Recent surface warming has probably been underestimated

Filling in data gaps with satellites makes the last few years a little warmer.

If you want to take someone’s temperature to see if they have a fever, you know where to put the thermometer. (Sorry, infants.) But where do you take the temperature of Earth’s climate? Inconveniently, the answer is “everywhere”—you need measurements covering the planet to properly calculate the global average surface temperature. That’s no big deal for Europe, where a local weather station is never far away, but it's much more of a problem for the North and South Poles where records are hard-won. A new analysis shows that how you deal with this problem makes a difference in what temperature you end up reading.

Building a global temperature dataset is a huge undertaking, because that’s only the half of it. Lots of careful corrections need to be made to the raw measurements to account for things like instrument changes, weather station placement, and even the time of day the station is checked.

See full Article: http://arstechnica.com/science/2013/11/recent-surface-warming-has-probably-been-underestimated/