When it comes to stopping global warming, climate scientists believe that planting some trees may actually do more harm than good, a new study suggests.
In the study – published Thursday (Jan. 4) in the journal Science – researchers found that the increase of forests in Europe, made primarily of dark green conifers, have fuelled global warming.
The new findings challenge the widespread beliefs that planting more trees can help slow the rising temperature on Earth, according to the researchers. It appears as though not all trees have the same beneficial effect on climate.
A team of researchers with the France’s Laboratoire des Sciences du Climat et de l’Environnement said that even after more than two hundred years of forest management in Europe, the climate has still not cooled.
Ever since the 1750s, Europe’s forests have increased by ten percent. However, the summer temperatures on the continent have also risen by 0.12 degrees Celsius (0.2 degrees Fahrenheit). According to scientists, that may be because most of the countries have planted conifers, like spruces and pines. The dark colour of these trees traps the sun’s heat, scientists explain.
Birch and oak, as well as other light-coloured trees with broad leaves reflect a lot more sunlight. Researchers said that fast-growing conifers in Europe have long outpaced light-coloured trees, especially since they are used for everything from pulp to building materials.
Kim Naudts, lead author of the study and an environmental scientist at the Max Planck Institute for Meteorology in Hamburg, Germany, said that forest management policies should focus on factors such as the trees’ colours.
According to the study, Europe’s forests have expanded 76,000 square miles since 1750. During that period, broad-leaved have forests decreased by 168,000 square miles, while conifer forests have expanded by 244,000 square miles.
The increase in temperature due to conifer forests equates to about six percent of the global warming caused by the burning of fossil fuels, the researchers found. Similar effects likely occurred in other areas in the United States, China, and Russia, where the same type of afforestation – which is the establishment of a forest in an area where there was no forest – took place.
Alessandro Cescatti, an ecologist at the European Commission’s Joint Research Centre in Ispra, Italy, also said that the shift from deciduous (trees or shrubs that lose their leaves seasonally, specifically during autumn) forests to coniferous forests could indeed increase local temperature.
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