Who We Are

Ken Caldeira

Coordinator of the Conceptual Investigations Unit

Ken Caldeira is the Coordinator of the Conceptual Investigations Unit, and a Visting Scholar at Stanford University housed in Steve Davis's Sustainable Solutions Lab. He is also a Senior Scientist at Gates Ventures.

ken@CIunit.org · caldeira@stanford.edu

Background

Prior to developing the Conceptual Investigations Unit and working at Gates Ventures, Ken was Senior Scientist at the Carnegie Institution for Science's Department of Global Ecology, and before 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 holds a PhD and Master's from New York University in atmospheric sciences, and a BA from Rutgers University, where he majored in philosophy.

Selected scientific contributions

Climate and carbon cycle

A modeling study of the climate response to longwave and shortwave radiative forcing at the altitude of aviation-induced cirrus clouds (Thomas et al., 2025).
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).
The first study to demonstrate that combustion of fossil-fuel resources could potentially melt the entire Antarctic ice sheet (Winkelmann et al., 2015).
Foundational work underlying the concept of the "carbon budget" — including the observation that physics and chemistry work in opposite directions, making the warming effect of a CO₂ emission largely insensitive to background scenario (Caldeira and Kasting, 1993), and that therefore each emission causes another increment of warming, so avoiding additional warming requires near-zero emissions (Matthews and Caldeira, 2008).
The first coupled three-dimensional climate–carbon model simulations of the combined biogeochemical and biophysical effects of deforestation (Bala et al., 2007).
The first estimation of the lifetime of a perturbation to atmospheric CO₂ concentrations in the combined atmosphere/ocean/land system resulting from fossil carbon emissions — about 300,000 years (Caldeira and Rampino, 1990).

Climate and energy

Studies examining constraints on wind and/or solar electricity generation from a geophysical perspective (Shaner et al., 2018; Tong et al., 2021; Antonini et al., 2024).
The first study to look at future commitment to emissions embodied in global infrastructure (Davis et al., 2010; see also Tong et al., 2019).
Reviews of energy systems that could potentially meet human needs without interfering in the climate system (Hoffert et al., 2002; Davis et al., 2018).
Studies on extraction-, production-, and consumption-based accounting of fossil carbon emissions (Davis and Caldeira, 2010; Davis et al., 2011).
The first peer-reviewed publication examining CO₂ emissions and carbon-emission-free energy requirements to meet temperature stabilization targets, focused on a 2 °C target (Caldeira et al., 2003).
The first peer-reviewed publication estimating how much carbon-free power would be needed to stabilize atmospheric CO₂ concentrations (Hoffert et al., 1998).

Climate and economics

Studies estimating the timescale for economic return on emissions abatement vs. climate adaptation, concluding that abatement benefits are mostly more than half a century away (Brown et al., 2020) whereas adaptation provides rapid returns (Duan et al., 2025).
An analysis of how economic development — through greater adoption of air conditioning — can offset the heat-related impacts of warming, introducing a "Cooling Deficit Index" to identify where high temperatures are most experienced without cooling (Wongel et al., 2025).
An examination of predictive skill in technology learning rates, finding that past learning rates are poor predictors of future learning rates (Carlino et al., 2025).
A simple integrated-assessment model illustrating how technology-cost reductions — i.e., reducing the "Green Premium" — can contribute to emissions abatement (Caldeira et al., 2023).
An analysis of how much more emissions would occur if only the wealthier countries mitigated their greenhouse-gas emissions (Duan et al., 2020).
A study applying Nordhaus's approach to estimating climate effects on GDP to population density instead, as an indicator of incentive for future climate migration (Chen and Caldeira, 2020).
A study showing that policy-induced energy-saving efficiency improvements can amplify the effectiveness of climate-change mitigation (Wang et al., 2019).
A study providing a rational basis for valuing temporary carbon storage (Herzog et al., 2003).

Solar geoengineering

"The Science of Solar Geoengineering" — a review paper (Caldeira et al., 2013).
A study examining the development of fast responses to changes in solar irradiance and atmospheric CO₂ on the time scale of days to weeks (Cao et al., 2012).
A study providing evidence that solar geoengineering might increase crop yields (Pongratz et al., 2012).
The first modeling study to consider solar geoengineering as an optimization problem (Ban-Weiss and Caldeira, 2010).
The first study bringing attention to the "termination shock" risk of sudden cessation of solar geoengineering (Matthews and Caldeira, 2007).
The first three-dimensional climate-model simulations of solar geoengineering (Govindasamy and Caldeira, 2000).

Ocean acidification and the ocean carbon cycle

The first experiments to add CO₂ and alkalinity to the natural marine environment and measure biological consequences on a coral reef without artificial confinement (Albright et al., 2016; Albright et al., 2018).
Evidence that CO₂ concentrations could reach levels this century sufficient to push coral reefs outside the range observed to support their survival through geologic time (Ricke et al., 2013).
Coordinating Lead Author of the Ocean Storage chapter of the IPCC Special Report on Carbon Dioxide Capture and Storage (Caldeira et al., 2005).
A key study bringing attention to the problem of ocean acidification (Caldeira and Wickett, 2003), which grew out of earlier work on the end-Cretaceous mass extinction event (Caldeira and Rampino, 1993).
Evidence of isopycnal mixing making the Southern Ocean a key locus of carbon uptake from the atmosphere (Caldeira and Duffy, 2000).
Evidence 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).

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).
The first global modeling study showing where in the atmosphere the available potential energy that drives winds is generated (Ahbe and Caldeira, 2017).

Paleoclimate and Earth-system dynamics in geologic time

A series of studies evaluating the statistical likelihood of periodicities in the geologic record (Rampino and Caldeira, 1993; 2015; Rampino et al., 2021).
Evidence that terrestrial plants limited the decrease in atmospheric CO₂ over the past 24 million years (Pagani et al., 2009).
A study looking at end-Permian warming as evidence that either climate sensitivity is very high or cyclic methane from wetlands contributed to end-Permian warming (Pagani et al., 2006).
Evidence that marine plankton help to stabilize climate on geologic time scales (Ridgwell et al., 2003).
A study updating Jim Lovelock's estimation of the lifespan of the biosphere, considering silicate-weathering feedbacks (Caldeira and Kasting, 1992).
Evidence that the subduction of carbonate minerals may be increasing CO₂ degassing in subduction zones (Caldeira, 1992).
A study showing that Gaian temperature homeostasis could not be the explanation for planktonic sulfur releases (Caldeira, 1989).

Macro-energy modeling

A stylized assessment of concentrated solar thermal energy with molten-salt storage for supplying carbon-free industrial process heat in competition with natural gas (Wongel et al., 2026).
Evidence of the importance of long-duration (seasonal and longer) energy storage in electricity systems reliant on wind and solar generation (Dowling et al., 2020), and evidence that such storage could also potentially meet short-duration storage needs (Li et al., 2024).
Evidence that nuclear power could be useful in zero-emission electricity systems, especially in locations with poor wind resources, and especially if the cost of nuclear generation could be reduced (Duan et al., 2022).
Evidence that the amount of battery deployed in a wind- and solar-based electricity system may be approximately inversely proportional to battery cost — so that, over a broad range, the total resources allocated to batteries are largely independent of battery cost (Tong et al., 2020).