Recent global warming may be greater than thought

Ars Technica : Although several techniques have been developed to monitor global surface temperature, they are all hampered by gaps in data from remote areas such as the North and South Poles. One of the most commonly used datasets, HadCRUT 4, which is compiled by the UK’s Hadley Centre, simply drops the gaps from its calculated average. Another technique, employed by NASA in its GISTEMP dataset, is to fill in the gaps with the closest surface temperature measurements. Now Kevin Cowtan of the University of York and Robert Way of the University of Ottawa have studied the different methods and evaluated their accuracy. The researchers also tried using satellite data to fill in some of the temperature gaps. According to their study published in the Quarterly Journal of the Royal Meteorological Society, global temperatures over the past decade may have been warmer than previously estimated.