ABSTRACT
In a recent study, we have introduced the concept of “outdoor days” –
the number of days with moderate temperature, neither too cold nor too
hot, allowing most people to enjoy outdoor activities – to describe how
climate change can affect quality of life for communities in a different
way compared to previous studies which emphasize changes in surface
temperature. Here, we use the same concept to investigate climate risk,
defined by the combination of vulnerability, exposure, and hazard.
Vulnerability and exposure are known to cause a sharp disparity in
climate risk between the wealthy north and the deprived south, implying
disproportionate risks of climate change. However, we know little about
how climate hazards contribute to this disparity of global climate risk.
Here, we present observational and modeling evidence of north-south
disparity in climate risk caused by changes in “outdoor days”. Under
high-emissions scenarios, CMIP5 and CMIP6 models project fewer outdoor
days for people living in developing countries, primarily located in
low-latitude regions. Meanwhile, developed countries in middle- and
high-latitude regions could gain more outdoor days, redistributed across
seasons. Our findings help inform ongoing debates on compensation for
losses and damages caused by climate change.
SIGNIFICANCE STATEMENT
Here, we contribute to the understanding of global disparities imposed
by climate risk by introducing the concept of outdoor days – thermal
comfort conditions allowing for outdoor activities, such as walking,
jogging, cycling, and those related to construction and tourism
industries, by most people. We project that the north-south disparity of
global climate risk is expected to increase considerably by the end of
this century with more frequent outdoor days in the wealthy north and
less frequent outdoor days in the deprived south under high emissions
scenarios. These findings have the potential to provide researchers,
policymakers, and climate advocates with evidence-based knowledge
informing more accurate depiction of climate risk, and more rational
debate regarding compensations for loss and damage.
1. Introduction
Climate change has potentially severe and far-reaching impacts that
affect nearly every Earth’s system and industry, putting the lives and
livelihoods of millions of people at risk (Rising et al. 2022; Schewe et
al. 2019). The potential risk of climate change is defined by the
interaction of climate hazards with the human and natural system’s
vulnerability and exposure (IPCC 2022) (Fig. 1; see Fig. S1 for
definitions of the three components of climate risk). Since countries
exhibit substantial differences in these elements (Shiogama et al.
2019), especially vulnerability and exposure, there are considerable
variations in the potential risks from changing climate between regions
and countries (Diffenbaugh and Burke 2019). Many previous studies
revealed that while some regions may experience severe negative impacts
from climate change, others may potentially gain some benefits (Kalkuhl
and Wenz 2020; Mendelsohn et al. 2006; Tol 2009). The intersection of
climate change and inequality, referred to as the climate-inequality
nexus (Onbargi 2022), is one of the most pressing challenges of climate
change and has significant social, economic, and environmental
consequences (IPCC 2022).