Many scientist argue the only way to track emission is to measure the actual atmosphere. Photo: Bloomberg

Euan Nisbet, a University of London earth sciences professor who has travelled the world testing the air for greenhouse-gas pollution, makes his way to a rocky outcrop on the coast of Hong Kong Island. He takes out a pump connected to a thin tube and a plastic bag to capture traces of the wind.

“This is a good day for collecting samples,” he says. “There’s a good, strong breeze blowing in from the mainland. It’s the breath of China.”

Hooking up his air-sucking device, Nisbet says the world puts too much faith in government estimates of carbon dioxide, methane and other heat-trapping gases blamed for climate change. That’s because companies and countries base emissions calculations on the raw materials that go into a process; they don’t check the pollution coming out.

“It’s like going on a diet without weighing yourself,” says Ray Weiss, a geochemistry professor at the Scripps Institution of Oceanography, whose article with Nisbet in an issue of Science argues for measuring the atmosphere.

As the world turns to climate treaties and emissions-trading markets to tame global warming, scientists and regulators are clashing over how to measure pollution.

Companies use bottom-up calculations and report their emissions estimates based on inputs: how much coal a plant burns; how much oil a factory consumes; how much lime is added to cement. Countries tabulate these estimates and add nationwide figures: how many vehicles drive within their borders; how much waste people plow into landfills; even how many methane-belching sheep graze in pastures.

Nisbet, Weiss and dozens of researchers say this bottom-up approach doesn’t reveal what we really need to know – what’s happening in the air. They’re sounding an alarm that greenhouse gases measured in the atmosphere can be double what companies and nations estimate.

In the case of one heat-trapping gas called sulphur hexafluoride (SF6), countries report that output has plummeted since 1995 based on their counts. Scientists say measuring the air shows levels surged since at least 2000.

Getting the measurement right is crucial because SF6 traps 23 900 times more heat per molecule than carbon dioxide and lingers for up to 3 200 years, the US Environmental Protection Agency (EPA) says.

Making sure the numbers add up is important for a more immediate reason: they underpin the only international climate treaty that sets mandatory limits for greenhouse gases. That 192-country pact, known as the Kyoto Protocol, went into effect in 2005 and set emissions targets for 38 of the countries that signed on. Nations will gather in Cancun, Mexico, tomorrow for annual UN-led climate talks.

Today, $141 billion (R994bn) worth of credits that help countries meet their Kyoto goals change hands in global emissions markets. And business is booming in offsets, the right for countries and companies that pollute too much to claim credit for green projects elsewhere. All of these efforts rely on bottom-up calculations being accurate.

“We have to get the emissions numbers right early on,” says Shakeb Afsah, a former World Bank environmental economist who founded data-analysis company Performeks. “We’ve seen how the cumulative effect of small errors that accumulated in the financial markets have blown up as little cracks turned into fault lines.”

Traders and regulators say Europe’s carbon market, called the Emissions Trading System, and the UN’s offset market, called the Clean Development Mechanism, are making a real dent in greenhouse emissions. From $570 million a year in 2004, the global carbon market may surge to as much as $1.4 trillion worth of deals by the decade’s end.

Trade in carbon options contracts alone soared to almost $10.6bn last year. Traders looking to profit from options for EU credits or UN offsets accounted for more activity than buyers actually trying to meet Kyoto caps, the World Bank says.

“It is working,” says James Cameron, the vice chairman of Climate Change Capital, a London fund manager that has invested more than $1bn in carbon credits. “This system is only there to take tons of carbon out of the atmosphere; it has no other purpose,” says Cameron

Jean-Pascal van Ypersele, vice chairman of the Intergovernmental Panel on Climate Change, a UN-led network of scientists, says companies and countries use tried-and-true formulas to calculate emissions. Auditors and expert panels review and sign off on the numbers companies and countries report.

“Emissions from burning fossil fuels are quite easy to monitor and quantify because burning 1 kilogram of carbon is going to provide 3.7 kilograms of CO2; that’s the law of chemistry,” Van Ypersele says. “As long as you know how much carbon is present in the fossil fuel you burn, you automatically know the amount of CO2.”

If there are discrepancies between emissions reduction figures, it may be because countries that calculate them don’t all follow one set of rules, van Ypersele says.

The Kyoto Protocol requires just 38 countries of the 192 in the pact to submit emissions data using stringent guidelines. The US refused to ratify Kyoto. And fast-growing polluters such as China and India can use looser calculations that aren’t audited, the treaty’s terms say.

India, the second-biggest earner of UN offsets, claims more than 550 green project. The UN says these projects have eliminated the equivalent of 80 million tons of CO2 from the air. India isn’t required to verify those calculations:

Nobody takes a measurement device to a plant or assesses the air across polluted cities to say CO2 levels have come down.

Countries at global climate talks in Copenhagen last did not make any progress on setting universal standards, and the issue is likely to be a stumbling block at the UN Climate Change Conference in Cancun.

Matthias Jonas, a physicist at Austria’s International Institute for Applied Systems Analysis, has studied emissions numbers that do adhere to UN guidelines. He says he’s sceptical about the gains European countries are claiming. Estimates are riddled with inaccuracies, and the margins of error are too wide to be useful, Jonas says.

“All the emissions we’re accounting for so far under the Kyoto Protocol are based on what we think the atmosphere sees by standing on the ground,” Jonas says.

“Real verification would be with a measurement device sitting in the atmosphere and saying, yes, what you have estimated is true and we can confirm by measuring what the atmosphere has received.”

With billions of dollars riding on markets that are literally based on thin air, emissions trading has to be especially transparent, says Pieter Tans, Colorado-based senior scientist with the National Oceanic and Atmospheric Administration.

“As soon as emissions become worth a lot of money, I start losing faith in self-reported numbers regardless of who signs off on them,” he says. “We need something more objective – like checking what’s actually appearing in the atmosphere.

“If you’re selling oil, you’re actually transferring something tangible,” US Department of Energy staff scientist Gregg Marland says.

“If somebody lies, somebody loses,” he says. “In a CO2 transaction, you can lie and both win. We’re going to create a situation where both sides can win by cheating.”

One recent carbon study shows how far off estimates can be.

Afsah’s Performeks compared emissions calculated by the Netherlands Environmental Assessment Agency with those calculated by BP. Both collect energy data and supply it to the public. The difference between the two sets of estimates for 23 nations added up to more than what Russia, the world’s third-largest emitter, spewed from burning fossil fuels in 2008.

The gap shows how widely results can vary depending on how calculations are tweaked and what statistics go into the number crunching, Afsah says.

“When it comes down to it, these estimates are all guesses,” says John Bosch, who retired from the EPA last year after 38 years. Bosch’s team designed ways to estimate pollution from oil refineries and petrochemical plants. Bosch says he left to become a consultant because he was frustrated regulators didn’t require precise measurements.

“In the real world, there are huge motivations for everyone to low-ball emissions,” Bosch says. Regulators want to report progress, and polluters want to pay less for permits.

Nisbet, the professor sampling air in Hong Kong, has seen how testing the atmosphere can make a difference. His data on methane were used in an early study that found that methane from human activities in France, Germany and the U.K. in 2001 was 50 percent to 90 percent higher in the air than what the countries had reported to the UN.

“You don’t always get the same result,” Nisbet says. “But it’s what’s really there. It’s there because we can measure it.” – Bloomberg