Lars Lokke Rasmussen, the Danish prime minister, said: "India is a key country in the global efforts to tackle climate change.
"Together these 105 leaders represent 82 per cent of mankind, 89 per cent of the world's GDP and 80 per cent of the world's current emissions."
China, India, Brazil and South Africa this week rejected a Danish suggestion to set a goal of halving world emissions by 2050, saying rich nations which have burnt fossil fuels since the industrial revolution must first cut their own emissions.
The UN said rich nations must accept deep cuts in their greenhouse gas emissions by 2020 and come up with at least $10bn a year in aid to the poor to kick off a deal.
It also wants new actions by developing nations to slow the rise of their emissions.
The talks have sparked protests in many European cities, adding to the pressure world leaders are under to reduce rising emissions that the UN says will cause desertification, mudslides, more powerful cyclones, rising sea levels and species extinctions.
About 20,000 people marched in London on Saturday to protest against global warming, and a Greenpeace demonstration in Paris drew 1,500 people.
Activists in Berlin, in Germany, sat inside a giant aquarium that was gradually filled with water to highlight the risks of rising sea levels from melting glaciers and ice sheets on Greenland and Antarctica.
But an opinion poll carried out by the Nielsen/Oxford University in the UK suggested world concern about climate change has fallen in the past two years.
The results, announced on Sunday, showed that 37 per cent of more than 27,000 internet users in 54 countries said they were "very concerned" about climate change, down from 41 per cent in a similar poll two years ago.
The poll linked the decline in concern to the world economic slowdown.
Yvo de Boer, head of the UN framework convention on climate change, said he was confident the climate summit would be a success.
On Sunday he tried to allay criticism among climate change skeptics after emails from climate scientists that appeared to cast doubt on their research were leaked to the public.
De Boer acknowledged the emails did serious damage, but said the review process by some 2,500 scientists of climate change research was thorough and credible.