From Rio de Janeiro to Copenhagen, global efforts to fight climate change, which is posing a threat to the survival of humanity, have been a long and bumpy process.

The first ever international treaty to call for control on green house gases was held in Rio De Janeiro in 1992. The meeting represented an important step forward in efforts to protect the Earth from climate change. However, it failed to reach concrete agreements on funds and technology transfer the developed countries should provide.

Then in 1997, in Kyoto, Japan, the Kyoto Protocol was signed.

It was here that the industrialised nations agreed to reduction of green house gases by 5.2 per cent below the 1992 levels.

Al Gore represented the USA and committed to reduction of 7 per cent below 1990 levels. But the US Congress did not ratify this.

In 2001, the then US President George Bush rejected Kyoto protocol outright, saying it is too expensive and should cover industrialised as well as developing nations. So, the USA is the only country that remains outside the Kyoto Protocol.

But what finally got the world to spring into action was the IPCC report discussed in Bali, Indonesia in 1997.

According to the report, the Earth is in danger if temperatures rise 2 degrees Centigrade above 'pre-industrial' levels.

Currently, temperature levels are 0.74 degrees Centigrade above 'pre-industrial' levels. If current trends continue, the Earth will overshoot 2 degrees Centigrade with dangerous consequences.

Ever since, there have been several conferences to discuss effective measures to reduce global warming, successor to Kyoto Protocol, and to tell the developing nations that it's time to take on responsibilities and commit to legally binding emission cuts.

All efforts of the past three years culminated in the three-day climate change summit in Copenhagen.