 At this point I would like to introduce our next speaker, David LaBelle. David is a professor at Stanford University in the Department of Earth System Science and he's the Gloria and Richard Cushill Director of the Center on Food Security and the Environment. The title of his talk is Can Climate Smart Agriculture Deliver Food and Carbon Mitigation Solutions? Over to you, David. So I am going to be addressing the agricultural side of the equation and just talked a lot about the forest and I should say I guess from the outset that this is an area that I've done some research on in the past. I am not a soil expert like Francesca but I've been teaching in this topic for a while and what I want to focus on is just kind of what I take students through to some extent of are really trying to get the numbers right on questions like this and understanding what really is the potential and also the tradeoffs. And I was given this title by the organizer. I put a question mark on it but this term climate smart agriculture means a lot of different things to different people. There's also a lot of other terms out there. I think regenerative agriculture has already been mentioned. For the purposes of today I'll treat these all as equivalent and basically we're talking about trying to build up carbon in agricultural systems as a way of providing natural managed carbon sink. Now I'll start with some of the reasons that I think there's some optimism here and I think this is reflected in to some extent in meetings like this. And one is that there is clearly growing interest both politically and commercially and those go together obviously but in a way that really we haven't seen at least in my say 20 years in the field. The fact that say a lot of rural America is quite intrigued and interested in climate solutions is definitely not something to take lightly and not something to not try to take advantage of. We see for example with the commercial interest was already mentioned some of the commercial interest. This is an example of some California initiatives that have been brought to my attention. Some different foundations really interested in how much regenerative agriculture in California can help. But on the commercial side which was already mentioned is indigo ag is really leading the way at least in the U.S. and really talking big about how much you can get out of agriculture as a natural carbon sink. This is a recent article talking about their additional funding in recent times and along with that announcement they really were pushing this idea that agriculture really can be a big part of fighting global warming. In fact they talk about a 15 trillion dollar opportunity for farmers to fight climate change and so you can maybe get some sense of why farmers are really paying attention when they're hearing numbers like this especially when typical margins on farms these days are very small and mostly through government payment. So I'll come back to this in a little bit but just to acknowledge that there is a very real money being directed at this and very real interest. And at the same time one of the longstanding I think obstacles to thinking about this has been the the fact that it's very difficult to monitor compliance with any sort of policy that is being incentivized or regulated. It's just the transaction cost of monitoring thousands or even millions of farmers in some countries is incredibly difficult. But in many of these practices that are part of what people would consider climate smart many of these practices are increasingly easy to to monitor. One example I'll put in is from where my group has done recently just showing that the practice of no-till or conservation tillage in the US is something that because of the the signatures of plant residue on the surface we can now do a fairly good job of mapping with satellites at at subfield resolution in the entire US and we can do this year after year to understand both when farmers are and are not doing this practice so you can look at permanence issues, reversibility at a very low cost and so that is not unique to this particular practice but it's there's a few practices where the cost of compliance or monitoring is is getting much more viable. Okay but I want to spend most of my time today in the in the pessimistics I think I've you know I guess the the message here would be not necessarily that this shouldn't happen but there are many reasons to be cautious and I just want to be air on the side of being super clear about these these reasons to be cautious. One is that in agriculture these are managed systems that first and foremost are going to be trying to to produce food it's it's possible in some foreseeable future that they'll be primarily focused on the carbon revenues but for the foreseeable future this is going to be an additional revenue stream not the main one and and when push comes to shove if there's things that need to be done to preserve their core business these carbon gains are easily reversible. One I think good example of this is is now the the concerns about weed resistance in the U.S. and not just in the U.S. but it's been certainly important here over the last decade the increasing resistance to glyphosate of many many important weeds including palmaramaranth where the the historically for the last 20 years a lot of these weeds have been controlled by chemicals which has facilitated the adoption of no-till because tillage is historically one of the main ways we control weed as as the resistance has built up many farmers have reverted back to tillage as a as a in an effort to try to stem the the rise of these of these weeds so things like this can can easily happen and that's true in in forests I suppose as well that you can have single events that can can reverse even decades of built up carbon so this is going to I think always be an issue but but is worth mentioning now I think the key thing to understand here is the numbers in terms of of what the impacts are relative to the claims that are being made and I think there's just inevitably a lot of overselling of certain solutions so let me walk you through at least my reasoning and I'll use as an example the indigo ag example there this is their advertisement here for their large carbon marketplace they're saying that you potentially have about a $15 this is per ton of co2 