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Burger with meat and French fries in aluminum tray on dark background
© Lisovskaya Natalia/The Picture Pantry/Corbis
23 March 2016 12:12

Guest post: Failure to tackle food demand could make 1.5C limit unachievable

Carbon Brief Staff

Multiple Authors

Guest postsGuest post: Failure to tackle food demand could make 1.5C limit unachievable

A guest post from Prof Tim Benton, professor of population ecology at University of Leeds and Champion of the UK’s Global Food Security Programme, and Dr Bojana Bajželj, formerly a doctoral researcher at the University of Cambridge and now a food sustainability specialist at WRAP.

In Paris in December last year, 195 countries agreed to try and keep global temperature rise to “well below” 2C above pre-industrial levels, and to “pursue efforts” towards 1.5C.

Many had expected the 1.5C temperature goal to drop out of the draft text during the fortnight of negotiations. Now, as the dust settles after the landmark agreement, scientists are grappling with the feasibility of meeting this more ambitious target.

But there was one sector that was largely absent from the talks in Paris. It’s something that we rely on everyday, and continuing to ignore it could mean waving goodbye to that 1.5C goal. It’s food.

30% of emissions

Agriculture and the production of food, or “agri-food” for short, is a very significant emitter of greenhouse gases.

Producing our three square meals a day causes emissions of CO2 through agricultural machinery and transporting crops and animals, nitrous oxide from the use of fertilisers (synthetic and manure), and methane from livestock and flooded paddy fields for rice.

Furthermore, the demand for food has led to global expansion of farmland at a rate of about 10m hectares per year during the last decade. Some of this cleared land is – or was – tropical rainforest, adding more emissions and reducing the capacity of land to absorb and store carbon.

When you consider emissions according to the services we use on a day-to-day basis, agri-food accounts for approximately 30% of all greenhouse gas emissions. As you can see from the chart below, that means producing and cooking the food we eat causes approximately the same amount of emissions as those from personal travel, lighting, heating and air conditioning, and washing machines put together.

Rising demand and emissions

During the mid-20th century, global food production benefitted from a “Green Revolution”, where improvements in farming technology across the world gave a huge boost to crop yields. But, more recently, there has been a worldwide deceleration in yield growth of major crops.

At the same time, as the world’s population grows and becomes richer, the demand for food is expected to increase by 60% or more by 2050. Given recent trends, demand is likely to rise more quickly than supply towards the middle of the 21st century. This will increase pressure to convert land for farming.

Putting these drivers together suggests that emissions from agri-food will continue to grow. Changing farming practises could offset some of this increase, but achieving such changes is easier said than done.

A paper published this week, for example, reviews the various ways we can cut emissions from raising livestock. Options include using feed additives to reduce how much methane is created in the stomachs of animals, and sequestering carbon in the soils of grasslands where they graze. But limited take-up of new farming methods and high costs means that less than 10% of what is technically possible is currently economically viable.

So what does this mean for keeping temperature rise below 1.5C?

The emissions pathway we’d need to follow for a 66% chance of staying within 1.5C suggests that food-related emissions at current levels would take up our entire greenhouse gas budget in 2050.

That means unless things change – radically – our demand for food could leave no space for emissions from any of the other services we require to live our daily lives.

In short, our demand for food alone could virtually guarantee that the Paris aspirations are unachievable.

Piles of doughnuts for the Fat Thursday celebrations in Poland

Elblag, Poland 4th, February 2016. 6th Donuts Fast Eating Championships in Elblag organized by the Dziennik Elblaski daily newspaper and Raszczyk confectionery to celebrate traditional Fat Thursday fest. During Fat Thursday Poles along the country eat large amounts fist-sized donuts filled with rose marmalade called Paczki. The competition winner was fireman Pawel Raczewski with 7 eaten donuts . © Michal Fludra/NurPhoto/Corbis.

Where to start

There are three possible ways we could respond to this sobering conclusion:

  1. We carry on as we are and miss the Paris targets, and therefore perhaps lock us into 4-5C of global warming by the end of the century;
  2. We rely on research and innovation to find ways to significantly increase yields to reduce the rate of land conversion and develop carbon capture and storage, or
  3. We recognise that demand for food is driving emissions and work to change that to meet the supply-side improvements halfway.  

