If this person were in a larger enclosed space with several buses running, it might take a few months, but eventually death is equally certain.
Now take 6 billion people on Earth with 200 million cars, 5,000 aircraft and 2,000 coal-fired power plants running 24/7 in a 30 mile deep atmosphere and of course it will take years, but as surely as in the garage, at some point large numbers of people will die.
Not one molecule of CO2 can escape our environment and we have no garage door to open.
If climate disasters are to be averted, atmospheric carbon dioxide (CO2) must be reduced below the levels that already exist today… PhysOrg.com
Carbon dioxide content in fresh air varies between 0.03% (300 ppm) and 0.06% (600 ppm), depending on the location. Concentrations higher than 1,000 ppm will cause discomfort in more than 20% of people, and their discomfort will increase with increasing CO2 concentration. At 2,000 ppm the majority of people will feel a significant degree of discomfort, and many will develop nausea and headaches.
“Out of sight, out of mind,” is a pithy saying that aptly sums up the attitude most industrialized countries have toward ocean acidification. While there has been much (justified) hand-wringing about the terrestrial impacts of climate change, policymakers have largely ignored the threats posed by acidic seas – which are considerable.
There is about 50 times as much carbon dissolved in the oceans in the form of CO2 and CO2 hydration products as exists in the atmosphere. The oceans act as an enormous carbon sink, having "absorbed about one-third of all human-generated CO2 emissions to date." Generally, gas solubility decreases as water temperature increases. Accordingly, carbon dioxide is released from ocean water into the atmosphere as ocean temperatures rise.
The oceans have long buffered the effects of climate change by absorbing a substantial portion of the greenhouse gas carbon dioxide. But this benefit has a catch: as the gas dissolves, it makes seawater more acidic. Now an international panel of marine scientists says this acidity is accelerating so fast it threatens the survival of coral reefs, shellfish and the marine food web generally. NY Times Jan 30, 2009
If we don't dramatically reduce our CO2 emissions, somewhere in the near future catastrophic failure of our eco system is inevitable.
The vast majority of world scientists agree the window is short to prevent disaster. We may have only 6 to 10 years - as the UN Intergovernmental Commission on Climate Change told U.S. Senators. "We're toast if we don't get on a very different path," James Hansen, Director of the Goddard Institute of Space Sciences, told The Associated Press.