Claims that the earth is warming and will warm further over the next fifty years are based on two things. First, temperature readings from both land based data stations and also from satellite data are used to determine the temperature at key locations around the world. Second, the claims are based on computer simulations or models of how the climate works, which enables scientists to develop scenarios of the future which, given the assumptions which are made, suggest what future temperature will be like.
Recent analysis of land stations suggests that the data they provide is problematic in three ways. First, many of the land stations are inappropriately placed. A review of the land stations in the US suggests that the majority are placed in places that give artificially high readings - they are near heat vents, close to buildings or in locations that do not meet international standards for land station placement. Second, the data used from land stations is not consistent over time. The stations used in the 1930's are different from the stations used in 2010. This means that we are not comparing like with like. Finally, there is good evidence that the data from land stations has been manipulated by climate scientists - Russian and Chinese scientists are making clear that the data from their own stations has been unduly manipulated. Satellite data is much more reliable.
What the data shows from these measures is in dispute. The "warmist" scientists indicate that the data is clear. The earth is warming and, by the end of the century, will be between 3 and 5 degrees centigrade warmer than it is now. The "cool it" scientist take a different view. They suggest that warming is within a normal range of less than 1 degree C in each century and that warming, at least using satellite data, has not occurred since 1995 - a view recently confirmed by the disgraced former Director of the Climate Research Unit at the University of East Anglia.
Linked to this dispute is another. It concerns the veracity of the claims about the future impact of the climate on the planet based on computer models. The "warmist" view of these models is that they suggest very strongly that CO2 produced by industrial activity is largely to blame for warming and that, unless CO2 emissions are reduced dramatically, glaciers will met, seas will flood coastal areas and engulf small islands and there will be a significant impact on agricultural production, the spread of illness and our basic way of life. The "cool it" scientists claim that the models themselves are flawed and exaggerate the impact of CO2 and minimize the impact of the sun, water vapour, ocean currents and other factors which have an impact on climate. While almost all scientists agree that the climate is changing - it always has and always will - and that CO2 is a factor, they differ on the extent to which man made CO2 is a factor and the impact of climate change on human systems.
A year ago the views of those who disputed "the consensus" were largely dismissed as heretical by mainstream science. Labelled as "deniers" by the dominant “warmists”, the sceptics were seen as a fringe group of scientists who did not fully understand the complexity of climate change and were ignorant about the data. The mantra was that there was a scientific consensus, climate change was real and an urgent problem and that a vast number of scientists were all agreed about the “science”.
Since the Climategate email scandal, the sixteen errors of fact in the Intergovernmental Panel on Climate Change (IPCC) fourth assessment, the obvious disagreements evident in the peer reviewed scientific literature and the discrediting of key analytic procedures used to reach the “warmist” conclusions, things have changed. The debate has shifted from one of politically correct science versus “odd ball” deniers to a real scientific discussion about the veracity of a theory, the reliability of the evidence and the process of scientific discovery.
There are now real debates about the Arctic sea ice and the fact that it has been both expanding and thickening for some time. There is a serious discussion as to whether or not our land station data is providing the evidence we need or whether we should take account of the data from more of these stations and move many of them to locations which meet internationally agreed standards. There is a growing call for a reform of the IPCC so that it no longer is an advocacy body for one theory of climate change, but that it should become a body which reviews all aspects of climate change science, not just that advocated by the World Wildlife Fund and a few other campaign organizations.
The sceptics have achieved a great deal in the last year. They have enabled a serious debate to take place about theories, methods, evidence and outcomes. Rather than being called “deniers” we may want to think of a new term for them – scientists, perhaps.