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Extreme weather and coronavirus-type pandemics are both leading global health concerns. Until now, no study has quantified the compound health consequences of the co-occurrence of them. We estimate the mortality attributable to extreme heat and cold events, which dominate the UK health burden from weather hazards, in England and Wales in the period 2020-2022, during which the COVID-19 pandemic peaked in terms of mortality. We show that temperature-related mortality exceeded COVID-19 mortality by 8% in South West England. Combined, extreme temperatures and COVID-19 led to 19 (95% confidence interval: 16-22 in North West England) to 24 (95% confidence interval: 20-29 in Wales) excess deaths per 100,000 population during heatwaves, and 80 (95% confidence interval: 75-86 in Yorkshire and the Humber) to 127 (95% confidence interval: 123-132 in East of England) excess deaths per 100,000 population during cold snaps. These numbers are at least ~2 times higher than the previous decade. Society must increase preparedness for compound health crises such as extreme weather coinciding with pandemics. [ABSTRACT FROM AUTHOR]

In 2015, El Niño caused severe droughts in equatorial Asia (EA). The severe droughts enhanced fire activities in the dry seasons, leading to massive fire emissions of CO2 and aerosols. Using large event attribution ensembles of the MIROC5 atmospheric global climate model, we suggest that historical anthropogenic warming increased the chances of meteorological droughts exceeding the 2015 observations in the EA area. Large probability increases in stronger droughts than the 2015 event are found in the ensemble simulations of 1.5 °C and 2.0 °C global warming according to the Paris Agreement goals. Further drying is projected in the 3.0 °C ensemble. We combine these experiments and empirical functions between precipitation, burned area, and fire emissions of CO2 and PM2.5. Increases in the chances of the burned area and the emissions of CO2 and PM2.5 exceeding the 2015 observations due to anthropogenic climate change in the past are not significant. In contrast, there are significant increases in the burned area and CO2 and PM2.5 emissions even if the 1.5 °C and 2.0 °C goals are achieved. If global warming reaches 3.0 °C, as is expected from the current mitigation policies of nations, the chances of the burned area, CO2 and PM2.5 emissions exceeding the 2015 observed values become approximately 100 %, at least in the single model ensembles. We also compare changes in fire CO2 emissions due to climate changes and the land-use CO2 emission scenarios of five shared socio-economic pathways, where the climate change effects on fire are not considered. There are two main implications. First, in a national policy context, future EA climate policy will need to consider these climate change effects regarding both mitigation and adaptation aspects. Second, the consideration of fire increases would change global CO2 emissions and the mitigation strategy, which suggests that future climate change mitigation studies should take these factors into account. [ABSTRACT FROM AUTHOR]

The article investigates how extreme the 2021 western North America heat wave was in the global context. Topics discussed include increasing magnitude of extreme temperature events, climatology of both the time period and region where the extreme temperature occurred, and use of Earth system models to estimate how the frequency of heat extremes will change as atmospheric greenhouse gases rise into the future.

Combined heat and humidity is frequently described as the main driver of human heat-related mortality, more so than dry-bulb temperature alone. While based on physiological thinking, this assumption has not been robustly supported by epidemiological evidence. By performing the first systematic comparison of eight heat stress metrics (i.e., temperature combined with humidity and other climate variables) with warm-season mortality, in 604 locations over 39 countries, we find that the optimal metric for modelling mortality varies from country to country. Temperature metrics with no or little humidity modification associates best with mortality in ~40% of the studied countries. Apparent temperature (combined temperature, humidity and wind speed) dominates in another 40% of countries. There is no obvious climate grouping in these results. We recommend, where possible, that researchers use the optimal metric for each country. However, dry-bulb temperature performs similarly to humidity-based heat stress metrics in estimating heat-related mortality in present-day climate., Competing Interests: Conflict of Interest Statement The authors declare no conflict of interest.