Energy implications of future stabilization of atmospheric CO2 content
Key finding. The standard no-policy baseline already assumes 10 terawatts of carbon-emission-free power by 2050 — equivalent to all of today's energy sources combined — and stabilizing atmospheric CO2 anywhere in the 750 to 350 parts-per-million range demands additional tens of terawatts of carbon-free primary power, even with sustained improvement in the economic productivity of energy.
What question did this research address?
The UN Framework Convention on Climate Change commits its parties to stabilizing greenhouse gas concentrations at a safe level, but says nothing about what that would take physically.
A concentration target is in the end a statement about energy supply: how much carbon-free power must exist, and by when. This paper asked what the standard stabilization targets imply in terawatts.
What did we find?
The result begins from an uncomfortable observation about the baseline. The IS92a scenario assumes no policy intervention at all, and it still contains 10 terawatts of carbon-free power by 2050 — as much as the entire present-day energy system.
A carbon-cycle and energy model is then used to estimate the carbon-free power required for a range of stabilization targets, so the answer is expressed in the units an energy system is actually built in.
Stabilization alongside continued economic growth requires innovative, cost-effective carbon-free technologies supplying additional tens of terawatts within decades, and certainly by mid-century.
The requirement grows steeply as the target tightens. Every step down through the 750 to 350 parts-per-million range raises the demand for carbon-free power.
Improving how much economic output each unit of primary energy delivers helps, but not enough to avoid the conclusion.
The authors read the scale of the implied infrastructure transition as an argument for massive investment in innovative energy research.
Why does it matter?
It reframed climate stabilization as an energy supply problem with a number attached. A concentration target sounds like an environmental goal; expressed in terawatts of carbon-free power it becomes an engineering and investment programme of a specific size.
The point about the baseline is the sharpest one, and still routinely missed. Scenarios described as business-as-usual already embed an enormous build-out of carbon-free energy, so the incremental cost of a climate target is smaller than it looks — and the unconditional task far larger.
Written in 1998, it set the framing that this group's later work continues to use, and the case for research investment rather than deployment alone follows directly from the size of the gap.
Citation
Martin I. Hoffert, Ken Caldeira, Atul K. Jain, Erik F. Haites, L. D. Danny Harvey, Seth D. Potter, Michael E. Schlesinger, Stephen H. Schneider, Robert G. Watts, Tom M. L. Wigley, and Donald J. Wuebbles (1998). Energy implications of future stabilization of atmospheric CO2 content. Nature 395, 881-884.
Related
- What would it take for the energy system to stop changing the climate?
- Advanced technology paths to global climate stability — energy for a greenhouse planet (Hoffert et al., 2002)
- Climate sensitivity uncertainty and the need for energy without CO2 emission (Caldeira et al., 2003)
- Net-zero emissions energy systems (Davis et al., 2018)