Scientists more convinced mankind is main cause of warming

1 of 3. Intergovernmental Panel on Climate Change (IPCC) Chairman Rajendra Pachauri (L) comments on the U.N. IPCC Climate Report presentation during a news conference in Stockholm, September 27, 2013.

Credit: Reuters/Jessica Gow/TT News Agency

By Alister Doyle and Simon Johnson

STOCKHOLM | Fri Sep 27, 2013 8:51pm EDT

STOCKHOLM (Reuters) - Leading climate scientists said on Friday they were more convinced than ever that humans are the main culprits for global warming, and predicted the impact from greenhouse gas emissions could linger for centuries.

The Intergovernmental Panel on Climate Change (IPCC) said in a report that a hiatus in warming this century, when temperatures have risen more slowly despite growing emissions, was a natural variation that would not last.

It said the Earth was set for more heatwaves, floods, droughts and rising sea levels from melting ice sheets that could swamp coasts and low-lying islands as greenhouse gases built up in the atmosphere.

The study, meant to guide governments in shifting towards greener energies, said it was "extremely likely", with a probability of at least 95 percent, that human activities were the dominant cause of warming since the mid-20th century.

That was an increase from "very likely", or 90 percent, in the last report in 2007 and "likely", 66 percent, in 2001.

U.N. Secretary-General Ban Ki-moon said the study was a call for governments, many of which have been focused on spurring weak economies rather than fighting climate change, to work to reach a planned U.N. accord in 2015 to combat global warming.

"The heat is on. Now we must act," he said of the report agreed in Stockholm after a week of talks between scientists and delegates from more than 110 nations.

U.S. Secretary of State John Kerry said the report was a wake-up call. "Those who deny the science or choose excuses over action are playing with fire," he said, referring to skeptics who question the need for urgent action.

They have become emboldened by the fact that temperatures rose more slowly over the last 15 years despite increasing greenhouse gas emissions, especially in emerging nations led by China. Almost all climate models failed to predict the slowing.

"LOOKING FOR THE CURE"

European Climate Commissioner Connie Hedegaard said it was time to treat the Earth's health. "If your doctor was 95 percent sure you had a serious disease, you would immediately start looking for the cure," she said.

Compiled from the work of hundreds of scientists, the report faces extra scrutiny this year after its 2007 edition included an error that exaggerated the rate of melting of Himalayan glaciers. An outside review later found that the mistake did not affect its main conclusions.

The IPCC said some effects of warming would last far beyond current lifetimes.

Sea levels could rise by 3 meters (9 feet, 10 inches) under some scenarios by 2300 as ice melted and heat made water in the deep oceans expand, it said. About 15 to 40 percent of emitted carbon dioxide would stay in the atmosphere for more than 1,000 years.

"As a result of our past, present and expected future emissions of carbon dioxide, we are committed to climate change and effects will persist for many centuries even if emissions of carbon dioxide stop," said Thomas Stocker, co-chair of the talks.

The IPCC said humanity had emitted about 530 billion tons of carbon, more than half the 1 trillion ton budget it estimated as a maximum to keep warming to manageable limits. Annual emissions are now almost 10 billion tons and rising.

Explaining a recent slower pace of warming, the report said the past 15-year period was skewed by the fact that 1998 was an extremely warm year with an El Nino event - a warming of the ocean surface - in the Pacific.

It said warming had slowed "in roughly equal measure" because of random variations in the climate and the impact of factors such as volcanic eruptions, when ash dims sunshine, and a cyclical decline in the sun's output.

Rajendra Pachauri, chair of the IPCC, told Reuters the reduction in warming would have to last far longer - "three or four decades" - to be a sign of a new trend.

And the report predicted that the reduction in warming would not last, saying temperatures from 2016-35 were likely to be 0.3-0.7 degree Celsius (0.5 to 1.3 Fahrenheit) warmer than in 1986-2005.

Still, the report said the climate was slightly less sensitive than estimated to warming from carbon dioxide.

A doubling of carbon in the atmosphere would raise temperatures by between 1.5 and 4.5 degrees Celsius (2.7 to 8.1F), it said, below the 2-4.5 (3.6-8.1F) range in the 2007 report. The new range is identical to the ranges in IPCC studies before 2007.

The report said temperatures were likely to rise by between 0.3 and 4.8 degrees Celsius (0.5 to 8.6 Fahrenheit) by the late 21st century. The low end of the range would only be achieved if governments sharply cut greenhouse gas emissions.

And it said world sea levels could rise by between 26 and 82 cm (10 to 32 inches) by the late 21st century, in a threat to coastal cities from Shanghai to San Francisco.

That range is above the 18-59 cm estimated in 2007, which did not take full account of Antarctica and Greenland.

Bjorn Lomborg, author of "The Skeptical Environmentalist" said "the IPCC's moderate projections clearly contradict alarmist rhetoric" of higher temperature and sea level rises by some activists.

