Earth ‘Serially Doomed’: UN Issues New 15 Year Climate Tipping Point – But UN Issued Tipping Points in 1982 & Another 10-Year Tipping Point in 1989! | Climate Depot:
"In 1982, the UN issued a two decade tipping point. 
UN official Mostafa Tolba, executive director of the UN Environment Program (UNEP), warned on May 11, 1982, the “world faces an ecological disaster as final as nuclear war within a couple of decades unless governments act now.” 
According to Tolba in 1982, lack of action would bring “by the turn of the century, an environmental catastrophe which will witness devastation as complete, as irreversible as any nuclear holocaust.”"

Earth ‘Serially Doomed’: UN Issues New 15 Year Climate Tipping Point – But UN Issued Tipping Points in 1982 & Another 10-Year Tipping Point in 1989!

Climate Depot Factsheet on Inconvenient History of Global Warming 'Tipping Points' -- Hours, Days, Months, Years, Millennium -- Earth 'Serially Doomed'

It's difficult to keep up whether it is hours, days, months or 1000 years. Here are few recent examples of others predicting "tipping points" of various duration.

HOURS: Flashback March 2009: 'We have hours' to prevent climate disaster -- Declares Elizabeth May of Canadian Green Party

Days: Flashback Oct. 2009: UK's Gordon Brown warns of global warming 'catastrophe'; Only '50 days to save world'

Months: Prince Charles claimed a 96-month tipping point in July 2009

Years: 2009: NASA’s James Hansen Declared Obama Only First Term to Save The Planet! — ‘On Jan. 17, 2009 Hansen declared Obama only ‘has four years to save Earth’ or Flashback Oct .2009: WWF: 'Five years to save world'

Decades: 1982: UN official Mostafa Tolba, executive director of the UN Environment Program (UNEP), warned on May 11, 1982, the 'world faces an ecological disaster as final as nuclear war within a couple of decades unless governments act now.'

Millennium: Flashback June 2010: 1000 years delay: Green Guru James Lovelock: Climate change may not happen as fast as we thought, and we may have 1,000 years to sort it out'

It is becoming obvious that the only authentic climate "tipping point" we can rely is this one:

Flashback 2007: New Zealand Scientist on Global Warming: 'It's All Going to be a Joke in 5 Years'