Global Warming Expected To Increase Extreme El Niño Events
January 20, 2014

Extreme El Niño Events Expected To Double Over The Next 100 Years

redOrbit Staff & Wire Reports - Your Universe Online

A new analysis of rain patterns has revealed that extreme El Niño events, such as the 1983 heat wave that caused Australia’s Ash Wednesday bushfires, will double as the planet warms in the years ahead.

“We currently experience an unusually strong El Niño event every 20 years. Our research shows this will double to one event every 10 years,” study co-author Dr. Agus Santoso, a professor at the University of New South Wales and an associate investigator with the ARC Centre of Excellence for Climate System Science (CoECSS), explained in a statement Sunday.

Dr. Santoso and an international team of colleagues, including experts from the US National Oceanic and Atmospheric Administration (NOAA) and Australia’s national science agency, the Commonwealth Scientific and Industrial Research Organization (CSIRO), reported those findings in the latest edition of the journal Nature Climate Change.

“El Nino events are a multi-dimensional problem, and only now are we starting to understand better how they respond to global warming,” he added. Extreme El Niño events develop differently from standard El Niños, which typically first appear in the western Pacific Ocean.

The stronger version of these phenomena occur when sea surface temperatures exceeding 28°C develop in the normally cold and dry eastern equatorial part of the ocean. Since the location for the origin of the temperature increase is different, it causes drastic changes in global rainfall patterns, the study authors explained.

“The question of how global warming will change the frequency of extreme El Niño events has challenged scientists for more than 20 years,” said co-author Dr Mike McPhaden of the NOAA Pacific Marine Environmental Laboratory. “This research is the first comprehensive examination of the issue to produce robust and convincing results.”

These extreme El Niño events can have a tremendous impact on regions all over the world. The 1997-1998 heat wave alone caused between $35 and $45 billion in damage, while also resulting in an estimated 23,000 fatalities worldwide.

“During an extreme El Niño event countries in the western Pacific, such as Australia and Indonesia, experienced devastating droughts and wild fires, while catastrophic floods occurred in the eastern equatorial region of Ecuador and northern Peru,” said lead author Dr. Wenju Cai of CSIRO.

Dr. Cai and his colleagues examined 20 different climate models, all of which consistently simulate major rainfall reorganization during extreme El Niño events. The researchers discovered a substantial increase in extreme El Niño events from now and over the next century as the eastern Pacific Ocean warmed in response to global climate change.

“This is a highly unexpected consequence of global warming,” co-author Mat Collins, a professor at the University of Exeter’s College of Mathematics, Engineering and Physical Sciences, told the Exeter Express and Echo on Sunday. “Previously we had thought that El Niño would be unaffected by climate change. Looking at the climate models in this way we have been able to indicate that there will be quite a dramatic rise in the number of extreme El Niño occurrences.

“This is why occurrences of extreme El Niños increase, even if variability of ocean temperatures does not,” Dr. Santoso added. “Looking through the lens of such a massive reorganization of atmospheric convection, extreme El Niño is by definition severe disruption of global weather patterns, affecting marine and terrestrial ecosystems, agriculture, tropical cyclones, drought, bushfires, floods and other extreme weather events worldwide.”