题型：阅读理解 题类： 难易度：普通
福建省福州市六校2023-2024学年高二下学期期末联考英语试题
According to a new Agriculture Department report, U. S. forests could exacerbate global warming because they are being destroyed by natural disasters and are losing their ability to absorb planet-warming gases as they get older. The report predicts that the ability of forests to absorb carbon will start declining after 2025 and that forests could release up to 100 million metric tons of carbon a year as their emissions (排放) from decaying (腐烂的) trees go beyond their carbon absorption. Forests could become a "substantial carbon source" by 2070, the USDA report says.
The loss of carbon absorption is driven in part by natural disasters such as wildfires, tornadoes and hurricanes, which are increasing in frequency and strength as global temperatures rise. The disasters destroy forestland, destroying their ecosystem and decreasing their ability to absorb carbon, according to Lynn Riley, a senior manager of climate science at the American Forest Foundation. Aging forests also contribute. The report found that older, mature trees absorb less carbon than younger trees of the same species, and U. S. forests are rapidly aging.
This trend is likely to continue, as forests come under increasing threat from climate change and exploitation (开采). The typical tropical (热带的) forest may become a carbon source by the 2060s, according to Simon Lewis, professor in the school of geography at Leeds University. "Humans have been lucky so far, as tropical forests are cleaning up lots of our pollution, but they can't keep doing that indefinitely," he said. "We need to cut down fossil fuel emissions before the global carbon cycle starts working against us."
U. S. forests currently absorb 11 percent of U. S. carbon emissions, or 150 million metric tons of carbon a year, equal to the combined emissions from 40 coal power plants, according to the report. The loss of forests as natural carbon absorbers will require the U. S. to cut emissions more rapidly to reach net zero. "As we work to decarbonize (碳减排), forests are one of the greatest tools at our handling. If we were to lose that, it means we will contribute that much more in emissions." Riley said.
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