Farm Carbon Cutting Toolkit


04.05.16 Estimating soil carbon content of salt marshes with new app

Source: Biodiversity and Ecosystem Service Sustainability, CBESS Project Officer, Meriem Kayoueche-Reeve.

We are an island nation, and yet we know surprisingly little about parts of our coastline. An appeal to ‘citizen scientists’ hopes to put this right by encouraging us to collect information about our salt marshes to fill in the gaps.

With the aid of The Saltmarsh App, CBESS is asking interested individuals and groups to investigate the salt marshes which surround our coast.

Once they have downloaded the free, mobile app, individuals can either use the guide to identify the unique plants and wildlife found on salt marshes or they can carry out an interactive plant and soil survey.

The survey will estimate the stored carbon in the saltmarsh soil and show how by preventing carbon from becoming the greenhouse gas carbon dioxide their marsh is helping limit climate change.

We know a great deal about land environments and have a detailed knowledge of the distribution of most soil types within the UK, with the exception of salt marshes. Every marsh survey uploaded will help the scientists at Bangor University learn more about UK saltmarsh soils and how they are helping fight climate change.

Salt marshes are grassland fields that fringe our coastline. They are washed by the tides and are criss-crossed by creeks. They are rich in wildlife and help protect our coastlines against storms and floods. Salt marshes are a great place for a walk, a run and a range of other outdoor activities.

The Saltmarsh App was developed by the University of St Andrews, Bangor University and the Centre for Ecology & Hydrology. The App will encourage people to visit salt marshes and gain more enjoyment from their visit, by providing a portable visual reference for the plants and animals found there. For the ‘citizen scientists’, the app also guides the user through some simple plant community and soil identification steps, which will be fed back to the scientists.

The Saltmarsh App and its accompanying website will be launched at the start of June, watch this space!

04.05.16 Livestock carbon footprint part 2

Following on from the first part of the blog, this second part explains some of the finer details and differences between GWP (global warming potential) and GTP (Global Temperature change Potential).  Again to read part one of the blog click here or for the link to the original on the Food Climate Research Network, written by Martin Persson click here.

To recap, the argument for favouring GTPs for livestock products, was that for a distant temperature target, it only matters how much warming is left lingering from an emission today at the point when the temperature target is reached (and not how much warming we get leading up to this point).

If this is the argument for choosing GTPs over GWPs, one must also be aware of the other implications of this choice.  First it is not reasonable to adopt a 100 year time horizon in GTP calculations. Instead the time horizon should reflect the time remaining until the temperature target is reached. For the 2 degree C target this is likely to happen sometime between 2050 – 2100. We have shown in a recent paper that if 40-90 years is a reasonable time horizon to use in GTP calculations, the resulting GTP value for methane today is 18, not 4. This is because the temperature impact of releasing a tonne of methane today increases rapidly the closer the point in time it is evaluated.

Second it does not make sense to adopt a constant time horizon for GTPs. (Why should we always be interested in the warming happening at some distant point in the future?).  Instead as we approach the temperature target, the time horizon  over which we evaluate GTPs should decrease, resulting in a valuation of methane that rise rapidly (since the short – term warming effects become increasingly important) reaching a value of 120 when the target is met.

Consequently, the impact of switching from GWPs to GTPs would have a modest impact on the carbon footprint of beef today: a reduction from 23.5 to 18.9kg CO2 – equivalents per kg carcasss weight, for average EU beef production. By mid-century however the carbon footprint calculated using GTPs could potentially rise to 63 kgCO2eq / kg beef, if it turns out that by then 2 degree C warming is imminent. The choice of metric this will have a large impact on the future role of the livestock sector in climate mitigation (more so than in the present).

Finally the discussion on metrics may partly obscure a key difference between emissions of fossil carbon dioxide and other, shorter lived greenhouse gases, while emissions of the latter will eventually be completely broken down and removed from the atmosphere, part of our carbon dioxide emissions (20-30%) will stay in the atmosphere for more than thousands of years. The practical implication of the latter is straightforward: the only way to stabilise carbon dioxide concentrations in the atmosphere is to bring down emissions close to zero. This is why we talk about a finite carbon budget; a target for cumulative carbon emissions we cannot exceed if we are to limit warming to 2 degrees C.

For other greenhouse gases, however, it is enough to stabilise emissions in order to stabilise atmospheric concentrations (though the higher the emissions, and the longer the lifetime of the gas, the higher the resulting concentration).  As a result cone can compare the long – term climate impacts of an emission pulse of carbon dioxide with a constant emission rate for more short-lived greenhouse gases. 

