Winter isn’t over yet and it has already been a tough one for flooding. Whatcom County, for example, saw multiple back-to-back atmospheric rivers in November lead to record-breaking flooding on the Nooksack River.
Floods on the Nooksack and elsewhere have severely impacted communities: damaging homes, closing roads, killing livestock and more. But in this devastation we have an opportunity to learn more about the impacts of extreme floods — and to ensure that future floods are less destructive.
As with all weather disasters we can’t pin the blame uniquely on climate change: Flooding like this could undoubtedly have happened in the absence of warming. But climate change has loaded the dice, making these kinds of floods more likely. Warmer temperatures mean that our storms bring more rain and less snow, and we’ve already seen several inches of sea level rise along most of our coastline. Both of these changes are already contributing to larger floods.
Research tells us the changes in snowpack and sea level will accelerate dramatically over the coming decades. Adding to our troubles, models project that today’s biggest atmospheric river events will bring 10% to 20% more rain by the end of the century.
All of these factors add up to bigger floods in the future, and more of them. For the big rivers in the Puget Sound region, the 100-year flood is projected to bring anywhere from about 20% to 50% more water by the end of this century, compared to what we’ve seen in the past. On the Skagit River, a recent study found that today’s 100-year flood will become a 22-year flood by the end of the century, occurring nearly five times as often. Studies project similar changes beyond Puget Sound, especially for rivers that draw from high-elevation snow-covered areas upstream.
Our challenge now is to reduce the impacts of flooding on our communities. We can do that by learning from these events when they happen. Weather disasters like the floods of this winter can show us where impacts are most severe, how people are affected by flooding and which strategies might work best for reducing risks.
Locals often have answers to these questions. I’ve talked to farmers, for example, who can point to the spot on the river gauge that means their fields will flood. Flood managers, similarly, understand the trade-offs that are required to balance limited time and resources, and sometimes conflicting interests. And residents can often speak to the systems issues that stood in the way of emergency response and recovery.
But to capture these lessons we need to plan ahead, setting aside resources and devising a strategy for learning. Communities will rightly be focused on emergency response and recovery from these disasters, so outside help may be needed. There are many ways this could be done; I won’t pretend to be the most qualified to devise a plan. What I can say is that, as devastating as they may be, our best way of understanding climate impacts is by documenting these events as they unfold. Let’s take that opportunity, using it to help us build a more resilient future.