Since 1884, GMT has been the international standard for timekeeping but it is now under expert scanner from a new definition of time itself based not on the rotation of the Earth but on atomic clocks.
France-based International Bureau of Weights and Measures (BIPM) has proposed the change in the GMT. GMT is based on the passage of the sun over the zero meridian line at the Greenwich Observatory in southeast London and became the world standard for time at a conference in Washington in the United States in 1884.
At the same conference, France had lobbied for 'Paris Mean Time'. In 1972, it was replaced in name by Universal Coordinated Time (UTC) but due to some reasons it remained the same as GMT. UTC is based on about 400 atomic clocks at laboratories around the world but then corrected with "leap seconds" to align itself with the Earth's rotational speed, which fluctuates.
The discussion in London will look at the implications of abolishing the leap seconds and moving fully to atomic time. The new direction would see atomic time slowly diverge from GMT, by about one minute every 60 to 90 years, or by an hour every 600 years, and there would need to be "leap minutes" a couple of times a century to bring the two in line.
Meanwhile, In January 2012, the International Telecommunication Union will meet in Geneva to vote formally on whether to adopt the new measure, despite strong protest from Britain.