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OP-ED SCIENCE A MYTH:
GLOBAL WARMING IS HAPPENING

THOMAS R. KARL,1 KEVIN TRENBERTH2 and JAMES HANSEN3

1 National Oceanic and Atmospheric Administration, National Climatic Data Center, Asheville, NC, USA

2 Climate Analysis Section, National Center for Atmospheric Research, Boulder, CO, USA

3 NASA/Goddard Institute for Space Studies, Greenbelt, MD, USA

The recent article by the chemists, Robinson and Robinson, appearing in The Wall Street Journal's Op-ed section on Thursday, December 4, 1997 "Science Has Spoken: Global Warming is a Myth" claims that, "there is not a shred of persuasive evidence that humans have been responsible for increasing global temperatures." The title of the article and the article itself contain many factual errors, unsubstantiated claims, and misleading statements. We enumerate some of these:

  • Robinson and Robinson state, "The rise in [carbon dioxide] probably results from human burning of coal, oil, and natural gas, although this is not certain." On the contrary, there is no doubt that the atmospheric carbon dioxide increase is due to human activities as well as the increase in atmospheric concentrations of other greenhouse gases, such as methane, nitrous oxide, hydrofluorocarbons, perfluorocarbons, ozone in the troposphere, and sulfur hexafluoride. What's more, scientific evidence shows that greenhouse gases, such as carbon dioxide, can remain in the atmosphere for centuries.

  • Robinson and Robinson state that the global warming hypothesis is no longer tenable, and that scientists have been able to test it carefully and it no longer holds up. A review of the scientific literature reveals this simply is not true. First, there is no question that adding greenhouse gases will change the climate. There is a greenhouse effect. Second, man-made causes play a role. Most climate change detection studies find a strong likelihood, a 95% chance, that the pattern and magnitude of global warming are related to man-made causes.

  • Robinson and Robinson state that the highest temperatures occurred about 1940. They further state that during the past 20 years, satellite measurements of atmospheric temperatures have actually tended to decrease. Unfortunately, the Robinsons' discussion is misleading. There are several salient facts to consider. (1) Near-surface temperatures where we live, work, and grow our food, reveal that through 1996, 1995 was the warmest year. (2) Seven of the ten warmest years on record (since 1853, when instrumental records begin) have all occurred in the past ten years. (3) During 1997, temperatures over the land are at near-record high levels as computed by both the National Oceanic and Atmospheric Administration and the National Aeronautics and Space Administration. Moreover, the United Kingdom's Meteorological Office projects 1997 to be the warmest since 1853 when both land and ocean data are combined. (4) Near-surface temperatures have increased by about 1 degree Fahrenheit (0.625 Celcius) over the past century. (5) High above the surface of the planet, one satellite temperature record (made up of contributions from nine different satellites) that averages data between about 5,000 and 30,000 feet in altitude shows some slight cooling since 1979, but the same satellite, averaging over a greater layer of the atmosphere between about 10,000 and 50,000 feet, shows warming over the same period. Moreover, weather balloons with a longer history show significant warming when they are analyzed further back in time, e.g., after 1957. (6) Lastly, extensive analysis of paleoclimatic data from tree rings, ice cores, and other sources suggest that Twentieth Century temperatures are definitely higher than any century since 1400 A.D. Prior to this time, global coverage is incomplete.

The scientific community has established an extensive peer-review process where well-qualified experts can assess and test the veracity of scientific claims. In atmospheric science, there are dozens of high-quality scientific journals with a long history of profound articles. An incorrect major scientific claim would be extremely difficult to maintain because scientists earn their reputations by developing better explanations of observed phenomena. We know of no major scientific articles since the 1996 Intergovernmental Panel on Climate Change statement that "The balance of evidence suggests a discernible human influence on global climate," that directly challenges this conclusion. On the contrary, improved analyses, data sets, and models continue to support global warming as a real phenomenon.

We may agree with Robinson and Robinson on one point. There may be more serious issues than global warming that threaten continued advances in the quality of life for humankind. One of these is the attempt by Robinson and Robinson to misinform the general public about the scientific process and what is known and unknown in the frontiers of science.

December 18, 1997

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