Not all forests are created equal when it comes to slowing down climate change.
A new analysis showed, for instance, that Europe’s summer temperature climbed by 0.12 degree Celsius or 0.2 Fahrenheit since 1750 due to the shift toward dark conifers, which absorb more sunlight and emit less water, therefore contributing to further warming.
The forests of the continent have expanded 10 percent since 1750, yet the movement to more commercially viable tree species – as well as timber harvesting – has led to a net release of carbon to the atmosphere, according to the Feb. 4 paper published in the journal Science.
The results were at odds with current assumption that all forests help in climate mitigation.
“We cannot say that is true, at least for Europe,” said study author and ecologist Kim Naudts, who conducted the research with a team while at the Laboratory of Climate Science and Environment in Gif-sur-Yvette, France.
About 190,000 square kilometers of forest in Europe were cut down from 1750 to 1850 for fuel and agriculture, and forests have since then rebounded on a site more than twice the said size.
However, fast-growing conifers such as pines and spruce have replaced deciduous or broad-leaf trees on over 600,000 sq km due to an interest in timber and building materials – a shift that means while European forests still take up carbon, they now retain 3.1 billion tons less than 1750 levels.
The authors concluded that “[t]wo and a half centuries of forest management in Europe have not cooled the climate.”
In addition, they asserted that it’s not all about carbon. Naudts told a news agency that government policies favoring forests should be reassessed to consider factors including color of trees (affecting sun heat-trapping ability) and changes to soils and moisture.
The Paris climate change conference back in December promotes forest creation and management to help limit temperature rise, which is pinpointed for increased sea level, flooding, and heat waves.
The average world temperature has risen by 0.9 degree Celsius or 1.6 degree Fahrenheit since the Industrial Revolution.
While the study was limited to Europe, similar effects were seen to affect other countries with huge forest planting initiatives, such as China, Russia, and the United States.
Ecologist Richard Houghton from the Woods Hole Research Center said the results may no longer be surprising, as forest management may lead to different results. “If the point is to store carbon, then afforestation is presumably good, but losing carbon to wood extraction is bad,” he explained.
A separate study also published in Science linked forest loss around the world to higher average and maximum temperatures, particularly in tropical regions.
Photo: Matthias Ripp | Flickr