price okay that's fine they they're talking about potentially two to three credits per acre per year and so the revenue for a farmer would be something like 30 to 45 dollars per acre per year which is which is a non-trivial amount of revenue if you're a farmer with hundreds of acres the the star here is is followed by a lot of small texts which I won't read at all but suffices to say that they're clear that this is for promotional purposes only and none of these numbers are they're going to be held to but this is how they're coming up with statements like 15 trillion dollars and in particular they're looking at something like two to three metric tons of co2 per acre per year which from the scientists we tend to think about hectares so this is something like on the order of five tons per hectare per year of carbon building up in the soil now if you want if you kind of trace back to where statements like this derive from an indigo ag is actually partnering with one of the main institutes that have been promoting a regenerative value for a long time with statements like this which is you know nothing if if not clear which is that data from farming systems and pasture trials show we could sequester more than a hundred percent of all annual co2 emissions from a switch to widely available and inexpensive management practices so this statement in in turn is based on some calculations that have been done off of some studies and this is a table from their their their white paper that I that I like to use where you can see basically their calculations they take some numbers in terms of tons per car of carbon per hectare per year and they may they just extrapolate to global cropland and there's obviously issues with doing that but I want to focus today on mainly understanding where these numbers come from relative to like some of the studies that Francesca had mentioned so these studies if you look at all of these descriptions encompass a lot of changes that are part of a package of of say regenerative agriculture but the thing that they all have in common especially these ones left here listed here is a very important role of manure and when you think about manure there's a lot of a lot of issues with manure but one of the primary ones is there's just not that much of it around so if you look at these trials for example that are reporting something like four tons per hectare per year which is again on the low side of what indigo ag is is talking about they're putting on 30 tons of manure per hectare in in these trials so if you look at the total amount of manure in the world and this is actually a homework problem in my class that students have the pleasure of going through and counting up all the animals in their and their excretion rates um you get uh you get something like 600 million tons of manure that's not already accounted for in the current sort of inputs to to think of it as traditional agriculture so you know most most farmers in most countries are recycling most of the nutrients and this is the that you could think of this as like the feedlot manure the the pig you know uh lagoons that that need to be uh they have problems disposing of all this manure in these centralized facilities etc there's cost obviously in recovering it which is why it's not recovered now but if you just look at the the available nutrients we're talking at something like 600 million tons that you could imagine activating at the current levels of of livestock now you've got um the simple math of dividing this out gives you something like 20 million hectares that you could cover with this surplus manure let's call it uh that is not a lot so globally we've got something like 1.5 billion hectares so we're talking something on the order of 1% crop area and if you were able to do it on that 1% and you and you accept this four tons per hectare then you're talking about something on the order of it of a gigaton if you do really well but not something that's going to quote offset all of the emissions in the world now there are other issues with manure uh in particular whether it's you know traditional livestock manure or what's often called green manure where you're growing cover crops and then incorporating them into the soil uh there's a lot of nitrogen in that and associated with that carbon and studies have shown in Francesca mentioned this but if you look for example at a recent study um looking just at green manures and trying to simulate what happens to the carbon flux you do see in this case an uptake of carbon in the soils but associated with that you actually see a very large increase in the amount of nitrous oxides coming off of these soils which is more than enough to offset from a greenhouse gas perspective the benefits in terms of carbon approval so notwithstanding all of the all of the energy in in terms of transporting manure etc there are very real benefits to soil fertility but in terms of net greenhouse gas savings it's really not going to just be a carbon story and even if it were just a carbon story it's not going to get you very far so i think we're left largely thinking if we're i think being you know responsive responsible accountants of the carbon fluxes and what's really being sequestered we're left thinking about the non-manure inputs um and this is a big one is is left is this no till or conservation tillage and and actually Francesca has already referenced this this great recent review but i'm taking a different figure which is instead of focused on the percent gains looking at the actual metric tons per hectare per year from these practices and when you look at that you can see something well below one ton per hectare per year on on average and they're looking both at no till here and then reduced till which which is having on average of almost no impact on the total uh columns column sum of of the soil carbon buildup as Francesca mentioned you you almost always get an increase in carbon in the very surface but you typically associate that also get a decrease lower down where you're not adding as many inputs because you're not tilling anymore so again this isn't to say that no till does not have real benefits even from a carbon perspective but they're not on the order of four or five tons per hectare that are going into a lot of these calculations and and so this is just to point out even when