Interesting tidbit in USA Today: air travel is down worldwide. According to the underlying source, Airports Council International:

  • Passenger numbers in North America declined 5.2 percent from 2008 to 2009, while passengers worldwide declined by 1.8 percent.
  • Air cargo dropped even faster, declining 7.9 percent worldwide.
  • 62 percent of airports worldwide lost traffic in 2009.

The major cause, of course, is the lousy economy, though ACI puts a portion of the blame on travelers’ fears of H1N1. It’s also hard not to believe that a contributing factor, at least in North America, is the increasingly unpleasant flying experience.

From a climate perspective, air travel is worth monitoring because it represents a significant share of total carbon emissions in its own right. But I also suspect (though I can’t say for sure) that it’s a halfway decent proxy for carbon emissions from other sources. Reduced air cargo, for example, is probably an indicator that global industrial production is down too.