Catch-22: polluting aerosols cool the Earth, removing them warms it
The Industrial Revolution and global warming
The Industrial Revolution, which began over 200 years ago, brought with it a rise in carbon emissions. This resulted in an increase in global temperatures. But over the same period of time, another man-made activity - that of pollution from aerosols - has helped to mitigate some of that warming.
But that doesn't mean aerosols are a good thing. In fact the inadvertent cooling effect of aerosols has created an unusual dilemma according to climate scientists like Dr. Bjorn Samset from the CICERO Center for International Climate Research in Oslo, Norway
Man-made aerosols come mostly from the burning of fossil fuels, but they are also produced by cooking in our homes or the smoke from fires.
But there are also naturally occurring aerosols. These are particles of dust or salt in the atmosphere. Aerosols have a cooling effect because they act like tiny mirrors and reflect sunlight away from the Earth.
Because they are a risk to human health, aerosols are targeted by clean air initiatives around the world. Cities in which air quality is especially poor - such as places in China and India - have made great strides to clean the air, especially with the reduction of sulphates.
The catch-22 is that cleaner air will increase global warming in those countries, and make it harder to meet the climate change goals of the Paris Agreement.
Dr. Samset suggests that "the regional effects of cleaning our air, in all their complexity, must be taken into account when developing climate adaptation and mitigation strategies, it we are to be prepared for changes to come."
It is also important to continue to reduce our reliance on fossil fuels.