Liberty Corner: Weather Wisdom

Wednesday, March 15, 2006

Weather Wisdom

Earlier today I read this subjective (and incorrect) assertion at Wired News:

The scientific evidence is now overwhelming that unchecked growth in fossil fuel use throughout the next half-century will produce a global climate catastrophe.

I was thinking about writing a post that lists all the debunking of the "evidence" of which I am aware. But World Climate Report comes to the rescue with data:

For over a century, a national network of “weather nerds” (for lack of a better term) have monitored backyard weather stations where they kept track of daily maximum and minimum temperature and precipitation using standardized instruments and measurement techniques. Called the U.S. Cooperative Observer Network (co-op for short), these data, which were submitted monthly for many decades on paper logs, were often used to fill in gaps from the more comprehensive observations taken by trained weather service employees at far fewer locations. But the utility of the co-op records to climate analysis was limited by their cumbersome, paper format. However, recently the interest in climate change spurred the government to digitize these paper records, thus adding many new stations to the existing network. With the addition of the co-op data, the number of stations from roughly 1890 to 1947 doubled or tripled relative to the previous baseline.
These updated records shed new light on the behavior of U.S. extremes. . . . The data since 1950 shows a clear positive trend that seems to be getting more extreme later in the record, with the last few years showing the greatest extremes. This fits very nicely with common journalistic sentiments that our climate is obviously in never-been-to-before territory. But inclusion of the pre-1950 data paints quite a different picture. Not only did the frequency of extremes vary markedly in the early 20th century days of very low greenhouse gas levels, but the frequency of extreme events in the late 1890s was at least comparable to that in our current climate. . . . [S]tatistical tests demonstrat[e] that the most recent period (1983-2004) was not statistically different from the earliest period (1895-1916) for many combinations of event severity and return period, although a few were significantly different. The bottom line here? The assumption that U.S. rainfall is clearly getting more extreme because of global warming is hardly obvious based on the new and improved record. . . .

The heat wave record . . . is dominated by the huge spike during the 1930s “Dust Bowl” era. In fact, the recent period is hardly noticeable in the longer-term context, even though the number of heat waves has increased recently compared to the cool summers of the 1960s and 1970s. . . .

If more cold waves are harbingers of global warming, then the peaks that dominated that 1980s have completely disappeared. And if we should expect fewer cold outbreaks, then how does one account for all the cold air outbreaks 1980s when the atmosphere had plenty of greenhouse gases? The cold wave record shows some interesting long-term variability but no obvious trend. . . .