Looks pretty ominous, doesn't it? Just one problem. He cherry picked both the supplier of data, and the data. Lets contrast it with some NOAA data:
You see what he did here? He picked one month out of the year, where the anomaly showed a slight upward trend, and ignored the overall trend. Since 2000, the temp has flatlined, but Plait's selected chart looks like there's a serious emergency.