The depth of the ocean plays a big role in how affected areas are. While the depths in the mid-Pacific allow cooler waters in the water, the shallower areas around tropical islands don’t get the same relief. Island nations are facing an even greater risk because the water gets bigger and bigger as it gets hotter, a phenomenon known as thermal expansion. “The same body of water takes up more volume, and so you see — sea level rise,” says Rudnick.
The world is getting warmer and the weather is getting worse. Here’s everything you need to know about what humans can do to prevent the planet from being destroyed.
In fact, about half of anthropogenic sea level rise is due to runoff from melting glaciers, and the other half comes from warmer waters that just take up more space. But more locally, almost all regional change Rudnick adds that when sea level rises it is due to thermal expansion. The hotter the coastal water, the higher the sea level. This can happen quickly with extreme heat events, while sea level rise from melting ice occurs at a faster glacial rate.
The ecological consequences of increasing heat — both in terms of overall warming and in the spikes caused by extreme heat — are both obvious and subtle. Species with the ability to flee, like fish, are moving towards the poles. “Like lobster, for example. “We are seeing some significant changes in the geographic distribution of fisheries off the northeastern United States,” said Van Houtan. “There used to be a fishery in New York and New Jersey, and that was basically non-existent. And now Maine is thriving, but 10 years from now Maine is likely to be lagging behind, and it may just be a Canadian fishery moving forward. Similarly, subsistence fishers in the tropics may lose their livelihood as entire fish populations move elsewhere.
But species that are fixed in place, like sponges and corals, can’t get it (or its fins) to cooler areas. “Fixed ones will probably encounter absolute heat thresholds where they cannot coexist, and so you will see a decrease in those thresholds,” says Van Houtan.
Extreme temperatures pose additional hazards, even for species that are in the process of migrating to cooler areas. “When you have sudden events like marine heatwaves, they don’t have time to adapt,” says Seegers. “So they can lead to really high mortality rates. This happens across ecosystems from coral reefs to kelp forests, and they can cause seabirds to die.”
“The system can take years to recover,” added Seegers, “because if you have a lot of mortality, it won’t necessarily return to normal.”
To complicate matters further, these extremes often coincide with low winds. Wind plays an important role in the ocean food chain, as it mixes water, bringing nutrients up from the depths. Tiny photosynthetic organisms called phytoplankton rely on these nutrients, the same way your garden plants rely on fertilizer. These phytoplankton provide food for animals called zooplankton, which feed on fish, marine mammals and seabirds. The phytoplankton is then lost under extreme heat, attacking the base of the food web.
