American Trees Are Moving West Due to Climate Change
As the consequences of climate change strike across the United States, ecologists have a guiding principle about how they think plants will respond. Cold-adapted plants will survive if they move “up”—that is, as they move further north (away from the tropics) and higher in elevation (away from the warm ground).
A new survey of how tree populations have shifted over the past three decades finds that this effect is already in action. But there’s a twist: Even more than moving poleward, trees are moving west.
About three-quarters of tree species common to eastern American forests—including white oaks, sugar maples, and American hollies—have shifted their population center west since 1980. More than half of the species studied also moved northward during the same period.
These results, among the first to use empirical data to look at how climate change is shaping eastern forests, were published in Science Advances on Wednesday.
Trees, of course, don’t move themselves. But their populations can shift over time, and saplings can expand into a new region while older growth dies in another.
While climate change has elevated temperatures across the eastern United States, it has significantly altered rainfall totals. The northeast has gotten a little more rain since 1980 than it did during the proceeding century, while the southeast has gotten much less rain. The Great Plains, especially in Oklahoma and Kansas, get much more than historically normal.
Atlantic Ocean invades the Arctic
The waters of the Arctic Ocean are becoming increasingly similar to those of the Atlantic as warm currents from the south flow in, according to a new report.
It says the intrusion of the warmer Atlantic currents is also contributing to the accelerated melting of sea ice. The increased Atlantic currents have removed a thick layer of cold surface waters that had previously insulated the polar ice cap, allowing it to thin.
“Rapid changes in the eastern Arctic Ocean, which allow more heat from the ocean interior to reach the bottom of sea ice, are making it more sensitive to climate changes,” said oceanographer Igor Polyakov.
Tree Massacre in Poland
Environmentalists say that changes to a Polish law have led to a “massacre” of trees across the country.
New legislation that went into effect on Jan. 1 removed previous requirements that private landowners who want to cut down trees must apply for permission, pay compensation, plant new trees or even notify authorities about the removal of trees.
“We used to receive around one telephone call a day from people concerned about trees being cut down in their area. But suddenly, we had two telephones ringing all day long,” said Pawel Szypulski of Greenpeace.
Freshly cleared spaces are now being reported around Polish cities and across the countryside.
Trees “held their breath” during the recent seeming pause in global warming, when the oceans were storing most of the planet’s excess heat.
Forests are considered to be the “lungs of the planet” because of their ability to remove carbon dioxide from the atmosphere and store the excess carbon.
An international study found that from 1998 to 2012, when atmospheric temperatures appeared to stop rising as quickly as in the years before, the world’s forests continued to breathe in the greenhouse gas through photosynthesis. But the trees reduced the rate at which they released the gas back into the atmosphere.