Cloud computing could be producing hidden greenhouse gas emissions


Server racks in a data centre

The amount of energy used for cloud computing, which contributes to climate change, needs to be more transparent says an Imperial researcher.

Information technology (IT) services are increasingly outsourced to huge data centres, but it is not clear how much energy these are using, or what greenhouse gas emissions they are responsible for.

David Mytton, Environmental Technology MSc student in the Centre for Environmental Policy, recently published a letter in Nature Climate Change about what progress has been made to reduce emissions from large data centres, but how more transparency is needed in accounting for emissions. Hayley Dunning spoke to David to find out more about the current situation and potential future for data centres.

What are data centres and how might they contribute to climate change?

When you run applications on your phone or laptop, the software is using the physical memory and processor inside the device. The same thing happens whenever you access services on the Internet, except those physical resources are located inside servers, which are big machines. Those servers need to be located somewhere, and those places are called data centres. These range in size from small 10m2 cabinets all the way to massive 40,000 m2 warehouses.

There are millions of servers in data centres all over the world, all of which need electricity to run. Estimates vary but the most commonly cited figure suggests that amounts to around 200 TWh/yr, or around one percent of global electricity demand, and that this may grow to between 15-30% of electricity consumption in some countries by 2030.

Data centre energy is a major component of the environmental footprint of data centres, although there are several others such as manufacturing of equipment and water consumption for cooling. The use of renewables for electricity generation is growing in general, but most electricity is still generated by fossil fuels, all of which contributes to climate change.

How are greenhouse gas emissions from data centre use accounted for?

Companies can create greenhouse gas emissions inventories to account for their contribution to climate change, which large organisations are required to report publicly in the UK.

If an organisation owns their own data centre, they can account for their emissions under the three scopes of the Greenhouse Gas Protocol. Scope 1 emissions are from activities that the organisation controls, such as backup generators or air conditioning units on site. Scope 2 covers the indirect emissions from the electricity the organisation purchases. All other indirect emissions, such as purchasing servers and other equipment, will fall under Scope 3.

Fewer people are running their own data centres because it makes sense for most organisations to use the cloud. Where an organisation is using the cloud for their IT, all those emissions are grouped under Scope 3. Where large organisations are required to report those emissions publicly, they are usually only required to report Scope 1 and Scope 2 emissions. Scope 3 emissions do not have to be publicly reported.

Some data centres and cloud computing services claim to be greener – what sorts of measures are they taking?

The big cloud computing companies – Amazon, Google and Microsoft – are some of the largest purchasers of renewable energy. Although it does not guarantee that all energy going into a data centre is renewable, due to the power mix of the local grid, they can at least match their electricity usage with purchases of renewables elsewhere. Google has been doing this since 2017 and both Microsoft and Amazon will do it by 2025. In the meantime, Google and Microsoft are already carbon neutral through purchasing offsets.

They are also innovating in hardware technologies, such as Microsoft’s underwater data centres (Project Natick), Google’s use of AI to reduce cooling costs by 40 percent, and Amazon’s use of recycled water for cooling.

Why might some claims of greener operations be questionable?

It is likely that using cloud computing is more environmentally friendly than running your own data centres. The big cloud computing companies have huge balance sheets to invest in the projects mentioned above, are the largest purchasers of renewables, and develop more efficient forms of computing at large scale.

However, we have to take their word for it. Most cloud customers cannot access the data needed to calculate their emissions, or the data simply isn’t published. Where data is reported, it is in aggregate. For example, most people know Amazon for online shopping, but they are also the largest cloud provider in the world. They do not publicly separate their cloud environmental footprint reporting from the significant emissions generated by their global logistics operation. It’s not so much that the claims are questionable, more that we don’t know enough to assess them.

What can be done to ensure transparency in greenhouse gas emissions?

Provide customers with cloud IT emissions reporting. Back in January, Microsoft announced a tool which does just this, but it is only available for ‘enterprise’ customers. This needs to be available to every customer, free of charge, just like billing reports. And every cloud provider needs to offer the same thing.

Cloud customers need to demand this, not just for energy but also for water usage – an issue which is not covered as widely as data centre energy. Transparent and consistent financial accounting rules allow for companies to be analysed and compared – the same should be expected for environmental reporting.


Hiding greenhouse gas emissions in the cloud’ by David Mytton is published in Nature Climate Change.


Hayley Dunning

Hayley Dunning
Communications Division

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