Graph on following website might be of interest:
http://www.google.com.au/imgres?imgurl=http://geology.com/news/images/global-warming-graph.jpg&imgrefurl=http://geology.com/news/2006/01/global-warming-graph-and-map.html&h=294&w=460&sz=92&tbnid=IEoTpuA93NoJ::&tbnh=82&tbnw=128&prev=/images%3Fq%3Dglobal%2Bwarming%2Bgraph&sa=X&oi=image_result&resnum=1&ct=image&cd=1
