The Anthropocene by the Numbers: A Quantitative Snapshot of Humanity's Influence on the Planet

TL;DR

This paper provides a comprehensive quantitative overview of human impacts on Earth by analyzing twelve key ratios that compare anthropogenic effects to natural processes, highlighting the extent of human influence across various planetary systems.

Contribution

It introduces a novel set of twelve dimensionless ratios to quantify and contextualize human impacts on Earth's systems, supported by a curated database for reference.

Findings

Human impacts often rival or exceed natural processes.

Quantitative metrics are provided for global and regional impacts.

A publicly accessible database consolidates these impact measures.

Abstract

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.