The first option is unthinkable. The second has possibilities, but there is little sign of research budgets on the scale necessary being deployed, and furthermore, there is a significant gap between mitigation potential and economic viability. The third option seems, at least initially, a no-brainer.  

We know our habits have changed rapidly in recent decades – we buy more, buy more cheaply, eat differently, waste more – but could it change again to achieve a “low carbon food lifestyle”?

There are a few places we could start.

First, reducing food waste. On a global basis, about a third of food is lost in fields or storage, or wasted in the supply chain and home. Throwing away food doesn’t just waste valuable resources, but also causes additional emissions when ending up in landfill. Food waste costs the average UK family with children £700 per year.

Second, cutting down on consumption of intensively-produced meat and dairy. Raising livestock is a much less efficient way of producing food than growing crops.  Currently, a third of the crops we grow is fed to livestock to produce meat.

Overall, nearly half of the emissions from agri-food are related to meat production – more than the entire transport sector. If we used the land growing feed to grow food, and ate only meat from pasture-fed animals, there is scope for very significant reductions in emissions. If we stick with non-pasture fed animals, then the choice of meat is important – producing beef emits more than five times as much as chicken and pork.

This ties with a third change – eating a healthy diet. Increasingly, people around the world eat more calories than are good for them (about two billion adults are overweight or obese). In Europe, for example, we eat around twice as much meat as is deemed healthy, while in the US it’s three times. Another paper published this week suggests that a global switch towards more plant-based diets would reduce global mortality by up to 10% and food-related greenhouse gas emissions by as much as 70% by 2050.

Putting all these factors together could reduce global food demand by a third or more, and that’s without considering ways for agriculture to become more efficient and higher yielding.

It means that adjusting our diets and attitude to waste has the potential to bring the Paris targets back in sight.

Main image: Burger with meat and French fries.
Sharelines from this story
  • Guest post: Failure to tackle food demand could make 1.5C limit unachievable
  • Naomi Dagen Bloom

    Practical suggestions for ways one person can impact climate change…starting with eating less meat and reducing our food waste. I can do that–you probably can too.

    • Kevin Schmidt

      The Adkins Diet proves eating too much meat will put you in an early grave.

  • The basic message of this article is very important and it is strongly worth taking note that when our diets are largely based on animal foods, the GHG signature of this alone is very significant.

    That said, the idea that there is still the remnants of a global carbon budget for 1.5°C by 2050 is not the case. As David King argued to the IEA in January (after Paris – Cop-21), carbon emissions need to zero globally by ~2030 as the budget between now and then is around 175 Gt C: –

    Changing diet is a crucial part of the total transformation needed to keep below 1.5°C.

  • GeoffBeacon

    “If we used the land growing feed to grow food, and ate only meat from pasture-fed animals, there is scope for very significant reductions in emissions.”

    Until we hear otherwise, I think we should assume that pasture-fed ruminants are terrible for the climate. They produce lots of methane and take up land that could be used for food crops or growing biomass for BECCS or if BECCS is too hard sinking the biomass in the ocean.

    Any beef is bad for the world (so is lamb) but I would like to have some measure of how bad. What is the carbon footprint of grass fed beef? – or to use a more vague concept, what is its ecological footprint?

    How much of our remaining carbon budget does one pasture-fed beef steak a week take?

    I just don’t see how a cow roaming around producing 100 kgs of methane a year can be good for the world. That might convert into 10 tonnes CO2e per cow per year.

    And surely something useful could be done with the acre of land the cow needs.

    Is this grass fed stuff just a green fig leaf for the wealthier beef eaters.

    (OK. Cheese is bad too – and I’ll try to cut down even more.)

  • rick spalding

    Their is going to be a great amount of wealth made in poor areas (southeast asia, africa) over the next 50 years. When wealth is created, the demand for meat is going to go up. What would be nice is a competing biotech company to be able to synthesize amino acids into a palatable form to supplant meat intake. Companies that are already making gmo animal feed have no interest in anything like that as it would compete against their ge corn and soy that goes mainly to animal feed.

