ANTHROPOGENIC WARMING ABOUT ONE DEGREE ABOVE PRE-INDUSTRIAL LEVELS
But what if global temperatures exceed the tipping point for one or two years and then drop away like they have in the past, just as they had during the thirty nine year cooling period that took place between 194o-1979, despite a rapid increase in GHG emissions due to car and arms production or the longest period of 20th century warming that happened between 1910 to 1939 when emissions remained stable.
It was futile talking about a global temperature tipping point of 1.5 C, above the average temperature of the pre-industrial period, while they won’t provide the data. The more you inquired the more the IPCC scientists would waffle: “In principle, ‘pre-industrial levels’ could refer to any period of time before the start of the industrial revolution”. “But the number of direct temperature measurements decreases as we go back in time”. “Defining a ‘pre-industrial’ reference period is, therefore, a compromise between the reliability of the temperature information and how representative it is of pre-industrial conditions”.However, they did provide a clue when they wrote: “Human-induced warming has already reached about 1°C above the pre-industrial level
which is similar to NOAA who estimated 13.72 C for the period.
NOAA and Met Office, two of the main players in global temperature measuring have just revealed, in a roundabout way, the average temperature for the periods 1850-1900 and 1880-1900, both arriving at similar levels, NOAA 13.72 C and Met Office 13.670 C. By adding 1.5 C to either and we have their approximate tipping points…. 15.220 C and 15.170 C respectively.
NOAA in their 2018 report, as they usually do, have shown the annual global temperature by adding the anomaly (0.79 C) to the 20th century average of 13.90 C to indicate a temperature of 14.69 C But in an earlier report they had identified a global temperature departure of more than 1.0°C (1.8°F) above the 1880–1900 average, which is a period that is commonly used to represent the pre-industrial conditions. However, 2018 was just shy of reaching the 1.0°C (1.8°F) mark at 0.97°C (1.75°F). A simple deduction o.97 C from 14.69 C is equal to 13.72 C for the pre-industrial average. NOAA is yet to finalise their data for 2019 which could yet exceed the global temperature in their 2018 climate report.
Scientists at the Met Office Hadley Centre and at the University of East Anglia’s Climatic Research Unit produce the HadCRUT4 dataset, which is used to estimate global temperature. The HadCRUT4 global temperature series shows that the average of January to October 2019 was 1.04±0.1 °C above pre-industrial levels, taken as the average over the period 1850-1900, and/or by adding 0.43±0.1 C to the 1981-2010 average, which according to their temperature data is 14.28 C and you get 14.71 C as the likely 2019 temperature. So if you subtract 1.04 C from 14.71 C the estimated average for the pre-industrial period is 13.670 C.
Special thanks to Jennifer for attachment and her efforts in contributing to this item.