New York - Major nations, including South Africa, the United States and China have thrown their weight behind the United Nations summit on climate change.
More than 100 Heads of State are expected to attend the summit to open in Copenhagen on 15 December.
In his message to UN Secretary General Ban Ki Moon on Tuesday, President Jacob Zuma said the world needs to act now to ensure there is a global agreement on the critical challenge.
"For Africa, the impact of climate change is devastating, and will severely undermine development and poverty eradication efforts. Climate change affects agricultural yields, and therefore food security," said Zuma.
The South African President said the global agreement on climate change should be guided by a shared vision. It should be inclusive, fair and effective.
"It affects people's access to water in an already water-stressed region. Rural people are compromised by the impact on ecosystems that support their livelihoods," he said.
These developments affect every aspect of society - social, economic and environmental.
Zuma, who is currently attending the UN General Assembly, said it must be recognised that solving the climate problem cannot be separated from the struggle to eradicate poverty.
"It must be based on sound science. It must strike a balance between adaptation and mitigation, and it must address the means of implementation.
"There needs to be agreement on new, additional, sustainable and predictable financing for adaptation. This should be for programmes that reduce the vulnerability of developing countries to the effects of climate change".
Zuma insisted that on mitigation, the agreement must contain ambitious, quantified, and legally binding emission reduction commitments by developed countries. "It must set the framework for mitigation actions by developing countries that are supported and enabled by finance and technology".
US President Barack Obama declared that the United States failure to address climate change could lead to an "irreversible catastrophe."
"It is true that for too many years, mankind has been slow to respond or even recognize the magnitude of the climate threat. It is true of my own country as well," Obama said. He said the United States government has placed climate change on the top of its diplomatic agenda.
Chinese President Hu Jintao said the international community should tackle global climate change through common development, calling for international joint work and pledging China's continued efforts on this issue.
"Global climate change has a profound impact on the existence and development of mankind and is a major challenge facing all countries," the president said, when addressing the UN climate change summit.
"Climate change is an environment issue, but also, and more importantly, a development issue.
"We should and can only advance efforts to address climate change in the course of development and meet the challenge through common development," Hu said.