The extreme weather predicted by global warming models may or may not be really happening.

Several predictions of the consequences of an enhanced greenhouse effect have been observed. The global mean surface air temperature has risen about 0.5° C over the last century, and cold season precipitation has increased in the high latitudes. One of the conclusions drawn by scientific consensus from global climate models is that weather events may swing to wider maxima as a result of the enhanced greenhouse warming. Findings by researchers at the National Climatic Data Center indicate that there is a trend toward more extreme U.S. weather in what has been observed. Compared to a century of climatic records, the period since 1970 has seen a much higher than normal occurrence of storms with large precipitation amounts. An increasing fraction of the precipitation falling in the U.S. has been associated with large storms rather than with showers. Globally, the picture is not so clear. There have been regionally observed increases and decreases in weather variability over the last few decades, but these are highly correlated with the interannual variation of the tropical belt associated with El Niño and the Southern Oscillation. A global greenhouse warming signal in weather variability has not been unambiguously detected.