The Heat Is Online

Current Changes Jeopardizing Sea of Japan

Scientists, fishermen fear Sea of Japan slowly dying

Reuters News Service, March 28, 2001

OSHIMA VILLAGE, Japan - As the sun sets over the island-specked coast of southern Japan, abalone fishing boats trail back to the small port of Oshima.

On the piers, fishermen check rows of dangling light-bulbs on their night-going vessels before heading out to sea to catch squid.

But for Yasuo Kajiki, the local prefecture fishing cooperative chief who has witnessed these timeless routines for more than 30 years, something has changed - the catch is growing smaller each year.

"We have more efficient equipment than before, but somehow we only manage 40 percent of what we used to catch 30 years ago when I started out," Kajiki says.

Scientists in Japan believe they know why, but it is an answer that points to global implications and it fills them with fear.

The very cold and very deep seas that surround this sea-going, fish-eating archipelago are warming up, and that could spell disaster.

Industrial pollution, overfishing and competition with neighbouring China, South Korea and Russia are often blamed for the loss of the sea's bounty around Japan's islands.

But scientists now see a disturbing change in underwater currents triggered by global warming as the main culprit behind what fishermen have been experiencing for several years.


At CREAMS, the Centre for the Research of East Asian Marginal Seas, a joint research team of scientists from Japan, South Korea and Russia, has since 1993 accumulated enough data to confirm what the fishermen fear.

They have been measuring the currents, salinity and oxygen levels up and down a stretch of water in the Sea of Japan.

What they have found confirms their worst fears.

The Sea of Japan's deep currents, which circulate nutrients for surface plankton and life-providing oxygen underwater, are slowing and failing, said Professor Yoon Jong-Hwa of the Research and Institute for Applied Mechanics (RIAM), a Japanese branch of the CREAMS project based in the southern city Fukuoka.

As this sea is considered by oceanographers to be a "model ocean" due to the complexity of its currents and geography that often mimics the greater oceans, the implications are enormous.

"If you look at water temperatures in the northern part of the Sea of Japan over the past 50 years, they've been rising definitively up 1.5 to three degrees, and global warming is thought to be behind this," said Yoon.

"It is possible that the Sea of Japan is one of the first expanses of water affected by global warming, if that is the case, then we very much fear that eventually the world's major oceans will also be affected," he said.


The underwater currents of the Sea of Japan are created by a rare phenomenon in which a bitter winter wind blown through a narrow opening in the mountain range bordering the Russian Far East cools the sea in a way that triggers a downward current.

Only seven other such vertical downward currents have been recorded worldwide, including one off Greenland that is believed to be the starting point of the Atlantic's rich Gulf Stream.

The complexity of much of the world's ecosystem depends on these currents, often known as global underwater conveyor belts.

The plankton whose life depends on the nutrients that the currents bring up from the ocean floor also consume and store much of the world's carbon dioxide.

A reduction in the plankton will mean more carbon dioxide in the air, accelerating the process of global warming into a vicious cycle, Yoon says.

Global warming is a phenomenon whereby an excess of greenhouse gases, such as carbon dioxide, are released by human activity, warming the atmosphere and creating meteorological havoc.

The earth's atmosphere naturally contains large amounts of cardon dioxide but human activity, such as burning fossil fuels in cars and power stations, is pushing the amount of the gas above historic levels.

Scientists have calculated that the earth's atmosphere has already warmed 0.6 degrees Celsius in the past 100 years and this may be behind the recent increase in droughts and floods worldwide.

The United Nations, in a report released in January, said the earth's atmosphere is warming faster than expected. The report projected the earth's average surface temperature will rise 1.4 to 5.8 degrees Celsius (2.5 to 10.4 degrees Fahrenheit) between 1990 and 2100, higher than its 1995 estimate of a one to 3.5 degree C rise (1.8 to 6.3 degrees F).


The fishermen of Japan are not surprised.

"There's been a change in the currents, in the water and in the air, I feel it in my bones," says 68-year-old Kajiki, patriarch of the small fishing community of Oshima. "That's why our catch has dropped over the years.

Kajiki's fishing village is not alone.

Latest figures from the Ministry of Agriculture, Forestry and Fisheries show Japan's fishing industry output from oceans around the archipelago has fallen 46 percent from just 10 years ago.

From the Sea of Japan, the fall is even more alarming - a slide of 62 percent.

"If these conditions continue for some time, within 300 to 350 years the deep waters of the Sea of Japan will become anoxic (devoid of oxygen)," Yoon said.

Such a change is too sudden for life to adapt and survive, Yoon said.

As for the fishing communities that live on the ocean's bounty, they are painfully aware of the bleak future.

"We used to believe that the fruits of the ocean were limitless," said Kajiki. "Now we have to impose our own fishing quotas and fishing seasons.

"I can't imagine what the next generation will have to do, whether they will even be able to make a living from the sea."