Tuesday, October 5, 2010

Planning for Extreme Weather Events

As I was sitting in the office one fine June day in 2009 watching a severe weather cell steamroll its way through the Willamette Valley, I couldn’t help but marvel at its awesome, enveloping presence and destructive potential. My officemates and I were first alerted to its impending arrival by the rapid darkening of the skies to the East and South of us. Then, almost imperceptibly at first but rapidly building to a crescendo, the riparian songbirds began filling the skies in what can only be described as a frenzy. The office was abuzz with nervous excitement as we all watched the wind begin whipping the waterfront vegetation – gently at first but rapidly increasing to “violent storm” and “hurricane” force winds (literally; 3-4 categories stronger than “gale force” winds on the Beaufort Wind Scale). According to the NOAA Severe Storm Alert for the area, winds had already been measured in excess of 70 mph and a tornado watch was issued for some of the surrounding areas (rumor had it that one had touched down about 5 miles east of us; it was later confirmed by the National Weather Service). And the excitement level in the office was fed by alarming statements in NOAA’s Tornado and Severe Thunderstorm warnings for the area:




But what I was most struck by (no, not lightning), was how these sorts of extreme weather events are becoming more commonplace in the Willamette Valley (throughout all of Oregon, the Pacific Northwest, and beyond, really). Indeed, tornadoes touched down in Oregon about 8.5 times per decade from 1950 through 1989, but touched down at three times that rate (~32 per decade) since (see below; data from NOAA’s National Climate Data Center). The trends look similar for Oregon’s extreme wind and precipitation events.

Number of tornadoes, by decade, that touched down in Oregon.

But extreme (think “outlier”) weather events are certainly not unique to Oregon. Globally, extreme weather events are cropping up with alarming regularity. One has only to watch the news for a couple of days to see a new high temperature “record setting day” in this place or that. Moscow, Russia, typically known for its cool (alright, cold) climate, had its first 100 degree Fahrenheit day last July. In fact, it had several 100 degree days this summer while dozens of other countries were also setting record high temperatures (see below). Los Angeles, California just set an all-time record high temperature (113 degrees F) while Seattle, Washington came one degree shy of setting an all-time record high September dewpoint (see an animation of the “moisture river” from October 2010, here).

Countries that set record high temperatures in 2010.

Climatologists indicate “extreme” weather events (think, 100-year flood event or the like) may become more commonplace as our planet experiences climatic changes. And extreme events can play a dramatic role in influencing a suite of biological and economic processes. One has only to search the web to find scores of examples (see some here, here, and here). Unfortunately, many of our biological and economic models do a relatively poor job of incorporating “infrequent” (and/or catastrophic) events. Partly as a result (see "The Black Swan"), natural resource management plans largely overlook these events when estimating future abundance and distribution of species. And disaster management plans are often ill-equipped to deal with large, catastrophic events that occur relatively frequently (project ARkStorm is a notable exception).

What is becoming increasingly clear is that as climate variability increases, the interval of “infrequent,” extreme events is decreasing. Is this novel in recorded human history? Not necessarily (think 1930’s US “Dust Bowl” droughts). We just happen to have recently been through a relatively stable period. But the importance of preparing for more frequent “extreme events” – both from a biological and economic perspective – should follow suit…but with enough urgency to put us ahead on the planning curve. Shouldn’t we at least have a sense for how the natural world might adapt to increases in frequency of these “extreme” events? Granted, extreme events are by their very nature, unpredictable. But we have smoke detectors and fire extinguishers in our houses in calculated anticipation of (and preparedness for) “the event,” even though the probability of it actually occurring is quite low. Shouldn’t we also be planning for these climatic, biological and economic low-probability, extreme events? Are we – as natural resource and economic managers – going to be prepared? Or are we going to maintain the status quo (e.g., crisis management) and be forced to shift our conservation efforts to “managed retreat”?