Scientists will undertake more than 120 projects using gliding underwater robots , giant icebreaking ships, satellites and other technologies to explore polar climate, biology, geology and ocean chemistry, and they will conduct physics and astronomy studies that can be done only at the poles.

In the Arctic, sea ice in summer has been in an accelerating retreat. In parts of Antarctica, coastal ice shelves and inland ice sheets have been disintegrating and surging seaward in ways that suggest a faster rise in global sea levels in coming decades.

The project will formally begin Thursday. Opening ceremonies will be held today in Washington, London and Strasbourg, France.