Once again we offer you what sounds like denialist sloganeering but which turns out to be a paraphrase of past conclusions from the IPCC worded in such a way that if you post it on Facebook you’re bound to get censored, banished and cancelled, after which you can show them the source and have a good chuckle about it (and hopefully get your job back). This week’s entry: “Scientists have shown that most ‘warming’ happens where economies have been growing, which means the temperature record is contaminated by urbanization. The IPCC tried to deny it in one of their reports but they later admitted their supposed counterevidence was made up out of thin air. And although some climate scientists also try to explain it away, the evidence shows the contamination of the temperature record is real.”
This week’s dare comes from the IPCC 5th Assessment (2013) Report Working Group I page 189. (Note that “AR4” means the 4th Assessment Report, LULC stands for Land Use and Landcover Change, LSAT stands for Land Surface Air Temperature and UHI stands for Urban Heat Island.) As for the actual quotation, here you go:
McKitrick and Michaels (2004) and de Laat and Maurellis (2006) assessed regression of trends with national socioeconomic and geographical indicators, concluding that UHI and related LULC have caused much of the observed LSAT warming. AR4 concluded that this correlation ceases to be statistically significant if one takes into account the fact that the locations of greatest socioeconomic development are also those that have been most warmed by atmospheric circulation changes but provided no explicit evidence for this overall assessment result. Subsequently McKitrick and Michaels (2007) concluded that about half the reported warming trend in global-average land surface air temperature in 1980–2002 resulted from local land surface changes and faults in the observations. Schmidt (2009) undertook a quantitative analysis that supported AR4 conclusions that much of the reported correlation largely arose due to naturally occurring climate variability and model over-fitting and was not robust. Taking these factors into account, modified analyses by McKitrick (2010) and McKitrick and Nierenberg (2010) still yielded significant evidence for such contamination of the record.
Yes, the IPCC reluctantly conceded there is good evidence that their data is contaminated by urbanization and land use change. But don’t get too excited. Having admitted the problem, they then decided it doesn’t matter and went on to use the data anyway. Still, dare you to post it on Facebook and see what they decide.