A slow-down in global warming is not a sign that climate change is ending, university researchers have found. The phenomenon is a natural blip in an otherwise long-term upwards trend, their research shows. In a detailed study of more than 200 years’ worth of temperature data, results backed previous findings that short-term pauses in climate change are simply the result of natural variation. The findings support the likelihood that a current hiatus in the world’s year-on-year temperature increases ‚Äì which have stalled since 1998 ‚Äì is temporary. —Reporting Climate Science, 20 July 2015
I can reveal that the US House of Representatives science committee, led by the Texas Republican Lamar Smith, also has doubts. At the end of last month, committee staff sent emails to several experts in Britain, saying Mr Smith ‘is making climate change data within NOAA a priority’. The committee, they added, was seeking outside help to ‘analyse’ NOAA’s claims ‚Äì apparently, it would seem, because some members do not trust NOAA’s ‘input’ alone. Among those submitting evidence that challenges NOAA’s assertion is the UK sceptic think-tank, which is chaired by Lord Lawson, the Global Warming Policy Foundation. –David Rose, The Spectator, 22 July 2015
Even accepting the statistical approach taken by Karl et al. it is clear that their errors are larger than they realise, and that the trends they obtain depend upon cherry-picked start and end points that include abnormal conditions, i.e. the 1998-2000 El Nino/La Nina and the 2014 northeast Pacific Ocean “hot spot.” I conclude that the elimination of the hiatus claimed by Karl et al 2015 is unsafe because of bias due to the choice of start and end points that are extremes of natural fluctuations in the global surface temperature record, as well as a overemphasis on statistically poor results. –David Whitehouse, Global Warming Policy Forum, 22 July 2015
The lesson is that no study should rely upon trends over selected short periods of time to make claims about a series with as much variability over time as global temperatures. That is as true for the relatively large increase from 1976 to 1998 as for the more recent period. Even that trend has been exceeded in 10% of all 23-year periods since 1880. Even if the study had not drastically underestimated the amount of variability in 17-year trends in the historical data, there is another problem that is not addressed. This is: what is or was the starting point of the trend? In the spirit of the classic warning to all statisticians ‚Äì Darrell Huff’s book titled ‘How to Lie with Statistics’ ‚Äì it is possible to use a particular set of data to generate a wide range of trends simply by choosing a suitable starting point. ‚ÄìGordon Hughes, Global Warming Policy Forum, 22 July 2015
