When Did The Land Warm?

In my last article I pointed out that there has been no statistically significant increase in Best land temperature data for the past ten years. I used the word 'confirms' because the Best data is showing the same thing as the other global temperature datasets. The standstill in the past decade is now described in many journals and accepted by many scientists who seek explanations for it in decadal variations.The current global warm period began around 1980, following four decades of unchanging temperatures, the cause of which is a matter for some debate. It is therefore interesting to look at the Best data for the past 30 years. Click on image to enlarge.As you will see the temperature between 1980 and 1995 is unchanging. The leader of the Best initiative has pointed this out several times. This means that if you look at the past decade’s standstill, and then extend the period backwards you will move into the period of warming which gives the false impression of an increase in the past decade or so.The implications of this are important. If the global temperature today was the same as it was in 1980 then there would be no talk of global warming. In the 30 years since, the Best data, which is land only, shows that between 1980 – 95 and 2001 -2010 there was no warming (note the obvious volcanic dips).All the warming that has taken place on the Earth’s land surface in the current warm spell has occurred in the 1995 – 2000 period, in the midst of which there was the strongest El Nino ever recorded.If you divide the data into decades it is easy to see that even with warming taking place between 1995 -2000 it is still possible to say the 1990’s were warmer than the 1980s and the 2000s is the warmest decade of all.What we see in the Best data is not a steady increase, but a transition between two levels of temperature (though inappropriate use of trendlines between start and end points will make it look like a linear increase by ignoring structure between start and end points.)Some might say this proves that 10-15 years is too short a period to detect the warming, so talking of the past ten years is meaningless because a similar standstill happened between 1980 -1995. However, saying that it's warmer now than it was in 1980 is one thing, ignoring the information in the data between then and now is another.Is this pattern of warming compatible with the models?Feedback: david.whitehouse@netzerowatch.com