A decline in levels of aerosols in the atmosphere will make it easier to forecast the speed of climate change, say scientists
By Megan Darby
Efforts to crack down on air pollution could help reduce uncertainty in climate modelling, scientists have found.
While there is a strong consensus that human activities cause climate change, how fast greenhouse gas emissions are driving temperature rise is up for debate.
Estimates of the “transient climate response”, or temperature rise expected if carbon dioxide doubles over a 70-year period, range from 1 to 2.5C.
A study published in Nature Geoscience on Monday concluded scientists should be able to narrow down that range without the need for more sophisticated models.
That is because air quality regulations are expected to reduce levels of aerosols, a complex group of warming gases, over the next few decades.
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Aerosols, a category of pollutants including soot, sulphur and nitrous oxides, can have cooling effects as they reflect sunlight away from the Earth.
These effects are less well understood than the relationship between carbon dioxide and temperature rise.
They also have a shorter lifespan in the atmosphere than carbon dioxide, meaning that policies to address their harmful impacts on health and the environment take effect quickly.
As aerosols decline, carbon dioxide will increasingly dominate the mix of emissions that influence climate change, leading to more precise forecasts.
That will have a “pronounced impact” on estimates of how much carbon dioxide can be emitted for a given temperature target, the report said.
For example, countries are aiming to limit temperature rise to 2C above pre-industrial levels with a climate deal in Paris this December.