Delegates from more than 150 countries are meeting in Vienna to discuss ways to widen and extend the United Nations Kyoto protocol on climate change.
The senior UN official on the issue says the talks will show how committed countries are to making progress.
The meeting is also seeking to mobilise public institutions and other bodies, as well as governments.
The Vienna talks are seen as a key step towards preparing for the UN climate summit, due in Bali in December.
The United Nations' senior climate change official Yvo de Boer says the talks in Vienna will give an indication as to whether countries are willing to move forward towards launching real negotiating on taking forward the Kyoto protocol after it expires in 2012. That decision is expected to take place in Bali at the end of the year.
This Vienna meeting is also due to discuss the new UN report looking at the financial aspects of climate change over the next 25 years.
The report says that by 2030 additional investments of around $200bn a year will be needed to hold greenhouse gas emissions to the current level. Meanwhile a number of developing countries are concerned at the slow pace of progress.
Lesotho's Minister of Natural Resources Monyane Moleleki said the number of droughts in his country had increased significantly since 1978 and that summers were getting progressively warmer.
(BBC News, 27/08/2007)