  • It is quite likely already too late to limit warming to just 1.5 C above 1880, in-fact the 1.5 C limit was
    already exceeded last month, after 6 straight months of the hottest month ever in recorded weather history as well as 14 of the last 16 months too.

    In the graphic below, their baseline is 1951-1980, figure 1965, which means that we must add roughly 0.3 C to reach the common 1880 baseline, which yields 1.65 C above the 1880 baseline for February, 2016 temperature anomaly.

    If we just substitute a 90% certainty of keeping average planetary warming below 2 C for a 66% chance, we have already exhausted our carbon budget two years ago according to David Spratt.

    The real budgetary emergency and the myth of “burnable carbon”,by David Spratt:

    Climate Code Red, May 22, 2014:

    It’s time to ‘Do the math’ again, David Spratt, Climate Code Red, April 22nd, 2015

    Gentlemen, we are in big trouble, and while I will agree that food supply is one of our biggest GHG emitters, we are also seeing a tremendous problem with fresh water supply sustainability as well as salinization of agricultural soils and a frightening loss of agricultural topsoil rate that could destroy more than half of today’s farmland by mid-century.

    I have studied this issue myself at the graduate-level and food loss rate in the US and perhaps most first-world countries is 51% according to published USDA food availability, USDA crop loss, and USDA end-user loss rate studies.

    From farm to retail the average loss according to the USDA is 30% of total crop, though the USDA study identifies some crops with lower loss rates and some with higher loss rates, for-instance, collard greens have a 62% loss rate from farm to retail. According to the USDA end-user loss rate study (2014) just end-user loss is 21% in the US.

    We are already facing a scenario where the residents of half the entire planet are stuck with severe water shortages on an annual basis in the coming decades, and in-order to produce 60% more food at the end user effectively we must produce considerably more than 60% more at the farm if we continue to insist-on shipping food in from all over our planet both in-season and out of season.

    Four billion people facing severe water scarcity, Mesfin M. Mekonnen* and Arjen Y. Hoekstra,
    Sci Adv. 2016 Feb; 2(2): e1500323. doi: 10.1126/sciadv.1500323

    Basically the third world has little if any water to spare with billions of people today only using 15-25 gallons of water daily, with giant localized droughts currently causing huge refugee flows, and even here across the greater Southwestern US and Mexico at least 50-80 million people are facing severe water supply shortages by 2050 along with the loss of substantial amounts of farmland.

    Just the US State of Colorado faces annual water supply shortages of 300,000 to 600,000 acre-feet annually by mid-century and the State of California could see annual water supply shortages of as much as 15 million acre-feet annually by mid-century also, with the majority of Mexico in even worse shape.

    Clearly the only way to produce more food is to produce as much food as-possible locally where it is used in giant climate-controlled hydroponic or aquaponic greenhouses, where average yield is 500% of crops grown in dirt, with as many as 3 crops annually possible. If food is produced locally the farm to retail loss rate should be substantially lessened too.

    Several years ago I came up with a simple model to estimate required farmland per-population to produce an average 2000-calorie daily diet on an annual basis, using USDA food availability, crop loss, end-user loss, and crop yield data from several sources. Basically according to my model, at a 10,000 lb average crop yield per-acre, the land requirement is 299 square miles of irrigated farmland per million population, based on a single crop annually. The beauty of my model is that any of its components can be adjusted.

    If we reduce the figure above by what could be produced by local urban hydroponic greenhouses divide 299 by 15 to represent three crops annually and 500% of yield, which comes out to just under 20 square miles of greenhouse capacity per-million population, and then we can further reduce the figure by 25% of so due-to a much lower enroute loss rate, so now we are down to just 15 square miles of such greenhouse capacity per million population.

