Monday, July 28, 2014
Will the Pacific Northwest be a Climate Refuge Under Global Warming?
A compelling case can be made that the Pacific Northwest will be one of the best places to live as the earth warms. A potential climate refuge.
Let's analyze this important question.
I will start with a clean map and highlight problematic areas as the climate warms.
Sea Level Rise
Low-lying coastal areas will be vulnerable as sea-level rises 1-2 feet during the next 85 years. Based on USGS (U.S. Geological Survey) publications (for example, the USGS threat maps below), I have indicated problematic locations in red. Forget Florida.
Climate models are emphatic that the SW U.S. will get less precipitation and evaporation will increase as the temperature increases. This will substantially reduce water availability for agricultural and other uses (see figure for the situation in 2050 that is in the recent U.S. National Climate Assessment). Texas, Oklahoma, Kansas, eastern Colorado, Nebraska and Florida are also heavily impacted.
Based on this document and others, I have marked up the U.S. map with yellow to indicate areas that will be highly stressed for water.
Hurricanes and Tropical Storms
Although the latest research does not suggest that the number of hurricanes will increase, much of the literature is emphatic the the most intensive hurricanes will get considerably worse. The regions influenced by hurricanes should not change much, as illustrated by the150-year hurricane track climatology (see graphic). The SE U.S. and the East Coast are most threatened, and I note that more severe hurricanes can cause both increased storm surge damage along the coast and heavy
precipitation/flooding in in the interior. I have marked (in orange) additional locations that might be significantly affected by hurricanes.
Heat wave can be big killers, particularly for the elderly. Here is the temperature change maps from the latest U.S. Climate Assessment
The interior of the continent really heats up, with the West Coast moderated by the cool Pacific Ocean. So, in the U.S. map I have put purple dots for the blank locations with substantial heat wave risk.
My own research has suggested that atmospheric rivers could be enhanced under global warming, which might result in increased flooding, but only near major rivers draining western U.S. mountains. To denote that risk I will put a few green dots on the map. No issue for Seattle assuming the Howard Hansen dam is properly maintained.
So what conclusion does one inevitably reach by studying the IPCC reports, the U.S. Climate Assessment, and the climate literature?
- Temperatures will rise more slowly than most of the nation due to the Pacific Ocean (see below)
- We will have plenty of precipitation, although the amount falling as snow will decline (will fall as rain instead). But we can deal with that by building more reservoir and dam capacity (and some folks on the eastern slopes of the Cascades have proposed to do exactly that).
- The Pacific Ocean will keep heat waves in check and we don't get hurricanes.
- Sea level rise is less of a problem for us due to our substantial terrain and the general elevation rise of our shorelines. Furthermore, some of our land is actually RISING relatively to the sea level because we are still recovering from the last ice age (the heavy ice sheets pushed the land down and now it is still rebounding).
- There is no indication that our major storms...cyclone-based winds (like the Columbus Day Storm)... will increase under global warming.
- Increased precipitation may produce more flooding, but that will be limited to river valleys and can be planned for with better river management and zoning.