Seasonal Differences in Changing Wet and Dry Spell Characteristics under Future Climate Change

Abstract:

Understanding how agriculture will respond to future climate change and the resulting impacts on food security is of crucial importance for successful adaptation to climate change. Previous studies have reported that climate change will result in longer dry spells and shorter wet spells during growing seasons. Longer dry spells may have negative impacts on crop yields and food production, as reductions in water availability limit crop growth. However, across the tropics most crops are grown during the annual wet season – therefore the timing of these longer dry spells in the annual cycle is of crucial importance. Using an ensemble of CMIP5 and CMIP6 simulations, under medium and high emission scenarios, here we examine changes in wet and dry spell characteristics under future climate change across the tropics in wet and dry seasons separately. An increase in both mean and maximum dry spell length during the dry season is found across South America, Southern Africa and Australia, with a drop in dry season rainfall also found in these regions. However, changes in dry spell length during the wet season are much smaller across the tropics with limited model consensus. Northern South America and southern European exhibit an increase in the proportion of dry days during the wet season and a decrease in wet season rainfall of 10-20%. These results indicate that the largest increases in dry spell length will be during the dry season. While this may reduce the impact on crops grown solely during the wet season, longer dry spells during the dry season may have detrimental consequences for perennial crops.