The goal of keeping planet warming in check has moved further out of reach, the United Nations warned Wednesday in the latest of a flurry of reports pointing to looming climate disaster ahead of key talks in Qatar.

Current country pledges for cutting climate-altering greenhouse gas emissions could see global average temperatures rise by three to five degrees Celsius (5.4 to 9.0 degrees Fahrenheit) this century, said a UN Environment Programme (UNEP) report.

The targeted limit is an increase of two degrees Celsius on pre-industrial levels.

In the last four days, the World Meteorological Organisation reported a record increase of Earth-warming gases in the atmosphere, while the World Bank warned of the planet-wide devastation a rise of four degrees Celsius would cause.

UNEP said swift action could still see the world get back on track, but it would mean increasing pledges and slashing emissions by 14 percent to about 44 billion tonnes in 2020 from an estimated 50.1 billion tonnes per year now.

"The message is, yes indeed, one of great alarm and concern about where we are," said UNEP chief Achim Steiner.

Scientists say global temperatures have already risen by about 0.8 degrees Celsius on average.

The planet has witnessed record-breaking temperatures in the past decade and frequent natural disasters that some blame on climate change -- most recently superstorm Sandy, which ravaged Haiti and the US east coast.

Observers and climate negotiators preparing for UN talks that open in Doha next Monday view the UNEP report as a timely red flag.

"Time is running out," said UN climate chief Christiana Figueres, "but the technical means and the policy tools to allow the world to stay below a maximum two degrees Celsius are still available to governments and societies".

European climate commissioner Connie Hedegaard said the data showed "the world is not getting its act together fast enough".

"Despite the facts and evidence in front of us, there are still many interests advocating doing nothing... or just forgetting the climate crisis until we have solved the economic crisis."

More than 190 countries will meet for two weeks in Qatar seeking to draft a work programme leading to a new, global climate deal to be signed by 2015 and enter into force by 2020.

They will also seek to put in place a follow-up phase for the Kyoto Protocol which binds rich nations to greenhouse gas emission cuts but runs out on December 31.

UNEP said the concentration of warming gases like carbon dioxide (CO2) in the atmosphere had increased by about 20 percent since 2000, picking up after a slump during the economic downturn of 2008-9.

Barring swift action, emissions were likely to reach 58 gigatonnes in 2020.

"The sooner countries will do what they promised, the better the situation will be. But even if they do all the things they promised to do, it's still not enough if you want to stay on the path to the two degrees," UNEP expert John Christensen told AFP.

Wael Hmaidan, director of the NGO Climate Action Network, said the data "shows us how urgent it is for us to have a clear action plan agreed in Doha on the pre-2020 mitigation ambition".

The Union of Concerned Scientists' Alden Meyer for his part said: "Without much more aggressive action, we will lose the fight to keep temperature increases below two degrees and avert the worst impacts of climate change."

In a report on Sunday, the World Bank said a rise of four degrees Celsius could see devastating effects on food production and disease spread, with more heatwaves and floods and rising sea levels inundating coastal areas and small islands.

The UNEP said large emission cuts are possible, to the tune of some 17 billion tonnes, by greening sectors such as building construction, power generation and transport.

"We can still keep warming below dangerous levels," said Greenpeace climate policy adviser Kaisa Kosonen.