Pan-Arctic Climate Change Projection Research Group

Developing a Highly Accurate Pan-Arctic Regional Model and Making Detailed Predictions for Several Decades into the Future

Under the overarching theme of “prediction,” our Pan-Arctic Climate Change Projection Research Group is using JAMSTEC’s “Earth Simulator” supercomputer in an effort to develop a highly accurate numerical model for the Pan-Arctic region. What will the Earth, or Japan, be like 10, 20, or 50 years from now owing to global warming and other climate change? To find out, it’s important to increase our understanding of the Arctic and its surrounding regions.

The Arctic is one of the places in the world where the effects of climate change are most pronounced. One major example is the rapid decrease in sea ice, which is ice that covers the ocean. The Arctic is strongly affected by climate change, but its changes can also have large effects on other regions, including Japan. For this reason, our research focuses not only on the Arctic itself, but also on the surrounding areas. Together, we call this wider region the “Pan-Arctic region.” We develop computer models, which are simplified representations of the real world, and use them to carry out various experiments.

Models for global-scale, long-term simulations, called climate models, have been created at research institutions in many countries with collaboration by many researchers. The results of those models have been collected, examined, and released through international frameworks such as the Intergovernmental Panel on Climate Change, an organization that assesses research results on global warming and other climate changes caused by human activities. But because performing simulations for the entire Earth requires enormous computing resources, there is a limit to detail even with the power of a supercomputer. For example, many of the climate models used in the latest IPCC report divide the Earth into large grid cells of about 100 km on a side for their calculations. This makes it difficult for these models to reproduce local changes and weather events in the Arctic region. To address this problem, we are developing sea ice–ocean models that use small grid cells of about 5 km on a side only in the Arctic region, while keeping larger grid cells in other parts of the world. We are also developing atmospheric models that cover only the Arctic region with fine grid cells. In this way, we aim to build more accurate models of the Arctic region while using limited computer resources efficiently. Considering the fact that rapid changes in the Arctic are greatly affecting other regions of the Earth, it is our expectation that the results obtained from such models will lead to a new understanding of, and more detailed predictions for, climate change not only in the Arctic but also the entire planet.

In addition, our group also develops models of the ice sheet in Greenland. Greenland is covered by a vast ice sheet, but unusual changes are now being observed there, such as large and rapid melting of ice in summer. When the ice sheet melts, a huge amount of freshwater flows into the ocean. This may contribute to serious climate changes, including sea-level rise and changes in ocean circulation. By working on advanced research that includes the Greenland ice sheet model as part of a climate model, we aim to make future projections for the Arctic region and the whole Earth more reliable.