"Fig. 1. (a) Global surface temperatures relative to 1880-1920 based on GISTEMP data, which employs GHCN.v3 for meteorological stations, NOAA ERSST.v5 for sea surface temperature, and Antarctic research station data[1]." Source: "Global Temperature in 2018" by James Hansen. (Speech bubble annotations mine; click to enlarge.)

Global surface temperature in 2017 was the second highest in the period of instrumental measurements in the Goddard Institute for Space Studies (GISS) analysis. Relative to average temperature for 1880-1920, which we take as an appropriate estimate of “pre-industrial” temperature, 2017 was +1.17°C (~2.1°F) warmer than in the 1880-1920 base period. The high 2017 temperature, unlike the record 2016 temperature, was obtained without any boost from tropical El Niño warming.

Consider a simple calculation. Most governments that try to show they are interested in ending man-made CO2 emissions have "exit rates" — rates at which humans go to zero emissions — which nonetheless have us increasing emissions as late as 2050. The underlying assumption is that if we start the count at 400 ppm in 2014 (per the monthly chart at the above), then add +2.11 ppm per year, we don't get to 450 ppm for roughly 20-25 years (allowing for modest acceleration in the growth rate). But if atmospheric CO2 growth suddenly zooms to +4 ppm/year starting with this year's 406 ppm, we're at 450 ppm in 11 years.

IPCC 1.5°C report: A clarion call for EU action on climate



A leaked draft of the IPCC’s forthcoming report on keeping global warming at 1.5 degrees Celsius gives reason to hope that the target is attainable. But only if urgent action is taken immediately, warns Dr Bert Metz.

global average temperatures" at "just 1 degree Celsius (°C) above pre-industrial levels" — noticeably lower than Hansen's number.

It has been widely reported that 2015 will be the first year where temperatures climbed to 1C above the pre-industrial. That might make it seem like we’ve got quite a ways to go until we breach the 2C limit. But the claim is wrong. We exceeded 1C warming more than a decade ago. The problem is that here, and elsewhere, an inappropriate baseline has been invoked for defining the “pre-industrial.” The warming was measured relative to the average over the latter half of the 19th century (1850-1900). In other words, the base year implicitly used to define “pre-industrial” conditions is 1875, the mid-point of that interval. Yet the industrial revolution and the rise in atmospheric CO2 concentrations associated with it, began more than a century earlier. ...



[U]sing the more appropriate 1750-1850 pre-industrial baseline, we see that the Northern Hemisphere average temperature (gray squiggly curve [in Figure 3 at the link]) has already warmed nearly 1.2C [as of 2013; Figure 3 was published in 2014]. Temperatures have exceeded 1C above pre-industrial levels for most of the past decade. [emphasis added]

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