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Researchers: Climate change is turning Earth’s northern latitudes green

Reporting in the journal Nature Climate Change, an international team of researchers writes that the northern latitudes have experienced a significant reduction in temperature and vegetation seasonality. They contend that vegetation growth at Earth’s northern latitudes is starting to look a lot like the green latitudes to the south. The study’s findings are based on a 30-year record of land surface and satellite data sets.

The researchers looked at the relationship between changes in surface temperature and vegetation growth from 45 degrees north latitude to the Arctic Ocean. The study’s findings reveal that temperature and vegetation growth at northern latitudes now appear like those found 4 degrees to 6 degrees of latitude farther south as recently as 1982.

Lead co-author Liang Xu, a Boston University doctoral student, says that increased warming in the northern latitudes above the Canada-USA border is lowering temperature seasonality because the colder seasons are warming faster than the summer.

Researchers note that total amount of heat available for plant growth in these northern latitudes is increasing because of the reduction in temperature seasonality. The extra heat is turning Earth’s northern latitudes green. Patches of “vigorously productive vegetation” are now equal to an area approximately the size of the United States.

According to a NASA news release, the Arctic’s greenness can be seen from the ground as a growing number of tall shrubs and trees in locations all over the northern latitudes.

Co-author Scott Goetz, a senior scientist at the Woods Hole Research Center, says that while some areas of the boreal forest will be negatively influenced by drought as well as insects and forest fires, this study revealed that most high latitude regions will see increased vegetation growth due to a reduction in temperature seasonality.

To determine what the future looks like, the team examined 17 climate models. These models revealed that increased temperatures in the northern latitudes would be the equivalent of a 20-degree latitude shift by the end of this century relative to a period of comparison from 1951-1980.

Researchers caution that plant growth in the north may not stay on its current trajectory because an amplified greenhouse effect will increase the frequency of forest fires, droughts and pest infestations. All of these factors may slow plant growth.

A decrease in temperature seasonality will impact local residents in the northern latitudes and the global community through changes in ecosystem services and regulatory ecosystem services connected to the emissions of greenhouse gases.