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The world’s air has reached what scientists call a troubling new milestone for carbon dioxide, the main global warming pollutant.

Monitoring stations across the Arctic this spring are measuring more than 400 parts per million of the heat-trapping gas in the atmosphere. The number isn’t quite a surprise, because it’s been rising at an accelerating pace. Years ago, it passed the 350 ppm mark that many scientists say is the highest safe level for carbon dioxide. It now stands globally at 395.

So far, only the Arctic has reached that 400 level, but the rest of the world will follow soon.

“The fact that it’s 400 is significant,” said Jim Butler, global monitoring director at the National Oceanic and Atmospheric Administration’s Earth System Research Lab in Boulder, Colo. “It’s just a reminder to everybody that we haven’t fixed this and we’re still in trouble.”

Carbon dioxide is the chief greenhouse gas and stays in the atmosphere for 100 years. Some carbon dioxide is natural, mainly from decomposing dead plants and animals. Before the Industrial Age, levels were around 275 parts per million.

For more than 60 years, readings have been in the 300s, except in urban areas, where levels are skewed. 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.

It’s been at least 800,000 years — probably more — since Earth saw carbon dioxide levels in the 400s, Butler and other climate scientists said.

Until now.

Readings are coming in at 400 and higher all over the Arctic. They’ve been recorded in Alaska, Greenland, Norway, Iceland and even Mongolia. But levels change with the seasons and will drop a bit in the summer, when plants suck up carbon dioxide, NOAA scientists said.

So the yearly average for those northern stations likely will be lower and so will the global number.

Globally, the average carbon dioxide level is about 395 parts per million but will pass the 400 mark within a few years, scientists said.

The Arctic is the leading indicator in global warming, both in carbon dioxide in the air and effects, said Pieter Tans, a senior NOAA scientist.

“This is the first time the entire Arctic is that high,” he said.

Tans called reaching the 400 number “depressing,” and Butler said it was “a troubling milestone.”

“It’s an important threshold,” said Carnegie Institution ecologist Chris Field, a scientist who helps lead the Nobel Prize-winning Intergovernmental Panel on Climate Change. “It is an indication that we’re in a different world.”

Ronald Prinn, an atmospheric sciences professor at the Massachusetts Institute of Technology, said 400 is more a psychological milestone than a scientific one. We think in hundreds, and “we’re poking our heads above 400,” he said.

Tans said the readings show how much the Earth’s atmosphere and its climate are being affected by humans. Global carbon dioxide emissions from fossil fuels hit a record high of 34.8 billion tons in 2011, up 3.2 percent, the International Energy Agency announced last week.

The agency said it’s becoming unlikely that the world can achieve the European goal of limiting global warming to just 2 degrees based on increasing pollution and greenhouse gas levels.

“The news today, that some stations have measured concentrations above 400 ppm in the atmosphere, is further evidence that the world’s political leaders — with a few honorable exceptions — are failing catastrophically to address the climate crisis,” former Vice President Al Gore, the highest-profile campaigner against global warming, said in an email. “History will not understand or forgive them.”

But political dynamics in the United States mean there’s no possibility of significant restrictions on man-made greenhouse gases no matter what the levels are in the air, said Jerry Taylor, a senior fellow of the libertarian Cato Institute.

“These milestones are always worth noting,” said economist Myron Ebell at the conservative Competitive Enterprise Institute. “As carbon dioxide levels have continued to increase, global temperatures flattened out, contrary to the models” used by climate scientists and the United Nations.

He contends temperatures have not risen since 1998, which was unusually hot.

Temperature records contradict that claim. Both 2005 and 2010 were warmer than 1998, and the entire decade of 2000 to 2009 was the warmest on record, according to NOAA.

As climate negotiators wrap-up talks in Bonn, Germany, this week, a major point of contention is who needs to do what to slow global warming. Nations such as China and the United States have held back from making substantial emission reduction pledges in the past, as both nations waited for the other to act. But new research out of MIT shows the importance of all major nations taking part in global efforts to reduce emissions—and in particular, finds China's role to be crucial.

The report—titled "The Role of China in Mitigating Climate Change"—published in the journal Energy Economics, compares the impact of a stringent emissions reduction policy with and without China's participation. It finds that China's actions are "essential."

"As the largest greenhouse gas emitter in the world, without China, climate goals—like the 2 degrees Celsius target that most agree is necessary to prevent serious irreversible consequences—are out of reach," says Sergey Paltsev, the lead author of the study and the assistant director for economic research at MIT's Joint Program on the Science and Policy of Global Change.

Specifically, the study finds that with China's help the global community is able to limit warming to 2 degrees Celsius, relative to pre-industrial levels. But without China, we miss that mark by about 1 degree Celsius.

Not only will it be close to impossible to achieve the 2 degrees mark without China's participation, but emissions reductions will also be more expensive because substantial costs would shift to only some countries. That is why the researchers argue for a global economy-wide greenhouse gas tax that spreads the burden of responsibility.

But even in this best-case scenario, reducing emissions comes with a steep price tag. China could experience substantial GDP losses by the end of the century under the most stringent policy cases. These losses come from higher energy prices, which influence consumption and export dynamics.

"While strong reductions may turn out to be costly in China and may require some incentives from developed countries," Paltsev says, "that doesn't make China's actions any less important."

The researchers stress, however, that reaching that 2 degrees threshold with China's participation is only possible in the most optimistic case. And these days, there isn't much cause for optimism.

