Himalayas act like an ‘aerosol factory’: Study

Aerosols are not entirely well understood. Most cool the planet, some have a warming effect. Some make clouds last longer, others make them disappear. Just about 10% are human-generated and the rest, naturally occurring, are barely understood. But scientists have now found that nearly every day for centuries now, winds blasting up from the forests on the foothills of the Everest, through the valleys to the sky-piercing summit, have been working up an “aerosol factory.”
A study by 29 scientists from Finland, Italy, Switzerland, the US, France, Estonia and China published in ‘Nature Geoscience’ last week recorded observations from the remote Nepal Climate Observatory Pyramid station at 5,079m above sea level, a few kilometres from the summit.
“The concept of the Himalaya aerosol factory is that you need processes to form particles — the trees, the mountains, the wind,” lead author Federico Bianchi from the University of Helsinki in Finland told TOI. So far, it had been assumed that there might be aerosols that high up but measurements have been extremely limited.
“Plants at the foothills of the Himalayas emit large quantities of gases. These are transported by the wind through the valley to high altitudes. These gases (while they are transported) react in the air with atmospheric oxidants and form tiny particles,” Bianchi said. The initial size of these particles is 1-2 nanometre. But, by the time they approach the summit, they reach the size of 50-100 nm and become seeds for clouds.
So, what impact do they have on climate change?
So far, the general scientific consensus is that the cooling effect of aerosols has been able to partially counter the warming effect of greenhouse gases since the late 19th century. Dr Bianchi added, “This new source of particles can now be used in climate models for better climate change predictions and modelling future scenario.”