Picture (above): Australian bushfires from space, September 2019. Credit: European Space Agency. Contains modified Copernicus Sentinel data (2019), processed by ESA, CC BY-SA 3.0 IGO
At a time when bushfires are making front-page news on an almost daily basis, the Heatwaves and Cold Air Outbreaks program produced important research that showed how human-caused climate change will impact the most dangerous of these fires. Pyrocumulonimbus are deep convective clouds produced by bushfires. They can generate fire tornadoes and hurricane-strength winds and were at the core of the 2003 Canberra Bushfire and the 2009 Black Saturday Bushfires. The research found the conditions that generate these pyrocumulonimbi will become more frequent as a result of climate in the next 30 years and they will begin to appear in spring. The research also revealed key agricultural and suburban fringe areas in Australia that would see the greatest increase.
Another hot topic (pun intended) was research that revealed how heatwaves over NSW and Victoria differed in an effort to understand the dynamics of these events, which could improve their forecasts. CLEX researchers found that Sydney heatwaves are associated with relatively weak anticyclones in the Tasman Sea in conjunction with relatively strong cyclones south of the continent, whereas in Victoria it is the opposite.
Often distant events can have an impact on extreme temperatures in Australia and this was revealed in fascinating research that showed how variations during spring of winds high above the Antarctic could cause hot and dry extremes in early summer over Australia. The study shows that a weakening of these winds in spring results in higher temperatures, lower rainfall and an increase in heatwave and fire-prone weather conditions (especially across NSW and southern QLD) over late spring to early summer.
Looking beyond Australia, our RP co-lead Jason Evans was a lead author on the Desertification chapter of the recent IPCC Climate Change and Land Special Report. If you had been following the mainstream media, you would have assumed that its key message was become vegetarian, but one quick look at the headline statements (pdf) will quickly disabuse you of that idea. With land temperatures rapidly outstripping the rise of the global average temperatures and constant change in land cover, this is a report that deserves time and proper consideration. You can find the full report and all the details here.
Chief investigator Julie Arblaster has also been involved in key work leading up to the next IPCC report, AR6, due to be released in 2021. She attended the Coupled Model Intercomparison Project (CMIP6) Model Analysis Workshop, held in Barcelona from March 25-28, 2019. It provided the first opportunity for results from CMIP6 models to be discussed and presented by the modelling community. It was held in conjunction with the World Climate Research Programme’s (WCRP) Working Group on Coupled Modelling (WGCM) and organised by the WGCM’s CMIP panel.
There have been some very interesting findings, particularly around the sensitivity of some of the CMIP6 models. Find out more about that workshop here.
In the meantime, the program continues to grow, with Dr Tess Parker, joining RP2 in late November. Tess has particular expertise in the dynamics of heatwaves over south-east Australia and will be a welcome addition to the team.