Establishment and assessment of a new WMO climate normal for global cloud properties (NEW_CLOUD_NORM)

Although clouds cover nearly 70% of our planet’s area and regulate precipitation and radiation, we know very little about the past and future changes in clouds.

The uncertainties and spread in our estimates of how much and how quickly Earth would warm for a given increase in greenhouse gases (climate sensitivity) remain high and have hardly changed in the last four decades.

This large spread in climate sensitivity can be traced back to poor understanding of clouds and now considered to be “a cloud problem”.

There is currently a dire need to provide a robust observational basis, in terms of harmonized climatology of cloud properties, trends therein and cloud-climate variability, to enable to understand how clouds change in a warming world and to anchor global climate models to such climatological features.

We are just about reaching a point where methods for cloud parameter retrievals based on historical satellite measurements have matured to a level where they are able to provide cloud information of climate quality.

Therefore, using nearly 40-years of satellite-based cloud climate data records, the proposed project aims to establish a new climatological normal for cloud properties during the last WMO-defined 30-year normal period (1991-2020) and also to contribute towards tackling one of the Grand Challenges on clouds outlined by the World Climate Research Program (WCRP).

Such a climate normal for clouds based purely on satellite observations is entirely novel.