Climate Change Killing Trees in Countries Around the World

The world’s forests are being damaged by climate change-related heat and drought, even in areas not traditionally known for water shortages, U.S. Geological Survey researchers say in the first global assessment of tree deaths from heat stress and drought.

The findings highlight the very real risk that tree mortality could become a bigger problem as global climate change progresses.

They also suggest that emissions offset programs designed to prevent logging and clear cutting of forests are missing the big picture: Allowing polluters to pay to preserve or plant trees rather than reduce their own greenhouse gas emissions may keep one area of trees alive, but it continues to endanger forests around the world.

The study's authors reviewed reports on 88 recent episodes of widespread tree deaths.

Although mass tree deaths aren’t always related to global warming, the findings suggest that “at least some of the world's forested ecosystems already may be responding to climate change.”

"The widespread examples of drought and heat-induced tree mortality that we document illustrate how climate can drive abrupt, broad-scale impacts to essential forest services ranging from timber and protection of watersheds and biodiversity to recreational, aesthetic and spiritual benefits," said Craig D. Allen, a USGS scientist who led the study.

Simply planting more trees will not solve the problem, because it’s not a simple one-for-one equation.

“Trees can die much more quickly than they grow," Allen points out. As the study notes, severe drought can kill a 200-year-old tree within months.

The number of documented episodes of tree loss related to warming and droughts has also risen rapidly in recently years, the study says. With scientists' knowledge today of the connection between greenhouse gas emissions and global warming, the findings are "a sign that far greater chronic forest stress and mortality risk should be expected in coming decades."

The study cites multiple examples of climate change-related tree loss over the past 30 years on every forested continent:

• In Africa, studies have linked heat and drought to widespread tree deaths in the tropical moist forests in Uganda, as well as mountain acacia in Zimbabwe, mesic savanna trees in South Africa’s Kruger National Park, and centuries-old Aloe dichotoma in Namibia.

• In Asia, severe droughts have been associated tree of several species dying in the tropical dry forests of western India. Recent droughts have killed pine trees across more than 2,000 square miles of China. In Russia, forestry officials have mapped out nearly 300,000 square miles of forest consider at high-risk.

• In Australia, long droughts have killed Eucalyptus and Corymbia. Even New Zealand’s thick forests, made famous by the Lord of the Rings movies, have not been immune.

• In Europe, studies document hot and dry conditions over the past two decades killing trees in the Mediterranean region, including oak, beech and pine species in France. Even Greece’s most drought-tolerant pines species have suffered.

• In North America, the northern of spread of insects with the warming climate has affected 77,000 square miles of forest from Mexico to Alaska, hitting ash, oak and pine particularly hard.

• In South America, a hot and severe drought in 2005 across the Amazon basin, linked to an abnormally warm North Atlantic, was blamed for an extensive deaths of trees, “indicating vulnerability of Amazonian forests to moisture stress.”

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