The World Meteorological Organization (WMO) has launched its first annual Airborne Dust Bulletin. The bulletin, issued on 12 April, provides an overview of atmospheric dust levels and geographical distribution in 2016. Estimates of dust content were derived from daily forecasts from the Copernicus Atmosphere Monitoring Service of the European Centre for Medium-Range Weather Forecast. The 2016 global average aerosol optical depth, a measure of the dust burden, was similar to previous years, according to the report, which highlighted particularly severe sand and dust storms in Iran and China/Mongolia. It found no clearly defined trend between 2003 and 2016, due to modelling capacity constraints and the relatively short time since systematic observations began in 2003. Every year, an estimated 2,000 million tons of dust is emitted into the atmosphere. While much of this is a natural part of Earths cycles, a significant amount is generated by human-induced factors, especially unsustainable land and water management, said Enric Terradellas, chair of WMOs Sand and Dust Storm Warning Advisory and Assessment System steering committee. Dust is a major component of atmospheric aerosols, which affect the global climate and have important effects on weather through their influence on atmospheric dynamics, clouds and precipitation, Terradellas added. Most of the dust in 2016 was concentrated around its main sources: the belt of tropical and subtropical deserts of the northern hemisphere, stretching from the Sahara through the Arabian and Syrian deserts to the Thar desert between India and Pakistan, as well as the mid-latitude deserts of Central Asia and China/Mongolia.