It got dry, and that must be the influence of global warming. Wait--then there were downpours, which proved the greenhouse effect. A monster hurricane crossed North Carolina; global warming must be the cause. No, wait--out comes a book about the most deadly hurricane in U.S. history, which hit in 1900, long before there was greenhouse gas buildup. Snowfall has decreased some in recent years, and that must prove global warming. But wait--when cities were snowed in during the winter of 1996-1997, commentators blamed greenhouse disruption. Annual temperatures have been high during the '90s, so the world must be warming. But wait--when winters were frigid during the 1970s, there were congressional hearings on whether an ice age was beginning. It's hot, it's cold, it's dry, it's wet--and don't get us started on El Nino.
As cable TV channels and extended local newscasts increasingly fill airtime by reporting weather details--and even the national networks send their reporters to hurricane areas to scrunch up inside designer slickers and shout, "I think I just felt a raindrop!"--the notion has taken hold that every barometric fluctuation must demonstrate climate change. This anecdotal case for global warming is mostly nonsense, driven by nescience of a basic point, from statistics and probability, that the weather is always weird somewhere. But, even as public attention has fixated on greenhouse claims by anecdote, the less dramatic, technical case for climate change has been gradually strengthening. Artificial warming is far from proven, but today the scientific evidence is stronger than it was five years ago. Most research suggests that a warmer world now seems probable; that altered climate patterns may be in store; that the chance of truly dangerous global warming, though still low, is rising. The worst aspect of attributing every dry spell or cloudburst to the greenhouse effect may be that such reasoning obscures the real concern: that credible signs of climate change are in fact beginning to appear.
One reason there is so much flummery in the global warming debate is that the weather in the Northeast United States, where the opinion-makers live, has a disproportionate effect on whether greenhouse concerns are taken seriously. During the summer of 1999, most of the Northeast experienced a drought; and, between July and September, The New York Times' op-ed page ran no fewer than four articles asserting that an artificial greenhouse effect was now proven, in part by dehydration. Then autumn brought drenching rains to the Eastern seaboard. The phase of wetness combined with the phase of dryness to make it an average year for precipitation, the apparent portent having "washed out," in statistician lingo, into normality. This did not prevent commentators from switching to a claim that showers proved global warming. "Go outside: try to understand that the sun beating down, the rain pouring down, the wind blowing by are all human artifacts. We don't live on the planet we were born on," one Times op-ed declared. Perhaps one shouldn't speak for all Times contributors, but I live on the planet I was born on, and feel it can be said without fear of contradiction that the sun is not a "human artifact."
Because weather is short-term and expected to vary, using it to draw conclusions about climate is treacherous. Weather is what happens today; climate is what happens during your lifetime. It is climate, not weather, that society needs to care about. In recent years, whenever a record high temperature is set, it has been common to hear global warming invoked as the reason. But record temperatures, high or low, are statistical "outliers," or nonstandard effects, that rarely reveal anything. The highest temperature ever recorded in the United States was in the year 1913; long before greenhouse gas accumulation began. Europe's record high occurred in 1881, Australia's in 1889, South America's in 1905, Africa's in 1922.
Hurricane incidence, currently spoken of as disturbingly high, is also inconclusive as an omen of climate change. Distribution of what the National Oceanic and Atmospheric Administration (NOAA) calls "major landfalling hurricanes" is basically equal before and after greenhouse gases, with the 1910s and '20s having about the same number of major Atlantic cyclones as the 1980s and '90s. A devastating hurricane, Andrew, struck in 1992, and an abnormally large hurricane, Floyd, arrived this year. But the strongest U.S. hurricane ever was in 1935. Hurricanes became a media obsession in the mid-'90s, when there were two consecutive above-average years for such storms. But those years stood out mainly because most of the period from 1964 to 1994 was below the historic average; commentators had forgotten how frequently hurricanes can occur.
Tornadoes are currently on a frightening upswing: there were more of them in the fourth quarter of 1998 than during any previous quarter in the nation's history, while January 1999 saw the most U.S. tornadoes ever in a single month. This is a somber concern for those who live in tornado zones, but does it suggest global warming? Greenhouse effect theory calls for warming mainly in high latitudes, which should reduce the poles-to-equator temperature gradients that power storm formation; a greenhouse world might have less violent weather. Charts of tornado incidence in the postwar period show 1998 and 1999 spiking up out of nowhere, not representing any slow-building trend; what's happening may be a harbinger, or it may be random variation.
This summer a strain of encephalitis was detected in New York City, and, being close to the media's oxygen, it occasioned one Times writer to opine that greenhouse triggered "outbreaks" of plague-like proportions are "descending on us." If so, our bodies are choosing a funny way to show it: by getting healthier. Though the World Health Organization has cautioned that climate change could cause the spread of some diseases, mainly by extending the range of tropical contagion, no such effect has manifested itself in public health data. As greenhouse gases accumulate, rates for almost all diseases are declining almost everywhere in the world, with the tragic exception of aids in Africa. (There is evidence that ocean-temperature changes relate to disease incidence among marine mammals.)
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