Previously is was thought that the result might have been due to some inadequacy in the data for the troposphere. However, Dian Gaffen from the US National Oceanic and Atmospheric Administration and colleagues have analyzed the data carefully and confirmed that although the temperature changes with height, the current average temperature measurements for the troposphere are correct (Science 287 1242).

Moreover, in related work, Benjamin Santer from the Lawrence Livermore National Laboratory and colleagues have shown that part of the discrepancy could come from uneven coverage by satellite and ground-based measuring stations, and from the vast plumes of material that are pumped into the atmosphere by volcanic activity (Science 297 1247).

"Understanding the difference between surface and tropospheric temperature trends is crucial for modelling climate and planning future climate monitoring," says David Parker from the UK Meteorological Office in Bracknell.