Oceans are warming far more quickly than previously thought, making 2018 the warmest year yet, according to a new study published in the journal Science.
A group of international researchers says the findings are dire because the ocean’s temperature is a clear indication of climate change.
“Global warming is actually ocean warming,” lead researcher Lijing Cheng told Global News. “The change in ocean heat content is considered to be one of the best — if not the best — way to measure climate change driven by greenhouse gases emitted by human activities.”
Unlike surface temperatures, ocean temperatures are not affected by year-to-year variations caused by climate events like El Niño or volcanic eruptions, the study states.
The study found that the world’s oceans are heating up 40 per cent faster, on average, than the United Nations predicted five years ago.
Cheng explains that global warming is driven by an increase in greenhouse gases being released into the air, which are in turn absorbed by water. In fact, he says 90 per cent of greenhouse gases are absorbed by oceans.
If it wasn’t for the oceans doing all the hard work, it would be much, much hotter on land, the group of researchers explained.
Higher water temperatures can result in the death of marine life, higher sea levels and an increased chance of destructive hurricanes and storms, Cheng said.
“It has also contributed to increases in rainfall intensity and stronger, longer-lasting storms, such as Harvey in 2017 and Florence in 2018,” according to a statement from the U.S. National Center for Atmospheric Research.
“In turn, declines in ice sheets, glaciers and ice caps, along with declining ocean oxygen levels, and destruction of coral reefs accompany the warming ocean.”
For the analysis, researchers used more than 3,000 robotic floats to measure the ocean’s temperature and salt levels. The technology is called Argo and has a satellite data recording system that covers 2,000 metres of ocean depth.
In the past, understanding ocean temperatures has been challenging. Before 2000, scientists relied on temperature sensors — in the form of copper wires — that were lowered into the water by ships. The wires often broke, and their data collection was not considered the most reliable.
As a result, it’s been hard to paint a real picture of climate change as it relates to the oceans without proper historical data from the last century. However, researchers from the study said that with the use of more reliable technology, they have a better understanding of the current situation.
The researchers have performed the same study three times since 2014, and there is a clear trend of increasing temperatures within our oceans, they say.
“Scientists are continually working to improve how to interpret and analyze what was a fairly imperfect and limited set of data prior to the early 2000s,” said Zeke Hausfather, a graduate student in the Energy and Resources Group at the University of California, Berkeley and co-author of the study.
“These four new records that have been published in recent years seem to fix a lot of problems that were plaguing the old records, and now they seem to agree quite well with what the climate models have produced.”
Researchers argue that it is up to humans to mitigate the increasing water temperatures by decreasing greenhouse gas emissions.