you see a lot of kind of global maps of what you can get out of regenerative agriculture or climate smart agriculture they're typically look showing you maps of what you get if you look at adding manure plus a few other things and those few other things like conservation tillage or agroforestry are not trivial in terms of especially in certain locations if for example you're putting in trees into farming you could you could sequester a non-trivial amount of carbon in some places but it's it's just important I think to understand that these are are really not in my view very credible assessments of what the net greenhouse gas gain is from these types of practices so this this figure has been shown it's there's actually two there's a group Bill Schlesinger and a bunch of others led these analyses of of both the global and the US potential and so I believe Ann showed that some a figure from the the US this is the global version of that but just to point out that studies that I think do a careful job like including this one they tend to find fairly low potent mitigation potentials per per year from most agricultural options especially if you're only looking in this case at the darker part of the bars which are the low costs or things that they think would be feasible at reasonable carbon costs and you can see that the biggest ones that emerge are actually biochar which has been mentioned planting trees and crop lands which I just mentioned and then nutrient management and this is really the the big low cost one and that's not a carbon story at all that's really about reducing nitrous oxide emissions by better timing of fertilizer better better choice of how much to apply etc so I think that's really where if you really want to think about climate smart agriculture I think that's really where where the the focus is is most deserved now the other I think reason to be pessimistic about it is is I think the the real potential of things backfiring and I mean that in a couple of ways and and I mean that not so maybe it's at least two ways but I've already talked about the sort of biogeochemical backfiring of other of trace gases coming from these practices but in this case what I mean more so is is that it can distract from from real solutions and in particular that it can it can distract from what I consider the main goal of agriculture which is to to reduce the pressure on a forest conversion and increase the possibilities for reforestation and a lot of these practices I think run the risk of distracting from real productivity enhancing practices there was a recent viewpoint that made this point quite strongly that the conservation agriculture which has been pushed a lot in tropical systems is is has very marginal if any yield enhancement for these systems and these are these are areas that are increasing populations rapidly the food demand is increasing and so if you are going to the opportunity cost of focusing on things that aren't productivity improving I think is very much along the lines of of increasing pressure on these and so if you look at the best climate investments from an agricultural standpoint I think we always have to come back to the whether whether they're intended or not to the implications for the pressures on forest land so I I could say more about that but I'll leave it at that for now and and just summarize kind of what I think are the the climate smart options that really deserve the the most attention with the recognition that none of these are going to be you know enough to be more than say a couple of gigatons per year of abatement but but number one is certainly the the nutrient management side of things including the opportunities that are presented from new technologies to really reduce the nitrous oxide emissions from fertilizer applications reducing pressures for land conversion and I think there's a lot of opportunity this is really more the area that I that I work in more directly but the the in particular looking at closing yield gaps trying to raise productivity in low yielding regions I'm trying to make sure that policies are in place to protect conversion because if you improve local productivity without those policies in place you often have perverse effects of of increasing incentives to to clear and then improving soil quality is a big part of this and I think that it's important from a productivity standpoint particularly in these in these tropical regions which may have some carbon benefits but I don't think that that should be the the motivation for them now one thing that that is related to that to some extent is is this use of biochar and or what has been mentioned enhanced weathering through through adding crushed basalt or or olivine or other types of minerals to to the soil and I think there's a lot of interest in this area now and I think it's it certainly can scale in a way that say manure cannot to to be a viable large-scale carbon sequestration approach I think there's two big questions one is the cost associated with these in terms of the getting the the bulk of of materials that you would need out to the farms for example you know Brazil had a massive effort to increase soil pH with with a huge infrastructure investment but in other places around the world where you've seen soil acidity be an issue for a very long time they still haven't really been able to get a significant transport of in this case lime to fields just because of the the the cost of doing it and and it's not the lack of of I think appreciation of what the impact could be so that we're in a similar situation here but the other issue is is especially with some of these crushed rocks is you introduce trace minerals and to some extent biochar if you're not careful although it's less of an issue you introduce potentially things like nickel and chromium that are not things you want in your food supply and so there's there's definitely real risk to the soil that need to be explored but this is I would say an area more deserving of attention and investment if we're looking for for some level of offset in agricultural systems great thank you so much Rob thank you for that balanced presentation just remind everyone please submit your questions through the chat I'm going to actually start with the first one Rob what do you think are the most important research opportunities going forward