Report on the observed climate, projected climate, and projected biodiversity changes for Okapi Wildlife Reserve, Democratic Republic of Congo under differing levels of warming

Critically important for the Okapi, and making up approximately 20% of the Ituri Forest, Okapi Wildlife Reserve, Democratic Republic of Congo, is among the top 40% of all non-marine protected areas, globally. In general, the western portions of the reserve are slightly more resilient to climate change, however as warming levels exceed 2°C, plant biodiversity is projected to be more exposed to climate change, indicating a potential climate driven decline of plant species richness. Mammals and birds fare somewhat better, with the western portions resilient to 3°C warming, but the potential loss of habitat would magnify the projected impacts on birds and mammals. As such, business as usual conservation, taking into account changes in the likelihood of extreme events, may be adequate except in the eastern parts of the reserve, at least to 2°C warming. Averaged over the entire area, with 4°C warming (global, above pre-industrial), the area is projected to remain climatically suitable for 56.5% of its terrestrial biodiversity (fungi, plants, invertebrates, and vertebrates), with none of the reserve remaining an overall refugia (remaining climatically suitable for >75% of the species) for biodiversity (10.9% for mammals). If warming levels were held to 2°C, only 0.3% of the area would remain an overall climatic refugia (but 80% for mammals) and the area would remain climatically suitable for 68.6% of its terrestrial biodiversity.

Between 1961-1990 and 1991-2020 the average monthly temperature has increased by 0.4° – 0.8°C. With warming levels of 1.5°C the new average monthly temperature is equivalent to that only seen 1 in 20 years in 1961-1990 for all months except January (new average equal to that seen on 1 in 3 years). Half of the months have become drier and the other half wetter. Models project that April-June will become drier and the rest increase. The number of months with severe drought has increased somewhat between 1961-1990 and 1986-2015 and this trend is projected to continue.  With 4°C warming, severe droughts lasting more than one year are projected to occur. 

Biodiversity adaptation options generally only allow for business-as-usual conservation to 2.0°C, especially in the western part of the preserve, taking into account changes in extreme events (especially heat and severe drought). However, at temperatures above 2.0°C all of the reserve will require substantial amounts of adaptation to maintain much of the current biodiversity, especially plants.  In general, mammals tend to fare somewhat better than biodiversity as a whole but would face indirect impacts from climate-driven changes in habitat.