Snow and ice in Dallas means that climate change is a fraud...or so some desperately believe.
But of course the key (in terms of temperature) to looking at the global climatic system is the avenge global temperature and temperature anomalies (departures from long term averages). This NASA animation shows the change in the five-year average anomalies from 1880 to 2010:
One consequence of over all warming is a change in the pattern of heat redistribution, which affects the way that air masses typically move and interact, in other words weather. Once again, climate is what you expect, weather is what you get. In a stable climate you can still get unusually cold, hot, wet, dry etc weather patterns, but overall those will not change what you expect over the long-term. But if these unusual events become more frequent, then what you would expect long-term would also shift, and you have climate change. As Chris Rowan at Highly Allocthonous pointed out recently, these unexpected events are the ones that have the greatest consequences, because we don't plan for them. Paul Krugman touched on a similar theme in a good synopsis of the current global weather situation, and what if may portend if it is indeed the result of growing climate instability. Not that a Keynesian economist will convince sociopathic denialists. The extreme weather is partly responsible for the rise of food prices globally (oil prices figure in as well), and ongoing drought in China is threatening their vital wheat crop.
Business as Usual cannot continue, changes will come in the way things are done, of that I am certain. What I do not know and what no one can know is how is will occur. Part of the American mythology is the idea that we can as individuals and a country re-invent ourselves. Many who tells us that this happened in the past ("people got things done")believe that all the argument, foot-dragging and denialsim means we can longer do so. What they never learned is that past past challenges and change were accompanied by much wailing and gnashing of the teeth similar to what occurs today. The past then is both sobering and reassuring.