By Richard Black
Environment correspondent, BBC News website, Nairobi
Ministers are holding last-minute discussions on several issues as UN climate talks enter their final day.
Some climate change issues remain unresolved after two weeks of talks
After nearly two weeks of talks, at least three outstanding areas of disagreement remain - among them plans for a review of the Kyoto Protocol.
The meeting in Nairobi will not result in firm targets for reducing greenhouse gas emissions.
But a group of provinces and states will announce a new collaboration aimed at constraining emissions on Friday.
The main issue of contention as the talks enter their final day is a review of the Kyoto Protocol.
The protocol states that it should be reviewed at this stage, with many of its measures open to discussion.
A number of developing countries view this with suspicion, believing that it may open the door to demands that they consider binding cuts in emissions, possibly impacting on economic development.
They are asking for a minimal review, whereas the European Union - with the support of a number of other nations - wants a root and branch examination not only of emission targets but other components such as the Clean Development Mechanism (CDM), a device for bringing money from Western countries to developing nations for clean development projects.
"I think that we needed to get better outcomes on a review," Australia's environment minister Ian Campbell told the BBC.
"I do hope we can achieve that in the next 24 hours - but on the bright side, you've got all of the countries in the world talking openly, trying to address the problem, putting a lot of effort in."
Another issue of disagreement is thought to concern the CDM itself, and whether carbon capture and storage (CCS) projects should be eligible for funds.
Ministers will discuss plans for new climate change technologies
CCS is viewed by many as an immature technology which is, in any case, better suited to Western nations.
A third area of contention is a Russian proposal to allow countries to join the Kyoto Protocol, or elements of it, on a voluntary basis.
Informal talks are expected to go into the small hours of the morning, with some convening again early on Friday.
On Friday, a group of states, provinces and local authorities will announce a voluntary collaboration aimed at reducing greenhouse gas emissions.
Farmers in southern Australia are suffering in an exceptional drought
The group, coordinated by the Climate Group, a UK organisation, includes such diverse regions as Scotland, California, Quebec and South Australia.
"Often the governments of states have a lot of power to regulate emissions, but they're not included in national negotiations," said Climate Group CEO Steve Howard.
"They may regulate electricity supply or energy efficiency standards.
"Some of them, like California, have enacted strict legislation on cutting emissions, while others, such as South Australia, with its exceptional drought, are experiencing severe weather conditions which is making them very aware of climate impacts."
Fifteen states are involved in the first phase, but Mr Howard anticipates membership growing quickly.
Carbon trading and exchanging best practice are two of the project's aims.
The UN talks are due to conclude late on Friday but may run on to early Saturday morning.