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The timing of anthropogenic emergence in climate extremes
Andrew King, Markus Donat, Erich Fischer, Ed Hawkins, Lisa Alexander, David Karoly, Andrea Dittus, Sophie
Lewis and Sarah Perkins
Illustration
Time
Time of Anthropogenic Emergence (TAE)
Motivation
• No previous global study of emergence in temperature and precipitation extremes.
• Previous studies use modern baseline period.
Methodology
• For TAE to have occurred:
– A 20-year moving window must be significantly different (p < 0.05) from a 51-year quasi-natural period (1860-1910).
– AND all subsequent 20-year windows must remain significantly different from the quasi-natural period.
Data
• Multiple runs (23 in total) from six CMIP5 models.
• Historical (1860-2005) and RCP8.5 (2005-2099).
Data
• Apply our methodology to mean and extreme temperature and precipitation indices.
Name of index Definition
Tas Mean temperature
Pr Total precipitation
TXx Highest daily maximum temperature
TXn Lowest daily maximum temperature
TNx Highest daily minimum temperature
TNn Lowest daily minimum temperature
RX1D Maximum 1-day precipitation
RX5D Maximum consecutive 5-day precipitation
TAE temperature maps
TAE precipitation maps
The global picture
Where can we attribute changes in climate to anthropogenic influences?
Where can we attribute changes in climate to anthropogenic influences?
Conclusions
• First study to look at Time of Emergence of extremes on a global scale.
• Climate extremes tend to emerge later than means.
• Spatial aggregation brings forward TAE.
• High uncertainty in TAE values.
• Results can be used as a guide for attribution studies.
Thank you
E: andrew.king@unimelb.edu.au W: andrewdking.weebly.com
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