Scientists have long known the world’s oceans are undergoing drastic transformations — now, it appears they’re in even worse shape than previously thought.
A new study published Thursday in the scientific journal Nature found that the world’s oceans have absorbed 60% more heat since 1991 than earlier estimates. That means that countries have significantly less time before the Paris climate agreement’s goal of keeping global temperatures from rising more than 1.5 degrees Celsius compared to pre-industrial levels becomes unreachable.
In fact, the study estimates that the world’s carbon budget — the amount of carbon that can be burned before catastrophic climate change occurs — has shrunken by 25%. Since carbon emissions are only rising and show no sign of slowing down, this reduction adds even more urgency to the United Nations’ recent call for “rapid, far-reaching, and unprecedented changes in all aspects of society.”
The oceans foreshadow changes in the global climate, because they absorb more than 90% of the excess heat trapped in the atmosphere from greenhouse gas emissions.
The study’s researchers used a novel approach to figure out how much heat they’ve actually absorbed, by measuring the volume of gases that rise off the oceans. They were then able to extrapolate temperature rise based on the fundamental principle that all liquids give off gas when heated.
“When the ocean warms, it loses some gas to the atmosphere,” Laure Resplandy, a geoscientist at Princeton University who led the study, told the Washington Post. “That’s an analogy that I make all the time: If you leave your Coke in the sun, it will lose the gas.”
The excess heat absorbed annually, which is eight times greater than humanity’s annual energy consumption, is accelerating dangerous environmental feedback loops.
For example, as oceans warm, ice sheets melt, causing more sun to be absorbed by surrounding oceans, leading to even warming waters and more ice melt.
The new study represents a breakthrough in climate science, according to the Post, but it also indicates a planet in crisis.
The oceans are already showing signs of collapse. Coral reefs are disappearing around the world, fish are being forced to migrate, ice melt is accelerating, and whole ecosystems are disappearing.
And that’s just from higher temperatures. The oceans are also experiencing acidification, plastic pollution, industrial pollution, and overfishing.
A report earlier in the year found that 87% of the world’s oceans are dying.
“We were astonished by just how little marine wilderness remains,” Kendall Jones, lead author of that report, told the Guardian. “The ocean is immense, covering over 70% of our planet, but we’ve managed to significantly impact almost all of this vast ecosystem.”
Taken together, the future health of the oceans call for drastic intervention today to curb greenhouse gas emissions and regulate human activity in marine environments.
The United Nations is spearheading efforts to protect the high seas later this year and the amount of marine protected areas is increasing, especially in areas with coral reefs and other valuable ecosystems.
But without a concerted effort to transition away from fossil fuels, the oceans could become unrecognizable in the decades ahead, vastly bigger because of melting glaciers, but barren of wildlife.