Droughts, heatwaves and floods: How to tell when climate change is to blame

Abstract

T he Northern Hemisphere is sweating through another unusually hot summer. Japan has declared its record temperatures a natural disaster. Europe is baking under prolonged heat, with destructive wildfires in Greece and, unusually, the Arctic. And drought-fuelled wildfires are spreading in the western United States. For Friederike Otto, a climate modeller at the University of Oxford, UK, the past week has been a frenzy, as journalists clamoured for her views on climate change's role in the summer heat. "It's been mad, " she says. The usual scientific response is that severe heatwaves will become more frequent because of global warming. But Otto and her colleagues wanted to answer a more particular question: how had climate change influenced this specific heatwave? After three days' work with computer models, they announced on 27 July that their preliminary analysis for northern Europe suggests that climate change made the heatwave more than twice as likely to occur in many places. Soon, journalists might be able to get this kind of quick-fire analysis routinely from weather agencies, rather than on an ad hoc basis from academics. With Otto's help, Germany's national weather agency is preparing to be the first in the world to offer rapid assessments of global warming's connection to particular meteorological events. By 2019 or 2020, the agency hopes to post its findings on social media almost instantly, with full public reports following one or two weeks after an event. "We want to quantify the influence of climate change on any atmospheric conditions that might bring extreme weather to Germany or central Europe, " says Paul Becker, vice-president of the weather agency, which is based in Offenbach. "The science is ripe to start doing it". The European Union is interested too. The European Centre for Medium-Range Weather Forecasts (ECMWF) in Reading, UK, is preparing to pilot a similar programme by 2020 that will seek to attribute Climate as culprit Weather forecasters will soon provide instant assessments of global warming's influence on heatwaves and floods.

Variations in start date, end date, frequency and intensity of yearly temperature extremes across China during the period 1961–2017

“…On a global scale, previous studies have demonstrated that historical warming over the past century has increased the frequency and intensity of warm extremes, while decreasing the frequency and intensity of cold extremes in most regions of the globe (Coumou and Rahmstorf 2012, Morak et al 2013, Donat et al 2016. Extreme temperature events have exerted more devastating influences on human societies and the natural environment than mean warming trends (Schiermeier 2018, Chen et al 2019. However, the pattern of change for extreme temperatures is not spatially uniform at the regional scale due to regional differences in the response of the climate system to increasing radiative forcing and the background noise of climate variability (IPCC 2018).…”

Higher Subseasonal Predictability of Extreme Hot European Summer Temperatures as Compared to Average Summers

“…Recent years have seen an increased number of extreme heat waves across the Northern Hemisphere, for example, over central Europe in 2003 (Fink et al, 2004;Fouillet et al, 2006;Schär et al, 2004;Trigo et al, 2005), over Russia in 2010 (Barriopedro et al, 2011;Dole et al, 2011), and over Europe in 2018 (Schiermeier, 2018). It has been evident for decades (IPCC, 1990) that extreme events such as heat waves are exacerbated by climate change (Coumou & Rahmstorf, 2012;Diffenbaugh et al, 2017;Imada et al, 2018;Mann et al, 2017;Sippel et al, 2016;Stott et al, 2004Stott et al, , 2015.…”

Analysis of Precipitation and Temperature Extremes over the Muda River Basin, Malaysia

“…The number and intensity of recorded natural hazards such as flood, drought, heatwave and wildfire have increased as climate change exacerbates. For instance, climate change caused the frequent occurrence of devastating heatwaves in northern Europe, Asia and many other places [2]. Elsewhere, based on Kundzewicz et al [3], the highest recorded annual flood loss occurred in China in 2010, causing a total loss of~USD 51 billion.…”