Is this month’s big snowstorm in the East a product of global warming?
An affirmative answer tends to bring derisive laughter. Nevertheless, it’s true. Hard as it may be to believe, blizzards like this one are part of what the experts tell us to expect of a warming climate.
A warming climate doesn’t mean there won’t be winters. It does mean more heat and therefore more energy in the atmosphere. Warmer air can hold more moisture. (Most skiers can remember being told that “it’s too cold to snow.”) Warmer temperatures also mean that moisture on the ground evaporates more rapidly. Together, these phenomena mean that more water cycles between the Earth and sky, evaporating more quickly and coming back down as rain or snow in greater volume. This more vigorous global hydrological cycle is one of the most certain characteristics of a greenhouse-altered climate.
More energy and moisture in the atmosphere also raises the probability of more intense weather events, particularly of more extreme precipitation. This predicted characteristic of greenhouse warming has already been documented for the United States. Based on a century-long record, our weather has become more extreme in the past 15 years, with an index 40 percent higher than natural fluctuation should produce. The greatest single change has been in the proportion of extremely heavy precipitation - 2 inches of rain or more in 24 hours. In the past year Midwesterners coped with the second “100-year flood” in two years, and Texans had flooding with hailstones the size of baseballs.
Capping a two-year review by several thousand scientists, 120 governments agreed last month that “the balance of evidence … suggests a discernible human influence on global climate.”
In other words, greenhouse warming is under way. There remains considerable uncertainty about how much and how fast climate will change, but even in the lowest case the average rate of warming is expected to be “greater than any seen in the last 10,000 years,” a major change in climatological terms.
No single weather event tells you anything about climate, and no single one can be linked to greenhouse warming. Natural variability can produce a blizzard or freak flood at any time. The key point is that events like these are what we should expect - not in the future but right now. We are already living in a changing climate that holds more potential for events like White Monday.
The old saw, “Everybody talks about the weather, but nobody does anything about it,” no longer holds. We are all doing something about it with carbon dioxide, methane and other greenhouse gas emissions every day.
That means keep the shovels handy, but don’t expect predictability. Greenhouse effects can be gauged most confidently as global averages. A few changes seem pretty certain on the continental scale, but very little can be said about local climate. Also - this only sounds like an oxymoron - expect surprises. Climate is what is known as a non-linear system. Even relatively simple non-linear systems are unpredictable. Infinitesimal change in one factor can produce enormous changes in outcomes. When subjected to large nudges, such as those caused by greenhouse gas emissions, such systems are, in the words of the international review panel, “especially subject to unexpected behavior.”
In other words, we can expect a class of predictable surprises - more weather extremes like this blizzard - and unpredictable surprise as well.
As the debate begins in earnest over what to do about greenhouse warming, the storm is a useful reminder of how vulnerable we still are to the weather. With air-conditioned cars, irrigated agriculture and artificial snow on the ski slopes, it’s easy to think that we’ve left behind the era of dependence on Mother Nature. It ain’t so.
From losses in air and ground transportation, food and retail sales, chaos in school schedules and lost worker productivity - not to mention cleanup costs - this will be a multibillion-dollar storm. The New York area alone is already estimating costs in excess of $1 billion. Federal disaster funds have been necessary to keep road and ambulance crews working. This comes on top of last year’s killing heat waves, the $12 billion flood of ‘93, and the $17 billion cost of Hurricanes Andrew and Iniki in ‘92, to mention just a few among recent (perhaps not wholly) natural disasters.
Adaptation to changing climate is perfectly possible, but it’s a tricky business. Cities could begin to budget for more snowplows, but with no certainty that they’ll be needed. With plenty of certain needs, that becomes a very tough call. Other adjustments will involve juggling much larger costs with the unknowns. Many could prove to be agonizingly difficult public choices.
Think of the blizzard of ‘96 as a glimpse of a part of the likely greenhouse future.