especially in the areas of biochar or crushed rock you have any specific research ideas that you think should be pursued I know I may defer a little bit to Steve I think he may talk about this a little bit but you know in my estimation the the the interesting opportunity from my standpoint is this is the situations in where you have sort of a double benefit of these additions so I mentioned the the pH problem in a lot of tropical soils which really reduces nutrient availability and plant productivity some of these things like basalt can actually increase the pH the same way lime does but in a way that actually is building up carbon as opposed to in the case of lime arguably releasing carbon so I think trying to look for those those areas where you get multiple benefits from these additions was going to make the economics much more attractive and also potentially make the carbon benefits if you think of the whole system much more attractive so it you know again I think it's it's it's not an area that that is very mature nor one that I work in but that would be I think the area I would focus also in tropical systems you the enhanced weathering effects tend to be higher because of the the high temperatures so you can there's a carbon argument to it to focus in those systems as well okay Jenny what additional questions do you have from the audience okay great thank you David nice presentation so we have a couple of questions and we'll start with Andrew Robertson Andrew can you unmute yourself when you're able to and ask your question please yes no problem thanks I really can hear me I had thanks for your presentation David I had a question quite generally around the pessimism story I guess as a whole that do you do you not think the regenerative agriculture or agricultural you know MBS as a whole is one of those low hanging fruit that we can get going with quickly I completely agree with you that a lot of the claims coming out from indigo and others are ridiculous there's no way that they can reach that level of sustained carbon gains but if you compare the agricultural MBS sector to things like reforestation it's cheaper it's faster and we can it doesn't require land use change so we should really be targeting those things and recognize that you know if we want to get things going quickly there's no silver bullet for MBS so shouldn't we be tackling agriculture still I mean to me it's it's as much a political economy question as anything like if you can get the buy-in of rural communities around the world especially in this country by pursuing this in a way that creates the the momentum to actually make progress on the fossil fuel question then by all means that you know I couldn't care less how much carbon it builds up if that's the political view of things but but as a scientist if I look at these I I view it as like for example if we're going to put a lot of resources into conservation tillage and no tillage you have to think about all the other things even from an agricultural standpoint that you're not pushing because because you know typically you're you're able to promote one or two practice changes at a time and and I'm thinking more in the context of the types of systems I work around the world so I'm not opposed to the idea of you know I don't think there's a lot of harm done from say promoting no till but I really would be hesitant to call it a low hanging fruit if if it's a you know if it's I think somebody mentioned kumquats before but you know it depends on the size of the fruit like it might be low hanging but it's it's you know it's a grape it's not a grapefruit so low hanging yes relative to forestry but not very big fruits thank you thanks david for your answer there we have a follow-up question from claire jams claire would you like to ask a question unmute yourself when you're able hi thanks thanks for your presentation and I have to say I too have been suspicious of indigo's two to three tons per acre so I asked them and read the protocol that's on car in in fact it does include all the other things that you say could happen right so it includes everything from reducing nitrogen emissions to fossil fuel switching to renewables on farms so I think that's where they get that from and I do agree that that's important to recognize and be really clear about because if we don't I guess if we don't really recognize this and pull apart you know what is an emission reduction versus what is a marginal carbon sequestration it's really hard for policymakers to move forward right and so I think maybe part of the problem is all of this work has developed in an offset space so obviously folks want the offset credit to be as large as possible um and meanwhile they're working in sectors that have not been regulated for emission reduction so I guess I'm just wondering from a policy perspective is it maybe more helpful to look at that kind of all-in operation wide approach that indigo is doing as opposed to trying to credit sort of each individual practice separately um yeah I think you know I I don't claim to know uh like from a marketing standpoint what works I think you're you're right that really what matters in these systems is sort of the the totality of their of their system and the energy use in the greenhouse gases associated with it um you know I've just I guess I've been around long enough that that I've seen the eventual blowback against false promises and and I think the um the the real risk that you know there's another decade spent pursuing things that actually in the end don't add up to very much so I guess that's my my bias but it's not to um again as I said to the prior question it's not to say that I say other than the opportunity cost that I see any any big harm of these types of practices I just think the when it comes down to really setting up rigorous sort of accounting mechanisms to account for these carbon that there's going to be a lot of um a lot of disappointment and a lot of uh kind of I don't know regrets of not pursuing maybe some more difficult but more um scalable solutions but you know I think they're again like I'm not a I'm not saying that they don't have a path towards other like maybe rock weathering is it's not it's not to say that they're constraining themselves to these practices but I just think that um the overall potential is going to be much lower