Read here and here. The recent cold and snowy weather that some regions of the northern hemisphere have recently suffered has been determined by climate scientists to be a direct result of major ocean/atmospheric oscillations - namely, the combined, simultaneous negative modes of: the NAO, the AO and the El Niño. In the most prominent analysis, NOAA climate scientists revealed what the greenhouse gas-based climate models predicted in terms of winter precipitation (top chart) and what was actually observed (bottom chart). (click on images to enlarge; images source here)
By comparing these two charts, the virtual world versus the real-world, it is obvious there are significant issues (problems? failures?) with the government, bureaucrat-scientist designed climate models.
Those issues? One, climate models are totally inept at predictions and forecasting, even in the short-run of several months. Two, CO2 and other human produced greenhouse gases have little, if any, causation for producing severe weather, such as cold and precipitation. Or, three, a combination of the latter two, which help explains why climate modellers are sooo wrong, sooo frequently.
To put this into greater context of CO2-based climate models' and modeller failures, recall the utter failure of recent hurricane/cyclone seasonal forecasts for their being more intense and frequent; the prediction failure of the 2010 Russian heat wave; and, the concurrent failure to predict the large Pakistan rain/flooding event.
Yet, left/liberal/progressive "scientists" pushing their favored political agenda continue to proselytize the idea that CO2 and global warming are the cause of severe weather events, including the current severe cold and snow. Their denial of both the actual empirical evidence and peer-reviewed scientific literature is a conclusive testament to the left's anti-science mentality and propaganda.