Climate change and flooded freeways

Climate Solutions Journal: In the late 1990s after pineapple express storms caused severe flooding and deadly mudslides across the Northwest, National Climatic Data Center Chief Scientist Thomas Karl said they were “an example of the type of weather patterns that would be expected to become more frequent and yield an increase in precipitation extremes as the climate continues to warm.” Welcome to the future. The Northwest was fire-hosed again in recent days, flooding communities and leaving them in the dark throughout western Washington state, while cutting I-5 from Portland to Seattle, and rail service to boot. As of today a lengthy detour to the east or an air flight remain the options for travel between the two major U.S. Northwest cities. Costs are placed at $4 million per day, and that is before expensive repairs to the I-5 roadbed are taken into account.

The connection of global warming to increased storms and rainfall is as easy to make as the connection of steam rising from a pot of water to the stove flame beneath – Heat causes evaporation. Global warming is heating the oceans, and the steamy, moist air rising from ocean surfaces is rocket fuel for storms. A warmer atmosphere can also hold moisture better. The line of clouds pointing from the tropical Pacific to the Northwest that show up on the weather report satellite photos are the physical illustration of these phenomena.

Of course, the scientific caveat is that no one weather event conclusively demonstrates global warming. The point here is that global warming loads the dice for more frequent and intense storms such as the Northwest has seen in recent days. When rainfall in the rain city of Seattle hits the second greatest one-day level in recorded history, and the record was set only in 2003, it provides a very suggestive indicator.

A new study just released by Environment America documents the increase in extreme precipitation events. The group examined rainfall records for 3,000 U.S. weather stations from the past 60 years and found a 24 percent increase. “We find that storms with extreme amounts of rain or snowfall are happening more often across most of America, consistent with the predicted impact of global warming.” The Northwest storms send another global warming alert, for they tie in to the single largest regional climate impact, snowpack loss. Climate scenarios project dramatic losses of mountain snowpack, ranging above 50 percent by mid-century. This will stress municipal water supplies, hydroelectric production, irrigated agriculture, river barging and salmon runs. This is because, even though greater autumn and winter precipitation is projected, more will fall as rain and less as snow.

Sometimes this will erode existing snowpack, as it did this week. The storms were a rain-on-snow event, the source of the greatest Northwest floods from the 1948 flooding that destroyed the city of Vanport on the Columbia, to the mid-1990s floods, to this week’s inundation. Climate Solutions reported on regional climate change impacts scenarios in our 1999 paper, In Hot Water. Unfortunately, the scenarios seem to be increasingly the reality of the local news. Climate change is moving far faster than human systems, especially our political system. We move slowly to respond even as we are swamped by the consequences of our climate pollution.

Flooded communities and a closed freeway underscore that climate disruption translates into economic disruption. Global warming will make a mess of us if we don’t deal with it in a serious way now, and that means commencing immediate and deep cuts in fossil fuel pollution. That means now.