  The particle physics community has agreed that an electron-positron collider
is the next step for continued progress in this field, giving a unique
opportunity for a detailed study of the Higgs boson. Several proposals are
currently under evaluation of the international community. Any large particle
accelerator will be an energy consumer and so, today, we must be concerned
about its impact on the environment. This paper evaluates the carbon impact of
the construction and operations of one of these Higgs factory proposals, the
Cool Copper Collider. It introduces several strategies to lower the carbon
impact of the accelerator. It proposes a metric to compare the carbon costs of
Higgs factories, balancing physics reach, energy needs, and carbon footprint
for both construction and operations, and compares the various Higgs factory
proposals within this framework. For the Cool Copper Collider, the compact 8 km
footprint and the possibility for cut-and-cover construction greatly reduce the
dominant contribution from embodied carbon.
