Great White Sharks Overheat as Oceans Warm, New Study Warns

## TL;DR Great white sharks and other mesothermic fish risk overheating as ocean temperatures rise, because their warm‑blooded metabolism demands up to four times more energy than cold‑bodied peers. A study in *Science* shows they make up less than 0.1% of marine life but could lose suitable habitat by mid‑century under current warming trends.

## Context Mesothermic species, including great white, thresher and porbeagle sharks, maintain body temperatures above the surrounding water to swim faster and hunt more effectively. Lead author Nick Payne, associate professor at Trinity College Dublin, warns that these predators cannot simply find more food as the ocean warms. The research appears in the journal *Science*.

## Key Facts Mesothermic sharks and tuna consume almost four times more energy than cold‑blooded marine animals to keep their bodies warm. Despite this high cost, they represent less than 0.1% of all marine species. The study combined physiological models of heat production and loss with sea surface temperature projections from the CMIP6 dataset to estimate how much extra energy these fish will need and where habitable waters will remain through 2100.

## What It Means As waters warm, mesothermic fish must either slow down, alter blood flow, or dive deeper to avoid overheating, all while prey becomes scarcer from overfishing and climate shifts. This “double jeopardy” of rising temperatures and declining food could shrink their viable habitats, especially during summer months, forcing longer migrations and greater competition for limited resources.

Researchers will monitor shifts in shark distribution and prey availability to gauge whether conservation measures can offset the looming habitat squeeze.