Controlling smog and soot is the classic win-win situation, so it's great that the world is finally waking up to the idea, says Drew Shindell.

The primary drivers of the Northern Hemisphere expansion of the tropical climate zone over the past several decades are shown to be the recent increases in black carbon aerosols and tropospheric ozone rather than in greenhouse gases, which contribute to a lesser extent.

South Asian emissions of fossil fuel SO2 and black carbon increased

Clouds and aerosol particles have bedevilled climate modellers for decades. Now researchers are starting to gain the upper hand.

Human activities are releasing tiny particles (aerosols) into the atmosphere. These human-made aerosols enhance scattering and absorption of solar radiation. They also produce brighter clouds that are less efficient at releasing precipitation. These in turn lead to large reductions in the amount of solar irradiance reaching Earth's surface, a corresponding increase in solar heating of the atmosphere, changes in the atmospheric temperature structure, suppression of rainfall, and less efficient removal of pollutants.

Time series analysis of Aerosol Optical Depth (AOD) derived from NOAA-AVHRR data during the period 1996–1999 and the MODIS data during 2000–2009 over the Arabian Sea revealed a systematic biennial variability in the high AOD during summer months. The variability is more prominent over the northern and central parts of the Arabian Sea and became less significant towards southern latitudes. The possible mechanisms for these are examined by estimating the source strength over coastal Arabia and AOD flow rate through the western boundary of the Arabian Sea.

Distributions and climate impacts of biomass-burning aerosols were simulated by a global aerosol climate model, SPRINTARS, which was fully coupled to a general circulation model. The model included calculations of the direct, semi-direct and indirect effects of aerosols.

About half of the global gas and particle emissions to the atmosphere resulting from the burning of biomass originate from sub-Saharan Africa. There are four principal pathways: wildfires, the use of biomass fuels for energy, burning associated with deforestation and the burning of agricultural residues.

Biomass burning is an important source of greenhouse gas emissions, most importantly carbon dioxide (CO2). In this study, we used burnt area estimates derived from the L3JRC product to estimate the CO2 emissions from forests. The results suggested than an average of 2,414 sq.kms is burnt annually.