Put differently, reducing annual emissions of methane and nitrous oxide will relax the carbon budget compatible with a 2 degree target. Or, conversely for every tonne of carbon dioxide emission mitigated, we can increase annual emissions of shorter lived greenhouse gases forever without affecting long-term warming.

For methane, emitting one kg per year has the same long-term temperature impact as would a one-time emission of around 5 tonnes of carbon dioxide. For nitrous oxide which is both a more potent greenhouse gas and has a much longer atmospheric lifetime, an annual emission of one kg compares to a one-time emission of about 100 tonnes of carbon dioxide.

Using these numbers, the annual emissions from the global livestock sector (some 112 million tonnes of methane and 8 million tonnes of nitrous oxide), if held constant, have the same long-term climate impact as carbon dioxide emissions of roughly 1000 billion tonnes. This is in the same order of magnitude as the total remaining carbon budget under a 2 degree target! 

Seen this way, achieving significant cuts in the global greenhouse gas emissions from the livestock sector – through productivity increases, technological development and dietary changes – can substantially raise the carbon budget compatible with the climate target currently agreed by the global community, hence increasing the likelihood that this target will actually be met. 

Source: Food Climate Research Network

03.05.16 Livestock’s carbon footprint and the importance of comparing greenhouse gases

This blog was published on the Food Climate Research Network and comes from Martin Persson at Chalmers University of Technology in Sweden.  This blog looks at the difficult issue of how to measure the climate impacts of the different greenhouse gases.  He begins by explaining what the two most common measurements (Global Warming Potential and Global Temperature Change Potential actually measure.

He also focuses specifically on beef and associated methane emissions. To read the article in its original form on the FCRN site, please click here.

The emissions conundrum

How do you compare the climate impact of, say, eating a hamburger and driving your car to the local supermarket? Making this comparison requires a conversion factor (a greenhouse gas metric) which adds up the emissions of the different gases that doing these different activities produces. In this example, the gases would include carbon dioxide from the combustion of fossil fuels, methane from the cow (through enteric fermentation and manure) and nitrous oxide from feed production (fertiliser).  The way that these are most commonly represented is using Global Warming Potential, where clever equations work out the gases different warming potentials over time and apportions them a value.  For anyone who has sat through a presentation on climate change and have heard the statistics about methane being 30 times more potent than carbon and nitrous oxide 300 times, that is what feeds into the carbon dioxide equivalents that are represented by global warming potential.

However, this is not the only way to convert methane and nitrous oxide into carbon dioxide equivalents.  Another option is to use the so called Global Temperature change Potentials (GTPs), according to which methane is just 4 times stronger than carbon dioxide as a greenhouse gas (when using the same 100 year time horizon that is used in Global Warming Potential).  Not surprisingly given the bad press associated with beef and dairy production when looking at emissions, using a different measure (Global Temperature Change potential, rather than global warming potential) makes the story seem much less dramatic. 

So how do you understand which metric to choose? As is always the case with reporting data, in order to answer that question, there is need for an understanding of what these different metrics actually are trying to measure (and balance).

Global Warming Potential and Global Temperature Change Potential

Global warming potential (GWP) focusses on radiative forcing, simply put a measure of the radiative energy imbalance due to increased levels of the greenhouse gas that cause the atmosphere, land and oceans to warm. To calculate the GWP of a gas, you add up the total cumulative radiative forcing resulting from the emission of one tonne of the gas today over a given time horizon, and then compare that to the total radiative forcing over the same time horizon resulting from emitting one tonne of carbon dioxide (comparing other gases to carbon dioxide in their ability to warm the radiative forcing). Global Temperature change potential (GTPs) compare the temperature change at a given point in the future, resulting from an emission of one tonne of a gas today and compare that to the temperature rise at the same point in time from emitting a tonne of carbon dioxide today.

This has been shown very nicely in a graph, which you can access through the original article here.

Reporting framework 

These graphs show that due to differences in atmospheric lifetimes of carbon dioxide and methane, there are marked differences in the time that the warming from the different gases will persist. Methane’s short atmospheric lifetime, about 12 years, implies that much of the change in temperatures that emissions today cause, will have dissipated in 100 years time (but not all of them). Consequently, when using global temperature potential calculations, the value for methane will be much less than when looking at global warming potential as GWPs reflects the cumulative warming effect of an emissions and as such, accounts for the near time climate impacts caused by the methane emissions.

