ecoglobe reproduces the BBC's report, with some comments inserted at the most salient issues.
Climate change 'can be tackled'The growth in greenhouse gas emissions can be curbed at reasonable cost, experts at a major UN climate change conference in Bangkok have agreed. Boosting renewable energy, reducing deforestation and improving energy efficiency can all help, they said.
This is the third report this year from the Intergovernmental Panel on Climate Change (IPCC), and aims to set out the costs and benefits of various policies.
IPCC chair Rajendra Pachauri said the report was "stunning".
If we continue to do what we are doing now, we are in deep trouble Ogunlade Davidson, IPCC
"Human society as a whole has to look for changes in consumption patterns," he told reporters at a news conference in the Thai capital. New clauses added to the report at the last moment clarify the potential for nuclear power and lifestyle changes to cut emissions.
Greenhouse gas emissions have risen by 70% since 1970, and will rise by between 25% and 90% over the next 25 years under "business as usual", with fossil fuels set to continue as the world's dominant energy source.
Renewable energy generally has a positive impact on energy security, employment and air quality IPCC report
"If we continue to do what we are doing now, we are in deep trouble," observed Ogunlade Davidson, a senior author on the report. During the early part of the week, China had repeatedly tried to tone down some elements of the draft text, delegates said, being keen to remove references to scenarios which it feared could affect its short-term economic growth.
But in later sessions it played a more consensual hand.
The Intergovernmental Panel on Climate Change (IPCC) has already this year produced the two other elements of this global assessment report - its fourth since 1990 - dealing respectively with the science of climate change and on the potential impacts.
The report assesses the likely costs to the global economy of stabilising greenhouse gases at various concentrations in the atmosphere.
Stabilisation at reasonable cost is possible, it concludes, commenting: "There is considerable economic potential for the mitigation of global greenhouse gas emissions over the coming decades, that could offset the projected growth of global emisions or reduce emissions below current levels."
The sharpest cuts, keeping greenhouse gas concentrations to levels equivalent to between 445 and 535 parts per million of carbon dioxide, might cost anything up to 3% of global GDP by 2030, while milder curbs could even enhance growth.
COSTS OF STABILISATION
IPCC assesses the likely impacts on global GDP by 2030 if cost-effective routes are used stabilisation between 445ppm and 535ppm would cost less than 3% of global GDP, it concludes between 535ppm and 590ppm would cost 0.2-2.5% between 590ppm and 710ppm would bring anything between a net benefit of 0.6% and a net cost of 1.2% different greenhouse gases have different impacts on warming per volume; total concentrations are expressed as the equivalent in parts per million of a certain volume of CO2 (ppm CO2-eq) current concentration is about 425ppm CO2-eq
The current atmospheric concentrations are equivalent to about 425 parts per million of CO2. Assessing the impacts of a given concentration is not an exact science, but many scientists believe that keeping concentrations below about 450ppm CO2-eq is necessary if the average global temperature rise is to be kept below 2C, and major impacts avoided.
The IPCC suggests that concentrations between 445ppm and 490ppm would keep the temperature rise to 2.0-2.8C. European Union policy is to avoid a rise greater than 2C.
"If you want to stabilise around 450ppm, that means in a decade or two you have to start reducing emissions far below the current level," said Dr Pachauri.
"So in other words, we have a very short window for turning around the trend we have in rising greenhouse gas emissions. We don't have the luxury of time.
Many technologies can play a role in cutting emissions, the IPCC says, but singles out the building sector as a potential major contributer, and energy efficiency as something that "plays a key role across many scenarios for most regions and timescales".
But, observed Dr Pachauri, economic incentives are needed to drive any technological transformation.
"Technology alone will not be enough," he told BBC News, "and in any case, technology has a clear connection with government policy. "Incentives... must come from taxes or a carbon price."
Catherine Pearce, international climate campaigner with Friends of the Earth UK, said there was now no economic excuse for inaction.
"This report shows that many affordable technologies and effective policies are readily available to tackle climate change," she said.
"By introducing measures and investment that will stimulate sustainable renewable energies and energy efficiency, governments can help to achieve cuts in global emissions by 50% by 2050. Without this, we face devastating consequences."
Story from BBC NEWS: http://news.bbc.co.uk/go/pr/fr/-/2/hi/science/nature/6620909.stm Published: 2007/05/04 06:39:05 GMT © BBC MMVII
Copyright notice: This story is reproduced for reference purposes only.
Helmut Lubbers, 4 May 2007