UN chief Ban Ki-moon urged negotiators at climate talks in Doha on Tuesday to put aside their quarrels and act with urgency to find the money and agree on mechanisms to tackle the global warming "crisis".

After eight days of tough talks, negotiators from nearly 200 countries were joined by some 100 cabinet ministers and a handful of heads of state for the final, high-level stretch of the annual United Nations huddle.

Despite many late-night efforts, parties remain in disagreement over details of extending the life of the Kyoto Protocol on curbing Earth-warming greenhouse gas emissions, and funding Third World climate projects.

Climate change "is a crisis," said Ban, as a string of scientific reports warned the world could be headed for calamitous warming above the limit of two degrees Celsius (3.6 Fahrenheit) being targeted by the UN.

Warming poses "a threat to us all. Our economies. Our security. And the well-being of our children and those who will come after," said the secretary general.

Noting "mixed feelings" among delegates hammering out a deal, Ban urged the parties to "work with a spirit of compromise".

Poor countries insist that Western nations sign up to deeper, more urgent cuts in carbon emissions under a follow-up, second commitment period for the Kyoto Protocol.

They also want the developed world to commit to new funding package from 2013 to help them cope with worsening drought, flood, storms and rising seas.

Resolution of both questions by the meeting's end on Friday should smooth the way to a new, universal treaty that must be signed by 2015 and enter into force in 2020 to roll back global warming.

The UN goal to limit warming to two degrees Celsius is the level at which scientists hope we can escape the worst climate change effects.

But a string of recent reports say Earth may be headed for warming more than double this target.

Scientists have been warning in recent days that climate change was happening before our eyes, with polar ice caps melting and sea levels rising faster than we thought, at the same time as greenhouse gas concentrations in the atmosphere reached new highs.

The latest report, issued on Tuesday, said even an impossible zero-percent pollution target for the developed world by 2030 would not stop calamitous climate change, and poor nations too must do their part.

The know-how and technology existed to close the growing gap between countries' pledges for curbing emissions, and what is actually needed to limit warming to 2C, but, said Ban, political will was lacking.

"The gap can be bridged. But time is not on our side," he warned.

"It is an existential challenge for the whole human race -- our way of life, our plans for the future."

The Doha talks are meant to finalise a second commitment period of the Kyoto Protocol, the world's only binding pact on curbing greenhouse gas emissions, but delegates disagree on its timeframe and country targets.

The protocol's first round, which runs out on December 31, bound about 40 rich nations and the EU to curbing emissions but excludes the two biggest polluters -- the US, which refused to ratify it, and China which was left out because it is a developing country.

Another area of disagreement is money.

Developed nations are being asked to show how they intend to keep a promise to raise funding for poor nations' climate mitigation plans to $100 billion per year by 2020 -- up from a total $30 billion in 2010-2012.

The developing world says it needs a total of $60 billion from now to 2015.

Britain on Tuesday became the first country to pledge money, saying it would spend some 1.8 billion pounds (2.2 billion euros/$2.9 billion) on international climate finance by 2014/15 -- a move welcomed by climate activists.