When something is apparently agreed by “everyone” including politicians from around the world who then meet together in giant “summits” and so on, I always get suspicious. “Climate Change” and “Global Warming” are the most recent example. It will no doubt soon be illegal under some EU law to “deny global warming” so I had better express my concerns now before the Thought Police arrive...
The first thing I have noticed is the loose terminology being used to describe Global Warming in terms of the “temperature”. I fully understand that the popular press, radio and television will use non-scientific and shorthand terminology when describing scientific subjects so it is no surprise that they will say that the “global temperature” will rise by x degrees by year so and so. But I notice that even those in the centre of these things, such as the UK Met Office use a variety of terms including “Global Temperatures”, “Global surface temperatures”, “Global average temperatures” and “Annual mean temperatures” just within the section of their website discussing Facts and Myths for media consumption.
So, what is the temperature that has been measured that is rising so worryingly? It seems to be that calculated by a complicated but sensible methodology described in a paper produced by the Hadley Centre. This involves combining the monthly average temperatures measured at over 4,000 land-based weather stations around the world with similar sea surface measurements made by marine weather stations from around the world's oceans. Some of the records go back as far as 1850 so these have been used to create a data-set for the last 150 years. However, various allowances have been made for uncertainties (such as the reliability or otherwise for some of the oldest data) and then for the larger number of readings made in the Northern Hemisphere than in the Southern Hemisphere. Finally, the mean figures for each hemisphere have been calculated and added together to produce a graph from 1850 to the present day of what is correctly called the “Global Mean Temperature”. Interestingly these figures correspond quite well with the actual ground air temperatures measured over a long period in Central England, starting in 1772 (the longest period known of such measurements) according to the Hadley Centre. I say interesting because this suggests that the complicated mathematical calculations being made combining ground and sea temperatures from all over the world plus adjusting them for uncertainties and anomalies, taking the mean in each hemisphere and adding them together produces an analogue of real world figures measured in Kew Gardens and a number of other places around Central England for 240 years!
So, Global Mean Temperature is the term that everyone should be using. It is this data-set that shows that the resulting figure has risen by 0.7 degrees C since 1850 and it is from this data-set that the Intergovernmental Panel on Climate Change (IPPC) derives its prediction of a further rise in the “global average temperature” of 2 to 3 degrees C by the year 2100.
Remember this when you next see an article (or hear a politician) saying that “the temperature will rise by x degrees over the next few years and there will be floods/water shortages, hurricanes, plagues of locusts etc.
The first thing I have noticed is the loose terminology being used to describe Global Warming in terms of the “temperature”. I fully understand that the popular press, radio and television will use non-scientific and shorthand terminology when describing scientific subjects so it is no surprise that they will say that the “global temperature” will rise by x degrees by year so and so. But I notice that even those in the centre of these things, such as the UK Met Office use a variety of terms including “Global Temperatures”, “Global surface temperatures”, “Global average temperatures” and “Annual mean temperatures” just within the section of their website discussing Facts and Myths for media consumption.
So, what is the temperature that has been measured that is rising so worryingly? It seems to be that calculated by a complicated but sensible methodology described in a paper produced by the Hadley Centre. This involves combining the monthly average temperatures measured at over 4,000 land-based weather stations around the world with similar sea surface measurements made by marine weather stations from around the world's oceans. Some of the records go back as far as 1850 so these have been used to create a data-set for the last 150 years. However, various allowances have been made for uncertainties (such as the reliability or otherwise for some of the oldest data) and then for the larger number of readings made in the Northern Hemisphere than in the Southern Hemisphere. Finally, the mean figures for each hemisphere have been calculated and added together to produce a graph from 1850 to the present day of what is correctly called the “Global Mean Temperature”. Interestingly these figures correspond quite well with the actual ground air temperatures measured over a long period in Central England, starting in 1772 (the longest period known of such measurements) according to the Hadley Centre. I say interesting because this suggests that the complicated mathematical calculations being made combining ground and sea temperatures from all over the world plus adjusting them for uncertainties and anomalies, taking the mean in each hemisphere and adding them together produces an analogue of real world figures measured in Kew Gardens and a number of other places around Central England for 240 years!
So, Global Mean Temperature is the term that everyone should be using. It is this data-set that shows that the resulting figure has risen by 0.7 degrees C since 1850 and it is from this data-set that the Intergovernmental Panel on Climate Change (IPPC) derives its prediction of a further rise in the “global average temperature” of 2 to 3 degrees C by the year 2100.
Remember this when you next see an article (or hear a politician) saying that “the temperature will rise by x degrees over the next few years and there will be floods/water shortages, hurricanes, plagues of locusts etc.
