How Can 390 parts per Million possibly matter? Here’s How.

December 22, 2010

I get this all the time. The amount of CO2 in the atmosphere is only 390 parts per MILLION! How can that possibly make a difference?

Dan Miller has a simple visual demonstration.

Admiral David Titley has an example on this issue – which goes as follows, — the portion of Co2 in the atmosphere is now about 390 parts per million, (ppm) or .039 percent — assuming a ‘business as usual’ approach to emissions, experts expect that level could reach over 800 ppm toward the end of this century.

To compare that to something readers may be familiar with, a blood alcohol level of .039 percent puts a party goer well on their way to intoxication. If we increase our blood alcohol to 800 ppm or .08 percent, we are legally impaired. If your denier friend still insists that such trace levels of a substance can have no effect, – have him tell it to a judge.

Titley’s presentation to the American Meteorological Society is here.

3 Responses to “How Can 390 parts per Million possibly matter? Here’s How.”


  1. wow! wow that was stupid! The global warming deniers are saying that the 0.28% that man contributes to the 0.039% won’t make a difference in changing the Earth’s temperature. Nobody is saying that it won’t exist. Also, up to 800ppm by the end of the century? Gimme a break… After 1 hour of research with even a minimal level of scrutiny anybody could conclude that anthropogenic global warming is not real. There is a reason these pseudo-scientists have switched their rhetoric from “global warming” to “climate change.”


  2. Poor example: Liquids are more dense than air…

    “At sea level, air is 784 times less dense than water. Expressed in another way, a volume of air at sea level has 0.1275% of the density of the same volume of water.”

    Arbitrary Blood Alcohol Levels do reflect the politics of Global Warm…, er, Climate Change

    The “legally impaired” threshold of 800ppm was the result of interest group lobbying of congress by, among others, MADD, and really has no connection to science. The .08% was limit subsequently forced on the states through the threat to withhold highway funding.


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