WHAT THE EVIDENCE SAYS
Researchers combined weekly water-temperature projections from 1976–2099 with thermal limits for 9,809 freshwater species. The analysis shows that gradual warming can produce abrupt thermal exposure and fragment otherwise connected river habitat. Under a high-emissions scenario, around 63% of riverine fish were projected to experience more persistent thermal barriers.
WHY IT MATTERS / OUR READ
Connectivity is not just a map of physical channels. A river reach can remain physically connected while becoming functionally impassable because of temperature. Conservation planning that tracks mean warming or habitat area without thermal continuity can therefore miss a major persistence mechanism.
CAVEATS / UNCERTAINTY
This is a global screening model rather than a site-specific population forecast. It does not fully represent acclimation, adaptation, evolutionary change, species-specific movement behavior or every local thermal refuge.
SOURCE
Nature Climate Change · Original evidence
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