Pan-Okhotsk: A Story of Climate Change

The Pan-Okhotsk region begins with the Sea of Okhotsk nestled between Russia and Japan. The area encompasses more than the sea itself, however, stretching east-to-west from Alaska all the way to Russia, and north-to-south from the North Pole to subtropics south of Japan. Studies conducted in this area have researchers concerned about the possible far-reaching effects of unabated climate change not only on the waters that comprise the region, but on the wildlife and geography found therein.

Pan-Okhotsk has seen a significant change over the past 30 years, according to Dr. Sumito Matoba, an Assistant Professor at Hokkaido University’s Pan-Okhotsk Research Center, Institute of Low Temperature Ice. Dr. Matoba has been a member of the Institute since 2005. Prior to joining the University, Dr. Matoba studied at Kyoto University and the National Institute of Polar Research. He has analyzed ice cores from the Svalbard ice cap as well as joining ice drilling expeditions to Canada, Alaska, Russia, Greenland, and Asia.

Dr. Matoba shared some of his findings related to Pan-Okhotsk as well as what the future may hold for the region.

Wenger: When did researchers first notice the effects of climate change on the Pan-Okhotsk region?

Dr. Matoba: After 2000, and especially after 2005, the sea ice began to noticeably decrease. However, oceanographical studies showed that a warming trend at the Sea of Okhotsk and North Pacific had already started beginning around 50 years ago.

Wenger: What were some of the findings that grabbed researchers’ attention?

Dr. Matoba: When sea water is frozen, the ice excludes impurities as sea salt to the outside layers of ice. The excluded water contains a high concentration of sea salt and the density becomes higher. This dense, concentrated water is called brine. The brine sinks to the intermediate layer of the waters in the Sea of Okhotsk. Dr. Takuya Nakanowatari and team analyzed the temperature in the intermediate water, and found that the temperature increased by the rate of 0.67C/50 years. This warming trend is a result of the decrease of sea ice production in the Sea of Okhotsk.

Wenger: What are the possible consequences of climate change in the Pan-Okhotsk region as they relate to wildlife or marine life?

Dr. Matoba: The decreasing effects on the thermohaline circulation of the Sea of Okhotsk and North Pacific could potentially affect marine ecosystems in these regions. From our studies of an ice core from Kamchatka, we did not see any trend of precipitation increase or decrease related to the recent climate change. But on the ice core from Alaska, we found two things. In the central part of Alaska, precipitation amount increased since 1900 and increased remarkably since 1970. In the southern part of Alaska, variation of precipitation amount is associated
with PDO (Pacific decadal oscillation) before 1990, but that correlates with enhanced cyclone activity at Gulf of Alaska after that same year. This shows that the climate system in Alaska
might be changing after 1990, and the change is not observed on the ground-level meteorological stations yet.

Wenger: Has any real-world human impact been felt on the region? What, if any, visible changes in weather or climate have been observed?

Environmental changes have been caused by not only recent climate change but also human activities. For example, the use of land in the Amur River basin has changed drastically over the past 30 years. We’re concerned that the human impact on the Amur River could change the terrestrial ecosystems as well as marine ecosystem in the Sea of Okhotsk.

In Hokkaido, Japan, we feel the change in climate directly. In winter, precipitation is often provided by rain, not snow.