The coastal US north–east is one of the fastest warming areas in the northern hemisphere, having heated up rapidly by 2C (3.6F) already over the past century due in part to the soaring temperature of the nearby Atlantic Ocean, new research has found.
The coastline that stretches from Maine down to Delaware hosts urban areas such as 纽约 City and Boston and draws millions of tourists each year to beaches and other attractions. But the region is rapidly changing due to the climate crisis, having heated up by 2C on average since the start of the 20th century, driven largely by much warmer summers.
This is one of the fastest temperature increases in the northern hemisphere, researchers found, and is double the level of heating that has taken place further inland in the same region.
The world’s governments have agreed to limit the overall global temperature rise to “well below” 2C to avoid disastrous heatwaves, floods and other impacts. The US north-east has itself now, in isolation, already breached this threshold.
“It really pops out, it’s a big jump in temperature,” said Ambarish Karmalkar, a climate scientist at University of Massachusetts Amherst and lead author of the paper, published in Nature Climate Change. “It’s an exceptional level of warming and what is surprising to me is that it’s so different within a small region. The interior of the US north-east has only warmed by 1C, whereas these popular coastal areas have warmed by 2C. That’s a big difference.”
Karmalkar and his colleague Radley Horton sought to establish the reasons for this brisk temperature increase and have pointed to a link between the rising heat of the northern Atlantic Ocean and that of the nearby land.
A large system of ocean currents, known as the Atlantic Meridional Overturning Circulation (or Amoc), acts as a sort of conveyor belt for the ocean, bringing warm, salty water from the tropics north towards Greenland, where it cools and sinks.
Recent studies indicate that this watery conveyor is slowing down as the climate heats up, meaning that warmer water is piling up along the US east coast, in places such as the Gulf of Maine and the Mid-Atlantic Bight. This warming, 哪一个 is upending traditional fisheries as marine ecosystems morph, has helped drive up temperatures along the coast with the aid of altered wind patterns, according to the researchers.
“The sea surface temperatures have gone up dramatically, much faster than the global average, and more heat is being dumped there by the slowing conveyor belt,” said Karmalkar. “You are also getting these anomalous winds, and these two factors together are driving warming trends.”
Cities in the US north-east have been primarily focused on the dangers of flooding wreaked by the climate crisis – record rainfall caused severe flash flooding that killed dozens of people in New York 本月初 – but Karmalkar said that authorities would increasingly have to focus upon rising heat if current trends continue.
“The exceptional warming we’ve seen can have serious implications for heat stress and human health,“ 他说. “Lots of people vacation on this coast but the warming may change how people use the space. This will become an important public health issue to deal with.”
Bob Kopp, a climate scientist at Rutgers University who was not involved in the research, said the study “nicely identifies” possible causes for the heating of the US north-east. Kopp added that adaptations to this heat would have to take place.
“当然, there are huge inequities within the United States, and within the region the harms of extreme heat will tend to be felt most heavily by lower-income people,“ 他说. “This is also a densely urbanized area, with a substantial urban heat island effect.”
Scientists have warned that countries are still not cutting planet-heating emissions quickly enough to avoid catastrophic consequences, with places from the US west 到 德国 到 中国 already experiencing recent severe climate crisis-fueled impacts. “These changes will only become worse if humans continue to emit carbon dioxide,” said Natalie Mahowald, a climate scientist at Cornell University.