Global carbon dioxide in atmosphere passes milestone level

Climate warming greenhouse gas reaches 400 parts per million for the first time in human history
Damian Carrington guardian.co.uk 10 May 13;

For the first time in human history, the concentration of climate-warming carbon dioxide in the atmosphere has passed the milestone level of 400 parts per million (ppm). The last time so much greenhouse gas was in the air was several million years ago, when the Arctic was ice-free, savannah spread across the Sahara desert and sea level was up to 40 metres higher than today.

These conditions are expected to return in time, with devastating consequences for civilisation, unless emissions of CO2 from the burning of coal, gas and oil are rapidly curtailed. But despite increasingly severe warnings from scientists and a major economic recession, global emissions have continued to soar unchecked.

"It is symbolic, a point to pause and think about where we have been and where we are going," said Professor Ralph Keeling, who oversees the measurements on a Hawaian volcano, which were begun by his father in 1958. "It's like turning 50: it's a wake up to what has been building up in front of us all along."

"The passing of this milestone is a significant reminder of the rapid rate at which – and the extent to which – we have increased the concentration of greenhouse gases in the atmosphere," said Prof Rajendra Pachauri, chair of the Intergovernmental Panel on Climate Change, which serves as science adviser to the world's governments. "At the beginning of industrialisation the concentration of CO2 was just 280ppm. We must hope that the world crossing this milestone will bring about awareness of the scientific reality of climate change and how human society should deal with the challenge."

The world's governments have agreed to keep the rise in global average temperature, which have already risen by over 1C, to 2C, the level beyond which catastrophic warming is thought to become unstoppable. But the International Energy Agency warned in 2012 that on current emissions trends the world will see 6C of warming, a level scientists warn would lead to chaos. With no slowing of emissions seen to date, there is already mounting pressure on the UN summit in Paris in 2015, which is the deadline set to settle a binding international treaty to curb emissions.

Edward Davey, the UK's energy and climate change secretary, said: "This isn't just a symbolic milestone, it's yet another piece of clear scientific evidence of the effect human activity is having on our planet. I've made clear I will not let up on efforts to secure the legally binding deal the world needs by 2015 to avoid the worst effects of climate change."

Two CO2 monitoring stations high on the Hawaiian volcano of Mauna Loa are run by the US National Oceanic and Atmospheric Administration and the Scripps Institution of Oceanography and provide the global benchmark measurement. Data released on Friday shows the daily average has passed 400ppm for the first time in its half century of recording. The level peaks in May each year as the CO2 released by decaying vegetation is taken up by renewed plant growth in the northern hemisphere, where the bulk of plants grow.

Analysis of fossil air trapped in ancient ice and other data indicate that this level has not been seen on Earth for 3-5 million years, a period called the Pliocene. At that time, global average temperatures were 3 or 4C higher than today's and 8C warmer at the poles. Reef corals suffered a major extinction while forests grew up to the northern edge of the Arctic Ocean, a region which is today bare tundra.

"I think it is likely that all these ecosystem changes could recur," said Richard Norris, a colleague of Keeling's at Scripps. The Earth's climate system takes time to adjust to the increased heat being trapped by high greenhouse levels and it may take hundreds of years for the great ice caps in Antarctica and Greenland to melt to the small size of the Pliocence and sea level far above many of the world's major cities.

But the extreme speed at which CO2 in now rising – perhaps 75 times faster than in pre-industrial time – has never been seen in geological records and some effects of climate change are already being seen, with extreme heatwaves and flooding now more likely. Recent wet and cold summer weather in Europe has been linked to changes in the high level jetstream winds, in turn linked to the rapidly melting sea ice in the Arctic, which shrank to its lowest recorded level in September.

"We are creating a prehistoric climate in which human societies will face huge and potentially catastrophic risks," said Bob Ward, policy director at the Grantham Research Institute on Climate Change at the London School of Economics. "Only by urgently reducing global emissions will we be able to avoid the full consequences of turning back the climate clock by 3 million years."

"The 400ppm threshold is a sobering milestone and should serve as a wake up call for all of us to support clean energy technology and reduce emissions of greenhouse gases, before it's too late for our children and grandchildren," said Tim Lueker, a carbon cycle scientist at Scripps.

Professor Bob Watson, former IPCC chair and UK government chief scientific adviser, said: "Passing 400ppm of carbon dioxide in the atmosphere is indeed a landmark and the rate of increase is faster than ever and shows no sign of abating due to a lack of political committment to address the urgent issue of climate change - the world is now most likely committed to an increase in surface temperature of 3C-5C compared to pre-industrial times."

