New study: Earth hasn't warmed in 19 years         



Remember the headline from this Guardian article from 2009?


The article even came with its very own predictive graph to scare people:


Yeah, well, turns out that this prediction was just wrong. In fact, virtually every prediction made by alarmists over…

The Met Office (one of the two organisations responsible for the HadCRUT temperature record) dealt with a similar version of this myth two years ago. Granted, the claim then was that there had been no warming between 1997 - 2012, but the response they gave is still worth reading as it highlights the pitfalls of cherrypicking a starting point, which, as I will demonstrate, is what the first graph above does.

From the Met Office News blog:

The linear trend from August 1997 (in the middle of an exceptionally strong El Nino) to August 2012 (coming at the tail end of a double-dip La Nina) is about 0.03°C/decade, amounting to a temperature increase of 0.05°C over that period, but equally we could calculate the linear trend from 1999, during the subsequent La Nina, and show a more substantial warming.

As we’ve stressed before, choosing a starting or end point on short-term scales can be very misleading. Climate change can only be detected from multi-decadal timescales due to the inherent variability in the climate system. If you use a longer period from HadCRUT4 the trend looks very different. For example, 1979 to 2011 shows 0.16°C/decade (or 0.15°C/decade in the NCDC dataset, 0.16°C/decade in GISS). Looking at successive decades over this period, each decade was warmer than the previous – so the 1990s were warmer than the 1980s, and the 2000s were warmer than both. Eight of the top ten warmest years have occurred in the last decade.

The first graph in the post, which purports to show no warming since 1995, is misleading because 1995 is clearly a warm year. It has been purposefully selected as a starting point, even though you could equally use 1996 or 1999 as a starting point, and it would have showed warming, or you could have started 1997 or 1998 and it would have showed cooling again. As the Met Office post stresses, these short timespans are often misleading and are insufficient in determining temperature trends.

Furthermore, from the raw data on HadCRUT global averages (guide on how to read it), it is clear that 1995 was cooler than 2014 has been. So the graph is misleading.

Moving on to the RSS temperature record, which was mentioned in the WUWT article. The official graph from the RSS website shows a constant rate of warming of 0.124K/decade in the lower troposphere.

As for the Arctic sea ice, it is very clearly getting smaller (context of that graph can be found here.) Antarctic land ice is also decreasing, but sea ice is increasing as a result of global warming.