Climate News Network: Global warming may already be taking its toll of air miles. As jet planes burn fuel and release carbon dioxide, the atmosphere warms and causes head winds to build up. Tail winds do too, but round trip journey times are nevertheless creeping up - and so are fuel costs. A team of US scientists say the cumulative effect of the longer flight times that they think may have resulted from climate variation would have added millions of dollars to airlines costs, and perhaps a billion gallons of extra...