An alliance of green groups on Monday unveiled their ideal for a new climate treaty, calling on rich nations to slash their carbon pollution by more than 40 percent by 2020 and by 95 percent by 2050.

Their envisioned "Copenhagen Climate Treaty" was released at the latest staging post in UN talks towards a real-life pact, designed to be completed in the Danish capital in December.

"Industrialised countries, as a group, should commit to an emissions pathway that includes targets for industrial greenhouse gases of at least 40 percent below 1990 levels by 2020," the 50-page text said.

Written by 50 climate experts working with non-governmental organisations (NGOs) such as Greenpeace and WWF International, the mock treaty challenges all 192 countries -- especially rich economies -- to set more ambitious goals for cutting CO2 output.

It also calls on rich nations to cough up at least 160 billion dollars (115 billion euros) per year from 2013 through 2017 to help poor countries to cut their own emissions and adapt to the warming already underway.

It says developing countries -- including major carbon polluters China and India -- should slow the growth of their CO2 emissions through national policies, but does not set any firm targets.

The goal of a 40-percent cut by rich nations goes far beyond what any advanced economy has offered.

The European Union has committed to a 20-percent reduction by 2020, deepened to 30 percent if others follow suit.

The United States, under President Barack Obama, has proposed a reduction of 14 percent by 2020, but uses a less ambitious benchmark year of 2005, which translates into a cut of around four percent compared with 1990.

It has also called prospects for a 40-percent cut by the US "unrealistic."

The greens' long-term target of a 95-percent cut by 2050 compares with a goal of 80 percent set by the EU and the United States.

Damien Demailly of WWF International said the NGOs' "treaty" was feasible and hoped it would speed up negotiations, with less than six months left on the clock.

"Every country will find things (in the text) they don't like but which are compensated by other things," he said.

The proposals are entirely within the existing format of talks and do not seek to "revolutionise" negotiations, he said.

More than 4,000 delegates are gathered in Bonn until June 12 to hammer out the parameters for a negotiation blueprint.

In its current state, the text on the table is little more than a compilation of positions, which vary widely on almost every key point.

There is no consensus among climate scientists about what is a safe level of warming, but many have urged policymakers to peg the rise to no more than two degrees Celsius (3.6 degrees Fahrenheit) above pre-industrial levels.

This would require cuts of between 25 and 40 percent by rich countries by 2020, but would also require a brake in the growth of emissions by the emerging giants, according the the UN's panel of climate scientists.