Analysis of climate change caused by aerosol-cloud-radiaton interaction

Aerosols can affect climate in multiple and complex ways through their interactions with radiation and clouds. They scatter and absorb sunlight, which modifies the Earth’s radiative balance. Aerosol scattering generally tends to cool the climate, but aerosol absorption has the opposite effect, tending to warm the climate system. Aerosols also serve as condensation and ice nucleation sites, on which cloud droplets and ice particles can form. When influenced by a higher amount of aerosol particles, clouds of liquid water droplets tend to consist of more, but smaller, droplets, which causes these clouds to reflect more solar radiation. To investigate aerosol-cloud-radiation effects, an earth system model called “MIROC-ESM” was used. Long-term simulations using this earth system model were performed for the period 1850 to 2005, using a set of external forces. One simulation used all external forcing, and the other used all external forcing except for anthropogenic aerosols. The comparison between the two simulations showed that anthropogenic aerosol increase leads to cooling of the climate. Additionally, an energy budget analysis indicated that climatic changes to clearsky radiative cooling are primarily determined by changes in column water vapor and aerosol optical thickness. The cloud radiative effect can be related to temperature change.

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