The Global Warming Scapegoat

Floods in Europe! Hurricanes in the US! Droughts in India! The scapegoat: Global warming, an irrefutable fact which remains unchallenged by any reputable scientist. Governments, bureaucrats and non-governmental organizations convening in New Delhi this week will attempt to stave off these looming environmental catastrophes with discussions and resolutions.

They'll be meeting at the 8th Conference of Parties (COP-8) to the United Nations Framework Convention on Climate Change. A discussion of how countries can deal with an increase in severe weather events due to global warming is on the agenda.

Climate crusaders have utilized individual weather events to buttress their argument that nations must act quickly to prevent death and destruction caused by human-induced global warming. The news media are quick to lap up this claim, treating any extreme weather event - be it hurricane, blizzard, drought or tornado - as more evidence of impending environmental doom.

A 1999 study by Sheldon Ungar of the University of Toronto confirms this phenomenon, indicating that American television viewers are substantially more likely to see coverage of disasters than their counterparts thirty years ago. Such increased coverage leads the viewer to perceive an overall increase in severe storm activity. However, the empirical evidence on actual trends tells a different story.

Most scientific analyses of historical severe storm records -- including thunderstorms, hail events, intense precipitation, tornadoes, hurricanes, and winter storm activity -- show no overall upward trend in severe weather over the past half century. The trends are downward in other severe storm categories, although well within the natural variability of the climate system. In other words, there is a severe mismatch between perception and reality.

Let's look at some examples. First, scientists have examined available tornado data, and have been unable to identify any realistic upward trend in tornado activity. Using historical data collected from 1950 to 2000, no observable trend in severe tornado occurrence is seen over the last fifty years. Tom Grazulis, head of The Tornado Project, notes that 'any link of tornado activity with climatic change of any kind should be treated with the greatest skepticism. The ingredients that go into the creation of a tornado are so varied and complex that they could never be an accurate indicator of climate change.'

Scientists with the United Nations Intergovernmental Panel on Climate Change (IPCC) concurred, saying 'No systematic changes in the frequency of tornadoes, thunder days, or hail events are evident in the limited areas analysed.'

Another popular misconception relates to the frequency of hurricanes. Media reports often claim that climate scientists believe hurricanes and tropical storms will increase in frequency and intensity as the planet warms in response to elevated concentrations of greenhouse gases.

Yet the many scientists who have examined selected hurricane records over the past century have found no upward trend. Some found declining levels of tropical storm frequency and intensity in the specific types of tropical cyclones they examined. Robert M. Wilson, a research scientist at the National Atmospheric and Space Agency in Alabama, examined intense hurricanes in the Atlantic Basin over the period 1950 to 1998, and found a decreasing trend, with fewer intense hurricanes during warmer periods.

The IPCC's view on tropical storms was that 'Changes globally in tropical and extra-tropical storm intensity and frequency are dominated by inter-decadal and multi-decadal variations, with no significant trends evident over the 20th century.'

The same applies to blizzards, extra-tropical cyclones, and winter storms: overall, there appears to be no upward trend in severe weather over the past half century. Many scientists have identified an increase in heavy precipitation, but this observation is consistent with models that show an invigorated hydrological cycle in a world warmed by greenhouse gas buildup. What may be observed in coming years is an increase in absolute damage caused by such events, because people are living closer to areas that are more prone to storm activity.

There is considerable concern about future climate change and potential impacts on severe storms. General circulation model simulations do exist that suggest an increase in greenhouse gas concentration could significantly warm the planet and create an environment more favorable for severe storms over mid-latitude continental areas. Nonetheless, the typical doomsday presentation regarding global warming often ignores or distorts crucial facts found in reports of the UN's Intergovernmental Panel on Climate Change.

Most scientists would agree that present-day numerical climate models (because of their low spatial resolution and poor quality of input data) have substantial limitations with regard to predicting future changes in severe weather events in any specific region of the planet, and their results should be interpreted with caution. Ultimately, weather patterns are only one part of a very complicated debate about the potential effects of higher greenhouse gas concentrations.

Woven together with increased news coverage of disasters, and a public audience prone to pay attention to bad news, the models and empirical data are often manipulated to rally support for misguided policies that would have little impact on greenhouse gas concentrations, and whose climate impact would be undetectable for many decades to come.

Though climate crusaders during COP-8 in New Delhi are likely to argue otherwise, uncertainty and disagreement still characterize the climate change debate. Many scientists agree that current proposed policies would actually have little impact, even if the public believes otherwise.

Dr. Robert C. Balling, Jr., is director of the Office of Climatology and associate professor of geology at Arizona State University (USA), and a contributor to Sustainable Development: Promoting Progress or Perpetuating Poverty? (Profile Books, 2002).

This article may be republished without prior consent if acknowledgment is given.