PHOTO: Pixabay
PHOTO: Pixabay

EXPERT REACTION/BRIEFING: How much of our extreme weather is down to manmade climate change?

Embargoed until: Publicly released:
Peer-reviewed: This work was reviewed and scrutinised by relevant independent experts.

Kiwi and British researchers extensively reviewed the evidence of how climate change has influenced five kinds of extreme weather events, the impacts of these events in recent years, and just how much these impacts are directly linked to climate change. For example, heatwaves have increased in likelihood and intensity around the world due to climate change, with tens of thousands of deaths directly attributable. In another example, climate change has increased rain during tropical cyclones and storm surge heights. This increased rain has caused around half a trillion US dollars in damages in the North Atlantic. The research team calls for such extreme weather events to be more systematically recorded around the world, saying a lack of data is a major barrier to mitigating future damages.

Journal/conference: Environmental Research: Climate

Organisation/s: Victoria University of Wellington, University of Oxford, UK

Funder: This work was supported by a NERC Doctoral Training Partnership grant NE/L002612/1 and the European Union’s Horizon 2020 research and innovation program under grant agreement No 01003469. R.F.S.-S. acknowledges support from the Natural Environment Research Council grant NE/S007474/1, Climate Analytics and the Oxford Martin Programme on the Post-Carbon Transition. L.J.H acknowledges funding from the New Zealand MBIE Endeavour Fund Whakahura programme (Grant ID: RTVU1906).

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Expert Reaction

These comments have been collated by the Science Media Centre to provide a variety of expert perspectives on this issue. Feel free to use these quotes in your stories. Views expressed are the personal opinions of the experts named. They do not represent the views of the SMC or any other organisation unless specifically stated.

María José Sanz, scientific director of BC3 Basque Centre for Climate Change

This is the most comprehensive review to date of the understanding of the influences of climate change on five types of extreme weather events: extreme temperatures, heavy rainfall, droughts, forest fires and tropical cyclones. This extends both the record of extreme weather impacts worldwide and the coverage of attribution studies across different events and regions, in particular the global south. The work represents an improvement over the analyses conducted in the Sixth Assessment Report of the Governmental Panel on Climate Change.

It indicates that the attribution of some of these events to a greater or lesser extent to climate change has so far been underestimated.

Last updated: 28 Jun 2022 11:40am
Declared conflicts of interest:
None declared.
Ernesto Rodríguez Camino, senior State meteorologist, head of Climate Assessment and Modelling at the Spanish State Meteorological Agency (AEMET) and expert in the generation of regionalised climate change scenarios for Spain

Dr Friederike Otto is a pioneer in near-real-time attribution studies of extreme weather events. Attribution studies determine the role of climate change in the frequency and intensity of extreme weather events, such as heat waves or tropical cyclones. This requires two essential sources of information. On the one hand, numerical simulations capable of reproducing the observed extreme event and, on the other hand, observations that allow the different aspects of the event to be characterised.

Limited access to observations has limited and continues to limit further attribution studies to prepare affected sectors for increasingly frequent and intense weather extremes, a consequence of ongoing anthropogenic climate change.

This paper comprehensively reviews the role of anthropogenic climate change in extreme weather and climate events. While the attribution of increased frequency, intensity and duration of heatwaves to climate change has high confidence in many regions of the world (including the Mediterranean), the attribution of intense precipitation events (and often associated floods) to climate change is more doubtful in most cases.

For other types of events, such as droughts, forest fires or tropical cyclones, there is even less confidence in their attribution to climate change and more studies are needed in different regions of the globe.

Last updated: 28 Jun 2022 11:38am
Declared conflicts of interest:
None declared.
Professor Tim Palmer, Royal Society Research Professor, University of Oxford

Attribution analyses for extreme weather events are much in demand. The authors review the current state of the art and highlight some areas where we need to advance our understanding. On this, they miss one very important area: improving the reliability of the very climate models used to do these attribution studies. As we very recently discussed in Nature Climate Change1, current climate models struggle to represent precipitation and related extreme events. This undermines attempts to attribute extreme weather events quantitatively. The solution requires new international partnerships to allow km-scale global climate models to be developed and run on dedicated exascale computers - a kind of ‘Climate CERN’.

Last updated: 28 Jun 2022 11:35am
Declared conflicts of interest:
None to declare.

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