Global heating has likely made El Niños and La Niñas more ‘frequent and extreme’ – the Guardian

Between Two Storms (by Peter Kurdulija CC BY-NC-ND 2.0 via Flickr).
Between Two Storms (by Peter Kurdulija CC BY-NC-ND 2.0 via Flickr).

Scientists say greenhouse gases have already affected climate patterns in the Pacific that could lead to more severe weather, floods and heatwaves

Global heating has likely intensified a climate pattern in the Pacific since the 1960s that has driven extreme droughts, floods and heatwaves around the globe, according to a new study.

The scientists said they had shown for the first time that greenhouse gas emissions were likely already making El Niños and La Niñas more severe.

The shifts in ocean temperatures and atmospheric conditions in the Pacific – known as the El Niño Southern Oscillation (Enso) – affect weather patterns around the globe, threatening food supplies, spreading disease and impacting societies and ecosystems.

Scientists have struggled to work out if adding greenhouse gases to the atmosphere – trapping enormous amounts of heat in the ocean – has already changed Enso.

But because the system has natural swings spanning decades and actual observations have been too sparse, the scientists looked instead at more than 40 models of the climate, analysed in several ways.

Dr Wenju Cai, lead author of the study from Australia’s CSIRO science agency, said the models showed a “human fingerprint” from 1960 onwards.

This meant climate change had likely made both El Niños and La Niñas “more frequent and more extreme,” he said.

But some other scientists not involved in the study had reservations about the findings, raising concerns about the reliance on modelling.

The study has been in the works for five years, and Cai said it showed “we are experiencing a vastly different climate to that of the distant past” and would help scientists understand how Enso will change in the future “given sea surface temperatures are continuing to increase”…


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