Clean Cloud Computing Guide

What impact cloud computing has on the climate; what major providers are doing about it; and how to choose a clean provider and region


Cloud computing is also a unique market, with fast growth across the board but significant consolidation in a few large providers. Globally, the top four providers (Google’s Cloud Platform, Amazon Web Services, Microsoft Azure, Alibaba Cloud) account for 75 percent of the market, with Alibaba dominant in China. 

The climate impact of cloud services, measured by emissions produced by energy used, is directly tied to a few key factors: data center infrastructure (e.g., lights, cooling systems), server efficiency, and electricity source.

Due to steady improvements in the first two categories, such as server power requirements and scaling abilities, storage and network infrastructure efficiency, and building operations like cooling, U.S. data center electricity usage has remained relatively steady for the past five years, despite large increases in demand. These efficiency gains are impressive, but show that the source of energy used is the dominant factor in determining emissions.

A data center running off mostly coal and natural gas that is 10 times as energy efficient will still produce far more emissions than one powered entirely by solar or wind.

Google Cloud Platform (GCP), Amazon Web Services (AWS), and Microsoft Azure (Azure) account for two-thirds of cloud computing services and are the de facto choice for startups operating in the United States. As a result, this guide will focus on the “big three” providers: GCP, AWS, and Azure.

Summary of Recommendations
  • If you are choosing a new cloud provider solely with the aim of minimizing your immediate climate impact, GCP (100% renewable energy) performs better than Azure (100% carbon neutral but not necessarily renewable), which in turn performs better than AWS in last place (50% renewable energy in 2018).
  • For any provider, you can further reduce your emissions by choosing specific regions powered by cleaner electric grids. AWS users in particular can minimize their footprint through shifting usage to one of their five fully carbon-offsetted regions: US West (Oregon), Europe (Frankfurt), Europe (Ireland), GovCloud (US-West), Canada (Central).
  • Some companies further reduce their impact through direct purchases of renewable energy, used to power data centers in real time. E.g., Google published a report that shares detailed information on how they reduced emissions from grid energy through additional renewable energy purchases in places like Finland, Iowa, and North Carolina.
How to Use This Guide

In order to understand the climate impact of your cloud computing use, it is important to understand the efficiency and underlying energy choices of your cloud provider. This guide highlights some top-level goals and actions the biggest providers have taken, and shares specific examples of how different cloud provider and region choices affect cloud emissions. It also includes links to more comprehensive analysis of the top cloud providers.

  • Use this guide to understand the different efficiency and emissions goals set by the top cloud providers in the country: AWS, GCP, and Azure.
  • Browse the region-specific data to inform which cloud provider and data center regions to use (or switch to) when seeking to minimize emissions.
  • If you’d like to learn more, read the associated reports or reach out to your cloud provider to request more information.

This guide is primarily for those who rely on self-serve usage or cloud computing providers. If you instead build or operate your own data centers, or are a large enough purchaser to be able to directly influence your cloud provider, read about other actions you can take here.

Comparing Cloud Providers: The Big Three

Overall, both Google Cloud Platform (GCP) and Microsoft Azure (Azure) perform much better than Amazon Web Services (AWS) across all measures, despite Amazon holding the largest market share for cloud services. Google leads the charge on renewable energy, by already reaching their goal of 100 percent global renewable purchases. Microsoft recently launched a new Sustainability Calculator that significantly increases transparency of climate impact and reporting, and is the first and only provider to share emissions data with their users. Google and Microsoft have both already committed to net-zero emissions in all regions, while Amazon only does so for five regions. 

This chart summarizes some of the main climate attributes of the big three providers. For more detailed analysis, including letter grading and analysis of other top providers (inc., Oracle, IBM, Alibaba), check out The State of Data Center Energy Use in 2018 and Greenpeace’s Click Clean online guide.

Cloud Provider Comparison Guide
Regional Differences

Emissions produced by cloud data centers can vary widely depending on the region. Here are some interesting examples of the potential variance in emissions data from different U.S. regional locations and providers based on published grid emissions data and research.

  • Virginia is home to a large number of data centers, and shows the biggest difference in net emission across providers;
  • California features regions from all three providers, and far lower emissions than in Virginia;
  • Oregon is an available region for both Google and Microsoft and is one of the cleanest regions overall, both in terms of actual grid emissions and net emissions; and
  • Ohio is only an Amazon region and likely one of the dirtiest in the country.
U.S. Data Center Emissions By Provider and Region

The estimates above came from a calculated snapshot based on published AWS, GCP, and Azure region locations, the EPA’s Emissions & Generation Resource Integrated Database (eGRID) 2018 and Greenpeace’s Click Clean 2017. Emissions numbers were calculated using data retrieved in March 2020.

Explore the full U.S. Data Center Region Estimated Emissions dataset in Airtable.

What this might mean in practice:

  • For any given location, migrating from AWS to either GCP or Azure will shift your net emissions down to 0.
  • Even if you choose to stick with one provider, switching from one region to another can have a significant impact on your actual grid emissions. For instance, as a GCP user, switching from us-east4 (Virginia) to gcp-us-west-1 (Oregon) could reduce your grid emissions by almost 60 percent. An AWS user switching from aws-us-east-2 (Ohio) to aws-us-west-2 (Oregon) could save 75 percent.

Additional Resources