Large-scale emergence of regional changes in year-to-year temperature variability by the end of the 21st century

Abstract

Global warming is expected to not only impact mean temperatures but also temperature variability, substantially altering climate extremes. Here we show that human-caused changes in internal year-to-year temperature variability are expected to emerge from the unforced range by the end of the 21st century across climate model initial-condition large ensembles forced with a strong global warming scenario. Different simulated changes in globally averaged regional temperature variability between models can be explained by a trade-off between strong increases in variability on tropical land and substantial decreases in high latitudes, both shown by most models. This latitudinal pattern of temperature variability change is consistent with loss of sea ice in high latitudes and changes in vegetation cover in the tropics. Instrumental records are broadly in line with this emerging pattern, but have data gaps in key regions. Paleoclimate proxy reconstructions support the simulated magnitude and distribution of temperature variability. Our findings strengthen the need for urgent mitigation to avoid unprecedented changes in temperature variability.

Contrasting State‐Dependent Effects of Natural Forcing on Global and Local Climate Variability

“…Decreasing sea ice dynamics and a smaller meridional temperature gradient are suggested as major causes. In line with other studies (Bathiany et al., 2018; Berdahl & Robock, 2013; Bethke et al., 2017; Brown et al., 2017; Olonscheck et al., 2021; Rehfeld et al., 2018), we find a clear zonal pattern, with greater reduction of variability in the mid and high latitudes (Figures 3b and 3c). This is corroborated by the small discrepancy between short‐term variability from observations and simulations in the mid and high latitudes (Figure 4a).…”

“…Consistent with previous arguments (Bethke et al, 2017), our results challenge the common usage of external forcing that shows no time-varying changes (O'Neill et al, 2016).…”

“…The question of state‐dependent variability has long motivated studies of past (Ditlevsen et al., 1996; Rehfeld et al., 2018; Shao & Ditlevsen, 2016) and future (Huntingford et al., 2013; Olonscheck et al., 2021; Rehfeld et al., 2020) climate. Our results reveal a decrease in mean local variability with warming (Figure 3).…”

“…Global warming also affects climate variability (Bathiany et al., 2018; Olonscheck et al., 2021). The underlying mechanisms remain poorly understood.…”

The Holocene temperature conundrum answered by mollusk records from East Asia

“…The variance contribution of seasonal temperature [ ] is used to evaluate the magnitude of temperature change (e.g. the magnitude of temperature increase or decrease) and the overall variation of the temperature in a specific time interval (1000 yr) relative to the mean temperature value of the season 42 , 43 , 69 , 70 , where Vi is the variance of temperature change in each season within this interval, Ti is the temperature of the ith sample in this season within this interval, and Tm is the mean temperature of a season within this interval. Since the MAT is the arithmetic average of all the seasonal temperatures 71 , a large seasonal variance denotes a significant increase or decrease in temperature change, which means that MAT fluctuations caused by this season will also be large 43 , 72 .…”