Report on the observed climate, projected climate, and projected biodiversity changes for Big Bend National Park, Texas under differing levels of warming

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Big Bend National Park, Texas, is among the top 26% of all non-marine protected areas, globally. Big Bend is projected to be largely resilient to climate change to 2°C warming. As such, business as usual conservation, taking into account changes in the likelihood of extreme events (heat and drought), should largely be adequate. Beyond that, only the higher elevations are expected to remain resilient with the lower elevations requiring increasing adaptation effort. Individual species will be expected to shift upward in elevation, if they are able and those at the very top of the mountains may be extirpated. Averaged over the entire area, with 4°C warming (global, above pre-industrial), the area is projected to remain climatically suitable for 65.1% of its terrestrial biodiversity (fungi, plants, invertebrates, and vertebrates), with only 4% of its area remaining an overall refugia (remaining climatically suitable for >75% of the species) for biodiversity. If warming levels were held to 2°C, 54.4% of the area would remain a climatic refugia and the area would remain climatically suitable for 81.7% of its terrestrial biodiversity.
Between 1961-1990 and 1991-2020 the average monthly temperature has increased by 0.4° – 1.4°C (February). With warming levels of 2°C the new average monthly temperature is equivalent to that currently seen 1 in 3 years in 1961-1990 for all months except May and June (new average equal to that seen in 1 in 20 years). Eight months have seen decreases in precipitation (especially September), and the rest wetter, especially July. Models project that all months except July and August will become drier. The number of months with severe drought has more than quadrupled between 1961-1990 and 1986-2015. With 2°C warming, more than half of the months in a 30-year period are projected to be in severe drought, with severe drought lengths of more than three years possible.
Biodiversity adaptation options generally only allow for business-as-usual conservation to 2.0°C, but this would only be possible if changes in extreme events (especially summer heat and severe drought) were taken into consideration. Even with warming of 2°C and less, water may become increasingly scarce so water holes or guzzlers may be required to maintain existing biodiversity. With warming above 2°C adaptation will become increasingly difficult as lengths of severe drought increase. Only the highest elevations in the park would be able to potentially get by with business-as-usual conservation.
Original languageEnglish
Number of pages51
Publication statusPublished - 11 Jun 2024


  • protected areas, biodiversity, climate change

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