Few organizations truly understand the quantity of carbon emissions they are producing through their use of cloud computing. Cloud service providers’ cloud carbon calculators are part of the problem.

Cloud computing alone already produces half the level of global emissions of the aviation industry (IEA, 2024), through a vast network of energy-intensive data centers. However, the detachment between user and data center that cloud services facilitate means that cloud computing carbon emissions are, to many organizations, an unknown unknown. For an organization to be truly accountable for its environmental impact, it must recognize, account for, and reduce all carbon emissions it is responsible for, including through cloud computing. 

The three major cloud service providers (CSPs) – Amazon Web Services (AWS), Microsoft Azure, and Google Cloud Platform (GCP) – all offer cloud carbon calculator tools. These tools enable their customers to understand the carbon emissions that have been emitted as a consequence of their use of the cloud computing services. There are varying degrees of quality between CSPs’ carbon tools, and shortcomings can be identified across five critical areas: accuracy, completeness, granularity, timeliness, and recommendations. 

Accuracy 

The most important aspect of a carbon emissions calculation is accuracy. To assess a CSP’s carbon calculator accuracy, their methodology must be made publicly available. AWS does not publicly release how it calculates customers’ carbon emissions, meaning that its methodology cannot be assessed for accuracy. Azure utilizes a customer distribution method, allocating responsibility for emissions proportionally to a customer’s usage as a percentage of all of Azure’s customers’ usage. This does not account for the wildly varying levels of emissions for different cloud services that utilize different hardware. GCP uses a more refined methodology based on the percentage of CPU time used by the customer’s service per hour, broadly in line with Tailpipe’s methodology.  

Tailpipe’s Grading: Accuracy 

Completeness 

A complete calculation of carbon emissions will consider both operational (Scope 1 and 2) and embodied (Scope 3) emissions, accounting for the various factors that contribute to both categories. AWS does not account for any embodied emissions in their calculation and does not disclose which aspects of operational emissions they account for. Azure and GCP both account for operational and embodied emissions, but across different definitions.  

Azure covers: 

Scope 1 – diesel fuel and fugitive emissions from cooling. 

Scope 2 – direct power consumption used to power the data centers that Microsoft leases and owns. 

Scope 3 – raw material extraction, select component aggregation, and end-of-life management. 

GCP covers: 

Scope 1 – all fossil fuels combusted on-site and fugitive emissions from cooling. 

Scope 2 – direct power consumption used to power GCP hardware in facilities that Google leases and owns, and in facilities owned by others. 

Scope 3 – Upstream lifecycle of data center hardware and buildings, business travel and commuting associated with data center employees, and the extraction, production, and transportation of fuels used to generate grid electricity. 

Tailpipe’s Grading: Completeness 

Granularity 

When it comes to granularity, no CSP provides a breakdown of their final emissions at the component level. Azure and GCP both provide some granularity by delivering separate carbon emission figures for Scope 1, 2, and 3. AWS only delivers one total emissions figure. This means that customers cannot tell which operational aspects of their cloud computing usage – such as storage, networking, or memory – are contributing to most of their emissions. 

Tailpipe’s Grading: Granularity 

Timeliness 

The data that CSPs provide can have a long latency. In AWS’s case, up to 90 days. Azure and GCP both deliver data on a monthly basis. This can prevent customers from being able to assess the carbon effectiveness of their operations in a timely manner. It can also interfere with customers’ legal or voluntary emissions reporting deadlines. 

Tailpipe’s Grading: Timeliness 

Recommendations 

Having delivered a carbon emission figure, only GCP suggests how a customer could then reduce their carbon emissions. AWS and Azure do not. This, in addition to the lack of granularity, means that the carbon figures delivered to customers by AWS and Azure have little practical viability – they cannot be translated into action to reduce carbon. All three CSPs do provide their customers with rightsizing data to help them find the most cost-effective solution to their cloud computing needs. However, no CSP cross references this cost effectiveness against carbon effectiveness, meaning that customers must decide for themselves whether to prioritize carbon or cost. 

Tailpipe’s Grading: Recommendations 

Example: AWS’ Customer Carbon Footprint Tool

As an example, compare the carbon emission figure that AWS provides for Tailpipe’s own cloud services, to the one Tailpipe calculates for itself. Tailpipe has been utilizing 12 AWS EC2 instances since January 2024. AWS claims that Tailpipe’s use of its cloud computing services from January 2024 to June 2024 (the latest date that AWS provides data for) is 0 kgCO2e. In contrast, Tailpipe’s own figure for just the month of September 2024 is 30.18 kgCO2e. This would suggest that from January to June 2024, Tailpipe’s use of cloud computing generated approximately 181.08 kgCO2e. See Tailpipe’s Emissions Explained for a breakdown of how this figure was calculated.

The only way that AWS’s figure of zero carbon emissions could be correct is if 100% of the energy that AWS used to power its data centers in that period came from renewable energy sources. Tailpipe is able to map that its use of cloud services was hosted from data centers in the AWS Regions of Virginia, Stockholm, London, and Ireland, which have energy grids that range from very carbon intensive to very sustainable. AWS states that as of 2023, ‘all of the electricity consumed by Amazon’s operations, including its data centers, was matched with 100% renewable energy’.  

This allows AWS to claim that Tailpipe’s use of cloud computing produced no emissions – but matching renewable energy is not the same as using renewable energy. AWS matches renewable energy by investing in renewable energy sources worldwide that produce the same number of gigawatts of low-or-no carbon energy as they operationally consume through fossil fuel energy sources. This means that Tailpipe’s use of cloud services released CO2 into the atmosphere, regardless of the renewable energy generation that was funded elsewhere by AWS. 

Tailpipe as a Solution 

Tailpipe was developed to address each of the five issues that CSP carbon calculators present, providing customers with accurate, complete, granular, timely, and actionable data on the carbon emissions resulting from their use of cloud services. Tailpipe’s comprehensive methodology is publicly available, ensuring full transparency, and accounts for the broad spectrum of cloud computing hardware and use cases.  

Tailpipe then delivers granular results at the component and service level, using hourly data as a basis and aggregating to a daily view. With these results, Tailpipe provides tailored recommendations that help organizations reduce their carbon emissions and cloud spend. These recommendations are provided on a sliding scale that can prioritize carbon and cost effectiveness in relation to one another.  

In addition, whilst Tailpipe currently supports AWS, it is developing a multi-cloud comparison system that will allow customers to compare the carbon emissions – and cost – of the same services across AWS, Azure, and GCP. With Tailpipe’s insights, organizations can take accountability for their emissions, saving money and reducing emissions simultaneously. 

To find out what Tailpipe can do to measure and reduce your cloud computing spend and emissions, get in touch with us here.