The graph of the rising CO2 at Mauna Loa is known as the Keeling curve, after the late Dave Keeling, the scientist who began the measurements in March 1958. The isolated Hawaiian island is a good location for measurements as it is far from the main sources of CO2, meaning it represents a good global average.

Carbon dioxide passes symbolic mark
BBC News 10 May 13;

Carbon dioxide levels in the atmosphere have broken through a symbolic mark.

Daily measurements of CO2 at a US government agency lab on Hawaii have topped 400 parts per million for the first time.

The station, which sits on the Mauna Loa volcano, feeds its numbers into a continuous record of the concentration of the gas stretching back to 1958.

The last time CO2 was regularly above 400ppm was three to five million years ago - before modern humans existed.

Scientists say the climate back then was also considerably warmer than it is today.

Carbon dioxide is regarded as the most important of the manmade greenhouse gases blamed for raising the temperature on the planet over recent decades.

Human sources come principally from the burning of fossil fuels such as coal, oil and gas.

The usual trend seen at the volcano is for the CO2 concentration to rise in winter months and then to fall back as the northern hemisphere growing season kicks in. Forests and other vegetation pull some of the gas out of the atmosphere.

This means the number can be expected to decline by a few ppm below 400 in the coming weeks. But the long-term trend is upwards.

Carbon by proxy

James Butler is responsible for the Earth System Research Laboratory, a facility on Mauna Loa belonging to the National Oceanic and Atmospheric Administration (Noaa). Its daily average CO2 concentration figure on Thursday was 400.03.

Dr Butler told BBC News: "Carbon dioxide has some variability on an hourly, daily and weekly basis, so we are not comfortable calling a single number - the lowest we will go is on a daily average, which has happened in this case.

"Mauna Loa and the South Pole observatory are iconic sites as they have been taking CO2 measurements in real time since 1958. Last year, for the first time, all Arctic sites reached 400ppm.

"This is the first time the daily average has passed 400ppm at Mauna Loa."

The long-term measurements at Mauna Loa were started by a Scripps Institution of Oceanography scientist called Charles Keeling.

In 1958, he found the concentration at the top of the volcano to be around 315ppm (that is 315 molecules of CO2 for every one million molecules in the air). Every year since then, the "Keeling Curve", as it has become known, has squiggled resolutely higher.

Scripps still operates equipment alongside Noaa on the mountain peak.

Its readings have been pushing 400ppm in recent days, and on Thursday recorded a daily average of 399.73.

But Noaa senior scientist Pieter Tans said: "Our measurements (Noaa) are in Coordinated Universal Time, while the Keeling measurements are in local Hawaii time. If you shift the Keeling definition of a day to the same as ours then we do agree almost completely on the measurements." By this definition, the Keeling team's Thursday number would be 400.08ppm.

And Dr Butler added: "Probably next year, or the year after that, the average yearly reading will pass 400pm.

"A couple of years after that, the South Pole will have readings of 400ppm, and in eight to nine years we will probably have seen the last CO2 reading under 400ppm."

To determine CO2 levels before the introduction of modern stations, scientists must use so-called proxy measurements.

These include studying the bubbles of ancient air trapped in Antarctic ice.

One of these can be used to describe CO2 levels over the past 800,000 years. It suggests that CO2 held steady over this longer period at between 200ppm and 300ppm.

British atmospheric physicist Prof Joanna Haigh commented: "In itself, the value 400ppm of CO2 has no particular significance for the physics of the climate system: concentration levels have been in the 300s for so long and now we've passed the 400 mark. However, this does give us the chance to mark the ongoing increase in CO2 concentration and talk about why it's a problem for the climate."

Scientists call for action to tackle CO2 levels
BBC News 11 May 13;

Scientists are calling on world leaders to take action on climate change after carbon dioxide levels in the atmosphere broke through a symbolic threshold.

Daily CO2 readings at a US government agency lab on Hawaii have topped 400 parts per million for the first time.

Sir Brian Hoskins, the head of climate change at the UK-based Royal Society, said the figure should "jolt governments into action".

China and the US have made a commitment to co-operate on clean technology.

But BBC environment analyst Roger Harrabin said the EU was backing off the issue, and cheap fossil fuels looked attractive to industries.

