The impacts of aerosols on climate are significant, but also very uncertain. There are several reasons for this, one of which is the uncertainty in how and how fast they are formed in the atmosphere by nucleation.

Aerosol particles can influence climate in several ways:

The mass of a freshly nucleated aerosol particle is more than 100,000 times smaller than that of an ‘aged’ aerosol of a size optimal to affect climate.

New particle formation has been observed all over the globe, from the Poles to the Tropics

Of these locations, only nucleation in the free troposphere and in the vicinity of clouds seems to agree with theoretical predictions. In most other cases the number of aerosol particles produced is under-predicted.

The dominant role of sulfuric acid has remained a steady conclusion over the years, whereas the potential roles of organic compounds and ions are still hotly debated.