Oceans

The Caribbean’s sandy beaches, clear turquoise water and vibrant coral reefs filled with an amazing variety of sea creatures have long been the pride of the islands. The big three – sun, sea and sand – have made this tropical paradise the most tourism-reliant region in the world. But now, all of that is under threat. The explosive growth of a type of seaweed called sargassum is wreaking havoc on economies, coastal environments and human health across the islands. I study the intersection of critical infrastructure and disasters, particularly in the Caribbean. The sargassum invasion has worsened since it exploded in the region in 2011. Forecasts and the seaweed already washing up suggest that 2024 will be another alarming year. Sargassum levels were already high around many eastern Caribbean islands in late May 2024. Forecasters expect increasing sargassum washing up in June on many of the islands and in the Gulf of M...

When people think about the risks of climate change, the idea of abrupt changes is pretty scary. Movies like “The Day After Tomorrow” feed that fear, with visions of unimaginable storms and populations fleeing to escape rapidly changing temperatures. While Hollywood clearly takes liberties with the speed and magnitude of disasters, several recent studies have raised real-world alarms that a crucial ocean current that circulates heat to northern countries might shut down this century, with potentially disastrous consequences. That scenario has happened in the past, most recently more than 16,000 years ago. However, it relies on Greenland shedding a lot of ice into the ocean. Our new research, published in the journal Science, suggests that while Greenland is indeed losing huge and worrisome volumes of ice right now, that might not continue for long enough to shut down the current on its own. A closer look at evidence from the past shows why. Blood and water The Atl...

Wetlands have flourished along the world’s coastlines for thousands of years, playing valuable roles in the lives of people and wildlife. They protect the land from storm surge, stop seawater from contaminating drinking water supplies, and create habitat for birds, fish and threatened species. Much of that may be gone in a matter of decades. As the planet warms, sea level rises at an ever-faster rate. Wetlands have generally kept pace by building upward and creeping inland a few meters per year. But raised roadbeds, cities, farms and increasing land elevation can leave wetlands with nowhere to go. Sea-level rise projections for midcentury suggest the waterline will be shifting 15 to 100 times faster than wetland migration has been clocked. Many wetlands, like these on Cape Cod, are now bordered by human infrastructure, including towns and roads. Lance Cheung/USDA I have been studying coastal g...

My colleagues and I mapped activity in the northeast Pacific of “dark” fishing vessels – boats that turn off their location devices or lose signal for technical reasons. In our new study, we found that highly mobile marine predators, such as sea lions, sharks and leatherback sea turtles, are significantly more threatened than previously thought because of large numbers of dark fishing vessels operating where these species live. While we couldn’t directly watch the activities of each of these dark vessels, new technological advances, including satellite data and machine learning, make it possible to estimate where they go when they are not broadcasting their locations. Examining five years of data from fishing vessel location devices and the habitats of 14 large marine species, including seabirds, sharks, turtles, sea lions and tunas, we found that our estimates of risk to these animals increased by nearly 25% when we accounted for the presence of dark v...

Superstorms, abrupt climate shifts and New York City frozen in ice. That’s how the blockbuster Hollywood movie “The Day After Tomorrow” depicted an abrupt shutdown of the Atlantic Ocean’s circulation and the catastrophic consequences. While Hollywood’s vision was over the top, the 2004 movie raised a serious question: If global warming shuts down the Atlantic Meridional Overturning Circulation, which is crucial for carrying heat from the tropics to the northern latitudes, how abrupt and severe would the climate changes be? Twenty years after the movie’s release, we know a lot more about the Atlantic Ocean’s circulation. Instruments deployed in the ocean starting in 2004 show that the Atlantic Ocean circulation has observably slowed over the past two decades, possibly to its weakest state in almost a millennium. Studies also suggest that the circulation has reached a dangerous tipping point in the past that sent it into a precipitous, uns...