Y Safle

In Nigel Calder’s piece in the Times he says:

The best measurements of global air temperatures come from American weather satellites, and they show wobbles but no overall change since 1999.

A case of selective use of the evidence. There is excellent data from a variety of sources. I have chosen two developed by scientists in conjunction with the Hadley Centre of the UK Met Office. These measure land and sea temperatures at multiple sites around the world. The datasets can be downloaded here and are described on that site and in the papers referenced below.

I then plotted these data sets, and it is quite clear that there is no loss of the warming trend since 1999. (Click the thumbnail to see the full sized graph). All I can think that Calder is referring to is the spike in 1998 (I have drawn a line to indicate this), making that year the hottest on record.

But such spikes are not a surprise. In any such dataset there will be outlyers – but what is quite clear is that there has been a strong warming trend, particularly over the last few decades. Compare this graph to my graph in my post earlier today, and you can see that there is also no correlation between the warming trend over these decades and cosmic rays.

So Calder is wrong to say that the warming trend has topped out, and he is wrong to attribute the warming to cosmic rays. He is also wrong to suggest that no-one would publish Svensmark’s paper – it is published in the august proceedings of the Royal Society. He is wrong to say that scientists who oppose global warming are locked out of the process – science thrives on people trying to prove other scientists wrong.

Calder is wrong on just about every point.

References (for the data sets used in this graph)

• Brohan, P., J.J. Kennedy, I. Haris, S.F.B. Tett and P.D. Jones, 2006: Uncertainty
  estimates in regional and global observed temperature changes: a new dataset from
  1850.
  J. Geophysical Research 111, D12106,
  doi:10.1029/2005JD006548
  – Available as PDF

• Jones, P.D., New, M., Parker, D.E., Martin, S. and Rigor, I.G., 1999: Surface air
  temperature and its variations over the last 150 years.
  Reviews of Geophysics 37, 173-199.

• Rayner, N.A., P. Brohan, D.E. Parker, C.K. Folland, J.J. Kennedy, M. Vanicek, T.
  Ansell and S.F.B. Tett, 2006: Improved analyses of changes and uncertainties in
  marine temperature measured in situ since the mid-nineteenth century: the HadSST2
  dataset.
  J. Climate, 19, 446-469.

• Rayner, N.A., Parker, D.E., Horton, E.B., Folland, C.K., Alexander, L.V, Rowell, D.P., Kent, E.C. and Kaplan, A., 2003:
  Globally complete analyses of sea surface temperature, sea ice and night marine air temperature, 1871-2000.
  J. Geophysical Research 108, 4407,
  doi:10.1029/2002JD002670

Finally – this graph is used to demonstrate that the warming trend in global mean temperatures still continues. Any reliance on this representation of the data beyond this is discouraged. I have deliberately used the variance data simply to demonstrate the trends. I have chosen two data sets to demonstrate that I am not being deliberately selective of data that supports my point of view.