Today marks the beginning of the International Polar Year (IPY), a two-year mission to explore Earth's poles. Some 50,000 scientists, artists and other participants from 63 nations will undertake 460 projects—ranging from lacing the Antarctic ice with neutrino-spotting sensors to a survey of historic Inuit knowledge of Arctic sea ice—in a massive effort to enhance scientific understanding of the poles before they change. "The scientific community feels that we need an urgent and comprehensive look at the polar regions," says David Carlson, director of the IPY's international program office.

This IPY is the first such multinational comprehensive look at the polar regions since 1958, when the International Geophysical Year (IGY) wrapped up. "Fifty years ago, we were motivated by discovery and now we are motivated by change," Carlson says. "Then we got the first measurements of ice thickness in Antarctica. Now we think that may be changing. Then we got the first look at ocean circulation in the polar regions, now that is changing."

Building on a tradition launched in the 1870s by Austrian polar researcher Carl Weyprecht—who attempted to unite the competing nations of the time in the pursuit of fundamental polar insight—this IPY will last two years, despite its name, because of the harsh Arctic and Antarctic conditions. Experts says that it may be the last chance to study the polar regions as they are now; global warming is already being felt most severely in these areas and transforming them as a result.

Following are a few of the myriad IPY projects:

Build an IceCube to Catch a Neutrino

Neutrinos are among the building blocks of matter. But because they lack a charge—hence the name—and have little mass, they are extremely difficult to detect. One of the ways to find the neutral particles is to wait for the extremely rare occasions when they collide with intact atoms, producing a shower of charged particles. "When a charged particle moves through a very transparent medium, it fills it with a blue light," explains Francis Halzen, a particle physicist at the University of Wisconsin–Madison. "Because the particle goes faster than the light [in this medium], it forms a bow wave like a speedboat in water. From that bow wave, you can map the direction of the original particle."

Neutrinos, because they carry no charge, travel in a straight line from wherever they are produced as long as they have not had any previous collisions. Many are manufactured in our own atmosphere, others travel from the sun and still others origin may be from distant regions of space. "The popular sources that people predict are like supernova[e], neutrinos, active galaxies, gamma-ray bursts," Halzen says. "The atmosphere is totally uniform in terms of the neutrinos it produces. So you look for hot spots in the map."

To produce the map in the first place, though, requires an enormous transparent medium. Halzen and his collaborators hit upon the idea of using the ice under the South Pole as that medium. The project, dubbed IceCube, will sink 4,800 photomultipliers—sensors that detect light—into a billion tons of ice, reaching one mile (2.4 kilometers) below the Antarctic surface. Some 1,500 sensors are already in place, transmitting data via satellite to researchers in Madison, and the ice has turned out to be the best place for such a sensor. "This ice is made from snow that was incredibly clear and pure. It's 100,000-year-old snow that is compressed," Halzen says. "We have found layers in Antarctic ice, where the absorption is 300 meters, as clear as salt crystals you make in a lab." Of course, the ice also offers one more benefit: "We can walk on our experiment."

Mapping the Tundra and the Permafrost

The Arctic is changing, but nowhere is this less immediately visible than in the thawing permafrost. "You don't see it, like glaciers and snow and sea ice," says Jerry Brown, retired geocryologist and president of the International Permafrost Association. But thawing permafrost can have dramatic effects both visible and invisible, from collapsing roads and leaning trees in Alaska to freeing greenhouse gases that had been frozen for millennia.

Two of the major projects for this IPY will be the creation of permanent permafrost observations and an expansion of the International Tundra Experiment (ITEX), a model experiment that uses easily constructed greenhouses to artificially warm portions of the tundra. "We measure growth rate of certain tundra species and the vegetation composition and abundance. We've moved into ecosystem functions, carbon fluxes and nutrient fluxes," says Greg Henry, an ecologist at the University of British Columbia. "The next phases are a lot more soil biology, measuring changes below ground in fungal and microbial communities to get a handle on how they are responding to the warming."

The tundra experiment has been ongoing in some locations for more than 16 years but will be expanded throughout the world—even away from the poles to tundra in mountainous Australia and the Tibetan plateau. Meanwhile, permafrost observers the world over will take measurements in boreholes at least 30 meters (100 feet) deep—the depth where temperatures do not fluctuate during seasonal cycles—though some will stretch much deeper. "It will be a permanent network of sites for these observations, including the active layer, the thawing layer," Brown says. "It will be a great legacy of the IPY to say that we measured the permafrost."

ITEX will also help predict what may happen in the polar regions in the future. Satellite observations have already shown that the tundra is greening while ground crews report the increasing influx of shrubs and woodier cover. Since these plants are darker than the typical light tundra cover, they will warm their regions even more. "This albedo feedback could result in the same amount of warming as a doubling of [carbon dioxide]," Henry says. "That's a major impact."

Undiscovered Mountains and the Legacy of Ice

There are few places on Earth that remain unmapped; Antarctica hosts a mountain range that shouldn't be there and has never been seen. "They are the size of the Alps and the birthplace of the Antarctic ice sheet," says geophysicist Robin Bell of the Lamont-Doherty Earth Observatory in New York City. "There aren't supposed to be mountains in the middle of stable continents."

Mapping this buried range will help scientists understand how glaciers formed in Antarctica as well as how today's ice sheets interact with the ground below. Scientists have already discovered enormous lakes deep under the ice, a result not predicted in any model.

Without an understanding of how ice interacts with the ground, models cannot accurately forecast how the ice will behave as conditions change. Given the potentially catastrophic contribution of such land ice to global sea level rise, a better understanding of ice dynamics is one of the key goals of the IPY. And it all begins in unexplored mountains. "At the last IGY, we thought the Antarctic sheet was a giant pillow," Bell says. "We now have a very different picture." And that picture will change yet again.

Peoples of the Poles

There are no greater guides to Arctic ice than the Inuit, who have studied its contours for generations. Known as siku, sea ice guides hunters on their annual quest for sustenance, providing access to hunting grounds and shelter from storms. The Sea Ice Knowledge and Use (SIKU) project aims to record some of this information as the sea ice the hunters have known changes before their eyes. "The sea ice becomes almost an extension of their land," says Claudio Aporta, an anthropologist at Carleton University in Ottawa. "Their records of those camps have been there year after year for at least 200 years of written history."

By mapping current conditions with the help of Inuit hunters as well as by compiling maps of the past based on oral histories and the memories of elders, the researchers hope to capture the Inuit's special understanding of sea ice. By combining that with modern tools such as the Global Positioning System and remote sensing, a deeper understanding of the fundamental nature of the ice can be gained as it changes. And maybe the lessons learned can help the Inuit in return. "The patterns of sea ice freezing and breaking up is changing," Aporta says. "They have to adapt."

These Are the Polar Years

The poles are on the front lines of climate change—melting ice, thawing permafrost, warming temperatures—but they are also at the forefront of weather patterns, global oceanic circulation and the marine food chain. For example, the current that circles Antarctica distributes cold water throughout the globe, influencing regional currents and regional weather, while the krill that thrive under Antarctic ice shelves feed animals as large as the blue whale.

The IPY will expand scientific knowledge of the poles as well as leave a legacy of ongoing projects to continue our understanding into the indefinite future. It will also have human impacts, from improving weather prediction to helping assess the health of those living in the Arctic. And, it will provide a snapshot of a region facing unprecedented transformation. As IPY's Carlson says: "We seem to be looking at a system of urgent change."