The environmental impact, carbon emissions and sustainability of computing in the ATLAS experiment

TL;DR

This paper discusses the environmental impact and carbon footprint of the ATLAS experiment's large-scale computing infrastructure, exploring mitigation strategies and sustainable practices for future upgrades.

Contribution

It evaluates the environmental impact of ATLAS's distributed computing resources and proposes mitigation strategies to reduce carbon emissions during HL-LHC upgrades.

Findings

Efforts to raise awareness about environmental impact within the community.

Adjustments in computing policies and data center configurations can reduce environmental footprint.

Investigations have led to actionable recommendations for sustainable computing in high-energy physics.

Abstract

ATLAS, a general-purpose experiment at the Large Hadron Collider (LHC), makes use of a large internationally-distributed computing infrastructure, including over $10^6$ TB of managed data on disk and tape and almost one million simultaneously running CPU cores. Upgrades for the High-Luminosity LHC (HL-LHC) will increase the required computing resources by a factor of 3-4 by the beginning of the 2030s, and by an order of magnitude before the conclusion of data taking at the beginning of the 2040s. These resources are spread over around 100 computing sites worldwide. Efforts are underway within the experiment to evaluate and mitigate various aspects of the environmental impact of the sites, with the additional long-term goal of making recommendations to the sites that will significantly reduce the total expected environmental impact in the HL-LHC era. These efforts take several forms: building awareness in the experiment community, adjusting aspects of the computing policy, and modifications of data center configurations, either in ways that take advantage of particular features of ATLAS workloads or in generic ways that reduce the environmental impact of the computing resources. This paper describes the ongoing investigations and approaches that have already provided useful and actionable outcomes.