Why am I wearing a tank top in the middle of December? Is this just how the weather turned out this year, or is this actually a small result of global warming? Ryan

MIKE MOSS SAYS:    Ryan,      It would be nice if there were a way to clearly separate simple excursions from normal that are a natural part of weather and climate from any long term anthropogenic warming trend due to greenhouse gas emissions. While there is pretty good agreement now among climate researchers that a large scale warming is underway and that it is influenced by human activities, it is very difficult to pin any given string of especially warm days (or any particular storm system, hurricane, drought episode, etc) to that as a cause. Record highs for the latter half of December at RDU hover mostly in the mid 70s, with those records having been set in some cases in the 1960s through the 1990s. Another difficulty is that our records for RDU, for example, only stretch back to 1948. Any time you have a finite time series of values that include random variations (even if there were no global warming or global cooling signal, for example), the longer that series is maintained, the greater the extreme departures from "normal" will become as well.