More extreme and violent climate is a direct consequence of human-caused climate change. There is a reason it isn't called global warming anymore. Higher temperatures are only one -- and not the most worrisome -- of the consequences of a changing climate.
Climate science tells us unambiguously that we are changing the climate and trapping more energy on the planet. Trapping more energy will cause more extreme events and worsen extreme events that would otherwise happen.
In the climate community, we call this "loading the dice." Rolling loaded dice weighted toward more extreme and energetic weather means more death and destruction. And it is only going to get worse and worse, faster and faster, the longer our politicians dither and delay and deny. Climate deniers who have stymied action in Congress and confused the public -- like the tobacco industry did before them -- need to be held accountable for their systematic misrepresentation of the science, their misuse and falsification of data, and their trickery.
The conservative (and economically driven) insurance industry understands the reality of data and observations: Munich Re (one of the world's leading reinsurers) has said:
"The only plausible explanation for the rise in weather-related catastrophes is climate change. The view that weather extremes are more frequent and intense due to global warming coincides with the current state of scientific knowledge."
The extreme nature of the ongoing severe weather is well described by Jeff Masters on his Weather Blog. The 3-day total of preliminary tornado reports from this week's outbreak is nearing 300, close to the 323 preliminary tornado reports logged during the massive April 14 - 16 tornado outbreak. That outbreak has 155 confirmed tornadoes so far, making it the largest April tornado outbreak on record.
According to NOAA's Storm Prediction Center, it is unprecedented to have two such massive tornado outbreaks occur so close together. Loading the dice. At least 11 of these tornadoes were killer tornadoes; deaths occurred in six states. (Wikipedia maintains an excellent and growing compilation of historical tornado outbreaks for those interested, and raw data can be obtained from NOAA.)
And it is not just the devastating tornadoes: parts of the Mississippi River are about to experience record flooding. As spring rain joins with winter snowmelt, a massive pulse of floodwater is moving south. As it joins with the record water levels coming out of the Ohio River it is expected to create the highest flood heights ever recorded on the Mississippi, according to the latest forecasts from theNational Weather Service.
Yet while we call this a "1-in-a-100 year" flood event, that term is losing its meaning. The August 1993 flood event was a "1-in-a-500 year" event. Yet in June 2008 there was another such event. Now, three years later, we see another massive flood on the Mississippi, and record floods elsewhere. Loading the dice. As FEMA's director, Craig Fugate, noted in December, "The term '100-year event' really lost its meaning this year." And that was last year.
The science community knows that we're affecting the climate; in turn, that will affect the weather; and that, in turn, will affect humans: with death, injury, and destruction. There is a cost to tackling climate change, but there is a real, growing, and far larger cost of continuing to deny it.