Water footprint is the answer: what’s the question?
07/03/2016
If you ask someone over dinner, “did you know that 7,000 litres of the world’s water have been consumed to bring the beef steak to your plate, but only 42 litres to provide the potatoes?” the answer is usually accompanied by shock (and disbelief). This provides a useful launch-point for a discussion about the sustainability of our lifestyles, but often ends up with the question “so, should we stop eating meat”?
Unfortunately the over-simplistic messages of water volumes have been widely abused to justify or encourage changes in diet and lifestyles. To answer the question about the impacts of our diet on the world’s water we need to unpack the numbers and think about potential impacts.
Firstly, how much of the total volume of water is “green” water (that is, rain water used by plants at the point where the rain falls)? Most British and Irish beef, for example, is largely fed on grass and grains that have been grown using rainfall only. We can argue that this water has a very low opportunity cost. If we stopped raising animals on that land, something else would be growing there (whether another crop, forest or natural vegetation) that would use at least as much water as the grass did and it would not make a substantial difference to the amount of water available in the basin for domestic, industrial and environmental uses. Secondly, what is the potential impact of using “blue” water (that is, water withdrawn from rivers, lakes and aquifers) on the availability of water for other users in the basin? 1 m3 withdrawn from a place (or time of year) with plentiful water resources has a much lower potential impact than 1 m3 withdrawn from a place where freshwater resources are scarce.
The modern western diet is rich in its diversity with foods coming from all round the world and grown in different agricultural systems; these will all have different potential impacts on the water footprint. Recently, we looked at the potential impact of the UK diet on water scarcity (Hess, et al. 2015. Food Policy, 50: 1-10) using the approaches of ISO14046. In total, we estimated that 56.2 Gm3 of water is consumed each year to support the diet of the UK. That is equivalent to 2,400 litres per person per day. However, most of this is from rain-fed agriculture, and the “blue” water consumed in supporting the UK diet is only 160 litres per person per day – which by coincidence is almost the same as the average daily per capita water use in our homes.
So what uses the largest amount of water? Read the full version of this blog post can be found on the Food Climate Research Network…
Categories & Tags:
Leave a comment on this post:
You might also like…
Systematic Literature Review – combining your search strings
Our previous posts on the systematic review have looked at: Systematic Literature Review – Where do I begin? Systematic Literature Review – Selecting your Sources Systematic Literature Review - Identifying your search terms and constructing ...
Academic writing and being critical
Academic writing is daunting. Capturing all your thoughts and analysis and putting them down onto paper in some sort of understandable fashion is a challenge. Did you know we have resources in our Cranfield Study ...
Bank holiday hours for Library Services: Monday 6 May
Library Services staff will be taking a break on Monday 6 May for the early May bank holiday. You will still be able to access all the resources and help you need via our library ...
Cranfield’s Manufacturing and Materials Students’ Showcase Innovation at Project Day
On 26 April, Cranfield University buzzed with excitement as students from across our Manufacturing and Materials MSc programmes presented their group projects at the annual Group Project Presentation Day. This annual event presents ...
Come to a virtual study session in May
What are virtual study sessions? These are online study sessions facilitated by Library staff, where you can study independently alongside other students via Teams. They are a great way for you to dedicate specific time ...
Getting started on your School of Management thesis
Writing a thesis, business plan, internship project or company project can be a daunting task, and you might have some uncertainty or questions around how to get started. This post will share some ideas and ...