A steel factory in Hebei, China, in 2015
Images Kevin Frayer / Getty
A recent increase in the global warming rate has been largely motivated by China's efforts to reduce air pollution, raising questions about how air quality regulations influence the climate and if we fully understand the impact of the elimination of atmosphere. This additional warming, which was masked by aerosols, represents 5% of the increase in global temperature since 1850.
In the early 2000s, China had an extremely bad air quality due to rapid industrialization, which led to a public outcry on the approach of the 2008 Beijing Olympic Games. In response, the Chinese authorities adjusted the exharators to the coal -fired power plants to slow down the dirty and the tightened rules governing vehicle escapes, resulting in a drop of 75% Sulfate.
But there is a bite in the tail of this environmental success. According to a new analysis, the dirty air of China had not cooled the planet, and now that it has disappeared, we are starting to see a greater warming effect.
We know that warming has probably accelerated over the past decade. Since 1970, the world has warmed at a constant rate of approximately 0.18 ° C (0.32 ° F) per decade, but since 2010, this seems to have increased to around 0.24 ° C (0.43 ° F) per decade, once the influence of the variability of the natural climate is removed. The researchers previously pointed out the blame for this increase in the warming of efforts to slow down air pollution, but so far, they had struggled to determine the individual regions of the contribution to the global trend.
Sulfate aerosols, released by burning fossil fuels, cool the planet in two ways. The particles themselves reflect sunlight in space, protecting the soil from solar radiation. They also influence the way the clouds are formed, increasing the occurrence of white clouds for lifespan which also reflect radiation. The abolition of these atmosphere aerosols therefore eliminates a cooling effect.
To unravel this effect, Samset bear In the Cicero Center for International Climate Research in Norway and its colleagues have used newly published emission data which has given a more precise image of Chinese action on aerosol pollution since 2005. They have used cutting -edge models to simulate how the climate system would respond to rapid aerosol levels, especially in China. They then compared these results with real world data, such as satellite observations and estimates of the pollution of sulfates drawn from emission reports, and found that the modeled scenario was consistent with the data signals of the real world.
This allowed the team to isolate the impact of global warming of the reductions in Chinese aerosol pollution, explains Samset. “When we started looking at the numbers, it turns out that it is definitely macroscopic – it is not a small effect,” he said. In total, the repression of atmospheric pollution of China is responsible for 80% of the increase in the global warming rate since 2010, concludes the team, approximately 0.05 ° C additional (0.09 ° F) per decade. If you look at the total quantity of warming since 1850, approximately 0.07 ° C (0.13 ° F) can be attributed to the cleaning of Chinese aerosols, or about 5% of the total, explains Samset. The analysis has not yet been evaluated by peers.
Part of this can be explained by the extent of the reductions in air pollution that China has delivered, reducing sulfur dioxide emissions by around 20 million tonnes per year since the mid -2000s. But China air quality also has a particularly strong impact on a global scale, explains Samset. “When you emit aerosols on China, they are taken by atmospheric traffic, transported on the Pacific, they therefore spread to a large area,” he said. “The same amount of India emissions would not have had the same effect on global warming.”
Satellite data have taken a tendency to warming the North Pacific in recent years, which, according to this new work, explains by the reduction of Chinese aerosols. “If you look at the real observations, the series of large temperatures … global warming has accelerated,” explains Samset. “If you look at the geographic model of this, a large part of it is above these two plots of the North Pacific. It therefore integrates.”
It is important to note that the action of China has not caused additional warming, the constraints of Samset. Rather, he “unmasked” what was already there. “Warming was still there, we just had an artificial cooling of pollution, and by removing pollution, we now see the full effect of warming leads to greenhouse gas,” he said.
Despite the impact on global temperatures, the action was worth taking to save lives, says Duncan Watson-Parris at the University of California San Diego. “The consequence of the climate is not great, but it is not as acute as the number of people who died because of air quality,” he said – previous research has suggested that the measures have helped to avoid 150,000 premature deaths per year.
The pace of cleaning air quality in China has slowed down in recent years. “There is really not a lot of air pollution to remove from China,” says Samset. This should mean that the warming rate should fall to nearly 0.18 ° C per decade recorded before 2010, he said.
But other factors could disrupt this. Just as the reductions of China lengthened, in 2020, the world navigation industry implemented new rules forcing ships to brake their aerosol emissions, causing a strong drop in pollution on the open ocean. This could be particularly important to change the cloud cover in these regions, notes Hugh coe At the University of Manchester, United Kingdom. “This happens in distant places where the clouds are super sensitive to change,” he says.
Scientists also warn that the rise in temperatures might ensure that the ocean clouds become less thoughtfulReducing their cooling effect, while there are also concerns that models have badly judged how sensitive the climate system is to changes in aerosols. “The question of the speed at which the world will continue to warm up is absolutely crucial NOW,“Said Samset.
The Chinese Ecology and Environment Ministry has not responded to a request for comments.
