things turn busy for my business, preventing me from researching more anti-global warming faux pas and exposing them for what they are – utter nonsense.
There is one making the rounds lately that is interesting – the idea that the years from 1998 on indicate a leveling off of the warming trend, or even a dip in the trend suggesting an end to AGW. Of course this is a bunch of garbage, but for some reason (OK, I know the reason), it has been embraced by the rabid anti-AGW crowd.
It goes something like this; 1998 was the warmest year on record and each year since then has experienced a lower temperature than 1998 so the climate has not been warming. If the climate is not warming each and every year then warming has come to an abrupt end.
Here are the figures: (Left figure is NASA, right HadCRUT3)
What should be obvious is that indeed all the years following 1998 are lower than 1998. Taken out of context, it appears that warming has indeed stopped. But this isn’t the entire story.
When determining a long term trend, any smaller chunk of data has to be examined in context of the larger trend in order to obtain an accurate image of what is really happening. This is, of course, what the Anti-AGW crowd do not want to do, because it undermines their claim of an end to warming.
The first thing that has to be mentioned is that, although lower than 1998, all following years are warmer than any other since 1890.
Secondly, the slope of the linear trend line calculated from these 10 years is still positive (.00468), meaning that statistically, the warming trend is still alive and well. Since 1890 there have been a number of times when 10 year trend lines have had negative slopes yet did not portend the end of warming.
This become obvious in the following graph:
When viewed in relation to the years preceding and following, 1998 can be seen to be highly unusual in that it varies from the mean far more than any other year. This in itself eliminates 1998 from being used as an end point in any trend line or analysis of a trend. For the anti-AGW people to try to use it as such is, in my opinion, dishonest.
I will have to leave a debunking of the idea that each year has to be warmer than previous years for a later date. I believe what I have visually shown here is that a short term downturn in temperatures is not significant when taken in context and that the years following 1998 are not an indication of a downturn.