評論
打印
Scientists: 2019 Ocean Water Temperatures Were Hottest Ever
Scientists reported this week that the world's oceans were warmer in 2019 than they had ever been before.
The report comes at a time when studies have linked rising ocean water temperatures to manmade pollution. Researchers say the rate of warming is speeding up and may cause a planet-wide disaster.
The oceans take in more than 90 percent of the extra heat created by carbon dioxide and other greenhouse gas emissions. Greenhouse gases are a product of pollution from factories, driving motor vehicles and other human activities.
Scientists are able to measure the rate of global warming when they compare current ocean water temperatures with those measured over the past few years.
For a better understanding of ocean warmth, scientists from around the world studied records shared by China's Institute of Atmospheric Physics (IAP). They found that the latest water temperature was 0.075 degrees Celsius higher than the average temperature from 1981 to 2010. Their findings were published in the scientific journal Advances in Atmospheric Sciences.
Effects of warmer oceans
The scientists pointed to the many extreme weather events of 2019 as one effect of warmer oceans. They added that warmer water also endangers some sea creatures and causes higher sea levels.
Lijing Cheng is with the International Center for Climate and Environmental Sciences at the IAP. He also was the lead author of a paper on the study. He says the heat the oceans have taken in to make the temperature change amounts to 228 Zetta Joules (228 billion trillion Joules) of energy.
"That's a lot of zeros indeed," he said. "To make it easier to understand, I did a calculation... The amount of heat we have put into the world's oceans in the past 25 years equals to 3.6 billion Hiroshima atom-bomb explosions."
One hundred hair dryers per person
Michael Mann is director of the Earth System Sciences Center at Penn State University in the United States. He says the energy that caused the warming is equal to "everyone on the planet running a hundred hairdryers or a hundred microwaves continuously for the entire year." He spoke to the French news agency AFP.
The past five years are the five hottest years for the ocean since scientists began keeping records, the study found.
John Abraham is a co-author of the paper. He said it is important to "understand how fast things are changing. The key to answering this question is in the oceans — that's where the vast majority of heat ends up. If you want to understand global warming, you have to measure ocean warming."
Abraham is a professor of mechanical engineering at the University of St. Thomas in Minnesota.
Target limit to global warming
In 2015, world leaders signed the Paris Agreement as part of efforts to limit climate change. The agreement took effect the following year. It aims to limit global temperature increases to "well below" 2 degrees Celsius, and to 1.5 degrees Celsius if at all possible.
There has been about 1 degree Celsius of warming since the start of the Industrial Revolution 200 years ago. Yet the result of rising water temperatures is not evenly spread in the world's oceans. The report says that warmer temperatures are partly to blame for heavy rainfall in Indonesia and the drying of Australia, leading to wildfires in Australia and the Amazon.
Hope remains
Mann explained that there is still hope for the climate to recover from this temperature increase. "If we stop warming the planet, heat will continue to diffuse down into the deep ocean for centuries until eventually stabilizing."
I'm Jill Robbins.
