Measuring the Carbon-Dioxide Cost of Last Year’s Worldwide Wildfires
Last year’s mammoth wildfires in the Amazon, Indonesia, and the Arctic Circle triggered a global conversation about the environmental and economic consequences of climate change. So it was with shock and still-raw emotion that, as 2020 began, the world absorbed the images of Australia’s devastating bush fires.
These enormous blazes—some the size of a small country—aren’t just destroying native forests and vulnerable animal species. They’re also releasing billions of tons of greenhouse gases into the atmosphere, potentially accelerating global warming and leading to even more fires.
Fire Trend
South America
South & Southeast Asia
Eastern Europe & Northern Asia
Australia
Africa & Middle East
North America
0
10 billion metric tons
’19
’15
’10
’05
’00
’97
South America
South & Southeast Asia
Eastern Europe & Northern Asia
Australia
Africa & Middle East
North America
0
10 billion metric tons
’19
’15
’10
’05
’00
’97
Africa & Middle East
Australia
Eastern Europe & Northern Asia
North America
South America
South & Southeast Asia
10 billion metric tons
7.5
Average
5.0
2.5
0
1997
2000
2005
2010
2015
2019
Total carbon emissions from forest fires in 2019 weren’t anomalously high compared with previous years’ counts. They rose last year by 26%, to 7.8 billion metric tons, the highest since 2002, according to the Global Fire Emissions Database (GFED). But overall they’ve been declining since the beginning of the century.
While emissions from fires have been going down, total human-generated emissions have been going up much more quickly. Fires were responsible for as much as a fifth of the 36.8 billion tons of carbon released last year from burning fossil fuels, down from about a quarter at the beginning of the century.
Emissions From Fossil Fuels and Fire
Emissions from fire
Fossil fuel emissions
40
30
20
10
0
1997
2010
2019
Emissions from fire
40
Fossil fuel emissions
30
20
10
0
1997
2010
2019
Emissions from fire
Fossil fuel emissions
40
30
20
10
0
1997
2000
2005
2010
2015
2019
Emissions from fires increased last year from 2018 and 2017 levels, “but it was still a fairly average year,” says Mark Parrington, a senior scientist at Copernicus. “What seemed to stand out was the unusual fire activity in places where we didn’t necessarily expect to see fire, or so much fire.”
In general, scientists agree that global warming will result in more wildfires. The big question now is whether last year’s spike is a one-time result or the start of a new trend.
metric tons of CO2 in summer 2019
Fires across the continent burned more than 6 million hectares, including national forests, with smoke reaching as far as Argentina.
In Australia, savannas, grasslands, and open woodlands burn every year. But last year’s bush fires were unprecedented, especially because the rate of destruction in the southeast, which is full of temperate forests that don’t usually burn, far exceeded the norm. According to researchers at Vrije Universiteit Amsterdam, about half of Australia’s carbon emissions during this fire season came from the southeast.
Carbon emissions from fires are typically reabsorbed a few years later when grasses regrow, says Rebecca Buchholz, a scientist at the National Center for Atmospheric Research in Boulder, Colo. But this year that cycle “may be being pushed out of balance,” she adds.
Even places like the Arctic Circle experience regular destruction from wildfires. But higher temperatures and less rain are making them larger, more frequent, and harder to extinguish.
What made 2019 extraordinary wasn’t the overall number of fires, or total fire emissions, but where they happened and how intense they were. Scientists were baffled to record fires burning in some parts of Siberia and Alaska for longer than they’d ever seen.
metric tons of CO2 in summer 2019
Fires in Siberia burned for three months. In Alaska, fires released more than double the amount of carbon dioxide emitted from fossil fuels in the state annually.
The Amazon rainforest—which straddles a number of South American countries, including Brazil, Bolivia, and Peru—experiences seasonal wildfires, which are sometimes linked to agricultural activities. Although it saw more fires last year than in 2018, its 2019 emissions were still less than half the levels of 2004, 2005, 2007, and 2010.
metric tons of CO2 in in 2019
While total figures for 2019 haven’t yet been released, the greenhouse gas emissions from last year’s Amazon fire were equivalent to more than 80% of Brazil’s 2018 greenhouse gas emissions.
Indonesia’s case was exceptional in that fires started burning there with more intensity in September, midway through the traditional fire season. This indicates that many of these fires were started deliberately to clear land for agriculture, particularly paper and palm oil, according to Copernicus.
Scientists were alarmed because what was burning in Indonesia included not only forests, but also peat, which can smolder underground at very low temperatures. It makes fires hard to extinguish and almost impossible to detect from satellite pictures, in turn making it difficult to accurately calculate CO2 emissions. To make matters worse, peat fires release carbon that’s been stored underground for tens of thousands of years.
metric tons of CO2 in summer 2019
Burning for more than six weeks, the fires emitted greenhouse gas equivalent to 60% of Indonesia’s 2018 emissions from burning fossil fuels.
Even as individuals and governments around the world are waking up to the immediacy of climate change, greenhouse gas emissions from human activities such as transport and industry are at historic highs. On Jan. 8, Copernicus declared 2019 the second-hottest year on record, less than one-tenth of a degree Fahrenheit behind 2016.
Such conditions are making the so-called fire weather—high temperatures, strong winds, low humidity—likely to occur more often, scientists say. “The predictions were already there,” Parrington says of last year’s fire season. “We already had studies showing if it becomes drier and hotter in places like the Arctic, at some point there will be fires on a bigger scale than we’ve seen in a long time.”