The latest climate change denial claim before the release of the Intergovernmental Panel on Climate Change assessment report on Friday is global warming stopped in 1998. A slowing in the observed rate of global warming has prompted dubious suggestions that temperatures have not increased significantly in the past 15 years.

It's true that, after rising rapidly in the 1990s, average temperature increases at the Earth's surface have slowed since 1998. But warming hasn't stopped.

The past decade was the hottest on record globally. Each year from 2000 to 2010, except 2008, was in the list of the 10 warmest.

What's most concerning is it should be considerably cooler than average. Since 1997, several natural climate factors have aligned that should have produced a cooling effect on global temperatures.

A lull in solar activity from 2005 to 2010, combined with two very strong La Nina episodes from 2010 to 2012, would be expected to produce a strong decrease in global temperatures.