A few days with heavy rain contribute disproportionately to total precipitation, while many days with light drizzle contribute much less. What is not appreciated is just how asymmetric this distribution is in time, and the even more asymmetric nature of trends due to climate change. We diagnose the temporal asymmetry in models and observations. Half of annual precipitation falls in the wettest 12 days each year in the median across observing stations worldwide. Climate models project changes in precipitation that are more uneven than present-day precipitation. In a scenario with high greenhouse-gas emissions, one fifth of the projected increase in rain falls in the wettest 2 days of the year and 70% in the wettest 2 weeks. Adjusting modeled unevenness to match present-day unevenness at stations, half of precipitation increase occurs in the wettest 6 days each year. Plain Language Summary Rain falls unevenly in time, which can lead to floods and droughts. It is widely known that precipitation is uneven, but it is difficult to quantify. Here we develop a measure for the unevenness of precipitation: the number of the wettest days each year in which half of the annual rain falls. We apply this to rain observed by gauges around the world. At all gauges combined, it takes only 12 days each year for half of the rain to fall. We also apply the measure to climate model simulations, with projections for the rest of the century. In the climate model simulations, the change in future rainfall is even more uneven than rainfall today: In a scenario with high greenhouse-gas emissions, half of the increase in rainfall happens in the wettest 6 days each year. Rather than assuming more rain in general, society needs to take measures to deal with little change most of the time and a handful of events with much more rain.

The uneven nature of daily precipitation and its change

Abstract Compound hot–dry events—co-occurring hot and dry extremes—frequently cause damages to human and natural systems, often exceeding separate impacts from heatwaves and droughts. Strong increases in the occurrence of these events are projected with warming, but associated uncertainties remain large and poorly understood. Here, using climate model large ensembles, we show that mean precipitation trends exclusively modulate the future occurrence of compound hot–dry events over land. This occurs because local warming will be large enough that future droughts will always coincide with at least moderately hot extremes, even in a 2 °C warmer world. By contrast, precipitation trends are often weak and equivocal in sign, depending on the model, region and internal climate variability. Therefore, constraining regional precipitation trends will also constrain future compound hot–dry events. These results help to assess future frequencies of other compound extremes characterized by strongly different trends in the drivers. 

https://www.nature.com/articles/s41558-022-01309-5.pdf

Precipitation trends determine future occurrences of compound hot–dry events

Observed trends in the intensity of hot and cold extremes as well as in dry spell length and heavy precipitation intensity are often not significant at local scales. However, using a spatially aggregated perspective, we demonstrate that the probability distribution of observed local trends across the globe for the period 1960–2010 is clearly different to what would be expected from internal variability. We detect a distinct intensification of heavy precipitation events and hot extremes. We show that CMIP5 models generally capture the observed shift in the trend distribution but tend to underestimate the intensification of heavy precipitation and cold extremes and overestimate the intensification in hot extremes. Using an initial condition experiment sampling internal variability, we demonstrate that much of the local to regional differences in trends of extremes can be explained by internal variability, which can regionally mask or amplify the forced long-term trends for many decades.

Detection of spatially aggregated changes in temperature and precipitation extremes

Higher Probability of Occurrence of Hotter and Shorter Heat Waves Followed by Heavy Rainfall

The Environmental Effects Assessment Panel of the Montreal Protocol under the United Nations Environment Programme evaluates effects on the environment and human health that arise from changes in the stratospheric ozone layer and concomitant variations in ultraviolet (UV) radiation at the Earth's surface. The current update is based on scientific advances that have accumulated since our last assessment (Photochem and Photobiol Sci 20(1):1-67, 2021). We also discuss how climate change affects stratospheric ozone depletion and ultraviolet radiation, and how stratospheric ozone depletion affects climate change. The resulting interlinking effects of stratospheric ozone depletion, UV radiation, and climate change are assessed in terms of air quality, carbon sinks, ecosystems, human health, and natural and synthetic materials. We further highlight potential impacts on the biosphere from extreme climate events that are occurring with increasing frequency as a consequence of climate change. These and other interactive effects are examined with respect to the benefits that the Montreal Protocol and its Amendments are providing to life on Earth by controlling the production of various substances that contribute to both stratospheric ozone depletion and climate change. 

/pdf/environmental-effects-of-stratospheric-ozone-depletion-uv-3kj0mack.pdf

Environmental effects of stratospheric ozone depletion, UV radiation, and interactions with climate change: UNEP Environmental Effects Assessment Panel, Update 2021

Detectable Increases in Sequential Flood‐Heatwave Events Across China During 1961–2018

Psychological resilience is characterized as the ability to recover from stress, which is essential for sleep quality. However, the neurological underpinnings of psychological resilience and the neural substrates of the links between psychological resilience and sleep quality in healthy brains remain not well understood. To address these issues, we adopted the method of resting-state functional connectivity (rs-FC) analysis in 144 young college students. The functional connectivity analysis indicated that psychological resilience was associated with the middle frontal gryus (MFG) functional connectivity, which mainly involved the right middle cingulum gyrus (rMCG), the right precentral gyrus (rPreCG), the left postcentral gyrus (lPoCG), and the left thalamus. Furthermore, mediation analysis suggested that psychological resilience played a mediating role in the relationship between MFG functional connectivity and sleep quality. Overall, the current study offered further evidence for the neurological underpinnings of psychological resilience and provided new insights into the relationship between psychological resilience and sleep quality from a neural basis perspective. 

