Aims and Objectives

ACtIon4Cooling aims to advance our understanding of aerosol-cloud interactions (ACI) and their implications for climate forcing and geoengineering strategies. Its primary scientific objectives include:

  1. Enhancing Measurement and Retrieval Techniques:
    The project seeks to improve the observational capabilities for aerosols and clouds by integrating high-resolution, vertically-resolved remote sensing data from both passive and active instruments. This is intended to overcome current limitations in cloud masking and aerosol retrieval, particularly in terms of capturing critical microphysical properties such as cloud droplet number concentration (Nd), cloud optical thickness (COT), and liquid water path (LWP).
  2. Reducing Uncertainties in Radiative Forcing Estimates:
    A key goal is to minimize the large uncertainties—over 50% spread—in estimates of aerosol-induced effective radiative forcing. This will be achieved by refining models of aerosol absorption and the processes governing CCN and ice-nucleating particles, thereby providing a more accurate quantification of aerosol-cloud interactions and their impacts on cloud albedo and lifetime.
  3. Supporting Solar Radiation Modification (SRM) Research:
    The project is designed to generate robust scientific evidence to assess the feasibility, timing, and potential efficacy of various SRM approaches, including stratospheric aerosol injection (SAI), marine cloud brightening (MCB), and cirrus cloud thinning (CCT). By elucidating the mechanisms that control aerosol-induced adjustments in cloud properties, the project will help evaluate how these SRM techniques could alter local and global climates, particularly in terms of mitigating rapid warming and extreme weather events.
  4. Informing Policy and Governance:
    Beyond its scientific pursuits, the project aims to contribute to the policy discourse on geoengineering by providing detailed assessments of the environmental risks and governance challenges associated with SRM deployments. This includes evaluating potential negative side effects, such as ozone depletion and unintended alterations of regional climate regimes, to support the development of comprehensive, evidence-based guidelines for responsible SRM research and implementation.