(Additional reporting by Nina Chestney in London, Barbara Lewis in Brussels, Valerie Volcovici in Washington; editing by Alistair Scrutton and Mark Trevelyan)

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U.N. panel to blame mankind for global warming, explain 'hiatus'

1 of 14. A truck engine is tested for pollution exiting its exhaust pipe as California Air Resources field representatives (unseen) work a checkpoint set up to inspect heavy-duty trucks traveling near the Mexican-U.S. border in Otay Mesa, California September 10, 2013.

Credit: Reuters/Mike Blake

By Anna Ringstrom

STOCKHOLM | Mon Sep 23, 2013 8:52am EDT

STOCKHOLM (Reuters) - A United Nations panel of experts met on Monday to review a draft report that raises the probability that climate change is man-made to 95 percent and warns of ever more extreme weather unless governments take strong action.

Scientists and officials from more than 110 governments began a four-day meeting in Stockholm to edit and approve the 31-page draft that also tries to explain a "hiatus" in the pace of global warming this century despite rising greenhouse gas emissions.

The Intergovernmental Panel on Climate Change (IPCC) will go through the document line by line and present it on Friday as a main guide for governments, which have agreed to work out a United Nations deal by the end of 2015 to fight global warming.

"I expect the world will understand the simplicity and the gravity of the message that we provide," Rajendra Pachauri, chairman of the IPCC, said after the opening session.

Climate change "will transform our lives, our economies and indeed the way our planet will function in the future," Achim Steiner, head of the U.N. Environment Programme, told delegates.

A shift towards a greener economy, based on renewable energies, would hold multiple benefits for society, he said.

IPCC drafts seen by Reuters say human activities, primarily burning fossil fuels, are "extremely likely" - at least a 95 percent probability - to be the main cause of global warming since the 1950s.

That is up from "very likely", or at least a 90 percent probability, in the last report in 2007 and 66 percent in 2001, draining hopes that natural variations in the climate might be the cause.

SEA LEVEL RISE

"There is high confidence that this has warmed the ocean, melted snow and ice, raised global mean sea level, and changed some climate extremes," the draft says of man-made warming.

Most impacts are projected to get worse unless governments cut greenhouse gas emissions sharply, it says. The report, by 259 authors in 39 countries, is the first of four due in the next year about climate change by the IPCC.

One of the hardest issues for the IPCC may be accounting for why temperatures have not risen much this century. "Fifteen-year-long hiatus periods are common," in historical climate records, an accompanying 127-page technical summary says.

A combination of natural variations, including a cyclical dip in energy emitted by the sun, and factors such as volcanic eruptions - which send ash into the atmosphere and help block sunlight - have caused the hiatus, it says, predicting a resumption of warming in coming years.

The report also finds that the atmosphere may be slightly less sensitive to a build-up of carbon dioxide than expected.

Thomas Stocker, a scientist from the University of Bern who is co-chair of the U.N. panel, urged delegates to produce a clear document "with no compromises to scientific accuracy."

The draft says temperatures could rise by up to 4.8 degrees Celsius (8.6 Fahrenheit) this century, but could be held to a rise of 0.3C (0.5F) with deep cuts in greenhouse gas emissions. Governments have promised to limit a rise in temperatures to 2 degrees C (3.6 F) above pre-industrial times.

The range differs from scenarios of 1.1 to 6.4C gains by 2100 in 2007, largely because of new computer models.

The draft also says sea levels, which rose 19 cm (7.5 inches) in the 20th century, could rise by an extra 26 to 81 cm towards the end of this century, threatening coasts.

That rise is more than was projected in 2007, although that report did not take full account of melting ice in Greenland and Antarctica.

The report is the main guide for governments planning action against global warming and steps to mitigate its effects. It will face extra scrutiny after the 2007 report exaggerated the rate of melt of the Himalayan glaciers. A review of the IPCC said that the main conclusions were unaffected by the error.

Environmentalists called for quick action. Greenpeace said governments should heed the report and shift to clean energies. The WWF's Samantha Smith said: "The natural world is sending a distress signal and we're ignoring it at our own peril."

(Writing by Alister Doyle; Editing by Janet Lawrence)

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Scientists more convinced mankind is main cause of warming

1 of 3. Intergovernmental Panel on Climate Change (IPCC) Chairman Rajendra Pachauri (L) comments on the U.N. IPCC Climate Report presentation during a news conference in Stockholm, September 27, 2013.

Credit: Reuters/Jessica Gow/TT News Agency

By Alister Doyle and Simon Johnson

STOCKHOLM | Fri Sep 27, 2013 1:20pm EDT

STOCKHOLM (Reuters) - Leading climate scientists said on Friday they were more convinced than ever that humans are the main culprits for global warming, and predicted the impact from greenhouse gas emissions could linger for centuries.

