  The presence and action of humans on Earth has exerted a strong influence on
the evolution of the planet over the past $\approx$ 10,000 years, the
consequences of which are now becoming broadly evident. Despite a deluge of
tightly-focused and necessarily technical studies exploring each facet of
"human impacts" on the planet, their integration into a complete picture of the
human-Earth system lags far behind. Here, we quantify twelve dimensionless
ratios which put the magnitude of human impacts in context, comparing the
magnitude of anthropogenic processes to their natural analogues. These ratios
capture the extent to which humans alter the terrestrial surface, hydrosphere,
biosphere, atmosphere, and biogeochemistry of Earth. In almost all twelve
cases, the impact of human processes rivals or exceeds their natural
counterparts. The values and corresponding uncertainties for these impacts at
global and regional resolution are drawn from the primary scientific
literature, governmental and international databases, and industry reports. We
present this synthesis of the current "state of affairs" as a graphical
snapshot designed to be used as a reference. Furthermore, we establish a
searchable database termed the Human Impacts Database (www.anthroponumbers.org)
which houses all quantities reported here and many others with extensive
curation and annotation. While necessarily incomplete, this work collates and
contextualizes a set of essential numbers summarizing the broad impacts of
human activities on Earth's atmosphere, land, water, and biota.