The laboratory, which sits on the Mauna Loa volcano, feeds its numbers into a continuous record of the concentration of the gas stretching back to 1958.
'Sense of urgency'

Carbon dioxide is regarded as the most important of the manmade greenhouse gases blamed for raising the temperature on the planet over recent decades.

Human sources come principally from the burning of fossil fuels such as coal, oil and gas.

Ministers in the UK have claimed global leadership in reducing CO2 emissions and urged other nations to follow suit.

But the official Climate Change Committee (CCC) last month said that Britain's total contribution towards heating the climate had increased, because the UK is importing goods that produce CO2 in other countries.

The last time CO2 was regularly above 400ppm was three to five million years ago - before modern humans existed.

Scientists say the climate back then was also considerably warmer than it is today.

Professor Sir Brian Hoskins, director of the Grantham Institute for Climate Change at Imperial College London, said a greater sense of urgency about tackling climate change was needed.

"Before we started influencing the amount of carbon dioxide in the atmosphere, over the last million years it went between about 180 and 280 parts per million," he said.

"Now, since the Industrial Revolution and more in the last 50 years, we've taken that level up by more than 40% to a level of 400 and that hasn't been seen on this planet for probably four million years.

"But around the world, there are things happening, it's not all doom and gloom," he added.

"China is doing a lot. Its latest five year plan makes really great strides."

China's plan for 2011-2015 includes reversing the damage done by 30 years of growth and increasing the use of renewable energy.

Experts: CO2 record illustrates 'scary' trend
Seth Borenstein Associated Press Yahoo News 12 May 13;

WASHINGTON (AP) — The old saying that "what goes up must come down" doesn't apply to carbon dioxide pollution in the air, which just hit an unnerving milestone.

The chief greenhouse gas was measured Thursday at 400 parts per million in Hawaii, a monitoring site that sets the world's benchmark. It's a symbolic mark that scientists and environmentalists have been anticipating for years.

While this week's number has garnered all sorts of attention, it is just a daily reading in the month when the chief greenhouse gas peaks in the Northern Hemisphere. It will be lower the rest of the year. This year will probably average around 396 ppm. But not for long — the trend is going up and at faster and faster rates.

Within a decade the world will never see days — even in the cleanest of places on days in the fall when greenhouse gases are at their lowest — when the carbon measurement falls below 400 ppm, said James Butler, director of global monitoring at the National Oceanic and Atmospheric Administration's Earth Science Research Lab in Boulder, Colo.

"The 400 is a reminder that our emissions are not only continuing, but they're accelerating; that's a scary thing," Butler said Saturday. "We're stuck. We're going to keep going up."

Carbon dioxide stays in the air for a century, some of it into the thousands of years. And the world carbon dioxide pollution levels are accelerating yearly. Every second, the world's smokestacks and cars pump 2.4 million pounds of the heat-trapping gas into the air.

Carbon pollution levels that used to be normal for the 20th century are fast becoming history in the 21st century.

"It means we are essentially passing one in a whole series of points of no return," said Michael Mann, a climate scientist at Pennsylvania State University.

Princeton University climate scientist Michael Oppenheimer said the momentum in carbon dioxide emissions has the world heading toward and passing 450 ppm. That is the level which would essentially mean the world warms another 2 degrees, what scientists think of as dangerous, he said. That 2-degree mark is what much of the world's nations have set as a goal to prevent.

"The direction we've seen is for blowing through the best benchmark for what's dangerous change," Oppenheimer said.

And to see what the future is, scientists look to the past.

The last time the worldwide carbon level probably hit 400 ppm was about 2 million years ago, said Pieter Tans of the National Oceanic and Atmospheric Administration.

That was during the Pleistocene Era. "It was much warmer than it is today," Tans said. "There were forests in Greenland. Sea level was higher, between 10 and 20 meters (33 to 66 feet)."

Other scientists say it may have been 10 million years ago that Earth last encountered this much carbon dioxide in the atmosphere. The first modern humans only appeared in Africa about 200,000 years ago.

Environmental activists, such as former Vice President Al Gore, seized on the milestone.

"This number is a reminder that for the last 150 years — and especially over the last several decades — we have been recklessly polluting the protective sheath of atmosphere that surrounds the Earth and protects the conditions that have fostered the flourishing of our civilization," Gore said in a statement. "We are altering the composition of our atmosphere at an unprecedented rate."

Carbon dioxide traps heat just like in a greenhouse. It accounts for three-quarters of the planet's heat-trapping gases. There are others, such as methane, which has a shorter life span but traps heat more effectively. Both trigger temperatures to rise over time, scientists say, which is causing sea levels to rise and some weather patterns to change.

