Anthropogenic influence on extremes and risk hotspots

Abstract

Study of the frequency and magnitude of climate extremes as the world warms is of utmost importance, especially separating the influence of natural and anthropogenic forcing factors. Record-breaking temperature and precipitation events have been studied using event-attribution techniques. Here, we provide spatial and temporal observation-based analyses of the role of natural and anthropogenic factors, using state-of-the-art time series methods. We show that the risk from extreme temperature and rainfall events has severely increased for most regions worldwide. In some areas the probabilities of occurrence of extreme temperatures and precipitation have increased at least fivefold and twofold, respectively. Anthropogenic forcing has been the main driver of such increases and its effects amplify those of natural forcing. We also identify risk hotspots defined as regions for which increased risk of extreme events and high exposure in terms of either high Gross Domestic Product (GDP) or large population are both present. For the year 2018, increased anthropogenic forcings are mostly responsible for increased risk to extreme temperature/precipitation affecting 94%/72% of global population and 97%/76% of global GDP relative to the baseline period 1961–1990.

Rainstorm variability is mainly influenced by the southwest monsoon in the Hanjiang River basin of China during 1985–2020

“…In particular, regional persistent rainstorm events often have multiple sources of water vapour that are closely related to the altitude layer, atmospheric circulation and complex interactions between various monsoon systems (Ding et al, 2020; Wang et al, 2021). Moreover, human activities also play an important role in the change in rainstorms (Estrada et al, 2023; Kong et al, 2017; Min et al, 2011). Especially for severe convective rainstorms, it can be found that the total explanation rate of large‐scale circulation factors is only about 50%.…”

Tropical nights in the Mediterranean: A spatiotemporal analysis of trends from 1950 to 2022

“…This change observed in the indices of tropical night numbers in the Mediterranean region can be attributed to anthropogenic warming. In most land regions, including Europe and the Middle East, the probability of extreme temperatures at least doubled, with an increase of about 2 W·m −2 by 2018 in anthropogenic forcing (Estrada et al, 2023). Increasing tropical nights is consistent with night‐time low temperatures increasing about twice as rapidly as daytime highs over northern hemisphere mid‐latitudes in response to anthropogenic forcing (Donat & Alexander, 2012; Dwyer et al, 2012).…”

On the persistence of near‐surface temperature dynamics in a warming world

“…Such modifications can be produced by changes in the mean (i.e., existence of trends) and/or variability, as well as in the persistence of some variables of the climate system, or a combination of them. While the first two have received significant attention, 13–15 studies about the effects of changes in persistence on the probabilities of occurrence of extremes are much scarcer 16–18 . However, recent events with seemingly larger than usual duration, magnitude, and frequency 19 have invigorated research efforts for better understanding of the influence and nature of trends, changes in variability, and persistence over extremes 15,18,20–25 .…”

“…[16][17][18] However, recent events with seemingly larger than usual duration, magnitude, and frequency 19 have invigorated research efforts for better understanding of the influence and nature of trends, changes in variability, and persistence over extremes. 15,18,[20][21][22][23][24][25] However, to obtain an adequate estimation of persistence, it is crucial to properly account for trends and noise. As discussed in the time-series literature, not accounting for trends or structural changes can bias persistence estimates upward, while the presence of noise imparts a downward bias.…”

“…While the first two have received significant attention, 13–15 studies about the effects of changes in persistence on the probabilities of occurrence of extremes are much scarcer 16–18 . However, recent events with seemingly larger than usual duration, magnitude, and frequency 19 have invigorated research efforts for better understanding of the influence and nature of trends, changes in variability, and persistence over extremes 15,18,20–25 . However, to obtain an adequate estimation of persistence, it is crucial to properly account for trends and noise.…”