Of the estimated 7,000 languages spoken in the world today, linguists say, nearly half are in danger of extinction and are likely to disappear in this century. In fact, they are now falling out of use at a rate of about one every two weeks.

Some endangered languages vanish in an instant, at the death of the sole surviving speaker. Others are lost gradually in bilingual cultures, as indigenous tongues are overwhelmed by the dominant language at school, in the marketplace and on television.

New research, reported today, has identified the five regions of the world where languages are disappearing most rapidly. The “hot spots” of imminent language extinctions are: Northern Australia, Central South America, North America’s upper Pacific coastal zone, Eastern Siberia and Oklahoma and Southwest United States. All of the areas are occupied by aboriginal people speaking diverse languages, but in decreasing numbers.

The study was based on field research and data analysis supported by the National Geographic Society and the Living Tongues Institute for Endangered Languages, an organization for the documentation, revitalization and maintenance of languages at risk. The findings are described in the October issue of National Geographic magazine and at www.languagehotspots.org.