WMO Secretary-General Michel Jarraud said International Polar Year "comes at a crossroads for the planet's future."
The project gets under way shortly after a major UN climate report in January warned that the poles are particularly vulnerable to global warming.
The report projected that sea ice in the Arctic could disappear in summers within a century, and that melting polar ice means rising sea levels worldwide.
Three other Polar Years have been observed since 1882.
View a photo gallery summarizing some key findings of the Stern report on the economic costs of global warming (epa)
THE STERN REPORT: In October, former World Bank chief economist Sir Nicholas Stern issued a 700-page report on the economic impact of global warming. The report, which was commissioned by the British government, estimates that climate change could cost between 5 and 20 percent of global GDP by the end of the century....(more)