Emissions of greenhouse gases have a warming effect on the climate, whereas small airborne particles in the atmosphere, aerosols, act as a cooling mechanism.
Emissions of greenhouse gases have a warming effect on the climate, whereas small airborne particles in the atmosphere, aerosols, act as a cooling mechanism. That is the received wisdom in any case. However, new research from Lund University in Sweden can now show that the tiniest aerosols are increasing at the expense of the normal sized and slightly larger aerosols – and it is only the latter that have a cooling effect.
The air is full of small airborne particles – aerosols. Some are naturally produced, while others are caused by humankind’s combustion of fuel. Some are harmful to our health, while others reflect sunlight.
One of the important natural sources of aerosols is the fragrant terpenes from coniferous forests. For example, the boreal coniferous forest area “the taiga” that stretches like a ribbon across the whole world, accounts for 14 per cent of the world’s vegetation coverage, and is thus the world’s largest coherent land ecosystem.
Through chemical reactions with the ozone in the atmosphere, the terpenes are transformed into highly oxygenated organic molecules which stick to aerosol particles that are already in the air. This leads to more cloud droplets, as each cloud droplet is formed through steam condensing on a sufficiently large aerosol particle. More cloud droplets lead to denser clouds and reduced insolation.
Read more at Lund University
Photo credit: suju via Pixabay
