"It's going to be unpopular with almost everyone," said Tasneem Essop, of WWF International, of the blueprint issued on the sidelines of 181-nation UN talks in Bonn about a UN pact to be agreed in December in Copenhagen.

"But we need more ambitious targets," she said of the draft, written by almost 50 leading environmentalists and with the backing of groups including WWF, Greenpeace, Germanwatch and the David Suzuki Foundation.

The suggested treaty would impose a peak on fast-rising world emissions of heat-trapping gases by about 2015 and then oblige cuts to limit a rise in temperatures to less than 2 Celsius (3.6 Fahrenheit) above pre-industrial times.

"Climate change is the most important issue facing the planet and its people today," the text begins. Curbs outlined in the 42-page draft are much tougher than those on offer at the June 1-12 meeting, by either rich and poor countries.

And it called on industrialized countries to raise at least $160 billion a year from 2013-2017, mainly via auctioning of carbon dioxide (CO2) emissions allowances, to help developing nations cope with climate change.

"It could be motivating to delegates to give them a vision," said Bill Hare of the Potsdam Institute for Climate Impact Research who worked for many years for Greenpeace. "There are quite heavy commitments required of the major emitters."

The text said the world should agree a "global carbon budget" -- the amount of greenhouse gases that can be emitted each year -- and cut global emissions back to 1990 levels by 2020 and to 80% below 1990 by 2050.

It also suggested creation of a "Copenhagen Climate Facility" to oversee everything from plans to curb emissions to preservation of forests that soak up greenhouse gases. It also called for a new authority to oversee carbon markets.

The proposal said that all rich nations should work out zero carbon action plans, or "z-caps" to cut emissions, relative to 1990 levels, by 40 percent by 2020 and by at least 95 percent by 2050. Developing nations' emissions should peak before 2020.

By contrast, US President Barack Obama's goals are less ambitious -- he wants to cut US emissions to 1990 levels by 2020 and by 80% below by 2050. US emissions were 14% above 1990 levels in 2007.

China and many developing nations have not set a peak year for emissions, mainly from burning fossil fuels that are blamed by a UN panel of scientists for stoking warming set to cause more heatwaves, droughts, floods and more powerful storms.

The proposals would also widen binding cuts in greenhouse gas emissions to newly industrialized countries -- such as Singapore, South Korea and Saudi Arabia. They are exempt from caps under the existing Kyoto Protocol.