1. cooling - indirect light scattering by clouds CCN phytoplankton DMS sulphate aerosols dust particles cooling - direct light scattering by aerosols + iron

2. cooling - indirect light scattering by clouds CCN phytoplankton DMS sulphate aerosols cooling - direct light scattering by aerosols SO 2

3. original photograph by freefoto.com Clouds, snow and ice have a high albedo - they reflect a large amount of sunlight back into space. Water surfaces and forests have a low albedo, they absorb a large fraction of the sun’s energy, reflecting only a small amount back to space. Over the whole earth, about 30% of incoming sunlight is reflected back to space, 50% is absorbed by the Earth’s surface and about 20% is absorbed in the atmosphere by chemicals, aerosols and clouds.

4. isoprene - 2, methyl buta-1, 3 diene. C C HCH 3 H H H H

5. Thanks to Alex Baker, UEA, for this diagram. phytoplankton seaweeds transfer of iodine to land in rain and aerosols O3O3 O2O2 reactive iodine compounds ozone destruction CH 3 I organic matter

6. Breaking waves introduce billions of bubbles into the sea. As the bubbles rise back up through the water they scavenge gases. When the bubbles reach the surface they burst and the gas they contain enters the air. From each bubble that bursts, a jet of seawater also enters the air. As this jet rises it breaks up into droplets. The water evaporates and leaves aerosol particles made up of seasalt. Billions of tonnes of salt enter the atmosphere this way. A lot falls straight back into the sea but a significant amount of salt is transported to land. Seasalt aerosol particles are very important in the atmosphere. Not only do they scatter sunlight back into space and so cause a direct cooling of our planet but they also can act as very efficient cloud condensation nuclei and start the formation of clouds. In this way they cause indirect cooling of the Earth. Seasalt aerosol levels are predicted to rise in the future due to higher windspeeds.

7. For those of you who like a bit of chemistry! N 2 O + ultra-violet light  N 2 + O O + N 2 O  2NO NO + O 3  NO 2 + O 2 NO 2 + O  NO + O 2 overall: O 3 + O  2O 2