As such, although emitting 30 tonnes of carbon dioxide or 1 tonne of methane today (remember these have equal emission if you are measuring using GWP), will have the same impact on total radiative forcing over the coming century, it will give very different absolute temperature changes at the end of this period (about seven times higher for carbon dioxide than for methane) as methane’s GWP value is about seven time higher than its GTP value.

This example (if you are still reading!) illustrates a general insight when it comes to greenhouse gas metrics, because of the differences in the atmospheric lifetime across greenhouse gases, there can never be a perfect metric that assures equivalence across all relevant impacts of climate change. Consequently which metric you use, will always reflect value judgement, such as:

  • Which impact to compare (e.g. radiative forcing, temperature change or sea-level rise)
  • Whether to compare these impacts at some future date or cumulative impacts over the whole period up until this date
  • Time-horizon over which impacts are assessed

How to choose which one to use?

This doesn’t imply however that the choice of metric is arbitrary. A common argument is that the choice of metric must reflect the climate policy goal the metric is to serve.  For example, cumulative radiative forcing, as measured by GWPs, relates directly to cumulative warming, which is a crude proxy for climate damages. Hence if our policy goal is to limit the total amount of climate damages over some specified time period, GWPs would be a good metric to use. However it we are simply interested in staying below some climate threshold, e.g. keeping warming well below 2 degrees C and do not care about the path leading up to this target we might favour GTPs.  This is because for a distant temperature target, it only matters how much warming is left lingering from an emission today at the point when the temperature target is reached (and not how much warming we get leading up to this point).

I will post part two of this article tomorrow, which deals with how this impacts on livestock.

Source: Martin Persson, published on the Food Climate Research Network

21.04.16 Reducing food waste could help mitigate climate change

Source: Postdam Institute for Climate Impact Research.

About a tenth of overall global greenhouse gas emissions form agriculture could be traced back to food waste by mid – century, a new study shows. A team from the Postdam Instititue for Climate Impact Research for the first time provides comprehensive food loss projections for countries around the world while also calculating the associated emissions. 

Currently one third of global food production never finds its way onto our plates. 

This share will increase drastically, if emerging countries like China and India adopt Western nutrition lifestyles, the analyses shows. Reducing food waste would offer the chance to ensure food security, (which is well known), but at the same time it could help mitigate dangerous climate change.

“Reducing food waste can contribute to fighting hunger but to some extent can also prevent climate impacts like more intense weather extremes and sea – level rise,” explains lead author Ceren Hic. Avoiding food loss and waste would therefore avoid unnecessary greenhouse gas emissions and help mitigate climate change.

What they did

The research analysed body types and food requirements for the past and different future scenarios accounting for demographic changes as well as food demand and availability, and associated emissions. They found that while global average food demand per person remains almost constant, in the last five decades already food availability has rapidly increased. 

More importantly, food availability and requirement ratio show a linear relationship with human development, indicating that richer countries consume more food than is healthy or simply waste it. Using the model that this research created in terms of future planning, greenhouse gas emissions associated with food waste could increase tremendously from today (0.5 Gigatons of CO2 equivalent per year) to 1.9 – 2.5 GtCO2eq.

Their model also indicated the growth of emissions from agriculture, due to demographic growth and lifestyle changes, with projections of a rise of 18 Gigatons of CO2eq by 2050.  The staggering statistic that this model found was that up to 14% of overall agricultural emissions in 2050 could easily be avoided by a better management of food utilisation and distribution.  Cutting food waste at a household (or even individual scale) could be one key to mitigating these emissions.  

How can the food supply chain be made smarter and more efficient, and are consumers ready to be convinced to reduce food waste?  More research is needed, but this study shines a light on the complex relationship between food security and climate change (that will become ever more important in the future with more people to feed). 

The researchers explain, “Avoiding food loss could pose a leverage to various challenges at one, reducing environmental impacts of agriculture, saving resources used in food production, and enhancing local, regional and global food security.” 

20.04.16 Reducing enteric methane for improving food security and livelihoods

This information comes from the FAO and was collated by the Global Research Alliance, and looks at the important issue of reducing enteric methane.  For more information on the Global Research alliance, please click here.

What is enteric methane?

Enteric fermentation is a natural part of the digestive process of ruminants where microbes decompose and ferment food present in the digestive tract or rumen. Enteric methane is one by-product of this process and is expelled by the animal through burping. Other by-products of the fermentation process are compounds which are absorbed by the animal to make milk and meat.

