What to Know
The Chesapeake Bay Program's latest Bay Barometer progress report is the first to assess climate change's interactions with the watershed
The six states around the bay, and Washington, D.C., are now factoring in how climate change will affect runoff and how to mitigate it
It's essentially certain that sea level will rise faster and temperature will warm, even in a best-case scenario, one climate expert said
The Chesapeake Bay was swamped by record rainfall last year. Across the vast watershed, streams swelled with churning water that picked up sediment and chemicals and rushed into the bay, one of the most vibrant and important ecosystems in the country. And oysters suffered.
Watermen say they've been pulling up dead oysters when they fish near rivers. They blame a sudden influx of fresh water that wasn't salty enough for the oysters to survive. Other possible culprits could be what was in the water: a smothering blanket of sediment or nutrients from lawn fertilizer or septic systems that can contribute to algae sucking oxygen from the water.
"It's the largest amount of rain that's ever been recorded. I mean, how do you predict that?" said Robert T. Brown, Sr., president of the Maryland Watermen's Association.
Yet climate scientists are predicting more storms. Due to climate change, storms will likely hit the region more often and drop more rain and snow, a serious danger to go with rising seas and rising temperatures. Any increased runoff from that precipitation would intensify the pollution that federal, state and local governments have worked for decades to mitigate.
"We know it's going to get wetter and wilder in the mid-Atlantic," said Ben Grumbles, Maryland's secretary of the environment.
What experts don't yet know is exactly how that increased precipitation would combine with rising and warming seas and what effect it will may on wildlife. But the Chesapeake Bay Program, a partnership between governments, nonprofits and universities that protects and restores the bay, has begun to gauge the effects of climate change. This month, those efforts went public.
The latest edition of the program's annual Bay Barometer progress report, released in early April, is the first to assess climate change's interactions with the watershed. It finds that air temperature near the Chesapeake has risen 1-3 degrees Fahrenheit since 1901 while sea levels have risen 7-10 inches around the bay since 1960. More new indicators tracking climate change not included in the report are newly available online, as well.
Also this month, Maryland and Virginia, along with Washington, D.C., and the four other states in the Chesapeake Bay watershed, released first drafts of their newest water pollution-control strategies, which must now take climate change into account.
The strategies may be tweaked over the next few years, but the Environmental Protection Agency expects them to be in place by 2025. The public can comment on each plan until June 7.
The climate change indicators and the pollution-control plans are some of the most concrete steps taken so far to assess how much the changing climate may change the Chesapeake.
A DIET TO STOP DEAD ZONES
Members of the Chesapeake Bay Program have been talking about climate change for at least 20 years, but the partnership has been working to counter the danger posed by excessive nutrients in the water for longer. The program was founded in 1983, about a decade after the alarm was raised over the bay's underwater grasses beginning a serious decline.
When the nutrients nitrogen and phosphorus seep from human development into the waterway, they feed algae blooms. The blooms suck oxygen out of the water when they die and decay, creating dead zones that suffocate plants and animals in the water. The bay's dead zone usually lasts for four or five months each summer, according to the Chesapeake Bay Program, and it has averaged 1.7 cubic miles since 1985.
Excess sediment in the water can block the sunlight that underwater plants need to survive or help carry contaminants and harmful nutrients further into the bay.
The EPA in 2010 put the Chesapeake on what Grumbles called "a one-of-a-kind pollution diet" to cut the amount of nutrients and sediment reaching the bay by about a quarter.
Delaware, Maryland, New York, Pennsylvania, Virginia, West Virginia and D.C. have a maximum amount of nutrients and sediment that each can let into the bay from the 64,000-square-mile watershed, the country's largest such plan. The EPA also requires the states to provide a detailed watershed implementation plan that explains how to achieve those goals — the latest version is the document submitted this month that factored in climate change.
In a sign that the diet may be working, this year's Bay Barometer report found that, for the third year in a row, underwater grasses are more abundant in the Chesapeake than ever before recorded. But the report also found that toxins like PCBs are also on the rise, found partially or fully impairing up to 83 percent of the bay and its tidal tributaries as of 2016.
"The patient is recovering but the patient has a long way to go yet," said Donald Boesch, an influential marine scientist and former president of the University of Maryland Center for Environmental Science.
Storms are dangerous because they can dramatically increase the amount of nutrients and sediment in the water through runoff, erosion and dam discharge, along with causing flooding and other physical damage. Some oyster reefs in the Chesapeake never recovered from the torrential Hurricane Agnes in 1972.
And climate science suggests that more precipitation — and intense storms — are on the way. In warmer temperatures, more water evaporates, and that brings heavier and more frequent rain- and snowfall.
The latest U.S. National Climate Assessment, released in November, observed that the Chesapeake Bay watershed is already seeing "stronger and more frequent storms," and that the northeast is likely to see more of both.