/pdf/psychological-resilience-mediates-the-association-of-the-2fay9vce.pdf

Psychological resilience mediates the association of the middle frontal gyrus functional connectivity with sleep quality

Compared to singular hot or wet extremes, their occurrence in close sequence might cause larger impacts, because the initial hazard either increases exposure/vulnerability of affected communities to the next or physically worsens the second hazard. Heatwave‐preconditioned hourly precipitation extremes in the Yangtze River Valley are typical of the latter situation. Fueled by soaring convective energy after heatwaves' passage, hourly precipitation extremes are heavier, intensifying faster, and more concentrated during afternoon to evening, compared to those not proceeded by heatwaves. Consequently, flash flood‐producing events (e.g., 50 mm/hr or stronger) account for larger fractions in preconditioned events than in the non‐preconditioned group, with the spectrum difference further exaggerated by warming. This drives the frequency increase in potentially high‐impact events several‐fold larger than expected from the widely‐adopted univariate perspective. These results point to heatwave‐preconditioned hourly precipitation extremes as an emerging hazard of climate change carrying greater flash flood risks.

Greater Flash Flood Risks From Hourly Precipitation Extremes Preconditioned by Heatwaves in the Yangtze River Valley

When co-occurring with elevated levels of ambient relative humidity (RH), hot extremes are more perceivable and consequently more health-damaging. Quantifying changes in humid-heat extremes has therefore gained considerable scientific and societal attention, but a fundamental yet critical aspect to the estimation—data reliability—has been largely downplayed in previous analysis. By comparing ∼10 observational and reanalysis datasets to fully-homogenized observations across China, we report ubiquitous inhomogeneity in RH series in these popularly-used datasets [including HadISD(H) and ERA5], which accordingly produce unrealistically strong drying trends 2–3 times the homogenized dataset-based estimate during 1979–2013 in warm-moist southeast China. Locally, an inhomogeneity-caused exaggeration of drying by a magnitude of 1% decade−1 translates into a significant underestimation of increasing rates for frequency and intensity of humid-heat extremes by more than 1.2 days decade−1 and .07% decade−1 respectively. From a regional perspective, these inhomogeneous records have underestimated the frequency increase of extremes by up to 2 days decade−1 and their intensification by up to .4°C decade−1 in southeast China. Extremes identified via homogenized and non-homogenized datasets also differ in the bivariate joint distribution structure, with former cases featuring similarly hot temperatures yet discernably lower humidity.

/pdf/underestimated-increase-and-intensification-of-humid-heat-2hf7ybv2.pdf

Underestimated increase and intensification of humid-heat extremes across southeast China due to humidity data inhomogeneity

Prosocial behavior plays a vital role in adolescents’ well-being and social functioning, with the recall of early emotional experiences being a major influence. Positive experiences such as early memories of warmth and safeness (EMWS) contribute to prosocial interpersonal characteristics, whereas adverse experiences such as child psychological abuse and neglect (CPAN) lead to social withdrawal or behavioral problems. The direct effects of EMWS and CPAN on prosocial behavior were investigated in this study, along with the mediation effect of psychological suzhi and the moderation effect of subjective socioeconomic status (SSS). A sample of 948 adolescents (Mage = 14.05 years, SD = 1.68 years; 43.6% females) was randomly recruited to complete self-report questionnaires. Correlation results indicated that EMWS promoted prosocial behavior, whereas CPAN was negatively associated with prosocial behavior. Path analyses confirmed the mediating role of psychological suzhi on the effects of EMWS and CPAN on prosocial behavior. SSS was shown to moderate the effects of EMWS on prosocial behavior and CPAN on psychological suzhi. Compared to lower SSS, higher SSS would reinforce the positive impact of EMWS on prosocial behavior and exacerbate the negative impact of CPAN on psychological suzhi. The current study provided new insight into understanding the underlying mechanisms of prosocial behavior from the perspective of early emotional experiences.

https://www.mdpi.com/2076-328X/13/4/283/pdf?version=1679665040

Yan Shi

Papers

Detectable Increases in Sequential Flood‐Heatwave Events Across China During 1961–2018

Psychological resilience mediates the association of the middle frontal gyrus functional connectivity with sleep quality

Greater Flash Flood Risks From Hourly Precipitation Extremes Preconditioned by Heatwaves in the Yangtze River Valley

Underestimated increase and intensification of humid-heat extremes across southeast China due to humidity data inhomogeneity

Early Emotional Experiences and Prosocial Behavior among Chinese Adolescents: The Roles of Psychological Suzhi and Subjective Socioeconomic Status