27 November 2023

Head of the Curve

Teagasc’s Marginal Abatement Cost Curve seeks to inform and steer agricultural policy toward hitting targets on emissions mitigation. Here, one of its chief architects, Gary Lanigan, gives us a breakdown.

Ireland has the world’s highest density of Eddy Covariance towers, making it a global leader in monitoring GHG emissions

Originally a plant physiologist by training, Principal Research Officer Gary Lanigan eventually found himself heading up Teagasc Johnstown Castle’s research on greenhouse gas emissions, and latterly focused on carbon sequestration. The field has become increasingly vital in recent years, and Teagasc has in turn provided key scientific guidance to agriculture policy and policymakers. The main tool for this is Teagasc’s Marginal Abatement Cost Curve, or MACC. Gary spoke to TResearch to explain its relevance.

How did the marginal abatement cost curve (MACC) first come about?

In 2012, the Department of Agriculture, Food and the Marine wanted to know the capacity of the agriculture sector to reduce greenhouse gas (GHG) emissions, and to identify the most cost-effective measures to do so. Marginal Abatement Cost Curves had been in use since the 1990s to look at measures that would decrease emissions to air and water and, indeed, had been used by the Irish Government to look at ways to decrease national GHG emissions across all sectors. So, we decided that it was an appropriate way to quantify the mitigation capacity of Irish agriculture.

What is the MACC?

Basically, the MACC is a tool to allow policymakers and decision-makers to be able to rank emission reduction measures based on cost. Measures are simply ranked from most cost-saving to most costly. So, policymakers can see what a given measure will cost and how much it will potentially mitigate, emissions-wise.

The MACC is presented in bar chart form and provides two elements of information. The vertical axis shows the cost of a given measure, with cost-beneficial and cost-prohibitive measures appearing below and above the x-axis respectively. The abatement potential of each measure, meanwhile, is given on the horizontal axis. Of note is that the magnitude of abatement is indicated by the width of the bar – i.e. the width is more important than the height on this chart.

What is the MACC used for?

The previous MACC formed the basis for what became agricultural policies going forward— Ag Climatise, for example. Over the past few weeks, we’ve been talking to government departments about how they might translate MACC into policy. All we say is “this is how much you need to mitigate or uptake” – it’s up to the departments to decide how to take it up. We provide scientific guidance to policy, but we’re not policy advisors.

How has this area of climate mitigation research developed over the years?

Climate research has exploded. When I started out at Teagasc in 2007, I was perhaps the only permanent researcher in the organisation whose whole focus was on GHGs. Now, there are over 15 permanent researchers in the field, alongside a plethora of PhDs and postdocs. So, now I can concentrate on one specific aspect of climate research, which is soil emissions. I’m looking at carbon sequestration, but also some nitrous oxide and ammonia emissions research. By training I’m a plant physiologist; as I happened to use a lot of cropland sites in my research, I fell into working on agriculture, rather than actually “doing” agriculture.

What research have you been doing in this field?

Carbon sequestration is my main focus now: looking at how much carbon is taken up by plants and sequestered into soil. This is quite difficult to measure, as you’re looking at a very small input going into a very large background. The analogy I would use is to imagine a swimming pool being filled by a dripping tap, and the only way to measure how much water is coming in is by measuring the height of the water!

If we can take carbon out of the atmosphere and lock it into soil, that’s good insofar as its being removed from the atmosphere. So ideally, you’d want to maximise how much carbon gets locked into mineral soils and minimise how much gets lost out of peat soils and back into the atmosphere. In a mineral soil there is about 100-500 tonnes of carbon per hectare, while in peat soil it’s 1,000-5,000 tonnes. The high carbon levels in peat are due to the fact that they are waterlogged and mostly acidic. This reduces decomposition to a huge degree, which is why ‘bog bodies’ and ‘bog butter’ have been found in almost perfect condition. Broadly, I’m leading the overall carbon research area in the new Teagasc Climate Centre, and that research includes our soil carbon monitoring and the eddy covariance towers we have spread around the country. Eddy covariance is a method for measuring gas transport between surface and atmosphere, so it’s widely used for quantifying rates of CO2 emission and sequestration.

