Cooling and Contraction of the Mesosphere and Lower Thermosphere From 2002 to 2021

Abstract

Introduction"Since carbon dioxide (CO 2 ) plays a significant role in the heat budget of the atmosphere, it is reasonable to suppose that continued increases would affect climate." With these words, the late Verner Suomi eloquently stated the hypothesis of climate change science in 1979, in his foreword to the seminal "Charney Report" (National Research Council, 1979) on the role of CO 2 and climate. The remarkable prescience of the Charney Report was noted upon its 40th anniversary (Nicholls, 2019). Specifically, the scientists who developed the report under the direction of the late Jule Charney predicted that, for a doubling of CO 2 in Earth's atmosphere, the Earth's surface air temperature would warm by approximately 3 C, with a probable error of 1.5 C. Prior to the Charney report, Sawyer (1972) made the case for a warming troposphere due to increasing CO 2 and presciently predicted 0.6 K warming by the year 2000. Remarkably, the most recent assessment of Earth's equilibrium climate sensitivity (ECS) (i.e., the average global surface air temperature change after a doubling CO 2 ) (Sherwood et al., 2020) sets its bounds between 2.3 and 4.5 C, nearly identical to the Charney report range. Verner Suomi's hypothesis statement, "carbon dioxide plays a significant role in the heat budget of the atmosphere" is true throughout the entire perceptible atmosphere from Earth's surface to the edge of space. It has long

Algorithm Stability and the Long-Term Geospace Data Record from TIMED/SABER

“…2. Finally, Mlynczak, Hunt, et al (2022) also note that temperature trends of this magnitude are inconsistent with the expected sensitivity of the mesosphere and lower thermosphere to a doubling CO 2 . The SABER team thus ruled out both anthropogenic CO 2 increase and a weaker solar minimum in 2019-2020 as the cause of the very large differences in temperatures at pressures less than 4 x 10 -3 hPa between 2009 and 2020 shown in Figure 1.…”

“…However, at pressures less than 4 x 10 -3 hPa (above 85 km) the data indicate the SABER temperature in 2020 is substantially colder than in 2009 by as much as 6 K. Solar cycle conditions, as indicated by the F10.7 index, were not markedly different in 2009 and 2020 (Mlynczak, Hunt, et al, 2022) as both years followed right after the occurrence of very quiet solar minimum conditions. The observed decreases in temperature of 2 K at 4 x 10 -4 hPa and 6 K at 10 -4 hPa from 2009 to 2020 correspond to the anticipated change from four or more decades of anthropogenic CO 2 increase based on trends reported by Mlynczak, Hunt, et al (2022) and Garcia, Yue et al, (2019). The temperature differences, particularly at pressures less than 4 x 10 -3 hPa are thus very difficult to explain based on solar activity or anthropogenic increases in CO 2 .…”

“…We chose to compare these two years because they are both near a solar minimum, such that any impact of the solar cycle on the temperature difference is expected to be small. From 10 hPa (approximately 30 km altitude) to 0.01 hPa (approximately 80 km altitude) the temperature differences are between -0.1 K and -0.9 K. The expected difference in temperatures from 2009 to 2020 over this altitude range from increasing anthropogenic CO 2 is between -0.5 K and -0.6 K (Garcia, Yue et al, 2019;Mlynczak, Hunt, et al, 2022). However, at pressures less than 4 x 10 -3 hPa (above 85 km) the data indicate the SABER temperature in 2020 is substantially colder than in 2009 by as much as 6 K. Solar cycle conditions, as indicated by the F10.7 index, were not markedly different in 2009 and 2020 (Mlynczak, Hunt, et al, 2022) as both years followed right after the occurrence of very quiet solar minimum conditions.…”

“…From 10 hPa (approximately 30 km altitude) to 0.01 hPa (approximately 80 km altitude) the temperature differences are between -0.1 K and -0.9 K. The expected difference in temperatures from 2009 to 2020 over this altitude range from increasing anthropogenic CO 2 is between -0.5 K and -0.6 K (Garcia, Yue et al, 2019;Mlynczak, Hunt, et al, 2022). However, at pressures less than 4 x 10 -3 hPa (above 85 km) the data indicate the SABER temperature in 2020 is substantially colder than in 2009 by as much as 6 K. Solar cycle conditions, as indicated by the F10.7 index, were not markedly different in 2009 and 2020 (Mlynczak, Hunt, et al, 2022) as both years followed right after the occurrence of very quiet solar minimum conditions. The observed decreases in temperature of 2 K at 4 x 10 -4 hPa and 6 K at 10 -4 hPa from 2009 to 2020 correspond to the anticipated change from four or more decades of anthropogenic CO 2 increase based on trends reported by Mlynczak, Hunt, et al (2022) and Garcia, Yue et al, (2019).…”

“…The first indication that there may be a problem with SABER temperatures for 2020 and onward came in developing the analyses reported recently by Mlynczak, Hunt, et al, (2022), who examined trends and changes in temperature and geopotential height measured by SABER from 2002 to 2021. Figure 1 shows the difference between the SABER Version 2.07 global annual mean temperatures in 2020 and 2009.…”