This article is from the source 'bbc' and was first published or seen on . It last changed over 40 days ago and won't be checked again for changes.

You can find the current article at its original source at http://www.bbc.co.uk/news/science-environment-23032890

The article has changed 10 times. There is an RSS feed of changes available.

Version 2 Version 3
Obama to outline climate strategy Obama to limit power plant emissions
(35 minutes later)
US President Barack Obama is preparing to lay out a package of measures aimed at curbing climate change, including limits on emissions from power plants.US President Barack Obama is preparing to lay out a package of measures aimed at curbing climate change, including limits on emissions from power plants.
He will also unveil plans for an expansion of renewable energy projects, improved flood resilience and seeking an international climate deal.He will also unveil plans for an expansion of renewable energy projects, improved flood resilience and seeking an international climate deal.
The President will make a speech at Georgetown University on Tuesday.The President will make a speech at Georgetown University on Tuesday.
But he is considered unlikely to broach the issue of the controversial Keystone XL tar sands pipeline.But he is considered unlikely to broach the issue of the controversial Keystone XL tar sands pipeline.
And administration officials have previously rejected any prospect of a "carbon tax".And administration officials have previously rejected any prospect of a "carbon tax".
The announcements will give shape to the President's intentions - voiced in his inaugural address in January - to act on climate change in his second term. The speech will give shape to the President's intentions - voiced in his inaugural address in January - to act on climate change in his second term.
"While no single step can reverse the effects of climate change, we have a moral obligation to future generations to leave them a planet that is not polluted and damaged," the White House said in a statement."While no single step can reverse the effects of climate change, we have a moral obligation to future generations to leave them a planet that is not polluted and damaged," the White House said in a statement.
The statement further argued that climate change posed an immediate threat, with the 12 hottest years on record all occurring in the past 15 years.The statement further argued that climate change posed an immediate threat, with the 12 hottest years on record all occurring in the past 15 years.
Executive action
Most of the strategy involves using President Obama's executive authority without congressional approval.Most of the strategy involves using President Obama's executive authority without congressional approval.
Other parts of the plan could face opposition in the US House, which is dominated by Republicans, and in the Senate.Other parts of the plan could face opposition in the US House, which is dominated by Republicans, and in the Senate.
The President is expected to reaffirm his 2009 commitment to reducing greenhouse gas emissions by 17% below 2005 levels by the end of the decade.The President is expected to reaffirm his 2009 commitment to reducing greenhouse gas emissions by 17% below 2005 levels by the end of the decade.
The centrepiece of the plan is a memorandum to launch the first-ever limits on carbon emissions from existing power plants. These are the single biggest source of carbon pollution, accounting for a third of US greenhouse gas emissions and 40% of its carbon output.The centrepiece of the plan is a memorandum to launch the first-ever limits on carbon emissions from existing power plants. These are the single biggest source of carbon pollution, accounting for a third of US greenhouse gas emissions and 40% of its carbon output.
But it remains unclear how strict these limits will be.
Last year, the Environmental Protection Agency (EPA) proposed regulating emissions from new power plants, but the body has delayed that ruling.Last year, the Environmental Protection Agency (EPA) proposed regulating emissions from new power plants, but the body has delayed that ruling.
President Obama is also calling for an end to US support for public financing for new coal-fired plants abroad, officials said, but will exempt plants in the poorest nations if the cleanest technology available in those countries is being used.President Obama is also calling for an end to US support for public financing for new coal-fired plants abroad, officials said, but will exempt plants in the poorest nations if the cleanest technology available in those countries is being used.
Don Stewart, a spokesman for Senate Minority Leader Mitch McConnell said imposing carbon rules on power plants amounts to a national energy tax. But Don Stewart, a spokesman for Senate Minority Leader Mitch McConnell, said imposing carbon rules on power plants amounted to a national energy tax.
"Will the President explain the massive costs to American jobs? Will the president explain how low-income Americans would pay for their new, higher utility bills?" he told the AP news agency. "Will the President explain the massive costs to American jobs? Will the President explain how low-income Americans would pay for their new, higher utility bills?" he told the AP news agency.
Pipeline challenge
The President also plans an expansion of solar and wind energy projects on public lands, with the aim of generating enough electricity to power the equivalent of six million homes by 2020. He will also set higher goals for renewables installed at federal housing projects.The President also plans an expansion of solar and wind energy projects on public lands, with the aim of generating enough electricity to power the equivalent of six million homes by 2020. He will also set higher goals for renewables installed at federal housing projects.
He is also announcing $8bn in federal loan guarantees to spur investment in green technologies. In addition, he is announcing $8bn in federal loan guarantees to spur investment in green technologies.
But the $7bn, 1,700 mile Keystone XL pipeline, meant to bring heavy crude from the tar sands of Alberta in Canada to the refineries of Texas, is unlikely to get a mention. But the $7bn, 1,700-mile Keystone XL pipeline, meant to bring heavy crude from the tar sands of Alberta in Canada to the refineries of Texas, is unlikely to get a mention.
Backed by industry and labour unions, but staunchly opposed by green campaigners, it has turned into one of the biggest environmental challenges of the President's time in office.Backed by industry and labour unions, but staunchly opposed by green campaigners, it has turned into one of the biggest environmental challenges of the President's time in office.
The project is currently being reviewed by the US State Department, with a decision not likely to come before the Autumn.The project is currently being reviewed by the US State Department, with a decision not likely to come before the Autumn.
Paul.Rincon-INTERNET@bbc.co.uk and follow me on Twitter