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作者:百科 来源:娛樂 浏览: 【大中小】 发布时间:2024-11-10 01:50:02 评论数:
Superlatives can describe 2020's fires in the Arctic Circle.
To illustrate, the 2020 fires trumped even 2019's Arctic blazes, which were already record-breaking, compared to the previous 16 years of the satellite wildfire record. The amount of heat-trapping carbon dioxide released into the atmosphere and the scale of the 2019 fires vastly exceeded earlier years. "Indeed, 2019 was already a big year for fires in the Arctic," said Thomas Smith, an assistant professor in environmental geography at the London School of Economics.
But so far in 2020, Arctic Circle fires have released about 35 percent more CO2 into the atmosphere than in 2019, according to data released Thursday by the European Union's Copernicus Atmosphere Monitoring Service. This amounts to 244 megatonnes, or 244 million metrics tonnes, of carbon dioxide.
"The Arctic fires burning since the middle of June with high activity have already beaten 2019’s record in terms of scale and intensity as reflected in the estimated CO2 emissions," Mark Parrington, a senior scientist and wildfire expert at the Copernicus Atmosphere Monitoring Service, said in a statement.
Take a look below. The red bars show the size of and energy detected from 2020's fires, while the yellow bars show 2019's observations. Both years dominate the average of the previous years (grey).
Left: CO2 emissions from Arctic wildfires. Right: Scale and intensity of Arctic wildfires.Credit: Copernicus Atmosphere Monitoring ServiceTweet may have been deleted
Importantly, Smith emphasized that it's crucial to figure out the netCO2 emissions from the Arctic fires, meaning how much heat-trapping CO2 is actually added to the atmosphere over time. Yes, the recent fires released bounties of carbon dioxide, more than entire nations like Sweden expel in an entire year. But eventually, much of this carbon is reabsorbed from the atmosphere when burned ecosystems (like forests and grasslands) naturally regrow.
Yet, if fires become more frequent (which may now be occurring in the Arctic Circle), forests won't naturally regrow, as this process takes decades. Instead, grass or shrublands might claim the burned and disrupted land. These ecosystems hold less carbon. "This would represent a net contribution of carbon to the atmosphere," noted Smith. In the coming years and decades, Arctic researches will observe these potentially momentous changes to this warming polar realm.
SEE ALSO:Weather prediction will always have a worthy adversaryAnother type of fire, however, may be the most significant problem concerning Arctic blazes: the burning of peatlands. These are wetlands composed of ancient decomposed plants, amassed over thousands of years. They are profoundly rich in carbon. Smith's analysis found that about half of the Arctic Circle fires have burned in peatlands in 2020. This contributes bounties of "net" greenhouse gas emissions to the atmosphere because these ecosystems take thousands of years to naturally restore and reabsorb carbon, if they do at all.
"The greenhouse gas emissions as a result of peat fires may be considered as ‘net emissions’ to the atmosphere, given that the peat soils will not recover in any timeframe relevant to anthropogenic climate change (over the next few centuries)," said Smith.
This is problematic, because these regions are often considered "carbon sinks," meaning natural places where the planet absorbs carbon from the atmosphere. Now, they might be potent sourcesof carbon. Already, atmospheric levels of carbon dioxide are the highest they've been in at least800,000 years, but more likely millions of years. (Momentous change is afoot in the atmosphere as humanity burns vast stores of fossil fuels.)
What's more, many peat fires go undetected from satellites, because they can smolder or burn at lower temperatures. This means the true amount of greenhouse gases entering the atmosphere from the Arctic Circle, while record-breaking for the second straight year, could likely be an underestimate.