According to an Economist article(Blowing in the Wind-12/15/09)it is often times difficult to verify the levels of greenhouse gases in the atmosphere.
"ONE of the many sets of initials being bandied about at the climate conference in Copenhagen is MRV—monitoring, reporting and verification. In theory, it seems fairly straightforward: if countries commit themselves to limiting the production of particular greenhouse gases, they need to be able to keep track of what they are doing and to tell the rest of the world, which must in turn be able to verify the claims. In practice, there are any number of problems, one of which is that when you start to look at what is actually happening in the atmosphere, it does not necessarily resemble anything that is being reported. Countries therefore commit themselves to actions without any real idea of the current state of play."
"Dr(Ray) Weiss (of Scripps Institute of Oceanography) and his colleagues excel at the precise measurement of gases present in vanishingly small amounts—things measured in parts per trillion, rather than the parts per million used for carbon dioxide.
There are a number of potent greenhouse gases produced and used by industry that are found in the atmosphere at this sort of level, and governments that are party to the United Nations’ Framework Convention on Climate Change, the document on which global climate politics are based, have to report on how much of some of them they emit, based on what they think their industries produce. Dr Weiss’s concern is that when he and his colleagues measure how much of any one of these gases has actually been added to the atmosphere in a given year, then compare that with the amount which the countries of the world own up to emitting, the two totals fail to tally. No prizes for guessing which is usually bigger."
"Dr Weiss’s late colleague at Scripps, Dave Keeling, had repeatedly to fight bureaucracy and budget cuts to keep making the accurate measurements of the atmosphere’s composition that constituted his life’s work. His perseverance gave the world great insight—and a new icon, the Keeling curve. This seasonally undulating record of carbon dioxide’s inexorable rise over the past 50 years goes a long way towards explaining why 190 countries have seen fit to gather now in Copenhagen. Things are better today, says Dr Weiss, than when Keeling fought his battles. But the seemingly simple matter of looking at which greenhouse gases are where, and in what quantities, still needs a lot more work."