When measurements of carbon dioxide were first taken in 1958, it measured 315 ppm. Some scientists and environmental groups promote 350 ppm as a safe level for CO2, but scientists acknowledge they don't really know what levels would stop the effects of global warming.

The level of carbon dioxide in the air is rising faster than in the past decades, despite international efforts by developed nations to curb it. On average the amount is growing by about 2 ppm per year. That's 100 times faster than at the end of the Ice Age.

Back then, it took 7,000 years for carbon dioxide to reach 80 ppm, Tans said. Because of the burning of fossil fuels, such as oil and coal, carbon dioxide levels have gone up by that amount in just 55 years.

Before the Industrial Revolution, carbon dioxide levels were around 280 ppm, and they were closer to 200 during the Ice Age, which is when sea levels shrank and polar places went from green to icy. There are natural ups and downs of this greenhouse gas, which comes from volcanoes and decomposing plants and animals. But that's not what has driven current levels so high, Tans said. He said the amount should be even higher, but the world's oceans are absorbing quite a bit, keeping it out of the air.

"What we see today is 100 percent due to human activity," said Tans, a NOAA senior scientist. The burning of fossil fuels, such as coal for electricity and oil for gasoline, has caused the overwhelming bulk of the man-made increase in carbon in the air, scientists say.

The world sent 38.2 billion tons of carbon dioxide into the air in 2011, according international calculations published in a scientific journal in December. China spews 10 billion tons of carbon dioxide into the air per year, leading all countries, and its emissions are growing about 10 percent annually. The U.S. at No. 2 is slowly cutting emissions and is down to 5.9 billion tons per year.

The speed of the change is the big worry, said Pennsylvania State's Mann. If carbon dioxide levels go up 100 ppm over thousands or millions of years, plants and animals can adapt. But that can't be done at the speed it is now happening.

"We are a society that has inadvertently chosen the double-black diamond run without having learned to ski first," NASA climate scientist Gavin Schmidt said. "It will be a bumpy ride."

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Online:

NOAA monitoring at Mauna Loa: http://www.esrl.noaa.gov/gmd/ccgg/trends/weekly.html

Climate change 'will make hundreds of millions homeless'
Carbon dioxide levels indicate rise in temperatures that could lead agriculture to fail on entire continents
Robin McKie, The Observer 12 May 13;

It is increasingly likely that hundreds of millions of people will be displaced from their homelands in the near future as a result of global warming. That is the stark warning of economist and climate change expert Lord Stern following the news last week that concentrations of carbon dioxide in our atmosphere had reached a level of 400 parts per million (ppm).

Massive movements of people are likely to occur over the rest of the century because global temperatures are likely to rise to by up to 5C because carbon dioxide levels have risen unabated for 50 years, said Stern, who is head of the Grantham Research Institute on Climate Change.

"When temperatures rise to that level, we will have disrupted weather patterns and spreading deserts," he said. "Hundreds of millions of people will be forced to leave their homelands because their crops and animals will have died. The trouble will come when they try to migrate into new lands, however. That will bring them into armed conflict with people already living there. Nor will it be an occasional occurrence. It could become a permanent feature of life on Earth."

The news that atmospheric carbon dioxide levels have reached 400ppm has been seized on by experts because that level brings the world close to the point where it becomes inevitable that it will experience a catastrophic rise in temperatures. Scientists have warned for decades of the danger of allowing industrial outputs of carbon dioxide to rise unchecked.

Instead, these outputs have accelerated. In the 1960s, carbon dioxide levels rose at a rate of 0.7ppm a year. Today, they rise at 2.1ppm, as more nations become industrialised and increase outputs from their factories and power plants. The last time the Earth's atmosphere had 400ppm carbon dioxide, the Arctic was ice-free and sea levels were 40 metres higher.

The prospect of Earth returning to these climatic conditions is causing major alarm. As temperatures rise, deserts will spread and life-sustaining weather patterns such as the North Indian monsoon could be disrupted. Agriculture could fail on a continent-wide basis and hundreds of millions of people would be rendered homeless, triggering widespread conflict.

There are likely to be severe physical consequences for the planet. Rising temperatures will shrink polar ice caps – the Arctic's is now at its lowest since records began – and so reduce the amount of solar heat they reflect back into space. Similarly, thawing of the permafrost lands of Alaska, Canada and Russia could release even more greenhouse gases, including methane, and further intensify global warming.

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