Lee, 69, beat five rivals for the job, including Belgian scientist Jean-Pascal van Ypersele in a run-off vote, and will be chair for 6-8 years to oversee a mammoth report on the risks of climate change.
The last series of IPCC reports in 2013-14 raised the probability that human activities, led by the burning of fossil fuels, have caused at least 95 percent of warming since 1950.
Lee, until now a vice-chair of the IPCC, will be the U.N.`s top climate scientist when almost 200 nations meet in Paris in from November 30 to December 11, seeking to agree a new global deal to slow climate change.
Pachauri, who had been due to stand down at the meeting in Croatia after 13 years, quit early in February after a female researcher accused him of sexual harassment, a charge he denies.
The IPCC shared the 2007 Nobel Peace Prize with climate campaigner and former US Vice President Al Gore.
More about:
