A top official of the United Nations Intergovernmental Panel on Climate Change says countries will have to make deep cuts in greenhouse gas emissions to avoid the worst impact of rising global temperatures. Environmental experts are preparing to discuss how to tackle climate change at a U.N. sponsored conference in Indonesia next month. Anjana Pasricha reports on the preparations from New Delhi.

Mayor of London Ken Livingstone (R) and the Chairman of IPCC Rajendra Kumar Pachauri in New Delhi, 20 Nov 2007

Pachauri addressed reporters in New Delhi after a recently released IPCC report stated the evidence for climate change is "unequivocal."

The IPCC report says there is 90 percent chance that climate change is caused by human activity. It warns that millions of people could be affected by more heat waves, melting glaciers, rising sea levels, and smaller harvests.

Pachauri says it is important for both developed and developing countries to act quickly.

"I think what is going to be critically important is for all the countries to realize that we are in it together," he said. "I mean that is the first common conclusion we have to arrive at that is we have to reduce emissions of greenhouse gases."

Most experts say that greenhouse gases, produced mainly by burning fossil fuels for energy, are causing much of the global warming seen in recent decades.

Pachauri says the current path of development is clearly not sustainable. He says lifestyle changes have been identified as an important measure to reduce the impact of rising global temperatures.

According to Pachauri, these are not drastic measures, but steps that societies can take.

"This change of lifestyles does not really mean that we start going back start living in caves all over again," he added. "Basically it just means a shift which gives you all the goods and services and benefits that modern living involves, but with a much lower footprint in terms of emissions of greenhouse gases societies will have to decide what they can and want to do."

Pachauri cites some examples: moving away from personal transport to public transport and buildings designed to use less energy.

In places where heating is needed, people can use warmer clothes and reduce temperatures. Pachauri hoped that developed countries will take the lead to tackle climate change in the conference next month in Indonesia .

He says public opinion will have to play a significant role in pressing leaders to take the steps necessary to reverse climate change.