Guest essay by John McLean
In his role as a property developer, Donald Trump was unlikely to sign a contract with key information missing so why did most of the leaders of the developed world commit to the Paris Climate Agreement?
Article 2.1(a) of the agreement sets out its aim –
“holding the increase in the global average temperature to below 2°C above pre-industrial levels and pursuing efforts to limit the temperature increase to 1.5°C above pre-industrial levels …”
But there’s something missing … what was that global average temperature and how was it determined? For that matter, when exactly was “pre-industrial”?
Addressing the last question first, some climate scientists have been known to use data from 1850, the start of modern temperature records, as the “pre-industrial” benchmark.
The IPCC takes a different position according to the text in the glossaries to its third to fifth climate assessment reports. In each of those glossaries, under the definitions of “Industrial Age”, we find “In this report the terms pre-industrial and industrial refer, somewhat arbitrarily, to the periods before and after 1750, respectively”. Even the IPCC is inconsistent because 5AR chapter 7 says that it uses data from 1750 to represent pre-industrial times.
Hawkins et al (2017), which we’ll return to shortly, argues instead for a time span from 1720 to 1800.
Okay, we don’t know when but what was the average global temperature and how was it calculated?
According to data from the UK’s Climatic Research Unit (CRU) only three observation stations reported temperature data in 1750 – Berlin (Germany), De Bilt (Netherlands) and Uppsala (Sweden). St Petersburg (Russia) reported data in earlier years but none 1750. The three reporting stations are all in Europe, which covers less than 10% of the Northern Hemisphere and at that time was in the grip of a Little Ice Age.
The ICOADS database provides information about temperatures recorded at sea that year. Only 136 temperature observations are recorded and all appear to be from a single ship travelling from near Kristiansand, Norway, to Britain and then to Mumbai, India, from April 10 to September 18. What’s more a single observation was made each day at midday Greenwich (UK) time, which at various points in the voyage was on the hour but varied from 7am to 1pm.
No meaningful and credible global average temperature can be determined from the 1750 data.
Year 1800 is hardly much better for temperature data. Station data from the CRU data indicates 37 observation stations were in operation, two on the east coast of the USA, one in Greenland and the remaining 34 all in Europe, which was still under the influence of the Little Ice Age.
There were more temperature measurements at sea that year, some 5438 of them, but almost all were along trade routes from Europe, particularly around the southern tip of Africa to European territories or trading ports in India, Singapore, Indonesia and China, again not a wide coverage of Earth’s surface.
Hawkins et al (2017) “Estimating changes in Global Temperature since the Pre-Industrial Period” (http://journals.ametsoc.org/doi/10.1175/BAMS-D-16-0007.1 ) uses a number of models to try to estimate pre-industrial average global temperature.
Firstly this paper was published about 18 months after the first commitments to the Paris Climate Agreement, so even if the paper could provide the information it was a bit late. Secondly IPCC 5AR, specifically text box 9.2 on page 769, says that 111 climate model runs estimated greater warming for the period from 1998 to 2012 than the temperature observations indicated and the credibility of climate models is approximately zero.
There is no base global average temperature for the Paris Climate Agreement, no credible means of calculating one and not even a clear definition of exactly when “pre-industrial” refers to.
Committing to such an agreement was foolhardy in the extreme or at least political posturing at the expense of common sense.
If the UNFCCC declared tomorrow that 2°C – or even 1.5°C – of warming had been reached and that more money was required from developed countries not one of those countries would be able to present any counterargument.
And if you think this wouldn’t happen then take a look at the IPCC first climate assessment report. It declared that global temperatures were already 1°C above those of pre-industrial times, although it provided no detail about how it reached that conclusion.
Saying that the governments in the developed world, those who are supposed to pay money to the less developed world, have taken leave of their senses would only address part of the problem. In most cases other political parties share the same beliefs about temperature and would also have committed to that agreement.
Let’s just hope that playwright Howard Koch was wrong and that we won’t always have Paris.