The summit was held on the margins of a UN General Assembly session
World leaders are trying to jump-start stalled negotiations toward a global climate pact at a climate change conference at the United Nations in New York.
Here are some of the key statements made by the world leaders.
UN SECRETARY-GENERAL BAN KI-MOON
Failure to reach broad agreement in Copenhagen would be morally inexcusable, economically short-sighted and politically unwise. We cannot go down this road.
I urge you to seal a deal in Copenhagen in December this year - an equitable, scientifically robust deal, that strengthens sustainable development and powers green growth for every country. The science demands it, the world economy needs it.
A successful deal must strengthen the world's ability to cope with inevitable changes. In particular, it must provide comprehensive support to the most vulnerable. They have contributed least to this crisis and are suffering first and worst.
US PRESIDENT BARACK OBAMA
The threat from climate change is serious, it is urgent, and it is growing... If we fail to meet it - boldly, swiftly and together - we risk consigning future generations to an irreversible catastrophe.
The security and stability of each nation and all peoples - our prosperity, our health, our safety - are in jeopardy. And the time we have to reverse this tide is running out.
For too many years, mankind has been slow to respond to or even recognise the magnitude of the climate threat. It is true of my own country as well.
But this is a new day. It is a new era. And I am proud to say that the United States has done more to promote clean energy and reduce carbon pollution in the last eight months than at any other time in our history.
CHINESE PRESIDENT HU JINTAO
At stake in the fight against climate change are the common interests of the entire world. Out of a sense of responsibility to its own people and people across the world, China fully appreciates the importance and urgency of addressing climate change.
First, we will intensify our effort to conserve energy and improve energy efficiency. We will endeavour to cut carbon dioxide emissions per unit of GDP by a notable margin by 2020 from the 2005 levels.
Second, we will vigorously develop renewable energy and nuclear energy. We will endeavour to increase the share of non-fossil fuels in primary energy consumption to around 15% by 2020.
Third, we will energetically increase forest carbon sink. We will endeavour to increase forest coverage by 40 million hectares and forest stock volume by 1.3 billion cubic metres by 2020 from the 2005 levels.
Fourth, we will step up our efforts to develop a green economy, a low carbon economy, and a circular economy and enhance research, development and dissemination of climate friendly technologies.
Developed countries should fulfil the task of emission reduction set in the Kyoto Protocol, continue to undertake substantial mid-term quantified emission reduction targets and support developing countries in countering climate change.
China stands ready to work with all countries to build an even better future for the generations to come.
JAPANESE PRIME MINISTER YUKIO HATOYAMA
For its mid-term goal, Japan will aim to reduce its emissions by 25% by 2020 compared to the 1990 level. Japan is prepared to provide more financial and technical assistance than in the past, in accordance with the progress of the international negotiations.
Public financial assistance and technology transfer to developing countries are critically important.
I will now seek to unite our efforts to address current and future climate change with due consideration of the role of science. I am resolved to exercise the political will required to deliver on this promise.
FRENCH PRESIDENT NICOLAS SARKOZY
We are on the path to failure if we continue to act as we have. Considering how complex this negotiation is, a new summit before Copenhagen is needed.
France proposes that the heads of state of the major economies responsible for 80% of emissions ... meet in mid-November. They will need to make clearer commitments to ensure Copenhagen's success.
THE MALVIDES PRESIDENT MOHAMED NASHEED
If things go on as business as usual, we will not live. We will die. Our country will not exist.
We cannot come out from Copenhagen as failures. We cannot make Copenhagen a pact for suicide.