Irreplaceable Smithsonian artifacts threatened by climate change

WASHINGTON — President Warren Harding’s blue silk pajamas. Muhammad Ali’s boxing gloves. The Star-Spangled Banner, stitched by Betsy Ross.

Nearly 2 million irreplaceable artifacts are housed in the National Museum of American History, part of the Smithsonian Institution, the biggest museum complex in the world.

Now, because of climate change, the Smithsonian stands out for another reason: Its cherished buildings are vulnerable to flooding, and some could eventually be underwater.

Eleven Smithsonian museums and galleries form a ring around the National Mall. But that land was once marsh. And as the planet warms, the buildings face two threats. Rising seas will eventually push in water from the tidal Potomac River and submerge parts of the mall, scientists say. More immediately, increasingly heavy rainstorms threaten the museums and their priceless holdings, particularly since many are stored in basements.

At the American history museum, water is already intruding.

An assessment of the Smithsonian’s vulnerabilities, released last month, reveals the scale of the challenge: Not only are artifacts stored in basements in danger, but floods could knock out electrical and ventilation systems in the basements that keep the humidity at the right level to protect priceless artifacts.

Scientists at the nonprofit group Climate Central expect some land around the two museums will be underwater at high tide if average global temperatures rise by 1.5 degrees Celsius (2.7 degree Fahrenheit), compared with preindustrial levels.

The planet has already warmed by 1.1 degrees Celsius and is on track to rise 3 degrees by 2100.

Smithsonian officials want to build floodgates and other defenses and move some collections to a proposed site in suburban Maryland. But Congress has yet to fund many of those efforts, and the changes would take years to implement.

Until then, the Smithsonian struggles, protecting the nation’s treasures with sandbags.