Paleoclimate reconstructions that find no unusual modern warming are nonetheless characterized as showing sharp temperature increases in recent decades anyway.
A new (Li et al., 2020) 1818-2012 temperature reconstruction determined 1955 (6.33 °C) and 2001 (7.17 °C) were the 1st and 5th coldest years in northeastern China in the last 200 years. The two warmest years were 1832 (9.63 °C) and 1900 (9.57 °C).
Further, the highest “continuous high decadal temperatures” recorded were in 1818–1844 and 1856–1873. The post-1950s temperatures were colder than nearly all of the first 100 years of the temperature record.
And yet in spite of the warmer 19th-century temperatures, the authors chracterize the slight temperature rise since the 1950s as heralding in “unprecedented” warming. They make this claim (of “unprecedented” recent warmth) in both the paper’s textual and graphical abstracts.
Image Source: Li et al., 2020
Forbes et al. (2020) use thermometer data from an Alaskan airport for the last ~90 years of their temperature record. The instrumentals show surface temperatures cooled -0.7°C in winter (January) and warmed 0.8°C in summer (July) from the 1950s-’80s decades to the 1990s to 2010s.
For the summer temperature record (shown in red below), nearly all the warming occurred during a step-change from the mid-1970s to mid-1980s. Since about 1985, summer temperatures seem to have been stable to slightly declining.
A lack of net overall warming in the last 50 or 60 years does not advance the anthropogenic global warming (AGW) cause, of course.
So the authors decided to add a “cumulative mean annual departure” statistic (see the sharply rising green line in the graphic below) to the summer temperature record that makes it appear there’s been a warmth accumulation of 30°C since mid-1980s.
This statistic does not seem to have any relevance to the measured summer temperature record, which, again, appears to show a slight cooling trend since about 1985.
Image(s) Source: Forbes et al., 2020
Aryal et al. (Aryal et al., 2020) even acknowledged the region they studied is “not yet warming” in the title of their paper.
And yet they nonetheless decided to select a cooler span of years (the bottom of a cycle) to start an arbitrary red-hot-colored “trend” line. In this way they could suggest there has been unusual warming in recent decades anyway.
Image Source: Aryal et al., 2020
September 21, 2020 at 10:54AM