The plan by G8 leaders is meaningless without a base year, scientists say [AFP] 

Scientists have criticised a pledge signed in Japan by the Group of Eight (G8) rich nations to halve global emissions of greenhouse gases by 2050, calling the plan insufficient to arrest climate change.

The G8 nations said on Tuesday that they want to work with nearly 200 states involved in UN climate change talks to adopt a goal to at least halve emissions by the middle of this century.

But critics of the pledge say the G8 statement did not mention a base by which any reduction in greenhouse gases could be measured, rendering the promise meaningless.

"They could have made progress here by being more specific on the near-term commitments that industrialised countries were willing to make to reduce their own emissions, but they don't have agreement on that," Alden Meyer, a spokesman for the Union of Concerned Scientists, said.

"They could have been more specific on reductions in 2050 by from what base year, but they don't have agreement on that."

No numerical target

Earlier, Yasuo Fukuda, the Japanese prime minister, hailed the agreement reached by the G8 leaders at the resort of Toyako.

The IPCC says rising levels of greenhouse gases are causing polar ice to recede [AFP]

Fukuda said the G8 nations had agreed to "aggressive" mid-term targets for reducing emissions.

But each nation can still set its own emissions targets to take into account the differences between major developed economies and developing economies.

George Bush, the US president, had said he will not back a numerical target until polluters such as China and India agree to binding commitments to curb their carbon pollution.

But China and India say it is up to the US to lead by example and commit to targets for change.

James Hansen, a scientist from Nasa's Goddard Institute for Space Studies in New York, said it is "a pretence that [industrialised nations] understand the problem."

"In reality, they are taking actions that guarantee that we deliver to our children climate catastrophes that are out of their control," he said.

Mid-term concerns

The G8 pledge also failed to commit to any emissions cuts in the next decade. Many scientists say it is during this period that details will emerge on whether the fight against climate change will suceed or not.

Rajendra Pachauri, chairman of the UN's panel of climate scientists, said "very vital details" were missing from the G8 statement, especially over plans for the medium term.

"The sooner we start reducing emissions, the greater the likelihood of avoiding some of the more serious impacts and temperature increases that are going to take place a decade or two down the road," he said.

Pachauri has said that substantial cuts must be made in the next decade [AFP]

Pachauri said G8 leaders had failed to refer to an agreement reached to work towards a new climate-change treaty to succeed the Kyoto Protocol, which expires in 2012.

"There is a serious omission in terms of not addressing the Bali action plan, which has called for deep cuts in emissions by 2020," Pachauri said.

"I think there should have been at least an endorsement, that the leaders of the G8 countries fully support actions to bring about those deep cuts," he said.

A recent assessment report by the IPCC says that the evidence says the Earth's climate is already changing for the worse, with human interference a major factor.

In the past century, the report said, the Earth's mean global temperature rose by 0.74 degrees Celsius over pre-industrial times.

Glaciers have eroded, alpine regions have lost snow and ice cover and permafrost has receded due to the increase in temperature, the IPCC says.

The IPCC has warned that global temperatures could increase by between 1.8 and  4.0 C by 2100, threatening drought, flooding, rising sea levels and intense storms.