It’s easy to be fooled by that claim and it is being used politically. Rodney Hide, the leader of the ACT party in New Zealand who will probably hold a place in the new National lead government is using this claim (which he falsely attribute to the UN) to argue against measures to control emissions of green house gases (see John, I’m only dancing).
I was also surprised to hear this argument used by Todd C. Riniolo in an interview on the Point of Inquiry podcast. He is the author of the book When Good Thinking Goes Bad: How Your Brain Can Have a Mind of Its Own which argues for application of critical thinking to people’s cherished and most certainly felt convictions. He discusses some of the mistakes people make and then made a big one of his own by claiming the 1998 high global temperature as evidence that global warming had stopped. He surely should have been aware that the same tactic could have been used to “prove” the opposite. Just compare today’s temperature with that for 2000!
You can’t determine a trend using just two data points
Any complex system will have inherent variability which masks long term trends when only limited data is used. Trends are only revealed by a large number of samples over a reasonable time. In the short term any long term trend in global temperature is buried in the variation from natural causes.
This is obvious in the figure. While a trend of 0.17 degree/decade is obvious over 30 years the trends over 10 years vary from -0.02 to +0.33 degrees/decade. And using just two data points is even more misleading.
What you do with the global temperature data depends on your motive.
- If you want to “prove” a pre-conceived idea or claim then you select the data appropriately. You compare today’s temperature with that for either 1998 or 2000 to support completely opposite claims. Standard fare for dishonest politics.
- If you want to determine what is actually happening, without a pre-conceived agenda, then you use all the available data. In this case you can derive a conclusion (+0.17 degrees/decade) which would be accepted by all scientists – whatever their personal politics or beliefs.
So there are two approaches to “scientific” data:
If we want to fool or mislead people – select the evidence.
If we want to discover the truth – follow the evidence. All the evidence.
See Global warming goes on for more information.