Wed, Jan 15, 2020 - Page 7 News List

Ocean temperatures hit record high

RISING RISK:One expert said that the rapidly increasing heat content in the upper layers of the world’s oceans would have a dramatic effect on their rich ecosystems

The Guardian

The heat in the world’s oceans last year reached a new record level, showing “irrefutable and accelerating” heating of the planet.

The world’s oceans are the clearest measure of the climate emergency, because they absorb more than 90 percent of the heat trapped by greenhouse gases emitted from burning fossil fuels, forest destruction and other human activities.

A new analysis found that the past five years were the top-five warmest years recorded in the ocean and the past 10 years were also the top 10 years on record.

The amount of heat being added to the oceans is equivalent to every person on the planet running 100 microwave ovens all day and all night.

Hotter oceans lead to more severe storms and disrupt the water cycle, meaning more floods, droughts and wildfires, as well as an inexorable rise in sea level.

Higher temperatures are also harming life in the seas, with the number of marine heat waves increasing sharply.

The most common measure of global heating is the average surface air temperature, as this is where people live.

However, natural climate phenomena, such as El Nino events, mean that this can vary significantly from year to year.

“The oceans are really what tells you how fast the Earth is warming,” said John Abraham, a professor at Minnesota’s University of St Thomas and one of the team behind the new analysis. “Using the oceans, we see a continued, uninterrupted and accelerating warming rate of planet Earth. This is dire news.”

“We found that 2019 was not only the warmest year on record, it displayed the largest single-year increase of the entire decade, a sobering reminder that human-caused heating of our planet continues unabated,” said Michael Mann, a Pennsylvania State University professor and another team member.

The analysis, published in the journal Advances in Atmospheric Sciences, used ocean data from every available source.

Most data was from 3,800 free-drifting Argo floats dispersed across the oceans, but also from torpedo-like bathythermographs dropped from ships in the past.

The results showed heat increasing at an accelerating rate as greenhouse gases accumulate in the atmosphere. The rate from 1987 to last year was four-and-a-half times faster than that from 1955 to 1986.

The vast majority of oceans regions are showing an increase in thermal energy.

This energy drives bigger storms and more extreme weather, Abraham said.

“When the world and the oceans heat up, it changes the way rain falls and evaporates. There’s a general rule of thumb that drier areas are going to become drier and wetter areas are going to become wetter, and rainfall will happen in bigger downbursts,” he said.

Hotter oceans also expand and melt ice, causing sea levels to rise. The past 10 years also saw the highest sea level measured in records dating back to 1900.

Scientists expect about 1m of sea level rise by the end of the century, enough to displace 150 million people worldwide.

Dan Smale of the Marine Biological Association of the UK, who was not part of the analysis team, said that the methods used are state of the art and the data is the best available.

“For me, the take-home message is that the heat content of the upper layers of the global ocean, particularly to 300m depth, is rapidly increasing, and will continue to increase as the oceans suck up more heat from the atmosphere,” Smale said.

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