The world’s second most populous nation has made big steps to clean up its skies, inadvertently raising thermometers across the planet.
It’s one of the most compelling examples of the delicate balance and interconnectivity of air pollution and global warming yet. By reducing the rate at which aerosols are being pumped into the atmosphere and bringing sulphate emissions down by 75% since the early-mid-2000s, Beijing has removed gases which were masking the true scale of how much Earth has been heating.
Dirty air had been keeping the planet cooler than it should have been, and now 5% of current warming – compared with planetary temperatures in 1850 – is thought to have been triggered by this phenomena. New Scientist reports the world has been warming at 0.18C per decade, but since 2010 this has leapt to 0.24C every 10 years.
It has long been understood that some gases which are harmful to humans and other animals actually help block out sunlight, effectively keeping sea and land surface temperatures lower than they otherwise would be. They also alter how clouds develop, leading to longer lasting, whiter formations which can also reflect solar radiation back into space.
The tightening of international regulations around shipping fuel to reduce sulphur dioxide emissions is one of the most famous examples, which is expected to contribute 0.05C to global warming by 2050.
Scientists have previously suggested that the surge in global warming was likely catalysed by air pollution policies, but until now have been unable to establish which countries were responsible for this.
According to the CICERO Center for International Climate Research in Norway, which used newly published emissions data for China and cutting edge computer modelling, the rapid drop in sulphate aerosols has had a ‘macroscopic’ influence on warming. Or, as Bjørn Samset puts it, this is ‘not a small effect’.
‘The warming was always there, we just had some artificial cooling from pollution, and in removing the pollution we are now seeing the full effect of the greenhouse-gas driven warming,’ he told New Scientist. But despite the negative impact, it is believed such measures have now saved around 150,000 premature deaths per year.
Image: Maxim Tolchinskiy / Unsplash
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