End in sight: The long battle against global warming

Paris: A near three decade-long effort to rein in dangerous planetary warming is set to culminate on Saturday in the first-ever universal pact to curb greenhouse gas emissions.

The road has been long.

Climate alarm

Alerted by scientists to signs that Earth's climate is warming, the UN establishes an international panel of scientists in 1988 to investigate. Two years later, the team reports that greenhouse gases generated by human activity are on the rise, and could intensify global warming. In a series of reports, evidence accumulates that human activity voracious burning of coal, oil and gas and destructive farming practices is warming Earth's surface and disrupting its climate system.

First response

A UN "Earth Summit" held in Rio de Janeiro in 1992 sets up a convention 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 Parties to chase that elusive goal.

A deal in Japan

Finally, in 1997, nations reach 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. 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

A year later, China overtakes the United States to become the world's biggest greenhouse gas emitter. And in 2007, the UN's climate science panel reports 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 share the Nobel Peace Prize with former US vice president Al Gore, but its reputation is later tarnished by revelations that its most recent report contains several errors.

From Copenhagen collapse, to Paris

It is still the stuff of climate envoys' nightmares. The 2009 Copenhagen conference seeking a post-2012 agreement to replace Kyoto, is a near-catastrophe. Rather than the first climate pact to include all UN nations, 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 the method. Importantly, however, it enshrines a promise by rich countries to muster $100 billion (91 billion euros) in climate aid for developing countries per year by 2020. 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. In December 2015, 150 heads of state and government converge on Paris to launch a new attempt to reach a universal greenhouse gas-cutting accord.