KlimaCampus Kolloquium: Extreme climate events with ecological relevance: from droughts and floods on land to marine heat waves along the coast

Mounting evidence points towards an increase in intensity and frequency of extreme weather and climate events over recent decades. These changes are being linked to human-induced climate change, while impacts on individual extreme climate events are more difficult to quantify. Limitations in the observational network, both for physical climate system parameters and even more so for long-term ecological monitoring, have hampered progress in understanding the effect of extreme climate events on bio-physical interactions. However, recent advances open new opportunities for developing a mechanistic understanding of how extreme climate events affect human and natural systems. This is illustrated with hydroclimatic extremes, such as droughts and floods, and their effect on terrestrial ecosystems for tropical rainforests, in semi-arid regions, as well as for marine heat waves in the coastal environment.

The hydroclimatic conditions in Australia are used as an example: in 2010/11, severe flooding in northeastern Australia occurred, as well as a rare filling of Lake Eyre and record terrestrial carbon uptake. The severity of the conditions across Australia was unusual, even considering that it was a strong La Niña event. Long-term ocean warming has resulted in 0.5°C warmer sea surface temperatures around the Australian continent over the past 60 years. It is demonstrated that the warmer ocean background state increased the likelihood of the extreme rainfall response and relevant mechanisms are identified. The unusual conditions of the 2010/11 La Niña also had severe implications on the coastal environment around Australia, including prolonged marine heat wave conditions off Western Australia. Using high-resolution ocean model sensitivity experiments, the upper-ocean structure of the marine heat wave is investigated and contributions from wind and buoyancy forcing are quantified.

Date

12.12.2019

Time

15:15 h

Place

Bundesstr. 53, room 022/023
Seminar Room 022/023, Ground Floor, Bundesstrasse 53, 20146 Hamburg, Hamburg

Speaker

Caroline Ummenhofer, Woods Hole Oceanographic Institution (WHOI)

Chair

Jochem Marotzke

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