Tag: Berkeley University

Food, agriculture, and our climate.

Locavore or vegetarian? What’s the best way to reduce climate impact of food?

With Thanksgiving Day just behind us and Christmas just around the corner, this is the season of feasting.

Just last Monday I published an essay written by George Monbiot, Pregnant Silence, that highlighted the impact on our climate of modern food production. Here are a couple of paragraphs from that essay:

Freshwater life is being wiped out across the world by farm manure. In England, as I reported last week, the system designed to protect us from the tide of crap has comprehensively broken down. Dead zones now extend from many coasts, as farm sewage erases ocean life across thousands of square kilometres.

Livestock farming causes around 14% of the world’s greenhouse gas emissions: slightly more than the output of the world’s cars, lorries, buses, trains, ships and planes. If you eat soya, your emissions per unit of protein are 20 times lower than eating pork or chicken, and 150 times lower than eating beef.

Thus it seemed both timely and appropriate to republish a further essay on the topic. This one published in The Conversation by Elliott Campbell, who is Associate Professor, Environmental Engineering, at the University of California.  It is republished here under the terms of essays published in The Conversation.


Locavore or vegetarian? What’s the best way to reduce climate impact of food?

November 25, 2015

Elliott Campbell

This year’s Thanksgiving feast falls only a few days before the start of the global climate summit in Paris. Although the connections are not always obvious, the topic of food – and what you choose to eat – has a lot to do with climate change.

Our global agriculture system puts food on the table but it also puts greenhouse gases (GHG) in the air, which represent a huge portion of global emissions. GHG emissions come directly from farms such as methane from cows and nitrous oxide from fertilized fields, while other emissions come from the industries that support agriculture, such as fertilizer factories that consume fossil fuels.

Still other emissions come from natural lands, which have massive stocks of natural carbon stored in plants and soils. When natural lands are cleared to make room for more food production, the carbon in those natural pools is emitted to the atmosphere as carbon dioxide.

Adding all these emissions together makes agriculture responsible for between roughly one fifth and one third of all global anthropogenic, or man-made, greenhouse gas emissions.

How can these emissions be reduced? My own research through the University of California Global Food Initiative has focused on evaluating a wide range of factors from biofuels to local food systems.

Undoubtedly, broad emissions reductions must come from political action and industry commitments. Nevertheless, an enlightened consumer can also help achieve meaningful reductions in GHG emissions, particularly for the case of food. The trick is to understanding what food means for your personal carbon footprint and how to effectively shrink this footprint.

On par with electricity

Zooming in from the global picture on emissions to a single home reveals how important our personal food choices are for climate change. You can use carbon footprint calculators, such as the University of California CoolClimate Tool, to get an idea of how important food is in relation to choices we make about commuting, air travel, home energy use, and consumption of other goods and services.

For the average U.S. household, food consumption will be responsible for about the same GHG emissions as home electricity consumption for the average US household.

Measuring the greenhouse gas impact of different foods is complex but in general, it’s commonly agreed that plant-based diets have a lower carbon footprint. davidwoliver/flickr, CC BY-NC
Measuring the greenhouse gas impact of different foods is complex but in general, it’s commonly agreed that plant-based diets have a lower carbon footprint. davidwoliver/flickr, CC BY-NC

That’s a significant portion of an individual’s GHG footprint but it could be seen as a blessing in disguise. While you may be stuck with your home or your vehicle for some time and their associated GHG emissions, food is something we purchase with great frequency. And every trip to the grocery store or farmer’s market is another opportunity for an action that has a significant and lasting impact on our climate.

Making concrete decisions, though, is not always straight-forward. Many consumers are faced with a perplexing array of options from organic to conventional foods, supermarkets to farmers markets, and genetically modified organisms to more traditional varieties.

And in truth, the carbon footprint of many food options is disputed in the scientific literature. Despite the need for more research, there appears to be a very clear advantage for individuals to chose a more plant-based diet. A meat-intensive diet has more than twice the emissions of a vegan diet. Reducing the quantity of meat (particularly red meat) and dairy on the table can go a long way to reducing the carbon footprint of your food.

Food miles and water recycling

Local food systems are popularly thought to reduce GHG emissions through decreased food transport or food miles. But in many cases food miles turn out to be a meaningful but small piece of the overall GHG emissions from food.

For example, a broad analysis of the US food supply suggests that food miles may be responsible for less than 10% of the GHG emissions associated with food. This general trend suggests that where you get your food from is much less important than first-order issues, such as shifting to a more plant-based diet.

A little-appreciated way of reducing the carbon footprint of food is to recycle nearby water rather than pump it long distances. The Pajaro Valley Water Management Agency (PVWMA) Water Resources Center in California sanitizes wastewater for direct use or blending with ground (well) water. US Department of Agriculture, CC BY
A little-appreciated way of reducing the carbon footprint of food is to recycle nearby water rather than pump it long distances. The Pajaro Valley Water Management Agency (PVWMA) Water Resources Center in California sanitizes wastewater for direct use or blending with ground (well) water. US Department of Agriculture, CC BY

Where, then, does this leave a rapidly emerging local food movement?

