Sunday, August 8, 2021

Max Planck Institut's MPI-M Earth System Model v1.2: To prevent a sensitivity of 7C in average temperature instead of the right value (2.77C), an atmospheric parameter had to be tuned by a factor of 10 (!)

Mauritsen, T., Bader, J., Becker, T., Behrens, J., Bittner, M., Brokopf, R., et al. (2019). Developments in the MPI-M Earth System Model version 1.2 (MPI-ESM1.2) and its response to increasing CO2. Journal of Advances in Modeling Earth Systems, 11, 998–1038.

Abstract: A new release of the Max Planck Institute for Meteorology Earth System Model version 1.2 (MPI ESM1.2) is presented. The development focused on correcting errors in and improving the physical processes representation, as well as improving the computational performance, versatility, and overall user friendliness. In addition to new radiation and aerosol parameterizations of the atmosphere, several relatively large, but partly compensating, coding errors in the model's cloud, convection, and turbulence parameterizations were corrected. The representation of land processes was refined by introducing a multilayer soil hydrology scheme, extending the land biogeochemistry to include the nitrogen cycle, replacing the soil and litter decomposition model and improving the representation of wildfires. The ocean biogeochemistry now represents cyanobacteria prognostically in order to capture the response of nitrogen fixation to changing climate conditions and further includes improved detritus settling and numerous other refinements. As something new, in addition to limiting drift and minimizing certain biases, the instrumental record warming was explicitly taken into account during the tuning process. To this end, a very high climate sensitivity of around 7 K caused by low-level clouds in the tropics as found in an intermediate model version was addressed, as it was not deemed possible to match observed warming otherwise. As a result, the model has a climate sensitivity to a doubling of CO2 over preindustrial conditions of 2.77 K, maintaining the previously identified highly nonlinear global mean response to increasing CO2 forcing, which nonetheless can be represented by a simple two-layer model.

3.6 Atmospheric Model Tuning

A major retuning of the model was required because all modifications taken together caused a decrease of the global top-of-atmosphere radiation budget by about 10 W/m2 due mainly to the corrected cloud fraction scheme (section 3.1) and also because the model climate sensitivity had roughly doubled to around 7 K, which would have prevented a reasonable match to the instrumental record warming. If the latter had not been addressed, the model's historical warming would have roughly exceeded that observed by a factor of 2. When reducing the historical warming in a model there are essentially three options: reduce forcing, increase deep ocean heat uptake efficiency, or reduce the climate sensitivity. The forcing can be reduced by increasing aerosol cooling by enhancing the indirect effect, but at the time (2014–2015) we did not have such a parameterization in the model, which was developed after that (section 3.3). Further, ocean heat uptake already exceed that observed (Giorgetta et al., 2013), and so we were left with reducing the climate sensitivity. Since the predecessor MPI-ESM model warmed slightly more than observed, and it had a sensitivity of 3.5 K, we decided to aim at an equilibrium climate sensitivity of around 3 K. The reduction of the model's sensitivity was primarily achieved by increasing the entrainment rate for shallow convection by a factor of 10, from 3 × 10−4 m−1 in ECHAM6.1 to 3 × 10−3 m−1 in ECHAM6.3, with the purpose to reduce tropical low-level cloud feedback. But also other convective cloud parameters, mixed-phase cloud processes, and the representation of stratocumulus were found to be important.

Women learn while men talk?: Women appear to need a sense of higher levels of competence in order to engage with online political content, especially for sharing and commenting

Women learn while men talk?: revisiting gender differences in political engagement in online environments. Darren Lilleker et al. Information, Communication & Society, Aug 7 2021.

Abstract: There is an inconclusive debate on whether male and female users of social media platforms engage with political content differently. While some highlight minimal differences, others evidence an engagement gap where male are more visible within online environments. Drawing on data from a representative survey of citizens in France, the UK and USA, we explore the engagement gap in more granular detail. Our data show minimal gender differences for most forms of online political engagement, but there remain some indications of a gendered divide. While the feeling of external efficacy is crucial to engage online regardless gender, women appear to need a sense of higher levels of competence in order to engage with online political content, especially for sharing and commenting. The study confirms interest in politics, extreme political ideological views and large social media network as prompt for more eager political engagement, but we do not find any substantial gender differentiation. Our findings suggest some minimal country differences on women engagement in commenting. Overall, our data indicate that while women may be as likely as men to participate in online political expression, through sharing and commenting, and may have an equal overall share of voice, the voices of many women are at least more muted in open public political discussions environment.

KEYWORDS: Gender gapsocial mediapolitical engagementpolitical activity

News Avoidance during the Covid-19 Crisis: Understanding Information Overload—News avoidance indeed has a positive effect on perceived well-being

News Avoidance during the Covid-19 Crisis: Understanding Information Overload. Kiki de Bruin et al. Digital Journalism, Aug 6 2021.

Abstract: This study investigates the degree of news avoidance during the first months of the Covid-19 pandemic in the Netherlands. Based on two panel surveys conducted in the period April–June 2020, this study shows that the increased presence of this behavior, can be explained by negative emotions and feelings the news causes by citizens. Moreover, news avoidance indeed has a positive effect on perceived well-being. These findings point to an acting balance for individual news consumers. In a pandemic such as Covid-19 news consumers need to be informed, but avoiding news is sometimes necessary to stay mentally healthy.

Keywords: Covid-19 crisisinformation overloadinfodemicnews avoidancenews consumptionwell-being

Check also COVID-19: 91pct of stories by US major media outlets are negative in tone vs 65pct for scientific journals; stories of increasing cases are 5.5x stories of decreasing cases even when new cases are declining

Why Is All COVID-19 News Bad News? Sacerdote, Bruce and Sehgal, Ranjan and Cook, Molly. National Bureau of Economic Research, Working Paper 28110, Nov 2020.