We collect a number of data sets to study our climate through such things as sunshine, rainfall, winds and temperature. The HadCRUT dataset is based on the measurements of surface temperature from close to 5,000 stations, going back to 1850. The latest version of HadCRUT includes observations from both land and sea (the HadCRUT3 data). The raw station data is put on to a grid and shows variations against the 30-year average from 1961-90. The difference from this average gives us a reference point against which we can see how the temperature varies from one year to the next.
The basic data is collected from a series of stations, all of which have to meet a standard criteria for how they place their thermometers and to make sure these are properly calibrated. That is quite important as you want to be sure that any changes are not down to differences in the way measurements are made. This means we have a very high quality of data, with low error-bars associated with the observations. The collected data is also quality-controlled to cope with obvious mistakes and misreporting.
One important point to note is that the basic data is not collected from some strange locations in some mysterious way. This data is the basic information that is also regularly used in our everyday weather forecasting work.
Good science by its nature should always be transparent and robust, that’s how it works. Scientists collaborate by sharing information with each other and comparing results. It is through this comparison that we understand where the uncertainty lies and how we can focus our efforts to improve knowledge and understanding.
The important thing about the problems surrounding the University of East Anglia, and the questions it has raised in people’s minds about climate science, is that lots of groups around the world have done similar things to the scientists there, and they’ve all been showing similar results. That gives us some confidence the information we’re getting from the data is well-founded.
Paul Hardaker is chief executive of the Royal Meteorological Society