A post from Tony Heller (aka Steve Goddard), on his Real Climate Science blog (aka The Deplorable Climate Science Blog) contains some good illustrations of how to mislead with graphs. The post Massive Increase In Arctic Ice Reflects The NASA Increase In Fraud claims that an increase in global warming since 2012 in GISTEMP contradicts the claim of a recent slowdown in warming, and that this shows NASA are engaging in fraud.
In this post Heller is suggesting that this doubling of global warming contradicts an article by John J Fyfe et al, Making sense of the early- 2000s warming slowdown which claimed there had been a slowdown in the rate of warming between 2000 and 2014.
He demonstrates his argument with reference to a couple of graphs from the Wood For Trees site, and I'll follow suit by demonstrating the problems using the same site.
Graph 1
The first graph shows 5 year rolling average temperatures since 1995, and has labels indicating there has been no warming in satellite data, but rapid warming from NASA.
Nothing surprising here, some satellite data shows rather less warming this century than terrestrial data sets. Heller assumes RSS 3.3 is reliable and there must be a mistake in all the data sets that shows quicker warming, including RSS 4 and UAH 5.6. What is odd is that he chooses to only show data for land, rather than the more usual combined land and ocean.
As far as I can see the reason he's only showing land temperatures is because over this period RSS is showing less warming over land than over the oceans.
The main problem is with Heller's claim that Satellites also show that there has been no warming over land since 2000
.
The problem being that this is a false claim, as he could have easily seen if he'd only added the trend line to the graph.
RSS has been warming since 2000 over land - at a rate of 0.83 °C / Century (up to August 2016).
Certainly a lot less than the trend for GISS, but not no warming
.
This is presumably the reason Heller prefers to show a rolling 5 year average. It obscures what's been happening the last few years. Here's what the RSS land temperatures look like with a 12 month rolling average.
Graph 2
The second graph is used to illustrate the main claim in the article:
Undeterred by facts or science, Mann's buddy Gavin Schmidt at NASA says global warming doubled since 2012, during the Michael Mann hiatus and remarkably concurring with Obama's second term in office.
Here's the graph used by Heller to illustrate this egregious doubling of warming.
I've no idea what Heller means by doubling the warming, and I doubt NASA made such a claim. If he means the anomaly has doubled since 2012, that would be true if you only consider the trend line, but it's only doubling relative to the chosen base line. If he means the rate of warming has doubled he'd need to say what rate he was comparing it with. The rate of warming since 2012 is far more than twice the overall warming rate. But all of this is irrelevant when you consider we are only talking about four and a half years!
But the real problem here is the way Heller uses this brief period of rapid warming to imply NASA's data is fraudulent as it doesn't agree with the claimed slowdown. Logically there is no contradiction with a slower rate of warming between 2000 and 2014, and a rapid rate of warming between 2012 and 2016, as this graph illustrates.
But the stupidest part of this claim is that he doesn't check the claim that NASA the rapid warming
shown by NASA by comparing it with other data sets.
The rate of warming NASA shows since 2012 is indeed staggering, 10.2 °C / Century.
This would be very alarming if it wasn't for the fact that it's only for a very short time and mostly caused by ending with an El Niñ'o.
But every other data set you look at shows very similar levels of warming - if NASA is wrong so are all the others.
And by others I include the supposidly reliable
RSS -
RSS version 3.3 shows a warming rate of 9.7 °C / Century since 2012 - almost identical to NASA.
If, as Heller claims, NASA's warming since 2012 contradicts the claim that there was a slowdown since 2000, then by his own logic the rapid warming shown by RSS since 2012 contradicts Heller's own claim that there was no warming in the satellite data since 2000.
Either Heller never bothered to check his claims by comparing other data, or more likely he did check but found the results inconvenient and decided to ignore it.
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