Ken Caldeira

Ken Caldeira is a Visiting Scholar at Stanford University. He is the Coordinator of the Conceptual Investigations Unit of Steve Davis’s Sustainable Solutions Lab. Caldeira is also a Senior Scientist at Gates Ventures.

Prior to working at Gates Ventures, Ken was Senior Scientist at Carnegie Institution for Science’s Department of Global Ecology. Preceding that he was in the Energy and Environment Directorate of Lawrence Livermore National Laboratory. He did a postdoc in the Department of Geosciences at Penn State University. He has a PhD and Masters from New York University in Atmospheric Sciences, and a BA from Rutgers University where he majored in Philosophy.

Some of Ken’s key scientific accomplishments include:

Climate and carbon-cycle

• The first estimation of the lifetime of a perturbation to carbon dioxide concentrations in the combined atmosphere/ocean/land system resulting from fossil carbon emissions (about 300,000 years) (Caldeira and Rampino, 1990).
• The first coupled three-dimensional climate-carbon model simulations of the combined biogeochemical and biophysical effects of deforestation (Bala et al., 2007).
• Key foundational work underlying the concept of the “carbon budget”, including the observation that physics and chemistry work in opposite direction making the warming effect of a carbon dioxide emission largely insensitive to background scenario (Caldeira and Kasting, 1993) and that therefore each carbon dioxide emission causes another increment of warming, and thus to avoid more warming, at some point, we will need near-zero emissions (Matthews and Caldeira, 2008).
• The first study to demonstrate that combustion of fossil fuel resources can potentially melt the entire Antarctic ice sheet (Winkelmann et al., 2015).
• A collection of studies examining fast and slow responses of the climate system to changes in radiative forcing (Cao et al., 2011; Cao et al., 2015; Rugenstein et al., 2016).

Climate and energy

• The first peer-reviewed publication estimating how much carbon-free power would be needed to stabilize atmospheric carbon dioxide concentrations (Hoffert et al., 1998).
• The first peer-reviewed publication to examine carbon dioxide emissions and carbon-emission-free energy requirements to meet temperature stabilization targets, focusing on a 2 C target (Caldeira et al., 2003).
• The first study to look at future commitment to emissions embodied in global infrastructure (Davis et al., 2010; see also Tong et al., 2019).
• Key studies looking at extraction, production, and consumption based accounting of fossil carbon emissions (Davis and Caldeira, 2010; Davis et al., 2011)
• Reviews of energy systems that could potentially meet human needs without interfering in the climate system (Hoffert et al., 2002; Davis et al., 2018).
• Key studies looking at geophysical limits of wind and/or solar energy production (Shaner et al., 2018; Tong et al., 2021; Antonini et al., 2024). 

Climate and economics

• A study providing a rational basis for valuing temporary carbon storage (Herzog et al., 2003).
• How much more emissions would occur if only the more wealthy countries mitigated their greenhouse gas emissions (Duan et al., 2020)?
• What would Nordhaus’s approach to estimating climate effects on GDP were applied instead to population density as indicator of incentive for future climate migration (Chen and Caldeira, 2020)?
• A study using a simple integrated assessment model to illustrate how technology cost reductions (i.e., reducing the Green Premium) can contribute to emissions abatement (Caldeira et al.,2023).
• Studies estimating the timescale for economic return on emissions abatement on climate adaptation, concluding that emission abatement benefits are mostly more than a half-century away (Brown et al., 2020) whereas adaptation provides rapid returns (Duan et al., 2025).

Solar geoengineering

• The first three-dimensional climate model simulations of solar geoengineering  (Govindasamy and Caldeira, 2000).
• The first study bringing attention to the “termination shock” risk of sudden cessation of solar geoengineering (Matthews and Caldeira, 2007).
• The first modeling study to consider solar geoengineering as an optimization problem (Ban-Weiss and Caldeira, 2010).
• Study examining the development of fast responses to change in solar irradiance and atmospheric carbon dioxide content on the time scale of days to weeks (Cao et al., 2012).
• Study providing evidence that solar geoengineering might be expected to increase crop yields (Pongratz et al., 2012).
• Review paper on “The Science of  Solar Geoengineering (Caldeira et al, 2013).

Ocean acidification and ocean carbon cycle

• A key study bringing attention to the problem of ocean acidification (Caldeira and Wickett, 2003), which grew out of earlier work studying the end-Cretaceous mass extinction event (Caldeira and Rampino, 1993).
• Study providing evidence that carbon dioxide concentrations could reach levels this century to cause enough ocean acidification to put coral reefs outside of the range that they were observed to survive through geologic time (Ricke et al., 2013).
• The first experiments to add carbon dioxide and alkalinity to the natural marine environment, and measure biological consequences [to a coral reef] in the absence of any artificial confinement (Albright et al., 2016; Albright et al., 2018).
• Study showing that brine rejection from Antarctic sea ice has the potential to influence the salinity, and therefore the density, structure of the global ocean (Duffy and Caldeira, 1997).
• Study providing evidence of isopycnal mixing making the Southern Ocean a key locus of carbon uptake from the atmosphere (Caldeira and Duffy, 2000).

Geophysics of wind power

• A collection of studies examining theoretical physical limits to the availability of wind power (Marvel et al., 2013; Possner and Caldeira, 2017; Antonini and Caldeira, 2021a; Antonini and Caldeira, 2021b).

Paleoclimate and Earth system dynamics in geologic time

• Study showing that Gaian temperature homeostasis could not be the explanation for planktonic sulfur releases (Caldeira, 1992).
• Study updating Jim Lovelock’s estimation of the lifespan of the biosphere, considering silicate weathering feedbacks (Caldeira and Kasting, 1992).
• Study providing evidence that the subduction of carbonate minerals may be increasing carbon dioxide degassing in subduction zones (Caldeira, 1992).
• Study providing evidence that marine plankton help to stabilize climate on geologic time scales (Ridgwell et al., 2003).
• Study looking at end-Permian warming as evidence that either climate sensitivity is very high, or perhaps cyclic methane from wetlands contributed to end-Permian warming (Pagani et al., 2006).
• Study providing evidence that terrestrial plants limited the decrease in atmospheric carbon dioxide content over the past 24 million years (Pagani et al., 2009).
• A number of studies evaluating statistical likelihood of periodicities observed in the geologic record of the Earth (Rampino and Caldeira, 1993; 2015; Rampino et al., 2021).

Macro-energy modeling

• Study providing evidence that amount of battery deployed in a wind and solar based electricity system may be approximately inversely proportional to battery cost, with the result that, over a broad range, the total amount of resources allocated to batteries is largely independent of battery cost (Tong et al., 2020).
• Study providing evidence that nuclear power could be useful in zero-emission electricity systems especially in locations with poor wind resources, and especially if costs of nuclear generation could be decreased (Duan et al, 2022).
• Study providing evidence of the importance of long-duration (i.e., seasonal and longer) energy storage in electricity systems reliant on wind and solar generation (Dowling et al, 2020) and study showing that that storage could also potentially meet short-duration storage needs (Li et al., 2024).