A new study tells us that the world’s oceans may be heated to seven times higher than current levels by the second half of this century even if greenhouse gases (GHG) emissions were reduced drastically. The research, Climate velocity reveals increasing exposure of deep-ocean biodiversity to future warming, published in the journal Nature, found that different parts of the ocean would change at different rates due to the extra heat from increasing levels of GHG. This will have enormous impact on ocean wildlife, as species that rely on each other for survival are forced to migrate, severely affecting biodiversity.

The researchers used a measure called climate velocity, which is the speed that species would need to move at to stay within their preferred temperature range as different ocean layers heat up to different temperatures. The study found that ‘contemporary (1955–2005) climate velocities are faster in the deep ocean than at the surface.’ Currently, global warming is forcing species to shift in all layers of the ocean from the surface to more than 4 km down and at different speeds.

Their future projection (2050–2100) shows that climate velocities are faster for all depth layers, except at the surface, even under the most optimistic GHG mitigation scenarios. In waters between a depth of 200 and 1,000 meters, the research found that climate velocities accelerated to 11 times the present rate. And climate velocity is moving at different speeds at different depths in the ocean and also in different directions. All of these findings have enormous implications and challenges to the ways protected areas are designed. 

The research implies that global warming is going to significantly impact marine life in the deep ocean with deep sea biodiversity at greater risk because they have adapted to much more stable thermal environments. The only way to partially mitigate this is urgent action on alleviating human-generated threats to marine life, such as seabed mining and deep-sea bottom fishing, and declare large, new protected areas in the deep ocean where such activities are prohibited.