Consistent Trends in Dry Spell Length in Recent Observations and Future Projections

We identify global observed changes in dry-spell characteristics that are consistent with future projections and involve common physical drivers. Future projections of longer dry spells in the dry season increase vegetation water stress and can negatively impact perennial vegetation. Lengthening dry season dry spells of up to similar to 2 days per decade over South America and southern Africa and shortening of similar magnitude over West Africa display a qualitatively consistent pattern to future projected changes under the Shared Socioeconomic Pathway 2-4.5 intermediate greenhouse gas emissions scenario. By combining a range of present-day climate model experiments, recent trends are linked with both natural and human-caused drivers. Longer dry season dry spells over South America are associated with relative warming of North Atlantic sea surface temperatures and amplified warming over land compared with adjacent oceans; both of which are projected to continue under further warming, suggesting a common driver for recent trends and future projections.

Automated summary

The study identifies global changes in dry-spell characteristics that are consistent with future projections and are driven by common physical factors. It is found that longer dry spells in the dry season can increase vegetation water stress and negatively impact perennial vegetation. The observed lengthening of dry season dry spells over South America and southern Africa, and the shortening over West Africa, are in line with projected changes under the intermediate greenhouse gas emissions scenario.