Posts Tagged ‘Climate extremes’
The Sacred Cowboys sang nothing grows in Texas. Last summer it came true. The Texan drought of 2011 was hotter and drier than any of the great droughts of the 1930s. Is it possible to diagnose what role climate change may have played? State Climatologist for Texas John Nielsen-Gammon asked this question last year in a preliminary post on the drought.
He concluded there was a strong anthropogenic evidence for warming but little evidence for its influence on the extremely low rainfall. The following analysis was developed without seeing his summary and happily, they have much in common. The big difference is the explicit treatment of non-linear warming.
I applied the methods for analysing step changes and attributing regional warming developed for SE Australia to the Texan climate. Was it possible to estimate the relative contributions of global warming for a single season? The results were more successful than I had anticipated. Tmax was 86% more likely to be due to anthropogenic warming and Tmin 95%. The method is unorthodox, so may be controversial. Details over the fold. Read the rest of this entry »
This posts looks at how climate shifts affect extremes using the example of heat extremes in SE Australia. We had another burst of hot weather this week, which led to rolling power blackouts in South Australia. These are becoming more common, as our electricity bills rise to pay for network infrastructure. In every year but one since 1997, the Laverton, Victoria climate record has registered at least 1 day above 40°C. For those of you interested in how the science of detecting and projecting extremes is carried out, there is a comprehensive background on methods. For those who are just interested in results, page down to the results section. Read the rest of this entry »
The Summary for Policymakers (SPM) for the IPCC Special Report Managing the Risks of Extreme Events and Disasters to Advance Climate Change Adaptation (SREX) was released late last night our time. The final plenary was held in Kampala Uganda, finishing on the 17th before the release yesterday. As usual, it is gone through line by line by IPCC country member representatives and the co-ordinating lead authors to craft a document that contains key policy messages while retaining true to the science in the report.
The SPM is complex and has already been given a number of interpretations in the press. The ABC news says extreme weather to worsen with climate change. The Australian focuses on the uncertainty Climate change effects unknown: IPCC report. A quick survey of Google news suggests that most outlets are focusing on extremes to worsen, or the qualified some extremes to worsen.
The Australian is different. Its header says:
GREAT uncertainty remains about how much of an impact climate change will have on future extreme weather events, the world’s leading climate scientists have found.
While there has been an increase in warm days and a decrease in cold nights, the likely impact on future weather events would not be evident for decades because of natural variability, the scientists say in a key review prepared for the UN’s Intergovernmental Panel on Climate Change.
This completely ignores the thrust of the report, which is to address the risks of extreme climate-related events and disasters and manage changing risk through adaptation. The great value of the report is not so much in its headline findings, which are complex but are in bringing the climate, adaptation and disaster communities together. These two communities had a hard time of it in the writing of the report bringing together different language, concepts, views of risk and methods of assessing vulnerability and adaptation. Read the rest of this entry »