    Might I also recommend this 2014 piece by Dr. William Rees, Professor Emeritus of the University of British Columbia’s City & Regional Planning program, entitled ”

    Avoiding Collapse: An agenda for sustainable degrowth and relocalizing the economy:

    My reason for recommending this piece is that I see perhaps the only way at this point to greatly reduce global greenhouse gas emissions is to localize our economies and greatly reduce or eliminate the practice of shipping products halfway around the planet just so that we can enjoy produce out of season or production rates cheaper than what is possible at-home.

    We also must work much more-quickly than forecasts made by the IPCC or COP-21 stipulate as over this past winter the Arctic has now seen four single-day record atmospheric methane-content spikes of several hundred parts per-billion higher than previous daily-content records set in 2013 and 2014, with the short-term heat-trapping ability of methane as high as 270 times that of CO2 at its maximum heat-trapping ability.

    Did we all see that the Arctic monthly average temperature anomaly for January was 6.1 C or that February’s average monthly anomaly was over 10 C, with local anomalies during the month as high as 16 C above the 1971-2000 baseline temperature? Did we all know that seawater off of Svalbard is running as high as 10 C above normal per-date today too?

    How long do any of us feel that such extreme temperature anomalies across the Arctic can continue before daily methane-content records surge into the 5,000 ppb range or higher considering the new all-time daily methane-content record of 3,096 ppb on February 20th, followed on February 28th by a 3,010 ppb daily-content reading above the Arctic too, considering the short-term 1-2 month heat-trapping ability of atmospheric methane is 270 times that of CO2 at its maximum impact a full decade after CO2 emission?

    Remember back when Arctic scientists were shocked beyond belief in the fall of 2013 when the daily-content record then hit 2,662 ppb or when readings in 2012 exceeded 2,575 ppb for the first time?

    Yes, we humans are in big trouble as we have already exceeded our carbon budget and are facing more than 2 C worth of warming globally and 3-4 C worth of warming across the northern hemisphere by mid-century plus or minus 10 years with Dr. Hansen and his associates recently forecasting utter disaster above 2 C, a disaster which includes large areas of our planet becoming unable to continue to support large urban populations or grow crops outdoors too.

    Say, what happens when we end-up with 1-2 billion refugees desperately searching for any livable amount of fresh water and food by mid-century? Did we all see this piece where Lord Stern calls for the same thing I just wrote above or even worse?

    Lord Stern: global warming may create billions of climate refugees, Guardian, September, 2014:

    Frankly there is no such thing as sustainability unless the human race can stop shipping products and raw materials all over the planet trying to save a buck or for convenience. When I was a kid in the 1960s we couldn’t get fresh vegetables or fruit out of season so why waste billions of tons of CO2 annually to provide this today, when we can grow fresh produce locally, meet our own food needs locally, and save billions of tons of annual CO2 emission in the process?

    I am a 58 year-old 2nd-year MURP student at the University of Colorado Denver specializing in Regional Sustainability. My primary research interest is climate change impacts to food and water supply sustainability across the Greater US Southwest and Mexico, and in-addition to my education, which includes a recent Sustainable Land Use Planning degree I also have 30 years of employment experience in wholesale fresh food warehousing and distribution serving the major cities of the US northern East Coast, the southern Great Lakes region, Denver, and California too.

    • Kevin Schmidt

      It is not too late. That kind of defeatist attitude is just more fossil fuel industry propaganda.

  • bobro

    What a bunch of climatist BS! Who decided that 2.0 degrees was the magic number? Someone’s computer model that has proven totally unreliable for any forecasting in the past. By now, according to some models, Florida and New York City should be underwater. The so-called “Climate Scientists” are, in reality, just an excuse for feeding at the public trough for billions every year. They want to dictate how we mere peasants eat, live, travel and behave while they can jet around the world for important meetings where they present their bogus papers dictating living conditions for the rest of us. An yet, millions believe in the climate hoax and support the politicians who will support any cause for money and power. It is time to call a halt to the massive subsidies that are drained out of the public and end up in the pockets (and Swiss banks) of the powerful and well connected!

    • Kevin Schmidt

      Got proof for any of your dubious claims? No? Thought so!
      That makes your comment the “bunch of BS!”
      No one believes your willfully ignorant, scientifically illiterate, fossil fuel monopoly propaganda.

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