Le Bourget, France: Decades of diplomatic efforts to tackle climate change culminated in Paris on Saturday with a common vision for curbing greenhouse-gas emissions and throwing a lifeline to vulnerable countries.
Here is a timeline of the odyssey:
Climate alarm
Alerted by scientists to fears that Earth's surface is warming, the UN establishes an international expert panel in 1988 to investigate. Two years later, the team reports that heat-trapping "greenhouse" gases generated by human activity are on the rise, and could intensify planetary warming. In a series of studies, evidence accumulates that human activity -- voracious burning of coal, oil and gas, rainforest logging and destructive farming practices -- is heating Earth's surface, a prelude to disrupting its climate system.
First response
The UN "Earth Summit" in Rio de Janeiro in 1992 sets up the UN Framework Convention on Climate Change (UNFCCC), with the aim of stabilising greenhouse-gas emissions to prevent "dangerous" interference with the climate system. All signatories -- now 195 nations -- have met every year since then in a gathering known as the Conference of the Parties, or COP, to pursue that elusive goal.
A deal in Japan
Finally, in 1997, nations reached an agreement in Kyoto, Japan, after all-night talks in a chilly conference centre, setting a 2008-2012 timeframe for industrialised nations to reduce greenhouse-gas emissions by an average 5.2 percent from 1990 levels.
Developing countries, including fast-growing China, India and Brazil, are not required to take on binding targets. Four years later, the world's then-leading carbon emitter, the United States, deals the protocol a body blow by refusing to ratify it. US President George W. Bush says the deal is unfair as it lets developing giants off the hook.
Nevertheless, the Kyoto Protocol takes effect in 2005 following its ratification by Russia -- the 55th signatory needed.
Evidence mounts
In 2006 China overtakes the United States to become the world's biggest greenhouse gas emitter. The UN's climate science panel reports the following year that evidence of global warming is now "unequivocal". It forecasts warming of 1.8-4.0 Celsius (3.2-7.2F) by 2100 and a rise in sea levels of at least 18 centimetres (7.2 inches). The report also warns that extreme weather events will probably multiply. In October 2007, the scientific team shares the Nobel Peace Prize with former US vice president Al Gore for their efforts in raising the alarm about climate change.
From Copenhagen collapse, to Paris
The 2009 edition of the annual COP in Copenhagen, seeking a post-2012 agreement to succeed Kyoto, is a near-catastrophe. The outcome is a watered-down, last-minute political "accord" among several dozen major emitters. The document sets a goal of limiting average global warming to 2C (3.6 F) but is vague on how to achieve it.
Importantly, though, it enshrines a promise by rich countries to muster $100 billion (91 billion euros) annually by 2020 to help developing countries fight climate change. In 2014, the science panel warns that average global temperatures by the end of the 21st century could be 3.7-4.8C (6.7-8.6F) higher than in the period 1850-1900 if nothing is done to ease the upward emissions trend.
On November 30 2015, 150 heads of state and government converged on Paris to launch a new attempt to reach a universal greenhouse gas-cutting accord. Nearly a fortnight later, after gruelling diplomatic battles among 195 nations, the Paris Agreement was forged.
