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The greenhouse gas emission impacts of
generational and temporal change on the UK diet
Christian Reynolds1 and S. L. Bridle2
1University of Sheffield, 2University of Manchester
Abstract: In the literature, only current (and future sustainable)
diets and their associated greenhouse gas emissions (GHGE)
are typically discussed. Little attention is given to existing
dietary patterns and trends, and how these impact on future
diets. We examine how embodied GHGE associated with UK
dietary preferences have changed over time, with attention
given to how age changes diet and how different generations
have had different GHGE due to their dietary composition. We
use dietary data from the National Food Survey (1975-2000),
the Living Cost and Food Survey (2000-2015) and GHGE
from Audsley (2010). We have calculated GHGE related to
household consumption of selected foods by age of main
diary keeper split in to 10 year ‘generations’ 1910-2000 with
diets reported at 5 year intervals. We find that differences in
generational eating habits (such as meat and dairy
consumption) do produce diets with different GHGE footprints.
4. Future work: For future work we would like to increase the granularity and signal-to-noise of the analysis by using all years of the food
surveys, instead of sampling every 5 years. We would add in the data from 1942-1975 to provide a wider range of ages for more cohorts. It
would be interesting to compare the changes in total GHGE and consumption of specific types of food with public health and advertising
campaigns. Ideally we would be able to build a model for changes in food GHGE with age and birth year and how this can be moderated by
campaigns, to predict future food consumption and potential GHGE reductions.
References:
Department for Environment, Food and Rural Affairs. (2016). National Food Survey, 1974-2000: Open Access Data. [data collection]. UK
Data Service. SN: 7945, http://doi.org/10.5255/UKDA-SN-7945-1
Living Cost and Food Survey (2000-2018)
Department for Environment, Food and Rural Affairs, Office for National Statistics. (2017).!Living Costs and Food Survey, 2015-2016. [data
collection].!2nd Edition.!UK Data Service. SN: 8210,!http://doi.org/10.5255/UKDA-SN-8210-4
Office for National Statistics (2016) . Mid-1838 to Mid-2015 Population Estimates for United Kingdom and it's constituent countries: Total
persons, Quinary age groups. https://www.ons.gov.uk/peoplepopulationandcommunity/populationandmigration/populationestimates/adhocs/
004358englandandwalespopulationestimates1838to2014
Audsley, E., Brander, M., Chatterton, J.C., Murphy-Bokern, D., Webster, C. and Williams, A.G., (2010). How low can we go? An
assessment of greenhouse gas emissions from the UK food system and the scope reduction by 2050.
Background Image https://www.pexels.com/photo/11-white-sheep-in-the-grass-field-85683/
Acknowledgements: This research was supported by the HEFCE Catalyst-funded N8 AgriFood Resilience Programme and matched funding from the N8 group of Universities.
2. Cohort analysis: Following each cohort through the survey years reveals emissions trends with age and birth year.
1. The data: We have concatenated the National Food
Survey (1975-2000) and the Living Cost and Food Survey
(2000-2015). Displaying data in 5 year intervals. GHGE
values for over 30 different foods taken from Audsley (2010).
For the purpose of understanding the impact of food choices
on GHGEs we have assumed that the GHGEs per food item
are constant with time. To illustrate the data we show a
snapshot of daily consumption in 2000, grouping the foods
into 9 major categories.
We have normalised the population in each year and age
bracket using the UK SYOA survey, which enables us to
divide the GHGE for each year between the age categories
available in the data
We can see that the overall greenhouse gas emissions due to
type and quantity of food chosen are broadly decreasing.
Furthermore, the fraction attributable to each age category is
roughly constant with time.
We find that the total calories per day is changing noticeably,
as shown below. However, due to the sampling time period
gap, this change has a lot of “noise”.
We find that the proportion of emissions
from ruminant meat is the strongest trend
with birth year, which significantly
contributes to the reducing emissions. To a
small extent this is partially balanced out
by the increasing emissions from drinks
and cereals.
3. Breakdown into food categories: to understand why the food choices lead to a reduction in food GHGE with increasing birth year,
we break down the total GHGE according to the food categories shown in section 1. For a given birth year we average over the age
range because we find the proportions of each food category is relatively constant with age.
We investigate whether food choices contribute to the
change in CO2e / day by repeating the CO2e / day plot after
normalising all age groups to the same number of calories
per day (for definiteness 2500 kCal).
We find that the same trend remains even after normalising
out the total calories: people from older birth years seem to
make food choices which lead to higher emissions.