For starters, there are some cases where food miles have greater importance. For example, food miles can play a big part in the carbon footprint of foods when airplanes or refrigeration are required during transport.

There is, however, untapped potential for locally produced food to deliver carbon savings around water and fertilizers.

When water is pumped long distances, it can add to food’s carbon footprint. Re-use of purified urban wastewater for irrigating crops represents one strategy for addressing this challenge but is only economically and environmentally feasible when food production is in close proximity to cities.

Using fossil fuels to produce fertilizers, such as ammonia, can also be a big piece of the carbon footprint of food. Nutrients in reclaimed wastewater and urban compost may provide a low-carbon alternative to fossil fuel-based fertilizers. But similar to water re-use, reusing nutrients is most easily done when there is a short distance between food production and consumption.

To be sure, buying local food doesn’t imply that food or nutrient recycling has happened. But developing local food systems could certainly be a first step towards exploring how to close the water and nutrient loop.


I am sure many, as with me, tend not to follow through on all the links in an online essay. But there was one that really caught my eye. It was the CoolClimate Calculator on the Berkeley Edu website. It allows one to fill in a number of figures in terms of living, travel, food and more, and determine one’s total tons CO2/year emitted and how that compares with other people in your neighbourhood.  Unfortunately, it only calculates CO2/year for US locations. Does anyone know of similar calculators online in, say, the United Kingdom? Would love to know.

The Long Emergency, part two.

The concluding extract from James Kunstler’s powerful book.

Last Friday, I published the first part of the extract that so powerfully articulated the madness of present global policies (especially US policies) with regard to oil.  Let me continue.

The first part finished thus, “Yet, I was not soothed by these thoughts, nor by the free eats, and even the liquor failed to lift me up because I couldn’t shake the recognition that in the short term we are in pretty serious trouble, too.”

There is near unanimity among the scientific community that global warming is happening.  There is also a definite consensus emerging that the term “climate change” may be more accurate than “global warming” to describe what we are in for.  The mean temperature of the planet is going up.  The trend is unmistakable.  Average global land temperature was 46.90 degrees Fahrenheit [Ed. 8.278 °C.] when modern measurements began and had reached 49.20 degrees F [Ed. 9.556 °C.] in 2003.  The rate of change has also increased steadily.  The total increase of 2.30 degrees might seem trivial, but has tremendous implications.  And the rise in temperature happens to correlate exactly with the upward scale of fossil fuel use since the mid-nineteenth century.

It may not matter anymore whether global warming is or is not a by-product of human activity, or if it just represents the dynamic disequilibrium of what we call “nature.”  But it happens to coincide with our imminent descent down the slippery slope of oil and gas depletion, so that all the potential discontinuities of that epochal circumstance will be amplified, ramified, reinforced, and torqued by climate change.  If global warming is a result of human activity, fossil fuel-based industrialism in particular, then it seems to me the prospects are poor that the human race will be able to do anything about it, because the journey down the oil depletion arc will be much more disorderly than the journey up was.  The disruptions and hardships of decelerating industrialism will destabilize governments and societies to the degree that concerted international action – such as the Kyoto protocols or anything like it – will never be carried out.  In the chaotic world of diminishing and contested energy resources, there will simply be a mad scramble to use up whatever fossil fuels people can manage to lay their hands on.  The very idea idea that we possess any control over the process seems to me further evidence of the delusion gripping our late-industrial culture – the fatuous certainty that technology will save us from the diminishing returns of technology.

So for the purposes of this book, the relevant question concerning global warming and climate change is not whether human beings caused  it or whether we will come up with some snazzy means to arrest it, but simply what the effects are likely to be and what they signify about the way we will live later on this century.

This extract from the book was published in 2005, although there is an Afterword included that was published in 2009.  So to bring things more up to date, here’s a video of James Kunstler speaking about peak oil just about a year ago.

In this fourth video in the series “Peak Oil and a Changing Climate” from The Nation magazine and On The Earth Productions, James Howard Kunstler discusses how finance and energy are running neck and neck to fuel the end of advanced industrial civilization.

For more videos in the series, visit The Nation.

Plus for those that are interested in the data of global land-surface temperatures, here’s a two-minute video showing the temperature change over the last 200 years.

For more information about this study visit http://berkeleyearth.org. Berkeley Earth video representation of the land surface temperature anomaly, 1800 to the present. The map of the world shows the temperature anomaly by location over time. The chart at the bottom, shows the global land-surface temperature anomaly. The Berkeley Earth analysis shows 0.911 degrees Centigrade of land warming (+/- 0.042 C) since the 1950s.