The amount of enteric methane expelled by the animal is directly related to the level of intake, the type and quality of feed, the amount of energy it consumes, size, growth rate, levels of production, and environmental temperature. Between 2 – 12% of a ruminant’s energy intake is typically lost through the enteric fermentation process. 

Why is enteric methane important?

Enteric methane is a Short – Lived Climate Pollutant (SLCP) and has a half-life of 12 years in comparison to carbon dioxide, parts of which stay in the atmosphere for many hundreds to thousands of years. Methane traps 84 times more heat than Carbon dioxide over the first two decades after it is released into the air.

Even over a 100 year period, the comparative warming effect of enteric methane is 28 times greater than carbon dioxide (per kg). Therefore reducing the rate of enteric methane emissions would help reduce the rate of warming in the near time, and if emissions reductions are sustained, can also help limit peak warming. 

Ruminants are responsible for 30% of global methane emissions.

Globally ruminant livestock produce about 2.7 GtC02 eq. of enteric methane annually, or about 5.5% of total global greenhouse gas emissions from human activities.

Cattle account for 77% of these emissions, buffalo for 14% and small ruminants for the remainder. 

What can farmers do?

Getting farms to improve the productivity of ruminants is a key way to improve rural livelihoods and improve food security. Farming systems that are much more productivity generally also reduce enteric methane emissions per unit of animal product. There are three key areas to focus on.

Feed and nutrition

Improving feed quality can be achieved through improved grassland management, improved pasture species, forage mix and great use of locally available supplements. Matching ruminant production to underlying grazing resources, ration balancing, undertaking adequate feed preparation and preservation will improve nutrient uptake, ruminant productivity and fertility.

Animal health and husbandry

Improving the reproductive rates and extending the reproductive life of the animal will increase their productivity and generally reduces methane emissions intensity. 

The most relevant method of achieving this is to limit the incidence of disease within the herd / flock, as healthier animals are generally more productive and have lower emissions per unit of product. 

Animal genetics and breeding

Genetic selection is a key measure in increasing the productivity of animlas. Breeding can help adapt animals to local conditions, and can also address issues associated with reproduction, vulnerability to stress, adaptability to climate change and disease incidence. Improved breeding management practices (using artificial insemination for example and ensuring access by farmers to wide genetic pools for selection) can accelerate those gains.

What the scientists / policy makers / industry need to do.

Care is needed ot identify the most effective package of interventions that fit local farm systems, resources and capabilities, and to avoid inadvertent trade-offs. 

Methods need to be practical and usable on the ground in order for them to be taken up, and communicated to farmers in a way which conveys their use.

Win-win opportunities for farmers

Rumninant production systems with low productivity lose more energy per unit of animal product than those with a high productivity (not rocket science I know). This energy that is lost per unit of product includes methane, so the more productive we can make our systems, the more of that energy will be going into producing meat or milk and not being expelled from the cow and lost to the environment.

There is a strong correlation between animal productivity and methane emissions, which implies large opportunities for low cost mitigation and widespread benefits.

Ruminants are essential to the livelihoods of millions of farmers and critical to human health, global food and nutritional security. Ruminants convert their feed (from a diverse range of sources and production systems) into high value products for humans through fermentation.  They also produce important components such as asset savings, traction, manure for fuel and fertilisers and fibre. 

Relative to other global greenhouse gas abatement opportunities, reducing enteric methane through productivity gains is the lowest cost option and has a direct economic benefit to farmers. 

What is happening?

Efforts to address enteric methane emissions in developing regions is relatively new and fragmented with a number of on-going initiatives each targeting a single component of the challenge.  The project which is a collaboration between the Food and Agriculture Organisation of the United Nations, and the New Zealand Agricultural Greenhous gas Research Centre funded by the Climate and Clean Air Coalition and the New Zealand Government in support of the Global Research alliance on Agricultural Greenhouse gases.

What are they going to do?

Analyse and prioritise opportunities for improved food security and resource use efficiency and the identification of production systems / countries for detailed assessment.

Develop packages of appropriate cost – effective technologies; recommend policy options that improve resource use efficiency.

Identify demonstration sites and partners for Phase 2 on-farm testing of the technical packages.

Communication, dissemination and outreach.

For more information on what’s happening click here.

For more information on reducing methane from ruminants and production efficiency click here to go to the Toolkit section. 

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