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Atmospheric aerosols affect the Earth's climate in many ways, including acting as the seeds on which cloud droplets form. Since a large fraction of these particles is anthropogenic, the clouds' microphysical and radiative characteristics are influenced by human activity on a global scale leading to important climatic effects. The respective change in the energy budget at the top of the atmosphere is defined as the effective radiative forcing due to aerosol‐cloud interaction (ERFaci). It is estimated that the ERFaci offsets presently nearly 1/4 of the greenhouse‐induced warming, but the uncertainty is within a factor of two. A common method to calculate the ERFaci is by the multiplication of the susceptibility of the cloud radiative effect to changes in aerosols by the anthropogenic change of the aerosol concentration. This has to be done by integrating it over all cloud regimes. Here we review the various methods of the ERFaci estimation. Global measurements require satellites' global coverage. The challenge of quantifying aerosol amounts in cloudy atmospheres are met with the rapid development of novel methodologies reviewed here. The aerosol characteristics can be retrieved from space based on their optical properties, including polarization. The concentrations of the aerosols that serve as cloud drop condensation nuclei can be also estimated from their impact on the satellite‐retrieved cloud drop number concentrations. These observations are critical for reducing the uncertainty in the ERFaci calculated from global climate models (GCMs), but further development is required to allow GCMs to properly simulate and benefit these novel observables. Plain Language Summary: Aerosols affect the climate in many ways, including serving as the basis for the formation of cloud droplets. Therefore, aerosols have profound impacts on clouds and through that on the Earth's energy budget. Increasing aerosols leads to additional cloud droplets, changing cloud properties such that they reflect more solar radiation back to space and offset nearly 1/4 of the warming induced by greenhouse gases, but with a large uncertainty within a factor of two. Here we review the ways by which aerosols and their radiative effects are retrieved from space. A major challenge is to reduce the uncertainty by better retrieval methods of atmospheric aerosol and cloud properties. This challenge is met by rapid satellite retrieval methodological developments and numerous new satellite missions, which are described here. These new methodologies have to be matched with parallel development in the global circulation models for the improved estimation of the actual climatic impacts. Key Points: Calculating the susceptibility of clouds to aerosols has to include the cleanest conditions where measuring the aerosols is challengingThe definition and use of regimes to group clouds with similar responses to aerosol is vital for future observation‐based effective radiative forcing due to aerosol‐cloud interaction (ERFaci) estimatesNew observational tools are vital for reducing ERFaci uncertainty but require further global climate model development to simulate these novel observables [ABSTRACT FROM AUTHOR]

The TROPOspheric Monitoring Instrument (TROPOMI), launched on 13 October 2017, aboard the Sentinel-5 Precursor satellite, measures reflected sunlight in the ultraviolet, visible, near-infrared, and shortwave infrared spectral range. It enables daily global mapping of key atmospheric species for monitoring air quality and climate. We present the first methane observations from November and December 2017, using TROPOMI radiance measurements in the shortwave infrared band around 2.3 μm. We compare our results with the methane product obtained from the Greenhouse gases Observing SATellite (GOSAT). Although different spectral ranges and retrieval methods are used, we find excellent agreement between the methane products acquired from the two satellites with a mean difference of 13.6 ppb, standard deviation of 19.6 ppb, and Pearson’s correlation coefficient of 0.95. Our preliminary results capture the latitudinal gradient and show expected regional enhancements, for example, in the African Sudd wetlands, with much more detail than has been observed before. [ABSTRACT FROM AUTHOR]