Complex interactions of extreme events in Southern Europe and Brazil: a compound event perspective
Authors: Russo Ana , Libonati Renata , Geirinhas João L. , Ramos Alexandre M. , Silva Patrícia S. , Sousa Pedro M. , DaCamara Carlos C. , Miralles Diego G. , Trigo Ricardo M. 
Published: March 2022

&lt;p&gt;Record-breaking natural hazards occur regularly throughout the world, leading to a variety of impacts [1]. According to the WMO, since 1970 there were more than 11000 reported disasters attributed to these hazards globally, with just over 2 million deaths and US$ 3.64 trillion in losses [2]. From 1970 to 2019, weather, climate and water hazards accounted for 50% of all disasters, 45% of all reported deaths and 74% of all reported economic losses [2]. Droughts and heatwaves are both included in the top 4 disasters in terms of human losses [2], with uneven impacts throughout the world and a high likelihood that anthropogenic climate forcing will increase economic inequality between countries [3].&lt;/p&gt;&lt;p&gt;Nowadays there is strong evidence that droughts and heatwaves are at times synergetic and that their combined occurrence is largely caused by land-atmosphere feedbacks [4]. In fact, increasing trends of Compound Dry and Hot (CDH) events have been observed in both South America [5,6] and Europe [7,8], some of them with aggravated impacts. Specifically, the severe 2020 Pantanal extreme fire season (Brazil) resulted from the interplay between extreme and persistent temperatures (maximum temperatures 6 &amp;#186;C above-average) and long-term soil dryness conditions [6]. Similarly, in the Iberian Peninsula, CDH events were shown to have an influence on the dramatic 2017 fire season [9] and also on crop losses [8]. Moreover, future climate projections suggest that CDH conditions are expected to become more common in a warming climate [4]. Therefore, it is very important to address weather events in a compound manner, identifying synergies, driving mechanisms and dominant atmospheric modes controlling single and combined hazards.&lt;/p&gt;&lt;p&gt;[1] IPCC, 2021: Climate Change 2021: The Physical Science Basis. Contribution of WGI to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change [Masson-Delmotte &amp;#160;V. et al., (eds.)]. Cambridge University Press.&amp;#160;&lt;/p&gt;&lt;p&gt;[2] WHO, 2021. Weather-related disasters increase over past 50 years, causing more damage but fewer deaths, https://public.wmo.int/en/media/press-release/weather-related-disasters-increase-over-past-50-years-causing-more-damage-fewer&lt;/p&gt;&lt;p&gt;[3] Diffenbaugh N.S., Burke M. (2019) Global warming has increased global economic inequality, PNAS, 116, 20, 9808-9813&lt;/p&gt;&lt;p&gt;[4] Zscheischler J. et al. (2018). Future climate risk from compound events. Nat. Clim. Change, 8, 469&amp;#8211;477.&lt;/p&gt;&lt;p&gt;[5] Geirinhas J.L. et al. (2021). Recent increasing frequency of compound summer drought and heatwaves in Southeast Brazil. Environ. Res.&amp;#160; Lett., 16(3).&lt;/p&gt;&lt;p&gt;[6] Libonati R. &lt;em&gt;et al&lt;/em&gt; (2022) Assessing the role of compound drought and heatwave events on unprecedented 2020 wildfires in the Pantanal,&lt;em&gt; Environ. &lt;/em&gt;&lt;em&gt;Res. Lett.&lt;/em&gt; &lt;strong&gt;17&lt;/strong&gt; 015005.&lt;/p&gt;&lt;p&gt;[7] Geirinhas J.L. et al. (2020) Heat-related mortality at the beginning of the twenty-first century in Rio de Janeiro, Brazil. Int. J. Biometeorol., 64, 1319&amp;#8211;1332&lt;/p&gt;&lt;p&gt;[8] Russo A. et al. (2019) The synergy between drought and extremely hot summers in the Mediterranean. Environ. Res. Lett., 14, 014011&lt;/p&gt;&lt;p&gt;[9] Ribeiro A.F.S. et al. (2020) Risk of crop failure due to compound dry and hot extremes estimated with nested copulas. Biogeosciences, 17, 4815&amp;#8211;4830&lt;/p&gt;&lt;p&gt;[10] Turco M. et al. (2019) Climate drivers of the 2017 devastating fires in Portugal. Sci. Rep., 9, 1&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;&lt;p&gt;&lt;em&gt;This work was supported by Funda&amp;#231;&amp;#227;o para a Ci&amp;#234;ncia e a Tecnologia (Portugal) under projects PTDC/CTA-CLI/28902/2017, PTDC/CTA-CLI/28902/2017 and FCT- UIDB/50019/2020 &amp;#8211;IDL. &lt;/em&gt;&lt;/p&gt;&lt;p&gt;&lt;em&gt;&amp;#160;&lt;/em&gt;&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;