Ice nucleation and its effect on the sensitivity of Earth´s climate
Ken Carslaw (University of Leeds, Great Britain)

Clouds containing a mixture of ice and supercooled water are expected to become more reflective in a warmer world as the ice is increasingly replaced by water. This response causes a negative “cloud-phase” climate feedback that acts to dampen global warming. In this presentation I will show that quantification of this cloud response hinges on understanding the properties of the rare particles that initiate ice formation – ice-nucleating particles. I will show results from modelling and observations that demonstrate the importance of these particles for cloud reflectivity. Substantial recent developments in our understanding of ice-nucleating particles from laboratory and field measurements now enable us to build reasonable global models of their distribution and to determine which properties matter for climate change.