evidence which disputes these assertions is found in the recently released Accu-Weather report: ``Changing Weather? Facts and Fallacies about Climate Change.''
Based on an analysis of weather over the past 100 years, Accu-Weather found that:
The slight increase in average climate temperature that has occurred during the past century falls well within the limits of natural climate variability and does not signal a man-made ``greenhouse'' crisis.
Severe storms such as tornadoes and hurricanes have not shown any tendency to occur more frequently today than they have in the past.
The heavy January rains in Southern California are not unprecedented.
Record high temperatures are not occurring more frequently now than they have at other times in the past 100 years.
Data collected from scientists and the National Weather Service confirm that hurricanes and typhoons have not increased in frequency. In fact, the number of tropical storms that eventually became hurricanes varies widely throughout the 109 years of record keeping. For example, there were four hurricanes in 1992 (the year Hurricane Andrew struck Florida and Louisiana), compared with 10 hurricanes in 1887, and 11 in 1916.
In addition, concerns that tornadoes are becoming more frequent and severe are not well-founded. The data show that tornadoes in the strong (winds from 113 to 206 mph) and violent (winds between 207 and 318 mph) classifications have not increased from 1953 to 1993, the last year data are available. Conversely, the reported number of weak tornadoes (winds less than 112 mph) has increased. Undoubtedly many small tornadoes sighted today would have gone unreported in years past. America's increased population, urban sprawl and greater public awareness have resulted in better detection. So, while we are spotting and reporting more small tornadoes, it is not clear that occurrences actually have increased.
January's 12 inches of rainfall and flooding in Southern California have led some to question whether those events are unusual and produced by global warming. Rainfall records in Los Angeles, dating back to 1878, provide the answer to both questions: No.
There were five monthly record rainfalls before this century. In December 1889, Los Angeles received 15.8 inches of rain. This superseded the record-setting month of February 1884, when the city received 13.37 inches of rainfall. Interestingly, the recent January rains, despite their drenching, were well below the record for that month. In January 1969, Los Angeles received 14.94 inches of rain.
Recent independent analyses of temperature records by university meteorologists have confirmed Accu-Weather's conclusions that high temperatures in the past decade across the entire nation are not unique.
For example, the severe midwestern heat wave and drought of the late 1980s was more than matched by the ``dust bowl'' of the 1930s. In fact, record-high summer temperatures have been set many times in the Midwest, Northeast and Southeast over the last 100 years.
Average global air temperatures have increased by approximately one-half degree Celsius over the past century, but this increase is well within the range of natural variation. It is significant that most of the increase occurred between 1916 and the mid-1940s - before the rapid increase of man-made carbon-dioxide emissions that global-warming theorists claim is responsible for increased temperatures.
A natural question arises: If weather events today are no worse than they were throughout the last century, why does it seem weather has gotten more volatile?
First, there are the advances in technologies used to detect and record weather data, not the least of which are global satellite systems.
Second, the electronic media efficiently gather and report dramatic weather information from around the world. In the age of instant communications, enterprising television networks can bring severe storms right into our living room, virtually as they are happening. Less than two decades ago, this kind of instant access to dramatic events was not available to television audiences.
Yet another factor in the perceived increase in catastrophic weather is the fact that more people are living in coastal areas. This increases the likelihood that when storms strike, property damage will be great. Increasing losses may be of significant concern to the insurance industry, but they do not signal climate change or global warming.
At the same time property damages have increased, the number of American deaths caused by natural weather disasters has declined during the latter part of this century. The same technology that contributes to the perception that modern-day weather is more severe also provides a much better early-warning system that gives people in high-risk areas more time to evacuate, thereby saving lives.
We are much more aware of hurricanes, tornadoes, floods and droughts, but there is no evidence that they are increasing in intensity and frequency.
Moreover, there is no evidence that extreme weather events are linked to greenhouse-gas emissions in the environment. The point is that weather data should not be misused to imply that global warming catastrophe lies just over the horizon.
Norman Macdonald and Joseph Sobel, meteorologists for Accu-Weather Inc. in State College, Pa., are the authors of ``Changing Weather? Facts and Fallacies about Climate Change.''
Knight-Ridder/Tribune
by CNB