How to Assess the Carbon Footprint of a Large-Scale Physics Project

TL;DR

This paper presents a methodology for estimating the main greenhouse gas emissions of large-scale physics projects, focusing on travel, digital, and hardware sources to identify major environmental impacts.

Contribution

It introduces a transparent, open-data-based approach to assess and compare the primary controllable GHG emission sources in large astrophysics collaborations.

Findings

Travel is the largest emission source.

Digital activities contribute significantly to GHG emissions.

Hardware production and use also impact the project's carbon footprint.

Abstract

Large-scale experiments are building blocks of the physics community: they involve a large fraction of the scientific staff working in multiple countries, and absorb a significant volume of the science budget. They are also a collection of carbon-emitting sources and practices. As such, it is essential to assess their environmental impact. We describe here a methodology to estimate the main greenhouse gas (GHG) emissions of a large-scale astrophysics collaboration project, using transparent open data. The goal is neither to consider all possible emission sources of a project, nor to calculate accurate values. It is rather to identify the biggest emission sources of the project, obtain orders of magnitude for them and analyse their relative weights. We discuss methods to quantify the GHG-generating activities and their related emission factors for the three typical biggest emission sources that can be controlled by the collaboration: travel, digital and hardware.