Last week there was an international media debate on climate data which appeared to be rather surreal to me. It was claimed that the global temperature data had so far shown a “hiatus” of global warming from 1998-2012, which was now suddenly gone after a data correction. So what happened?
One of the data centers that compile the data on global surface temperatures – NOAA – reported in the journal Science on an update of their data. Some artifacts due to changed measurement methods (especially for sea surface temperatures) were corrected and additional data of previously not included weather stations were added. All data centers are continually working to improve their database and they therefore occasionally present version updates of their global series (NASA data are currently at version 3, the British Hadley Centre data at version 4). There is nothing unusual about this, and the corrections are in the range of a few hundredths of a degree – see Figure 1. This really is just about fine details. More »
Last Friday, NASA GISS and NOAA NCDC had a press conference and jointly announced the end-of-year analysis for the 2014 global surface temperature anomaly which, in both analyses, came out top. As you may have noticed, this got much more press attention than their joint announcement in 2013 (which wasn’t a record year).
In press briefings and interviews I contributed to, I mostly focused on two issues – that 2014 was indeed the warmest year in those records (though by a small amount), and the continuing long-term trends in temperature which, since they are predominantly driven by increases in greenhouse gases, are going to continue and hence produce (on a fairly regular basis) continuing record years. Response to these points has been mainly straightforward, which is good (if sometimes a little surprising), but there have been some interesting issues raised as well…
The landscape for science blogging, the public discourse on climate and our own roles in the scientific community have all changed radically over the last 10 years. Blogging is no longer something that stands apart from professional communications, the mainstream media or new online start-ups. The diversity of voices online has also increased widely: scientists blogging and interacting directly with the public via Twitter and Facebook are much more prevalent than in 2004. The conversations have also changed, and (for the most part) have become more nuanced. And a bunch of early career researchers with enthusiasm, time to spare and things to say, have morphed into institute directors and administrators with lots of new pressures. Obviously, blogging frequency has decreased in the last year or so in response to these pressures and this raises the question: where does RealClimate go now?
As the World Meteorological Organisation WMO has just announced that “The year 2014 is on track to be the warmest, or one of the warmest years on record”, it is timely to have a look at recent global temperature changes.
I’m going to use Kevin Cowtan’s nice interactive temperature plotting and trend calculation tool to provide some illustrations. I will be using the HadCRUT4 hybrid data, which have the most sophisticated method to fill data gaps in the Arctic with the help of satellites, but the same basic points can be illustrated with other data just as well.
Let’s start by looking at the full record, which starts in 1979 since the satellites come online there (and it’s not long after global warming really took off).
Fig. 1. Global temperature 1979 to present – monthly values (crosses), 12-months running mean (red line) and linear trend line with uncertainty (blue) More »
I was disappointed by the recent summary for policymakers (SPM) of the intergovernmental panel on climate change (IPCC) assessment report 5, now that I finally got around to read it. Not so much because of the science, but because the way it presented the science.
The report was written by top scientists, so what went wrong?
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