What are the challenges surrounding the reduction of agricultural greenhouse gases?

The main challenge is that we have a pretty hard target to reach, so we need a fair bit of policy to get us there. Also, there can be resistance to some measures, especially land measures such as forestry uptake or managing peat soils. So our main challenge is knowledge transfer to farmers and land-owners: our Knowledge Transfer Office and Signpost farms will hopefully help with uptake; high and quick uptake being the key message from the MACC.

Another issue within uptake is that we want farmers to largely stop using ammonium nitrate and switch to protected urea; this has led to a degree of disquiet in the fertiliser industry, as this is a less profitable product for manufacturers. However, my colleagues are working with the industry to develop and test new products. So, in terms of a ‘top three’ challenges, one would be the need for policy guidance; two, a greater need for knowledge transfer; and three, the need to engage industry.

What impacts is this research having?

The MACC tends to be quite impactful, precisely because it forms a scientific foundation for agricultural policy on greenhouse gases and ammonia. As noted, Ag Climatise was a response to the previous MACC, so we’re likely to see a version two of that in response to both the new MACC, and attempts to meet 2030 targets.

Every sector has a response to meet its own targets. I think something that speaks in favour of the agricultural sector is that we’ve put proper numbers on it. We’ve got a tangible, clear path mapped out. What I would say, though, is that we now need to get into the implementation stage. We’re past the point of writing reports. This is where the Knowledge Transfer Office and Signpost Programme will come in and assist, but this absolutely also requires departmental guidance on policy, so policy supplementing the knowledge transfer.

What has the industry response been?

In terms of process: industry is committed, engaged and pretty much on board with the measures mapped out in the MACC. Other aspects of industry have been slightly more difficult – but in general we’re quite encouraged by the response so far, especially from processors. When we talk to the industry, they’re very concerned with reducing the footprint of their products, which is a marketing issue as much as anything else. However, this lines up with abatement measures – and in any case, these companies all have to reduce their supply-chain emissions.

What are your plans for this research?

Now that we’ve finished the MACC, we are looking at land-use out to 2050, the year by when we’re meant to be climate neutral. We’re modelling out how much forestry we’ll need and how much emissions reduction can be gleaned from grasslands and peatlands, for example.

Afforestation is a key area now; you’re no longer allowed to afforest peat soils, so there’s competition with dairy, tillage and beef for land access. However, as this has a knock-on effect on other land-uses, it requires lots of iteration and reiteration of modelling; currently, we’re weighing up about 13 different scenarios. The current MACC figure is 8,000 hectares of afforestation per annum; ideally, we’ll be at that rate by 2030, and sustain it between 2030 and 2040, so we’d reach 80,000 hectares of afforestation over a ten-year period. Afforestation makes a huge rate of difference per annum, so the quicker the better!

Up close and personal

What’s your favourite animal?

That’ll be the cat, Hermione! She’s the only one of our three cats left, probably because all she does is eat and lounge around all day. She’s a bit overweight and isn’t very agile but she rules the roost at home!

If you hadn’t ended up in research, what other job would you have wanted to give a go?

That’s a tough one… When I was going to college, I had a choice between Science in UCD and Fine Art at the National College of Art and Design. I chose UCD last minute but I still keep the painting and sculpting going. My real passion though has always been astronomy. Unfortunately, while my maths was OK it was never at the level required to make a career of it. Still, I’m happiest staring up at the stars with my telescope. It gives you a sense of perspective!

What are you most proud of professionally?

Seeing a lot of my former students doing so well. Many of them have permanent positions in research and academia, both in Teagasc and further afield and that’s easily the most pleasing thing. I’m very proud of all of them!

[pic credits] Photography: Karl McDonough