Issue link: https://maltatoday.uberflip.com/i/1398274
13 maltatoday | SUNDAY • 1 AUGUST 2021 OPINION How summer 2021 has changed our understanding of extreme weather A succession of record-break- ing natural disasters have swept the globe in recent weeks. There have been serious floods in Chi- na and western Europe, heat- waves and drought in North America and wildfires in the sub-Arctic. An annual report on the UK's weather indicates extreme events are becoming common- place in the country's once mild climate. August 2020 saw temperatures hit 34°C on six consecutive days across south- ern England, including five sticky nights where the mercury stayed above 20°C. In the future, British summers are likely to see temperatures greater than 40°C regularly, even if global warm- ing is limited to 1.5°C. The Canadian national tem- perature record was shattered in June 2021 meanwhile, with 49.6°C recorded in Lytton, Brit- ish Columbia – a town that was all but destroyed by wildfires a few days later. Many of these events have shocked climate scientists. The Lytton temperature record, for example, was head-and-shoul- ders above those set during pre- vious heatwaves in the region. Some scientists are beginning to worry they might have un- derestimated how quickly the climate will change. Or have we just misunderstood extreme weather events and how our warming climate will influence them? Everything is connected Floods and wildfires are not discrete events: they are the result of numerous intercon- nections and feedback loops in the climate system. Take the mid-July flash floods in London. These were caused by summer rainstorms, which were in turn driven by warm air rising from the Earth's surface that built up during the preceding heatwave, stacking the deck for the down- pours that were to follow. The wildfires raging in the western US, meanwhile, are a catastro- phe whose stage was set by long- term drought. The Earth's climate is com- plex, dynamic and chaotic, in- volving interactions and energy fluxes between the land, ocean and atmosphere. The idea that scientists can study one part of this system in relative isolation is flawed. But it was not always possible to model or understand all of these complexities, so sci- entists had to break them into manageable pieces in order to fit them into linear systems and models. These were often split across the scientific disciplines that most of us are still some- what confined to today, such as atmospheric sciences, hydrol- ogy, Earth systems sciences, or engineering. As a result, we are used to treating each natural hazard in- dependently from another. But it takes more than rain to create a flood, and more than a spark to start a wildfire. All of the el- ements of our climate system – and the hazards it produces – are connected in one way or another. It's not that these interactions and combinations are new, it's just that we haven't always thought about them in such a joined-up way. It may seem shocking when disaster follows disaster, seemingly in increas- ingly quick succession. This is because we are trained to think about weather hazards singu- larly, focused on one type – a drought or flood, for example – at a time. Just about all risk assessments underestimate the risks associated with intercon- nected events. But as our climate continues to warm, its baseline is shifting. How these hazards and their causes interact is therefore al- so changing fast, challenging the very definition of extreme weather events. The interconnections between extreme weather events have, until recently, been largely over- looked by the science commu- nity. But there is now growing international research tasked with mapping these complex re- lationships. Compound events – a term only adopted by the IPCC in 2012 – describe the outcomes of a combination of causes that ultimately surpass the capacity of an underlying system to cope. These include events where a hazard like a wildfire was made worse by something which had preconditioned the environ- ment, like drought. Wariness of these compound events should influence the way we live our lives in a warmer world. More research across disciplines is needed, as well as new approaches to disaster risk assessment and climate change adaptation that look across all weather-driven hazards and their complex and changing interactions. Improvements in climate modelling mean we can do more of this type of science – the climate crisis dictates that we must. TheConversation.eu Christopher J White is Head of the Centre for Water, Environment, Sustainability & Public Health, University of Strathclyde Christopher J White The tiny German village of Kordel, poplulation 2,900, is swamped by rising flood waters July 15 (Photo by Sebastian Schmitt)