RISING, WARMING WATER
The effects of increased precipitation aren't completely clear, Boesch said, given that climate models forecasting precipitation and seasonal patterns differ for the massive estuary and watershed. But other effects of climate change, like the sea level rising faster and temperatures warming, are essentially certain. Even a best-case scenario for the bay includes the sea rising faster than it has in the past, according to Boesch.
"We might lose some species, gain others," he said. "We might be able to achieve that environmental quality that we're striving for. The sea level though … is going to continue to rise."
The worst-case scenario, if carbon emissions go unchecked, would be 3-5 feet of sea level rise by the end of the century, he said. That would likely be enough to flood Baltimore's historic waterfront, parts of the Virginia Air and Space Center in Hampton and large swaths of Maryland's Blackwater National Wildlife Refuge as they stand today, according to a federal sea level rise tool. In the following centuries, the sea would rise tens of feet beyond that, Boesch said.
At the base of the bay, Norfolk, Virginia, is one of the U.S. cities most likely to see sea level rise in the coming years. In fact, it already has more "sunny day flooding" that makes it tough to get around, according to councilwoman Andria McClellan.
Home to a major port and an important naval shipyard, Norfolk revamped its zoning code to account for climate change, effectively ceding parts of the city to rising seas while requiring new buildings by the water to be elevated above the level of a 100-year flood, according to a 2018 Inside Climate News report on the change.
The city also launched a nonprofit "resilience accelerator" called RISE to foster new ideas for climate adaptation. Last week, RISE awarded $1.5 million to fund six entrepreneurial ideas, including a concrete-based oyster reef habitat system and technology that would transfer energy from vehicle traffic on roadways to pumps that would clear the roads of flooding.
The city isn't "throwing up our hands in the air and retreating" but trying to take advantage of the difficult position it finds itself in by innovating, McClellan said.
"We're the tip of the spear. Every coastal community in America is going to have to deal with what we're dealing with in Norfolk," she said.
Climate change is also believed to be warming the oceans, which can stress some species, increase their susceptibility to diseases and, because warmer water holds less oxygen, worsen dead zones, Boesch said. If the bay warms, it will make it more difficult for colder-water species like the soft-shell clam to prosper; New England lobster fisheries are already seeing the lobster shift to the north.
Another victim of higher temperatures could be the underwater grasses like eelgrass, which provides an important habitat for animals like the Chesapeake's famed blue crab, according to Boesch. While the crab likely won't be stressed by a few degrees of warming, they look for protection and food in the eelgrass, and losing it could cause a "critical" drop in the crab's population in the bay.
It's less clear how climate change affects oysters than some other species, said Stephanie Westby, Chesapeake oyster restoration program manager for the National Oceanic and Atmospheric Administration. They live in a wide range of salinities, and while too much fresh water can kill them, some oyster diseases thrive in saltier water, so it will take time to learn how they adapt to changes in the bay.
Oysters have also been dealing with existential threats since long before climate change became a global issue. Thanks in large part to overfishing that began in the colonial period, the Chesapeake oyster population is less than 1% of its historic level, and even lower in some places, Westby said. Depleted oyster reefs are more vulnerable to being smothered by sediment or suffocated by decomposing algae blooms.
That's bad for the watermen who fish oysters, but also bad for the health of the bay. Oysters filter feed, cleaning dozens of gallons a day, and if they were more plentiful, they would likely have a measurable affect on reducing water pollution across the bay.
"We've got more people, we've got more development, we've got more of everything in the watershed and then we've got more storms, and all that washes down into the Chesapeake," Westby said, adding, "we've largely removed one of the very few mechanisms that the bay has to get that stuff out."
The Bay Barometer has some good news about oyster restoration efforts: two of 10 tributaries selected for projects have completed reef construction and seeding.
The projects will only add a few thousand acres of reef to the bay, but Westby said they're great for the local ecosystem. She's buoyed by an "astounding" recent study that found the $28.6 million spent on reef restoration at Harris Creek, Maryland, will result in an estimated $3 million a year in removal of nitrogen and phosphorus.
And she hopes that ramping up oyster production through a thriving, private oyster farming industry would bring multiple benefits to the region through a "local and sustainable food source that's actually good for the environment."
That would at least help humans in the Chesapeake on one front in the fight to adapt to the changing climate.
One simple way for anyone to contribute is to use alternatives to herbicide, the source of the algae-feeding nutrients, on weeds in the yard, according to the Chesapeake Bay Program. It also recommends common conservation tips, like reducing emissions, buying native plants and using less water.
Boesch, who was named an admiral of the Chesapeake by former Maryland Gov. Martin O'Malley for "extraordinary commitment" to conserving and restoring the bay, thinks it's feasible to keep global warming to 2 degrees Celsius (3.6 degrees Fahrenheit), the goal set in the Paris climate accords.
"I see signs in various parts of the word we're at least beginning to turn the ship around and head in the right direction," he said.
Noreen O'Donnell and Wendy Rieger contributed to this report.