Damien Irving - Anthropogenic aerosols, greenhouse gases and the uptake, transport and storage of excess heat in the climate system

Event type: 
Seminar
Date: 
17 April 2019
Time: 
2.00 - 3.00pm
Location: 

Climate Change Research Centre, Seminar Room, Mathews Building 4th floor, UNSW, Sydney

Presenter: 
Dr. Damien Irving
Climate Change Research Centre, UNSW, Sydney
Host: 
Climate Change Research Centre

Human activities have substantially altered the radiative properties of the atmosphere, giving rise to a planetary energy imbalance. The largest contributor to this imbalance is well-mixed greenhouse gases (GHGs), which are partially offset by poorly-mixed (and thus northern mid-latitude dominated) anthropogenic aerosols (AAs). To isolate the effects of GHGs and AAs, we analyse data from the CMIP5 historical (i.e. all natural and anthropogenic forcing) and single forcing (GHG-only and AA-only) experiments. We find that over the duration of the historical experiment (1861-2005), global excess heat uptake at the top of the atmosphere and ocean surface occurs almost exclusively in the Southern Hemisphere (SH). The influence of GHGs is similar for both hemispheres, with AAs completely offsetting that influence in the Northern Hemisphere (NH) but having little impact in the SH. The interplay between GHG and AA forcing also explains key features within each hemisphere, with AAs offsetting GHG-forced local maxima in ocean heat uptake in the NH but not SH. The interhemispheric asymmetry in ocean surface heat uptake results in a northward transport of excess heat in the ocean, as there is little hemispheric difference in oceanic heat storage after accounting for ocean volume. Data from the 1pctCO2 and RCP 8.5 experiments suggests that the future storage of excess heat will be skewed towards the NH oceans.

 

Brief Biography: Damien is a new postdoc with the CCRC, working with John Church and Jan Zika on the detection and attribution of changes in ocean temperature and salinity. His previous research interests have included excess heat budgets/pathways in the climate system, atmospheric planetary wave activity in the Southern Hemisphere, regional climate projections for Australia and its Pacific island neighbours, and the reproducibility crisis in modern research.