The frequency of extreme climate events, their magnitude and extent are increasing and there is enough basis for strong action to enforce mitigation and adaptation measures, according to director of the World Climate Research Programme Ghaseem R. Asrar.

Presenting a snapshot of some extreme events over the past decade here on Tuesday, Dr. Asrar said a research of such events in the last 10 years looked at the connection between climate change and the frequency, magnitude and the extent of extreme events based on case studies.

“The findings are consistent with the first report of the Inter-governmental Panel on Climate Change (IPCC) in 1990, which said that episodes of high temperature would most likely become more frequent in the future and cold episodes less frequent. However, there is a limit to the predictions and correlations that can be made and to say if all these events are due to climate change. For example, there is scientific evidence that supports the link between climate change and the frequency of heat waves,” he said.

The 10 warmest years on record have all occurred since 1998.

The 2000s were warmer than the 1990s and the Nineties were warmer than the Eighties and earlier decades.

On September 19, 2010, at the end of the melt season, the sea ice extent was the third smallest on satellite record after 2007 and 2009. “Global mean sea level is higher now and is rising more rapidly than at any other time in the past 3000 years at the pace of around 3.4 millimetres a year.”

In the absence of a standard definition of an extreme event, the research looked at a single or a succession of weather phenomena leading to abnormal meteorological and/ or climate conditions with high impacts such as heat waves, severe storms, flooding and drought.

The snapshot looks at 34 major events from the extreme cold winter in Siberia in 2001 where temperatures dropped to minus 60, hurricane Catarina in 2004 that developed in the South Atlantic Ocean for the first time, the worst drought in Brazil, the deadliest hurricane since 1928 — Katrina, the tropical cyclone Nargis that hit Myanmar, floods in Pakistan and exceptional rainfall in many parts of the world.

“There is one striking feature that has been observed and that is that most of the extreme events like hurricanes, tropical storms, heat waves, rainfall are regional in nature and it would be difficult to generalise or make projections on a global scale,” Dr. Asrar said.

However, the magnitude and frequency were showing an upward trend.

The episodes of high temperatures were likely to be more frequent than cold. The heat wave in July in Russia was worse than the heat wave of Europe in 2003, which was in a class of its own.

The heat wave in Russia was unprecedented since the 1500s.

“These events, which are large in magnitude and different from past events, support the IPCC findings that the frequency, magnitude and extent of events are going to be different from the past,” he added.

Even the IPCC's fourth assessment report warned that the number of heat waves was going to increase and warm nights are on the rise. Dr. Asrar said the heat was drying the soil and causing droughts in some parts.

Using the case studies of extreme events in the last decade, it was possible to project that extreme events would be greater in the future, he said.

The frequency of tropical storms, hurricanes, cyclones would be higher in magnitude as the IPCC had said.

More intense storms

The latest projections bear out the same thing and point to more severe events.

The projections also indicated a warmer climate and more intense storms and hurricanes. “What we know of extreme events is that they are significantly different in the last decade from historical records. We can't quantify or attribute with great certainty the influence of warming on extreme events but these things are possible in a warmer climate,” he said.


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