Yowzer! “sea ice extended to the equator 716.5 million years ago”. Anthony Watts offers this interesting report from Harvard University – Scientists find signs of ‘snowball Earth’. It states that sediments from the Canadian Arctic, which owing to plate tectonics were on the equator 700 million years ago, indicate that there have been periods of truly global sea ice coverage.

Gray carbonate sediments (tropical) underlying thinner dark brown glacially influenced sediments. I've done field work in this beautiful region.

Anthony wants to imply that this means that huge and rapid climate changes can easily have a natural cause. Unfortunately, in geological terms “rapid” means tens of thousands of years, not decades. Also these geological climate changes are the product of physical changes to the earth impacting atmospheric gases and hence climate. The fact that we are not seeing planetary changes driving the observed changes in atmospheric gases and climate is why there’s such a fuss being made about man-made influences.