VIRTUAL CLIMATE ALERT

February 24, 2003 Vol. 4, No.4

It seems that each recent Washington, DC winter brings interesting weather to the Nation’s Capital and that every bit of interesting weather generates inevitable attribution to an enhanced greenhouse effect. Whether the winter is unusually warm, dry, wet, or cold – icy or snow-filled, or just plain wonderful – someone, somewhere trumpets “global warming” as its cause. What used to be considered “the hand of God” now is attributed to humankind’s misdeeds with regard to use of fossil fuels and driving of SUVs.

What might analysis of actual weather measurements by observers in or near downtown Washington since the late 1800s lead a reasonable person to conclude? Surely it should be easy to discern evidence in such a long historical record of how humans have altered the DC climate in a way that makes life more miserable.

So far, winter 2002-2003 has been quite cool, especially in comparison with recent winters. This winter is about 10ºF colder than last year’s. It also has been relatively snow-filled. DC’s first snowfall came on December 5th. The city and its suburban environs still are digging out from under February’s whopper. The snowfall between February 15 and February 18 appears to be the fifth largest snow event in the historical record. For several surrounding locations the event was the biggest ever experienced. Rainfall and warmer temperatures just this weekend unleashed torrents of water stored as snow and added to a sense of weather crisis as sewers backed into basements as Great Falls in the Potomac above Georgetown tumbled with milk-chocolate-colored water topped with off-whitecaps.

It only took two days following the final snowflake for an Environmental Defense spokesperson to opine that February’s snow event was “very much in line with the predictions of climate models” that depict the potential effects of human-induced global warming. As early as January 28, the Boston Globe attempted to ascribe global warming as the source of the Northeast’s cold winter. What is left unascribed is how, according to the laws of physics, warmth causes cold – in other words how a cold and snowy winter can possibly result from an enhanced greenhouse effect.

Let’s begin our weather history lesson with a comparison of DC’s last two winters.

The winter of 2001-2002 recorded a total snowfall of 3.2 inches in the District of Columbia. There only are five winters since 1888 with less snow accumulation. Admittedly, as winters go, last year’s was quite warm. The December 2001 through February 2002 average temperature was the third-warmest on record. The mercury topped out at 77ºF on both January 30th and February 1st. There was not a single day when the high temperature fell below the freezing mark.

When, last winter, folks enjoyed the warm temperatures by spending more time out-of-doors than is usual strolling the city’s numerous parklands and trails, hitting the links, and picnicking on the Mall, we were scolded that our seeming good fortune in enjoying a warm, dry winter was a result of global warming. We were reminded that our wonderful weather surely must come at the expense of unfortunate others elsewhere in the world. The warmth was an indicator that our climate was changing; we could expect warm, snowless winters to become commonplace in our emerging greenhouse world.

But, let’s turn back the hands of time and recall winter in DC before there possibly could have been any large anthropogenic effect on our weather – back in the time when God or Mother Nature (not humans) were running the weather show.

In the Mid-Atlantic region, 1932 was “the year without winter.” December through February’s average temperature was 44.6ºF (about 8ºF above average) and was the warmest in the preceding hundred years, by far. Total DC snowfall was 5.0 inches, with four of those falling in a single March storm. Meaning winter’s “heart” virtually had been snow free.

In three days between January 13 and January 15, 1932, the mercury hit 74ºF, 75ºF, and 76ºF, respectively. Those temperatures still stand as records for those dates. The January 15, 1932 edition of The Washington Post reported, “Flowers have never ceased to bloom in the Capital this year, coaxed out by the succeeding days of warm weather…frogs are croaking in the reservoir…just like they do in the summer.” But, those poor, unenlightened staff writers made no mention of human activities being responsible for such strange goings on. To the contrary, people seemed happy with what they regarded as a fortunate turn in the weather.

Now for the winter of 1898-1899; it still is the All-Time Record Holder for the most snow-filled winter in Washington, DC. There were a total of 54 inches of the white stuff. A huge blizzard from February 11 through 13, 1899 dumped 20.5 of those 54 inches. Locations just outside the city reported up to 45 inches of snow. But even without that particular storm, the winter snowfall was more than twice the normally anticipated amount. Temperatures were bitterly cold, dropping to -7ºF on February 9 and -8ºF on the 10th; then it got really cold. When the mercury plummeted to -15ºF on the morning of February 11th, it set a record that still stands as the all-time lowest temperature recorded in DC. Such conditions at the close of the 19th Century hardly could have been given a nudge by any human-induced greenhouse effect.

Figures 1, 2, and 3 provide the complete history of combined January and February winter conditions recorded in downtown DC from 1888 through February 20, 2003. Figure 1 reveals how winter temperatures gradually have risen since very early in the record. Figure 2 shows how total (melted) precipitation declines a bit from the start of the record through about 1950 and then remains relatively steady. Figure 3’s record of snowfall is dominated by inter-annual variations and reveals no long-term trend.

Here is the simple, unadorned and un-spun fact: current Washington, DC winters are no different than winters of the past. This is not to say that an enhanced greenhouse effect and global warming have no influence on climate and weather in the Nation’s Capital. It is to say that it is absolutely impossible to detect any signal in the natural noise (variability) of DC’s wintertime climate. Until it becomes possible to detect such a “signal,” there is absolutely no scientific justification to support a claim that winter conditions this year, last year, next year, or in any winter one chooses, are attributable to an enhanced greenhouse effect.

Figure 1. The history of January and February average temperature in downtown
Washington, DC since 1888 (Note: The 2003 value includes data through February 20).

Figure 2. The history of January and February total precipitation in downtown
Washington, DC since 1888 (2003 value includes data through February 20).

Figure 3. The history of January and February total snowfall in downtown Washington, DC
since 1888 (2003 record includes data through February 20).

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Greening Earth Society Virtual Climate Alerts are published periodically in response to news coverage of climate-change advocacy that seeks to portray weather events and hypothetical climate scenarios generated by computer-based climate models as "climate reality." Virtual Climate Alert is coordinated by New Hope Environmental Services of Charlottesville, Virginia.