Emissions of Asian Anthropogenic Aerosols (A3) are rapidly changing - most notably black carbon and sulphate aerosol precursors from India and China. The resulting range of climate impacts and societal hazards may dominate regionally over greenhouse gas induced trends for the next several decades, but the implications are as yet insufficiently explored. CATHY (Climate implications of rapid changes in Asian Anthropogenic Aerosol emissions: Temperature, Hydrological cycle and variabilitY) tackles the urgent need for quantifying climate related hazards resulting from ongoing and projected changes in A3 emissions.
Why: Today, the Earth’s climate is significantly influenced by Asian aerosol emissions, with impacts affecting up to two billion people in the near-source regions alone. This regional influence is set to change, along with teleconnections affecting remote regions (Arctic, Europe, North Africa). The implications for climate and society are however highly uncertain, due to limited knowledge of physical processes, modelling capability, and future policy choices. Improved quantification of the aerosol-climate influence on physical hazards – in Asia and around the globe – is therefore critical.
How: CATHY will merge observed changes, projected emission patterns, and advances in modelling and analysis techniques. Key opportunities for scientific breakthroughs include recent trends in Chinese and Indian emissions, Large Ensemble modelling and the diversity of aerosol assumptions made in the Shared Socioeconomic Pathways.
Novelty: CATHY will disentangle dynamical responses to localized forcing through development of a novel reduced-complexity Green’s function, investigate remote impacts via a machine learning based circulation pattern analysis, separate the active mechanisms differentiating absorbing and scattering aerosols, and frame the resulting improved understanding as quantification of physical hazards driving climate risk.