Detection of continental-scale intensification of hourly rainfall extremes

Abstract

Temperature scaling studies suggest that hourly rainfall magnitudes might increase beyond thermodynamic expectations with global warming 1,2,3 ; that is, above the Clausius-Clapeyron (CC) rate of ~6.5% °C -1 . However, there is limited evidence of such increases in long-term observations. Here, we calculate continental-average changes in the magnitude and frequency of extreme hourly and daily rainfall observations from Australia over 1990Australia over -2013Australia over and 1966Australia over -1989. Observed changes are compared to the uncertainty from natural variability and to expected changes from CC-scaling as a result of global mean surface temperature change. We show that increases in daily rainfall extremes are consistent with CC scaling, but are within the range of natural variability. By contrast, changes in the magnitude of hourly rainfall extremes are close to or exceed double the expected CC-scaling, and are above the range of natural variability, exceeding 3xCC in the tropical region (north of 23°S). These continental-scale changes in extreme rainfall are not explained by changes in the El Niño-Southern Oscillation or changes in the seasonality of extremes. Our results indicate that CC-scaling on temperature provides a severe underestimate of observed changes in hourly rainfall extremes in Australia, with implications for assessing the impacts of extreme rainfall. MainA warming climate is expected to cause an intensification of heavy rainfall 4 . Basic physical arguments suggest that, in the absence of changes in large-scale circulation (and associated moisture advection), the intensification will follow the water holding capacity of air, dictated

Larger Increases in More Extreme Local Precipitation Events as Climate Warms

“…Although some studies have found that more extreme precipitation events tend to be more sensitive to daily temperature variations than less extreme events in some regions (e.g., Lenderink et al, 2011;Lenderink & van Meijgaard, 2008;Wasko et al, 2016), it has recently been recognized that the sensitivity to day-to-day temperature changes represents only an aspect of the variation in precipitation extremes that is distinct from the response of extreme precipitation to long-term warming (Guerreiro et al, 2017;Zhang et al, 2017). Although some studies have found that more extreme precipitation events tend to be more sensitive to daily temperature variations than less extreme events in some regions (e.g., Lenderink et al, 2011;Lenderink & van Meijgaard, 2008;Wasko et al, 2016), it has recently been recognized that the sensitivity to day-to-day temperature changes represents only an aspect of the variation in precipitation extremes that is distinct from the response of extreme precipitation to long-term warming (Guerreiro et al, 2017;Zhang et al, 2017).…”

Precipitation From Persistent Extremes is Increasing in Most Regions and Globally

“…Using the Clausius‐Clapeyron relation to predict precipitation extremes is considered a better approach than using mean precipitation changes (Allen & Ingram, ; Emori & Brown, ). However, precipitation extremes scaling with temperature change can be different among various timescales of precipitation accumulation (Guerreiro et al, ), as well as among different regions (Kharin et al, ) mainly due to different changes in dynamics (Pfahl et al, ). Most of these studies focused on fixed‐duration (e.g., hourly or 1 day) precipitation.…”

Evidence for Increasing Rainfall Extremes Remains Elusive at Large Spatial Scales: The Case of Italy

“…Some gridded 10.1029/2019GL083371 interpolated rainfall products are indeed available for free (e.g., Donat et al, 2013aDonat et al, , 2013b; however, various authors warn on the validity of results obtained using these products for analyzing extreme rainfall amounts, especially in areas with complex orography (King et al, 2013;Libertino et al, 2016). The shortage of studies on the short-duration extremes is then a remarkable issue, considering that it is not possible to directly downscale conclusions from daily data analyses, due do the different generating mechanisms of extreme rainfall at different time scales (Barbero et al, 2017;Guerreiro et al, 2018).…”