The Antarctic ozone hole did not cause global warming. But there is a connection between climate and the annual thin spot that forms each spring in Earth’s UV-blocking ozone layer: colder winter temperatures tend to lead to larger ozone holes.
NOAA’s National Climatic Data Center announced that last month was the warmest September on record for the planet. If the surface temperature remains elevated at the same level for the remainder of the year, 2014 will set a new record for the warmest annual average temperature since records began in 1880.
Last September’s widespread flooding in northeast Colorado, which saw just over 17 inches of rain in one week in the city of Boulder, was not made more likely or more intense by the influence of human-induced climate change on atmospheric moisture.
Temperature extremes have been pretty unusual across the United States so far in 2014. Looking back over this time period quickly reveals at least part of what was going on: the polar jet stream got into a serious rut.
Through June, the eastern Pacific was warmer than average, but the lack of a strong gradient in sea surface temperature anomalies between the eastern and western Pacific may have kept the atmosphere from getting in sync with the developing El Niño.
For the billions of people in Asia who depend on the Indian Monsoon for the majority of their yearly rainfall, the precise location where the Pacific warms during El Niño may be the difference between a relatively normal year and a devastating drought.