United Nations Secretary General Ban Ki-moon attends a press conference after the Climate Action Special Executive Session at the Commonwealth Heads of Government Meeting (CHOGM) in Mellieha, Malta, Nov. 27, 2015. [Xinhua/Jin Yu]

UN Secretary-General Ban Ki-moon said that he is "optimistic" about the success of the upcoming Paris conference on climate change.

"The principle of common but differentiated responsibilities should be respected," he said, and "enhanced global collaboration is the only way to address this global common challenge" of climate change.

In an exclusive written interview with Xinhua, the UN chief said "I am optimistic that we will have a meaningful, universal agreement in Paris."

The Paris conference, known as the 21st United Nations climate change conference (COP21) due to be held from Nov. 30 to Dec. 11 in the French capital, will strive to unite world leaders into finding solutions to cut greenhouse gases.

"I have been consulting with world leaders and they say they want an agreement, and that they will work with other governments to build political momentum for Paris," Ban said. "We are seeing greater support from CEOs, cities, and citizens around the world for an agreement, and we have seen countries demonstrate their desire to reach an agreement by submitting national climate plans in advance of Paris."

The Paris meeting is aimed at achieving, for the first time in over 20 years of UN negotiations, a binding and universal agreement on climate, from all the countries of the world.

The agreement, to be adopted at the Paris climate conference in December and implemented from 2020, is expected to take the form of a protocol, another legal instrument or "an agreed outcome with legal force", and will be applicable to all Parties.

As for the coming conference's significance for both developed states and developing countries, the secretary-general said, "I think we are at the point where everyone understands that we all have to do our part, to the extent of our resources and capacities."

"The principle of common but differentiated responsibilities should be respected," Ban said. "While developed countries need to lead, developing countries also need to take increasing responsibilities in line with their respective development levels and capacities."

"We will never reach the goal of limiting global temperature rise to less than 2 degrees Celsius without everyone's participation, contribution and cooperation," he said, adding that "Enhanced global collaboration is the only way to address this global common challenge."

Asked whether there is a mechanism to monitor the efforts to implement the upcoming Paris agreement, Ban said, "I certainly hope so."

"The agreement should have a credible and clear mechanism to measure, report and verify the progress of each country so we can build the trust and confidence that everyone is doing what they say they will do," he said.

"In the meantime, it also should be observed that the capacity of many developing countries is still limited and support should be provided to improve their capacity in this regard," he said.

"The United Nations is working to facilitate and support the process for parties to reach a successful outcome in Paris in many ways," he said.

In addition to convening the process under the United Nations Framework Convention on Climate Change (UNFCCC), the UN is at the forefront of assessing the science under the Intergovernmental Panel on Climate Change (IPCC), and in helping developing countries meet the challenges of climate change, he said.

For example, the UN Development Programme (UNDP) has helped many developing countries formulate their national climate plans -- the Intended Nationally Determined Contributions (INDCs) -- to the UNFCCC, he noted.

The World Meteorological Organization (WMO) has been working to bring weather information to countries and a number of agencies have been working to improve food security while reducing the carbon footprint of agriculture, he said.

Asked about the great challenge before the Paris conference, Ban said, "Trust and ambition -- recognizing that all countries have their own unique national circumstances, it will be necessary for the agreement to balance the interests of all with the need to take concrete action that will effectively respond to climate change."

"Also, ambition -- everyone has to recognize that it is in their best interest to increase the level of action going forward," he said.

Since taking office as the UN chief in 2007, Ban has been designating the issue of climate change as one of top priorities of his work.

"In my first year as secretary-general, I called climate change the defining issue of our time," he said. "While the world has many challenges to face, climate change is different in that it is a uniquely global problem that must be addressed by the global community."

"It has been a difficult undertaking, but I am proud of the fact that I have been part of a global effort to move action at all levels toward a sustainable future," he added.