Sunday, April 17, 2005

OPINION/COMMENTARY

How the West Was Wet

One of the problems in communicating climate science concerns peoples' perceptions versus climate reality. For example, most middle-to-slightly-older-agers who grew up in the Mid-Atlantic region will tell you that it just doesn't snow like it did in their youth (and usually they will blame global warming). Indeed, the 1960s were a very snowy decade. But somehow, we tend to view what we grew up with as "normal," while everything different in our adult lives is "abnormal." [Caution: this applies to more than weather and climate.] Consider what happened in the American West in the early 20th century, when population grew roughly 50% from decade-to-decade, the largest regional growth spurt in post-colonial American history. People were lured by warm temperatures and abundant moisture. For much of that period, believe it or not, the West was a green paradise. Abundant moisture was so much du jour that allocation rights for Colorado River water, which have been contended ever since, were based upon what turns out to be the wettest period in nearly 1200 years. Had early 20th century planners had modern climatological analyses in their hands, it's doubtful they would have been so profligate with water distribution from what really is the only big river in the Pacific Southwest. Connie Woodhouse and three co-authors have just published an interesting paper that puts the southwestern moisture picture in long-term perspective. It contains some remarkable findings, which includes an obvious transition from domination by persistent and severe drought to relatively wet conditions some five centuries ago. Woodhouse et. al. also show how remarkably wet the 1905-1917 period was....

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