Digitized Congo Weather Archives Document Decades of Warming

The Congo Basin has been a gap in IPCC assessments of long-term changes in heat and rainfall because usable records were scarce. Researchers digitized more than 9,000 pages of handwritten weather logs from archives in Belgium and the Democratic Republic of Congo, covering 1908 to 2023 and containing over a million observations. The rescued data show a warming trend from 1961 to 1990, including about a 0.9 degree F rise in average daily temperature and nearly twice as many hot days per year, plus increases in extreme heat and heavy rain.

The Congo Basin had been missing from IPCC long-term assessments of heat and rainfall extremes because accessible records were scarce. Researchers recovered handwritten logs from Belgian and Congolese archives, spanning 1908–2023. Scanning over 9,000 pages yielded more than a million observations.

From 1961 to 1990, the digitized records indicate average daily temperatures climbed roughly 0.9°F and hot days nearly doubled. They also point to more severe heat and heavier rain. The findings, published in Earth System Dynamics, add to a large Congo Basin climate dataset and underscore the vulnerability of paper archives, including one partly damaged by fire.