Expert Comment on Nature paper on surface temperature

Climate scientists from the University of California, Berkeley, and Harvard University in the USA have published a new analysis of more than a hundred years of global surface temperatures showing some unexpected subtleties in the way that the Earth is warming.

Martin Manning, Professor of Climate Change at Victoria University’s Climate Change Research Institute comments on the research:

(Stine, A.R.; Huybers, P.; Fung, I.Y. (2009).  Changes in the phase of the annual cycle of surface temperature. Nature 457: 435-441.  22 January 2009.)

“The new study has provided a more detailed picture of the way that winter – summer temperature differences have changed. Over most mid-latitude land areas, winter to summer differences were stable during the first half of the 20th century but became smaller during the second half of the century. This can be explained by winters warming faster than summers as expected due to the increase in greenhouse gases, but the changes that have been found are larger than those calculated with climate models.

“An unexpected result from the analysis is that the timing of the winter minimum and summer maximum temperatures has also moved slightly earlier in the year for much of the Northern Hemisphere. These new results confirm that warming in the first half of the 20th century was different in character from that in the second half, consistent with the finding from the international assessment of climate change in 2007, that the last 50 years warming has been dominated by an increasing greenhouse effect.

“This new work shows a great deal of regional detail and suggests that effects like a long term drying trend in soil moisture may be important. This gives us a new way of testing regional climate models and that should lead to improvements in our ability to project future climate change in New Zealand.”