What is the carbon footprint of a Google search?


Almost 50% of the world’s population is now online, with internet usage in the developed world more than around 80%.

While internet access has increased, so has the use of search engines such as Google, Bing and Yahoo.  Many of us now instinctively search for websites even if we know the correct web address.  This is reflected by the increasing number of adverts, which instead of listing a website simply encourage us to search for a product keyword.

But, as more of us log on what is the carbon cost?

Until recently this issue had been little discussed.  However the most popular search engine Google, which handles 65% of all internet searches (3.5 billion daily) has been the subject of discussion over its carbon footprint.

Discussion followed research by Harvard University physicist Alex Wissner-Gross on the environmental impact of computing.  While Google doesn’t disclose its energy usage or carbon footprint, using available information the researchers calculated each Google search generates an estimated 5-10g CO2.  This considers that often a user will execute multiple searches to locate the information sought and that this may take several minutes.  Each Google search is equivalent to boiling a kettle (7g CO2).

Carbon is produced because Google replicates queries across multiple servers, that then compete to provide the fastest answer to the query.  In contrast, basic web browsing generates about 0.02g CO2 for every second viewed.  More complex websites with rich animations and video can be responsible for the emission of CO2 at up to 0.3g per second.

For a typical browsing experience, the dominant contribution to its footprint comes from the electricity consumed by its visitors’ computers, followed by the network infrastructure needed to transmit the website, with the servers and data centres providing the website as the smallest contributor.

The wide media coverage generated forced Google to respond with a statement.

Google estimates that a single internet search that takes less than a second, generates about 0.2g CO2.  The search engine estimates that through its own efficiencies, that in the time it takes to do a search, the user’s own computer will likely use more energy than Google will use to answer the query.  For a typical user searching the internet over the course of a year this is the equivalent CO2 of a load of washing.  Google itself claims to run the world’s most energy-efficient servers and is undertaking many green corporate initiatives.  It also co-founded the Climate Savers Computing Initiative to help the IT industry cut energy use.

Whether the true environmental cost for a Google search is closer to the tiny figure suggested by Google, or closer to the larger figure suggested by the Harvard study remains unclear.  What is clear, is that as the global ICT (Information, Communication & Technology) industries grow more transparency over carbon emissions is needed.  The global ICT industry currently produces about 3-4% of global carbon emissions.

Reducing your search footprint

Firstly you could think about the energy efficiency of your computer hardware and software.  That is a completely different (& much larger) topic than this, but there are easy things you can do such as choosing energy-efficient equipment and not running screen savers.

But in terms of reducing the impact of your individual search here are two ideas.

  1. Minimise your use of search engines.  If you visit the same websites regularly it will make sense to bookmark links.
  2. To reduce your computer’s energy use when searching Google you could consider using a custom search such as Blackle.  Blackle presents a black Google search page that uses less energy per search.  Another is Ecosia, that plants a tree every 7 seconds.

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