The researchers tested various levels of emission reduction plans—a global carbon tax of $10, $30 or $50. The various taxes would slow warming to 3.5, 2.4 and 2 degrees, respectively, by the end of the century, according to their analysis. With no global policy, the increase in warming is projected to be about 5.5 degrees Celsius.

These scenarios show that, "Even more modest and realistic goals require near universal participation of major greenhouse gas emitters," Paltsev says.

Top energy user today, climate leader tomorrow?

The importance of China's participation in a global climate treaty increases with each year, as the country's population, economy and energy use continue to grow rapidly.

From 2000 to 2010, China's energy use grew 130 percent. That's up from a growth of just 50 percent the previous decade. With a growing, wealthier population, China has become the world's largest energy consumer—and with it, the world's greatest source of greenhouse gas emissions.

China's share of global energy-related CO₂ emissions has increased in just eight years from 14 percent in 2000 to 22 percent in 2008. Eighty percent of those emissions came from coal, making China the consumer of about half the world's coal.

But China is on a path toward doing something about their rapidly escalating energy use and emissions. They've recently announced they will be testing a pilot cap-and-trade program in select major cities in 2013, and plan to make the program national by 2015.

John Reilly, the co-director of the Joint Program on Global Change, pointed out recently the irony behind the plan. While the United States created the idea of cap and trade, he says, "just as many of our best innovations are produced in China, they may beat us in implementing such a system ... we're really being left behind."

Paltsev agrees that the system would be "a very good start" for China, allowing the country to reach its goal of reducing carbon intensity by 40 percent relative to 2005, and increasing the share of non-fossil fuels by 15 percent by 2020. But, he says, "these actions are still not enough, making almost no substantial difference in reducing global emissions."

In fact, the change, taken by China alone, would only reduce global temperature by about 0.1 degree Celsius in 2020.

But Tim Yeo, who chairs the United Kingdom Parliament's energy committee, recently told The Financial Times that if China did impose a national cap and trade system, "It's game over for the rest of the world ... Everyone will have to do it, including the U.S."

Paltsev agrees. "While the system would only be a start for China, as the country would still have a long way to go in reducing emissions, it would likely influence other countries—like the U.S.—to follow. But time is really of the essence."


To learn more about the Joint Program on Global Change's work in China, visit the China Energy and Climate Project website at: http://globalchange.mit.edu/CECP/.

The dramatic decoupling of crude oil and natural gas prices in 2009 has created a riddle of profound importance to energy investors and company balance sheets, two Massachusetts Institute of Technology researchers conclude in a new study.

Traditionally, oil prices have been used to gauge the natural gas market; but new research shows that the future of what is currently a cheap fuel is really anyone's guess.

Natural gas prices neared the lowest they've been in about a decade this past winter, as utilities scrambled to take advantage of the fuel's low price tag and producers began to turn away from the low-profit fuel. According to new numbers from the U.S. Energy Information Administration, the proportion of natural gas used to generate electricity soared to almost 35 percent in February—the highest ever for that month—while production saw its biggest decline in a year. These factors have led some to believe prices will rise again, and soon. Not so fast, say researchers at MIT.

Their study, featured in the latest issue of The Energy Journal, compares oil and natural gas prices from the early 1990s to today, showing a relationship between the pricing of the two fuels. But the nature of that relationship is constantly changing and is subject to external pressures, making it extremely difficult—if not impossible—to predict the price of natural gas in the short or long term.

"The tie between gas and oil has been exaggerated," says John Parsons, the lead author of the study and executive director of MIT's Joint Program on the Science and Policy of Global Change and Center for Energy and Environmental Policy Research. "Parity will get re-established, but it might take a long time and it might be at a different level than you thought."

The research shows that, besides the price of oil, two forces heavily influence the gas market: long-term forces, like technological change, and short-term volatility due mostly to weather or seasonal changes. Both of these forces are currently at work, as prices per million British thermal units have fallen from $10 back in 2008 to $4 last fall to $2.40 today.

Parsons attributes a majority of the drop since last fall to weather, but points to new technology known as hydraulic fracturing—along with other factors such as the global recession—as the cause of the much larger drop in price over time. He says the price may recover from the short-term drop quickly—perhaps back to $4 in just a couple years—but price recovery from the effects of hydrofracking technology could take much longer.

"And so the danger is [that] we say that there's parity" between oil and gas prices, Parsons says, "and it gives people the impression that the parity establishes itself quickly and they discount the price signal and try to keep going with producing gas."

This is what happened when prices fell in the past: Producers were slow to take the price fall seriously because of the usual short-term volatility attributed to weather and seasonal changes.

How the gas market will shape up in the long term is anyone's guess, Parsons says, largely because untapped resources are a wild card. Right now, the U.S. has a very cheap resource that provides a short-term cushion of low-priced gas. If hydraulic fracturing turns out to have limited applications, gas prices probably won't stay low for very long. But if other parts of the world rich in natural gas choose to use hydraulic fracturing, natural gas could turn into a revolutionary fuel, he says.

That will "affect the price of gas and the price of oil and the pattern of electricity production globally," Parsons says. "But none of us know."

The researchers conclude that as much as oil and gas prices have been somewhat intertwined in the past, it is likely they will continue to affect each other. Future changes in gas-to-liquid technology, for example, would further strengthen the gas-oil relationship—likely driving oil prices down, gas prices up, and re-establishing some parity between the two.

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