Hi! I'm Jonah Bloch-Johnson (he/him), a climate scientist living in Boston, Massachusetts, USA. I am currently the Chang Family Assistant Professor in the Department of Earth and Climate Sciences at Tufts University. I previously worked at the UK's National Centre for Atmospheric Science, in the Department of Meteorology at the University of Reading, in Jonathan Gregory's group.

My research is focused on state-dependent climate sensitivity, which is the study of how the severity of climate change depends on the background conditions when it occurs. State-dependent sensitivity can arise due to nonlinearities in the response of humidity, cloudiness, and ice cover to carbon dioxide and surface temperature changes, and can lead to particularly extreme warming scenarios, including runaway warming.

My past research explored how climate sensitivity can depend on where warming occurs (the "pattern effect"; see papers [16] and [6] below) and on how much temperature change has already occurred ("feedback temperature dependence"; see papers [10] and [1]). For more information, you can watch my April 2023 talk to the ECS Symposium or my talk for the 2021 AGU Fall Meeting.

I am the lead organizer of the forthcoming Green's Function Model Intercomparison Project (GFMIP), which explores the response of the atmosphere to the spatial field of sea surface temperature change. I worked with Maria Rugenstein to create the LongRunMIP data archive, which was the first collection of thousand-plus year simulations of coupled atmosphere-ocean general circulation models. I help organize the ECS Symposium, a monthly climate dynamics discussion group. I also was the lead organizer of the first Rossbypalooza summer school.

I work with Eric Potash on Is The Weather Weird?, which allows you to see how weird the current temperature in a number of locations is compared to the past. Thanks for reading, and feel free to send me an email at me@jonah.org.

Publications

in preparation
  1. Bloch-Johnson and Gregory:
       Nonlinear Climate Sensitivity. Part 2: A Closer Look at Spatial Feedbacks
  2. Bloch-Johnson and Gregory:
       Nonlinear Climate Sensitivity. Part 1: A Taxonomy
  3. Risi and co-authors, including Bloch-Johnson:
       Amplification of temperature changes with altitude in the tropics and subtropics
2024
  1. Bloch-Johnson, Rugenstein, Alessi, Proistosescu, Zhao, Zhang, Williams, Gregory, Cole, Dong, Duffy, Kang, and Zhou:
       The Green's Function Model Intercomparison Project (GFMIP) Protocol, Journal of Advances in Modeling Earth Systems
2023
  1. Gregory, Bloch-Johnson, Couldrey, Exarchou, Griffies, Kuhlbrodt, Newsom, Saenko, Suzuki, Wu, Urakawa, and Zanna:
       A new conceptual model of global ocean heat uptake, Climate Dynamics
  2. Cael, Bloch-Johnson, Ceppi, Fredriksen, Goodwin, Gregory, Smith, and Williams:
       Energy budget diagnosis of changing climate feedback, Science Advances
  3. Williams, Jeevanjee, and Bloch-Johnson:
       Circus tents, convective thresholds and the non-linear climate response to tropical SSTs, GRL
2022
  1. Bloch-Johnson, Rugenstein, Gregory, Cael, and Andrews:
       Climate impact assessments should not discount 'hot' models, correspondence in Nature, in reply to Hausfather et al. 2022
  2. Cael, Britten, Calafat, Bloch-Johnson, Stainforth, and Goodwin:
       Climate nonlinearities: selection, uncertainty, projections, and damages, ERL
2021
  1. Bloch-Johnson, Rugenstein, Stolpe, Rohrschneider, Zheng, and Gregory:
       Climate sensitivity increases under higher CO2 levels due to feedback temperature dependence, GRL (SI: )
  2. Callahan, Chen, Rugenstein, Bloch-Johnson, Yang, Stein, and Moyer:
       Robust decrease in El-Niño/Southern Oscillation amplitude under long-term warming, Nature Climate Change
  3. Schwarzwald, Poppick, Rugenstein, Bloch-Johnson, Wang, McInerney, and Moyer:
       Changes in future precipitation mean and variability across scales J. Climate
  4. Zhang, Bloch-Johnson, Romps, and Abbot:
       Evolving CO2 Rather Than SST Leads to a Factor of Ten Decrease in GCM Convergence Time, JAMES
2020
  1. Bloch-Johnson, Rugenstein, and Abbot:
       Spatial radiative feedbacks from internal variability using multiple regression, J. Climate (SI: )
2019
  1. Rugenstein, Bloch-Johnson, Gregory, Andrews, Mauritsen, Li, Frölicher, Paynter, Danabasoglu, Yang, Dufresne, Cao, Schmidt, Abe-Ouchi, Geoffroy, and Knutti:
       Equilibrium climate sensitivity estimated by equilibrating climate models, GRL
  2. Rugenstein, Bloch-Johnson, Abe-Ouchi, Andrews, Beyerle, Cao, Chadha, Danabasoglu, Dufresne, Duan, Foujols, Frölicher, Geoffroy, Gregory, Knutti, Li, Marzocchi, Mauritsen, Menary, Moyer, Nazarenko, Paynter, Saint-Martin, Schmidt, Yamamoto, and Yang:
       LongRunMIP - motivation and design for a large collection of millennial-length AO-GCM simulations, BAMS
2018
  1. Abbot, Bloch-Johnson, Checlair, Farahat, Graham, Plotkin, Popovic, and Spaulding-Astudillo:
       Decrease in hysteresis of planetary climate for planets with long solar days, The Astrophysical Journal
2017
  1. Köhler, Stap, von der Heydt, de Boer, van de Wal, and Bloch-Johnson:
       A state-dependent quantification of climate sensitivity based on paleodata of the last 2.1 million years, Paleoceanography
2015
  1. Bloch-Johnson, Pierrehumbert, and Abbot:
       Feedback temperature dependence determines the risk of high warming, GRL