Concurrent 2018 Hot Extremes Across Northern Hemisphere Due to Human‐Induced Climate Change

Abstract

Extremely high temperatures pose an immediate threat to humans and ecosystems. In recent years, many regions on land and in the ocean experienced heat waves with devastating impacts that would have been highly unlikely without human‐induced climate change. Impacts are particularly severe when heat waves occur in regions with high exposure of people or crops. The recent 2018 spring‐to‐summer season was characterized by several major heat and dry extremes. On daily average between May and July 2018 about 22% of the populated and agricultural areas north of 30° latitude experienced concurrent hot temperature extremes. Events of this type were unprecedented prior to 2010, while similar conditions were experienced in the 2010 and 2012 boreal summers. Earth System Model simulations of present‐day climate, that is, at around +1 °C global warming, also display an increase of concurrent heat extremes. Based on Earth System Model simulations, we show that it is virtually certain (using Intergovernmental Panel on Climate Change calibrated uncertainty language) that the 2018 north hemispheric concurrent heat events would not have occurred without human‐induced climate change. Our results further reveal that the average high‐exposure area projected to experience concurrent warm and hot spells in the Northern Hemisphere increases by about 16% per additional +1 °C of global warming. A strong reduction in fossil fuel emissions is paramount to reduce the risks of unprecedented global‐scale heat wave impacts.

Estimating the Health‐Related Costs of 10 Climate‐Sensitive U.S. Events During 2012

“…Global Change Research Program, 2018). These case studies are consistent with the long-term projections for climate change impacts for extreme heat (Christidis et al, 2011;Hansen et al, 2006;Meehl et al, 2007;Vogel et al, 2019;Zwiers et al, 2011), hurricanes (Keellings & Hernández Ayala, 2019), harmful algal blooms (Hilborn et al, 2014;Poh et al, 2019) and other extreme weather (Nilsen et al, 2011;Papalexiou & Montanari, 2019); allergenic pollen (Anenberg et al, 2017;L. H. Ziska et al, 2019), ozone air pollution (Fann et al, 2015;Kinney, 2018), wildfires (Abatzoglou & Williams, 2016;Liu et al, 2016), West Nile virus (Belova et al, 2017;Paull et al, 2017), and Lyme disease (Monaghan et al, 2015).…”

Verification of extreme event attribution: Using out-of-sample observations to assess changes in probabilities of unprecedented events

“…Because the CMIP5 Historical and Natural simulations were only run through 2005 (48,49), simulations using the actual climate forcings do not cover the most recent period of observations. Attribution analyses that use CMIP5 can thus either restrict the historical analyses to this pre2006 period [e.g., (4-6, 12, 20)] or use the early period of the CMIP5 future pro jections to extend the historical simulations (in which case the an thropogenic and nonanthropogenic simulations cover different time periods) [e.g., (8,38)]. In the case of previously published global attri bution analyses, which used the CMIP5 Historical and Natural simulations to quantify the influence of historical forcing on the probability of unprecedented hot, wet, and dry extremes at each area of the globe, the attribution analysis was limited to the pre2006 period (5).…”

Application of soil moisture information for operational water management

“…European heatwave had considerable impacts on water management, agriculture, and nature reserve protection (Vogel et al, 2019;Arcadis, 2019). Hence, the grand challenge for national and regional water managers is to optimize water availability for di erent functions according to users' demands.…”

“…We give an example application of the SWDI drought indicator for the dry summer period of 2018, as Vogel et al (2019) showed that heat waves will occur more frequently in the future. Martinez-Fernandez et al (2015) de ne the SWDI as:…”

“…for drought assessments (Grillakis, 2019;Mishra et al, 2017;Moravec et al, 2019;Sehgal and Sridhar, 2019), ood predictions (Brocca et al, 2017;Tramblay et al, 2010) and irrigation management Rai et al, 2018). The soil moisture drought caused by the 2018 European heat wave signi cantly impacted water management and agricultural practices (Vogel et al, 2019), which shows the importance of retrieving up-to-date soil moisture information.…”