The Intergovernmental Panel on Climate Change (IPCC) said in a report that a hiatus in warming this century, when temperatures have risen more slowly despite growing emissions, was a natural variation that would not last.

It said the Earth was set for more heatwaves, floods, droughts and rising sea levels from melting ice sheets that could swamp coasts and low-lying islands as greenhouse gases built up in the atmosphere.

The study, meant to guide governments in shifting towards greener energies, said it was "extremely likely", with a probability of at least 95 percent, that human activities were the dominant cause of warming since the mid-20th century.

That was an increase from "very likely", or 90 percent, in the last report in 2007 and "likely", 66 percent, in 2001.

U.N. Secretary-General Ban Ki-moon said the study was a call for governments, many of which have been focused on spurring weak economies rather than fighting climate change, to work to reach a planned U.N. accord in 2015 to combat global warming.

"The heat is on. Now we must act," he said of the report agreed in Stockholm after a week of talks between scientists and delegates from more than 110 nations.

U.S. Secretary of State John Kerry said the report was a wake-up call. "Those who deny the science or choose excuses over action are playing with fire," he said, referring to skeptics who question the need for urgent action.

They have become emboldened by the fact that temperatures rose more slowly over the last 15 years despite increasing greenhouse gas emissions, especially in emerging nations led by China. Almost all climate models failed to predict the slowing.

"LOOKING FOR THE CURE"

European Climate Commissioner Connie Hedegaard said it was time to treat the Earth's health. "If your doctor was 95 percent sure you had a serious disease, you would immediately start looking for the cure," she said.

Compiled from the work of hundreds of scientists, the report faces extra scrutiny this year after its 2007 edition included an error that exaggerated the rate of melting of Himalayan glaciers. An outside review later found that the mistake did not affect its main conclusions.

The IPCC said some effects of warming would last far beyond current lifetimes.

Sea levels could rise by 3 meters (9 feet, 10 inches) under some scenarios by 2300 as ice melted and heat made water in the deep oceans expand, it said. About 15 to 40 percent of emitted carbon dioxide would stay in the atmosphere for more than 1,000 years.

"As a result of our past, present and expected future emissions of carbon dioxide, we are committed to climate change and effects will persist for many centuries even if emissions of carbon dioxide stop," said Thomas Stocker, co-chair of the talks.

The IPCC said humanity had emitted about 530 billion tons of carbon, more than half the 1 trillion ton budget it estimated as a maximum to keep warming to manageable limits. Annual emissions are now almost 10 billion tons and rising.

Explaining a recent slower pace of warming, the report said the past 15-year period was skewed by the fact that 1998 was an extremely warm year with an El Nino event - a warming of the ocean surface - in the Pacific.

It said warming had slowed "in roughly equal measure" because of random variations in the climate and the impact of factors such as volcanic eruptions, when ash dims sunshine, and a cyclical decline in the sun's output.

Rajendra Pachauri, chair of the IPCC, told Reuters the reduction in warming would have to last far longer - "three or four decades" - to be a sign of a new trend.

And the report predicted that the reduction in warming would not last, saying temperatures from 2016-35 were likely to be 0.3-0.7 degree Celsius (0.5 to 1.3 Fahrenheit) warmer than in 1986-2005.

Still, the report said the climate was slightly less sensitive than estimated to warming from carbon dioxide.

A doubling of carbon in the atmosphere would raise temperatures by between 1.5 and 4.5 degrees Celsius (2.7 to 8.1F), it said, below the 2-4.5 (3.6-8.1F) range in the 2007 report. The new range is identical to the ranges in IPCC studies before 2007.

The report said temperatures were likely to rise by between 0.3 and 4.8 degrees Celsius (0.5 to 8.6 Fahrenheit) by the late 21st century. The low end of the range would only be achieved if governments sharply cut greenhouse gas emissions.

And it said world sea levels could rise by between 26 and 82 cm (10 to 32 inches) by the late 21st century, in a threat to coastal cities from Shanghai to San Francisco.

That range is above the 18-59 cm estimated in 2007, which did not take full account of Antarctica and Greenland.

Bjorn Lomborg, author of "The Skeptical Environmentalist" said "the IPCC's moderate projections clearly contradict alarmist rhetoric" of higher temperature and sea level rises by some activists.

(Additional reporting by Nina Chestney in London, Barbara Lewis in Brussels, Valerie Volcovici in Washington; editing by Alistair Scrutton and Mark Trevelyan)

View the original article here

Scientists more convinced mankind is main cause of warming

1 of 3. Intergovernmental Panel on Climate Change (IPCC) Chairman Rajendra Pachauri (L) comments on the U.N. IPCC Climate Report presentation during a news conference in Stockholm, September 27, 2013.

