Effects of global warming and solar geoengineering on precipitation seasonality

Abstract

The effects of global warming and geoengineering on annual precipitation and its seasonality over different parts of the world are examined using the piControl, 4xCO 2 and G1 simulations from eight global climate models participating in the Geoengineering Model Intercomparison Project. Specifically, we have used relative entropy, seasonality index, duration of the peak rainy season and timing of the peak rainy season to investigate changes in precipitation characteristics under 4xCO 2 and G1 scenarios with reference to the piControl. In a 4xCO 2 world, precipitation is projected to increase over many parts of the globe, along with an increase in both the relative entropy and seasonality index. Further, in a 4xCO 2 world the increase in peak precipitation duration is found to be highest over the subpolar climatic region. However, over the tropical rain belt, the duration of the peak precipitation period is projected to decrease. Furthermore, there is a significant shift in the timing of the peak precipitation period by 15 days-2 months (forward) over many parts of the Northern Hemisphere except for over a few regions, such as North America and parts of Mediterranean countries, where a shift in the precipitation peak by 1-3 months (backward) is observed. However, solar geoengineering is found to significantly compensate many of the changes projected in a 4xCO 2 scenario. Solar geoengineering nullifies the precipitation increase to a large extent. Relative entropy and the seasonality index are almost restored back to that in the control simulations, although with small positive and negative deviations over different parts of the globe, thus, significantly nullifying the impact of 4xCO 2 . However, over some regions, such as northern parts of South America, the Arabian Sea and Southern Africa, geoengineering does not significantly nullify changes in the seasonality index seen in 4xCO 2 . Finally, solar geoengineering significantly compensates the changes in timing of the peak and duration of the peak precipitation seen in 4xCO 2 .

Impact of rainfall seasonality on intraspecific trait variation in a shrub from a Mediterranean climate

“…Seasonality has also been observed or predicted to be altered in other regions (e.g. Ashfaq et al, ; Bal et al, ; Deng et al, ), with such changes instigating significant shifts in species diversity, distributions and ecosystem processes (Allen et al, ; Guan et al, ).…”

“…These distinct patterns in rainfall seasonality should result in divergent patterns of relationships between traits and climate, or even trait-trait relationships (Moore, Schlichting, Aiello-Lammens, Mocko, & Jones, 2018), but how a single species might respond along such gradients has never been explicitly examined. Given that climate change is likely to alter rainfall seasonality and amount (Ashfaq et al, 2016;Bal, Pathak, Mishra, & Sahany, 2019), understanding intraspecific variation in trait-climate relationships across contrasting patterns in seasonal rainfall should enhance predictions of plant responses to future climate change. The rainfall seasonality gradient in the GCFR and associated gradients in other environmental variables ( Figure 1) provide an ideal opportunity to examine the understudied effects of variation in rainfall seasonality on functional trait variation and relationships.…”

Heterogeneous response of global precipitation concentration to global warming

“…This is generally consistent with the findings of Bal et al . (2019) that the precipitation seasonality index would increase under the 4xCO2 scenario over many parts of the global monsoon regions. Monsoon regions include almost two‐thirds of the world's population and play a key role in global freshwater resources distribution (Zhang et al ., 2019).…”

“…The rising concentration of atmospheric CO 2 affects the hydrological cycle by increasing the global mean temperature and altering the atmospheric water vapour content (Manabe and Wetherald, 1975; Trenberth, 1999; Bony et al ., 2013). Previous studies have attempted to investigate how precipitation responds to changes in greenhouse gas (GHG) emissions, specifically CO 2 emissions (Bony et al ., 2013; Lau et al ., 2013; Pendergrass and Hartmann, 2014; Zhang et al ., 2017; Samset et al ., 2018; Bal et al ., 2019; Sillmann et al ., 2019). Precipitation is projected to increase over many parts of the globe in a 4xCO2 world (Bal et al ., 2019).…”

“…Previous studies have attempted to investigate how precipitation responds to changes in greenhouse gas (GHG) emissions, specifically CO 2 emissions (Bony et al ., 2013; Lau et al ., 2013; Pendergrass and Hartmann, 2014; Zhang et al ., 2017; Samset et al ., 2018; Bal et al ., 2019; Sillmann et al ., 2019). Precipitation is projected to increase over many parts of the globe in a 4xCO2 world (Bal et al ., 2019). Lau et al .…”