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| Earth on Nov 20, 2011

Extreme weather expected to worsen with climate change

A new IPCC summary report suggests that extreme weather events – heat waves, heavy rains, coastal flooding – will worsen in this century as climate warms.

Over the past three years, more than 200 contributors from 62 countries with expertise in climate science and disaster risk management have been working on a comprehensive assessment of the role of climate change in altering extreme weather events, under the auspices of the IPCC (Intergovernmental Panel on Climate Change). The IPCC released a summary report of their findings on November 18, 2011 suggesting the severity of some extreme weather events has changed since 1950 and will likely continue to worsen over the 21st century.

The report outlines how extreme weather events including heat waves, heavy rains and coastal flooding are expected to worsen as Earth continues to warm. You’ll find the complete summary report here.

Water distribution during a drought in Africa. Droughts in western Africa are expected to worsen accoring to the 2011 IPCC Report. Image Credit: Oxfam International.

Heat waves in particular show a high probability (90 to 100%) of worsening over most land areas in upcoming years due to rising global air temperatures. Heavy precipitation events will likely (66 to 100% probability) increase in some regions, and Earth’s high latitudes and tropics are thought to be the most susceptible. More coastal flooding is also expected in this century (90 to 100% probability) due in part to rising sea levels from melting glaciers and ice sheets.

Extreme Weather 101 via

Future trends in cyclone activity, floods, droughts and tornadoes were more difficult to assess due to limitations in monitoring records and climate forecasting models. While findings related to these types of weather extremes are less certain, says the IPCC, the data do suggest the possibility that future cyclones might become more intense (stronger winds and heavier rains), though the number of annual cyclones is not expected to increase. Also, droughts and floods might worsen in some areas.

According to the IPCC report, there is evidence that increasing atmospheric concentrations of greenhouse gases from human activities have contributed to the observed changes in weather extremes.

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In addition to examining the role of climate change in altering extreme weather events, the authors have also been busy exploring a range of options that could be used by organizations and communities to minimize impacts from weather-related disasters. The report aptly notes that adverse impacts from extreme weather, which include economic losses and human fatalities, are influenced by a combination a factors that not only include human-caused climate changes but also natural climate variations and degrees of socioeconomic development. Hence, risk management strategies that act to reduce the exposure and vulnerability of communities to climate extremes can help populations become more resilient before disasters strike.

Rajendra Pachauri, Chair of the IPCC, stated in a press release (pdf):

This summary … provides insights into how disaster risk management and adaptation may assist vulnerable communities to better cope with a changing climate in a world of inequalities. It also underlines the complexity and the diversity of factors that are shaping human vulnerability to extremes – why for some communities and countries these can become disasters whereas for others they can be less severe.

Chris Field, left, and Rajendra Pachauri of the IPCC. Photograph by Franz Dejon/IISD via

Some of the risk management strategies being proposed to deal with future impacts from extreme weather events include the installation of early warning systems and the development and enforcement of land use plans and building codes.

Chris Field, the Co-chair of the IPCC Climate Change Adaptation Working Group, stated in the press release:

We hope this report can be a scientific foundation for sound decisions on infrastructure, urban development, public health, and insurance, as well as for planning—from community organizations to international disaster risk management.

Bottom line: A new summary report from the IPCC suggests that extreme weather events will worsen as climate warms in this century. The report was released at an IPCC meeting in Kampala, Uganda on November 18, 2011. The full comprehensive IPCC report titled “Special Report on Managing the Risks of Extreme Events and Disasters to Advance Climate Change Adaptation” will be available in February 2011.

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