High tide flooding along the waterfront in Alexandria. Jacob Fenston / WAMU

USA - Extreme Weather and Sea Level Rise Among Top Climate Risks To D.C. Area, New Assessment Says

The latest National Climate Assessment shows the D.C. region is especially at risk of extreme weather, flooding, and sea level rise as the earth warms.

The congressionally mandated assessment, released today, also shows uneven progress in the region responding to a hotter planet.

“Adapting to climate change and reducing greenhouse gas emissions is an ultramarathon, it’s not a sprint,” says Jessica Whitehead, lead author of the assessment’s chapter on the Northeast region. “We all just got out of the gate.”

For the purposes of the assessment, the country is broken up into regions — there are seven in the contiguous U.S. The D.C. area is split between the Northeast and Southeast regions, with the Potomac River as the dividing line. This is the fifth National Climate Assessment; the last one was released in 2018.

In the Northeast, precipitation has increased in all seasons, according to the new assessment. Worryingly, the biggest increases have been in days with the heaviest rainfall.

“We’re getting these rainfalls in larger amounts over shorter periods of time,” explains Whitehead, director of the Institute for Coastal Adaptation and Resilience at Old Dominion University in Norfolk. “That has huge implications because all of our stormwater infrastructure, all of our sewer infrastructure, was built to handle much smaller storms.”

More rain is falling in shorter periods of time.National Climate Assessment

The D.C. region is also at heightened risk of flooding from storm surges, when tropical storms or nor’easters push water inland from the ocean. This type of flooding is exacerbated by sea level rise.

“Sea level rise could be upwards of two feet by mid-century, which is less than 30 years away,” says Jeremy Hoffman, lead author of the chapter on the Southeast, and director of climate justice and impact at the nonprofit Groundwork USA. The mid-Atlantic has experienced some of the fastest rate of sea level rise in the nation.

In many areas, these climate threats are compounded by social factors.

“The Southeast region is really uniquely threatened by climate change impacts, and this is partially due to the region’s history of racial and economic marginalization, which has placed many of our poor communities and communities of color at really rapidly growing risk from things like extreme heat, extreme precipitation, hurricanes and droughts,” Hoffman says.

In the Southeast, one of the most quickly growing regions in the country, suburban sprawl is making communities less resilient to climate change, according to the assessment. Since 1985, an area equivalent to 1.7 million football fields was turned from forest to developed land — the most of any region.

This land-use change leads to an increase in greenhouse gas emissions — encouraging car dependence — and also elevates climate risk.

“You can think of it as kind of like an expanding bull’s eye,” says Hoffman. “So, if a hurricane or severe storm is the dart, and climate change is throwing that dart faster and more intensely, then the larger the bull’s eye is, the easier it’s going to be for that storm to affect that place.”

The assessment documents that many cities and states in the Northeast region have put in place aggressive climate action plans, including Maryland and D.C. In the Southeast, such progress has been more spotty.

“Decision-makers frequently use outdated and/or limited information on climate-related risks to inform adaptation plans, which as a result fail to account for worsening future conditions,” reads the chapter on the Southeast. “These climate adaptation efforts also tend to be concentrated in wealthier communities, leaving under-resourced and more rural populations, communities of color, and Tribal Nations at growing and disproportionate risk.”

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