The United Nations Framework Convention on Climate Change(1) calls for
''stabilization of greenhouse-gas concentrations in the atmosphere at
a level that would prevent dangerous anthropogenic interference with
the climate system...''. A standard base-line scenario(2,3) that assum
es no policy intervention to limit greenhouse-gas emissions has 10TW (
10 x 10(12) watts) of carbon-emission-free power being produced by the
year 2050, equivalent to the power provided by all today's energy sou
rces combined. Here we employ a carbon-cycle/energy model to estimate
the carbon-emission-free power needed for various atmospheric CO2 stab
ilization scenarios. We find that CO2 stabilization with continued eco
nomic growth will require innovative, cost-effective and carbon-emissi
on-free technologies that can provide additional tens of terawatts of
primary power in the coming decades, and certainty by the middle of th
e twenty-first century, even with sustained improvement in the economi
c productivity of primary energy. At progressively lower atmospheric C
O2-stabilization targets in the 750-350 p.p.m.v, range, implementing s
tabilization will become even more challenging because of the increasi
ng demand for carbon-emission-free power. The magnitude of the implied
infrastructure transition suggests the need for massive investments i
n innovative energy research.