Figure 2. The level of
hourly downward total solar irradiance at BRW, 1 Jan 2014 – 31 Dec 2014
The average annual temperature at BRW has increased significantly since
1985 (Figure 3). Specifically, the average annual temperature over the
2015-2020 time period was about 3.37 oC higher than in
1985-1990. The temperature data
reported by the PABR weather station at the nearby Barrow Airport from
1985 through 2020 are consistent with the trend at BRW (Figure 4). The
PABR data also indicates that the four warmest years since 1921 occurred
in 2016, 2017, 2018, and 2019. In
these four years, the average annual temperature was about 5.03o C higher than the average annual temperature from
1921 through 1939. These findings do not support the assertion by
Lindzen that the recent warming is about the same as before the 1940s
(2020, pp. 12-13). In terms of the magnitudes of the recent warming, the
increases are consistent with Arctic amplification, as explained by
Pithan & Mauritsen (2014) and Winton (2006).
The upward trend in temperature at both BRW and PABR is consistent with
the temperature trend for the Arctic noted by Post et al. (2019), Markon
et al. (2018, p 1190-1192), and Thoman et al. (2020, p. 4). Box et al.
(2019) have reported significant changes in nine key measures of the
Arctic climate system over 1971 through 2017. The qualitative story is
clear: “the transformation of the Arctic to a warmer, less frozen, and
biologically changed region is well underway.” (Thoman et al., 2020, p.
1). Consistent with these changes, the annual mean permafrost
temperatures have increased at many locations throughout the Arctic
(Romanovsky et al., 2017, p. 69). For example, based on data reported by
EPA, the average annual permafrost temperature at the Deadhorse
Permafrost Observatory ( https://permafrost.gi.alaska.edu) over
the years 2015 through 2020 was about 2.81 oC higher
than during the years 1985 through 1990 (EPA, 2021). In four of the 11
permafrost observatories whose 2020 annual temperatures are reported by
EPA, the 2020 average temperatures were between -1 and 0oC. There is evidence that thawing has adverse
implications for carbon emissions because of stimulated microbial
decomposition (Schuur et al., 2021).
According to AMAP, “Arctic warming can also have effects far beyond the
region: for example, the recent rapid warming of the Arctic appears to
have created conditions favoring a persistent pattern in the jet stream
that provokes unusual extreme temperature events in the Northern
Hemisphere.” (AMAP, 2019, p. 4). Taylor et al. (2017, p. 303) have
indicated it is very likely that human activities have contributed to
these trends. While the literature supports this finding, it has also
been suggested that the
significant natural weather and
climate variability in the Arctic poses an attribution challenge (Taylor
et al., 2017, p. 319). Consistent with this reported variability, both
downward total solar irradiance and temperature at the hourly level are
highly variable (Figures 5 and 6). Concerning the hourly
CO2 concentration levels, there is a significant upward
trend in the hourly CO2 concentration levels over the
sample (Figure 7). Despite the upward trend in both CO2concentrations and temperature, there is no visually obvious
relationship between the two variables (Figure 8). While some climate
deniers may be tempted to claim that the data in this figure vindicates
their position, the view here is that a lack of correlation between two
variables only rules out causality when the hypothesized relationship is
quite simple.