Contrary to long-held hypotheses, American scientists reported on December 6 that planting trees in temperate regions could absorb sunlight and warm the Earth in the long term. 
Tree planting seems like a good idea in the fight against global warming, as trees have the ability to absorb carbon dioxide.
However, forests in the mid-latitude regions of the Earth influence the climate in more complex ways, according to researchers at the Carnegie Institution and Lawrence Livermore National Laboratory. Planting trees in these areas may have more positive effects on carbon dioxide sequestration alone.
The researchers used advanced climate modeling software to simulate changes in forest cover and then examined their effects on the Earth’s climate. They found that while tropical forests help cool the Earth by evaporating large amounts of water, northern forests tend to warm the Earth because they absorb a lot of sunlight without losing much moisture.
In one simulation, the researchers covered most of the Northern Hemisphere with forests and noticed that surface air temperatures jumped by 3 degrees Celsius. Covering all of the planet’s land with forests resulted in a more modest temperature increase of about 1 degree Celsius.
Initially, the cooling effect of removing carbon dioxide offsets the warming effect from absorbing sunlight. However, after several decades, carbon dioxide will begin to escape from the oceans into the atmosphere, diminishing the cooling effect and leading to long-term warming of the Earth.
The researchers warn against planting forests on abandoned cropland as a strategy to combat global warming, as some have suggested. However, they also recognize the importance of forests.
They stated: “Forests provide a good habitat for plants and animals, and tropical forests are very beneficial for the climate, so we should particularly focus on conserving them. But in terms of climate change, we should emphasize efforts such as improving efficiency and developing clean, renewable energy sources.”
KHÁNH NHẬT
