Potential heat-risk avoidance from nationally determined emission reductions targets in the future

Abstract

The increasing heat stress from the combined effect of changes such as temperature and humidity in the context of global change receives growing concerns. However, there is limited information for future changes in heat stress, as well as its potential socioeconomic impact, under the intended nationally determined mitigation scenarios. This study established an efficient evaluation method to quantify the benefits from the potential heat stress reduction from a continued Intended Nationally Determined Contributions (INDC) mitigation effort. The future heat stress over global land, quantified by the wet bulb globe temperature, was investigated based on the temperature sensitivity approach and multi-model simulations from the latest generation global climate models. The INDC continuous-effort scenario and the delayed-effort scenario, as well as the target-control scenarios of 2 °C warming, were compared. We found that with the delayed mitigation efforts, the increase in frequency, duration, and cumulative intensity of extreme heat stress relative to the INDC continuous-effort scenario in the late 21st century could reach to 113%, 193%, and 212%, respectively. If more ambitious efforts above current INDC pledges were implemented to achieve the 2 °C global temperature goal, the corresponding avoided impact of heat stress frequency, duration, and cumulative intensity in the late 21st century was estimated to be 32%, 37%, and 40%, respectively. Future changes in heat stress in low latitudes, where most developing countries are located, are most sensitive to emission reduction. Our results highlighted the potential avoided heat stress-related impact of global warming from efforts towards climate change mitigation.

Inequality of Global Thermal Comfort Conditions Changes in a Warmer World

“…(2015), population exposure to different thermal comfort conditions (i.e., comfortable/uncomfortable weather) is defined as the product of population counts with comfortable/uncomfortable days at each grid cell. Following previous studies (Z. Liu et al., 2017; Y. Liu et al., 2020; F. Wang et al., 2022), a low, moderate, and high GHG concentration scenario is paired with SSP1, SSP2, and SSP3, respectively. The 2°C, 3°C, and 4°C global warming scenarios generally correspond to low, moderate, and high GHG concentration scenarios, respectively.…”

“…So, will the overall impact of future change on the global population be positive or negative? Here the analysis of future changes in population exposure is performed in two steps (Harrington & Otto, 2018; F. Wang et al., 2022): first, we use the same population (i.e., the reference year 2010) for all warming levels, to show the climatic effect alone (excluding the effect of population growth on exposure changes), and then we use projected population for 2100 under SSP1–3 scenarios to pair the scenarios of 2°C, 3°C, and 4°C global warming levels, respectively (see Section 2.3), to show the combined effect of climate and population changes.…”

“…Another study focused on the Middle East and North Africa further suggested that the mortality risk from heat stress (measured by risk ratio) is higher in the poorest countries (Ahmadalipour et al, 2019). The projected results of heat stress exposure indicate that areas with the greatest population exposure all have relatively low GDP per capita, except for a sustainable scenario via highly mitigated GHG emissions and low population growth (F. Wang et al, 2022). Alizadeh et al (2022) further emphasize that the difference in the rate of increase in heatwave exposure in the poorest regions compared to the richest regions will be magnified if macroscopic societal efforts to adapt to thermal impacts are assumed to be proportional to GDP per capita in terms of the rate of adaptation to changing environmental conditions.…”

“…Multiple studies prove that the most perceptible climate changes in the future would generally occur in tropical regions, based on the signal‐to‐noise ratio approach (King et al., 2015; Mahlstein et al., 2011; Schleussner et al., 2016). Other studies have also shown that low‐income regions are expected to face significantly higher risks of facing extreme heat events compared to high‐income regions (Alizadeh et al., 2022; Harrington et al., 2016; Lee et al., 2021; Ullah et al., 2022; F. Wang et al., 2022). These results highlight the negative impacts of climate change, such as severe losses of labor productivity (Kjellstrom et al., 2009; Orlov et al., 2020) and increasing morbidity and mortality from heat‐related illness (Ahmadalipour et al., 2019; Mora et al., 2017), may fall mostly on low‐income populations that are least capable of adapting.…”

Projected changes in mild weather frequency over China under a warmer climate

“…global mean temperature, sea level; Gillett et al 2021, Hermans et al 2021 or climate extremes (e.g. heatwaves, heavy precipitation, droughts; Perkins-Kirkpatrick and Lewis 2020, Ukkola et al 2020, Wang et al 2022, Dong et al 2022, Luo et al 2022, You et al 2022. While these aspects are important for public health, multiple facets of society, and the environment, focussing on the above neglects the study of meteorological conditions that occur more regularly and are of societal significance in a different way.…”