Credit: Reuters/Jessica Gow/TT News Agency

By Alister Doyle and Simon Johnson

STOCKHOLM | Fri Sep 27, 2013 1:20pm EDT

STOCKHOLM (Reuters) - Leading climate scientists said on Friday they were more convinced than ever that humans are the main culprits for global warming, and predicted the impact from greenhouse gas emissions could linger for centuries.

The Intergovernmental Panel on Climate Change (IPCC) said in a report that a hiatus in warming this century, when temperatures have risen more slowly despite growing emissions, was a natural variation that would not last.

It said the Earth was set for more heatwaves, floods, droughts and rising sea levels from melting ice sheets that could swamp coasts and low-lying islands as greenhouse gases built up in the atmosphere.

The study, meant to guide governments in shifting towards greener energies, said it was "extremely likely", with a probability of at least 95 percent, that human activities were the dominant cause of warming since the mid-20th century.

That was an increase from "very likely", or 90 percent, in the last report in 2007 and "likely", 66 percent, in 2001.

U.N. Secretary-General Ban Ki-moon said the study was a call for governments, many of which have been focused on spurring weak economies rather than fighting climate change, to work to reach a planned U.N. accord in 2015 to combat global warming.

"The heat is on. Now we must act," he said of the report agreed in Stockholm after a week of talks between scientists and delegates from more than 110 nations.

U.S. Secretary of State John Kerry said the report was a wake-up call. "Those who deny the science or choose excuses over action are playing with fire," he said, referring to skeptics who question the need for urgent action.

They have become emboldened by the fact that temperatures rose more slowly over the last 15 years despite increasing greenhouse gas emissions, especially in emerging nations led by China. Almost all climate models failed to predict the slowing.

"LOOKING FOR THE CURE"

European Climate Commissioner Connie Hedegaard said it was time to treat the Earth's health. "If your doctor was 95 percent sure you had a serious disease, you would immediately start looking for the cure," she said.

Compiled from the work of hundreds of scientists, the report faces extra scrutiny this year after its 2007 edition included an error that exaggerated the rate of melting of Himalayan glaciers. An outside review later found that the mistake did not affect its main conclusions.

The IPCC said some effects of warming would last far beyond current lifetimes.

Sea levels could rise by 3 meters (9 feet, 10 inches) under some scenarios by 2300 as ice melted and heat made water in the deep oceans expand, it said. About 15 to 40 percent of emitted carbon dioxide would stay in the atmosphere for more than 1,000 years.

"As a result of our past, present and expected future emissions of carbon dioxide, we are committed to climate change and effects will persist for many centuries even if emissions of carbon dioxide stop," said Thomas Stocker, co-chair of the talks.

The IPCC said humanity had emitted about 530 billion tons of carbon, more than half the 1 trillion ton budget it estimated as a maximum to keep warming to manageable limits. Annual emissions are now almost 10 billion tons and rising.

Explaining a recent slower pace of warming, the report said the past 15-year period was skewed by the fact that 1998 was an extremely warm year with an El Nino event - a warming of the ocean surface - in the Pacific.

It said warming had slowed "in roughly equal measure" because of random variations in the climate and the impact of factors such as volcanic eruptions, when ash dims sunshine, and a cyclical decline in the sun's output.

Rajendra Pachauri, chair of the IPCC, told Reuters the reduction in warming would have to last far longer - "three or four decades" - to be a sign of a new trend.

And the report predicted that the reduction in warming would not last, saying temperatures from 2016-35 were likely to be 0.3-0.7 degree Celsius (0.5 to 1.3 Fahrenheit) warmer than in 1986-2005.

Still, the report said the climate was slightly less sensitive than estimated to warming from carbon dioxide.

A doubling of carbon in the atmosphere would raise temperatures by between 1.5 and 4.5 degrees Celsius (2.7 to 8.1F), it said, below the 2-4.5 (3.6-8.1F) range in the 2007 report. The new range is identical to the ranges in IPCC studies before 2007.

The report said temperatures were likely to rise by between 0.3 and 4.8 degrees Celsius (0.5 to 8.6 Fahrenheit) by the late 21st century. The low end of the range would only be achieved if governments sharply cut greenhouse gas emissions.

And it said world sea levels could rise by between 26 and 82 cm (10 to 32 inches) by the late 21st century, in a threat to coastal cities from Shanghai to San Francisco.

That range is above the 18-59 cm estimated in 2007, which did not take full account of Antarctica and Greenland.

Bjorn Lomborg, author of "The Skeptical Environmentalist" said "the IPCC's moderate projections clearly contradict alarmist rhetoric" of higher temperature and sea level rises by some activists.

(Additional reporting by Nina Chestney in London, Barbara Lewis in Brussels, Valerie Volcovici in Washington; editing by Alistair Scrutton and Mark Trevelyan)

View the original article here