Food and Earth Systems: Priorities for Climate Change Adaptation and Mitigation for Agriculture and Food Systems

Round 1

Reviewer 1 Report

Comments provided have all been taken into account in the revised version.   The text reads smoothly.  The focus on small and family farms is not always evident  in some of the sections of the paper, namely section 4., e.g. food waste and losses, changes in food consumption patterns and climate-smart agriculture.   It may be worth considering reading through these sections and make reference to small and family farms, where applicable.

Author Response

Following the academic editor suggestion, we changed the title of the paper to the following: “Food and earth systems: Priorities for climate change adaptation and mitigation for agriculture and food systems” and we removed the mention of focusing on small-farms in the abstract, but in the introduction, we included an extra sentence on the focus of the paper. It now reads, “While many of the adaptation and mitigation options are relevant globally, our focus is on small and family farms in developing countries, for it is that sector that will face the greatest challenges with respect to climate change. Some of the key mitigation options, e.g. reducing loss at the demand end of the supply chain and changes in consumption, are more relevant to developed countries, but will become global priorities as countries develop.”

Reviewer 2 Report

“Food and earth systems: Priorities for climate change adaptation and mitigation for small and family farms” has been edited but the changes do not really address the problems of this paper.  The paper claims to be focused on farms but it cannot help itself and try to address all the problems of the world that are vaguely related to food. This shotgun approach has something for everyone but the paper is totally scattered and ends up making many claims it cannot support. The major themes of the paper such as a synergy between adaptation and mitigation or even what farms can and cannot do are lost and distorted.  The many sweeping statements have little support and are often misleading.

The paper is largely qualitative and vague. The parts that are clear and precise are too small. It is not clear that the qualitative insights have empirical foundation or what they actually mean. One serious deficiency is that the paper treats all farmers, small and family farms as a group.  But the critical small farmers in this paper are subsistence farmers and the other group are commercial farmers. Many of the sweeping statements of this paper are relevant to one group or the other but not both. Commercial farms practice intensive farming, these farmers are generally wealthy, they produce most of the world’s food, and they are responsible for most of the direct GHG emissions from agriculture. In contrast, subsistence farmers are poor, they have low quality land, they use little inputs, and they generate few emissions.  Subsistence farming’s primary contribution to warming is through deforestation. 

Both mitigation and adaptation for these two distinct groups of farmers is different. Lumping these two groups together leads to nothing but confusion. For example, the authors are concerned about global food supply. How much of this will be met by subsistence farmers versus commercial farmers? Commercial farmers have produced more food by increasing inputs. This leads to more GHG emissions. There is a tradeoff between more food and fewer emissions. This is not a synergy.  More inputs on the poor quality land of subsistence farmers will actually reduce their net income. To grow more food, all subsistence farmers can do is farm more land.  If the only new land available is forested, that means they must cut down forests which will increase carbon emissions. So whether the topic is supplying more food to global agriculture, mitigation of GHG emissions, reduction of deforestation, adaptation to climate, or implications for rural poverty, it is very important to distinguish between commercial and subsistence farmers.  

Authors go back and forth between a global mitigation program and what can be done in agriculture. An examination of any of the global programs to reduce greenhouse gases to reach a low temperature target reveals that agriculture can remove only a relatively small percentage of global emissions. The most important mitigation activity involving agriculture is bioenergy from crops. This dramatically increases the price of food which falls heavily on the poor.  It also requires a great deal more crop production which will lead to more emissions. A serious deficiency of crop bioenergy is that it provides an incentive to do more deforestation. The paper does not address crop bioenergy at all. 

The discussion of food safety nets, food distribution, food waste, and food consumption may address diverse sustainability goals but they have nothing to do with farmers. Title suggests the paper is about farmers but they cannot help themselves and talk about these topics. Authors travel over these topics quickly because to actually address them would require a lot deeper discussion. This only adds to the sense that there is no substance to this paper.  The global poor who might not be able to buy food and are not necessarily rural or farmers.  How is food distributed today?  What food programs work?  How do these food programs affect subsistence and commercial farmers? Although these are an important issues for sustainable development goals, these topics are not adequately developed and are clearly outside the scope of this paper.

Authors confuse weather effects (climate variability) with climate change (changes in mean climate).   Climate variability is a feature of the current climate.  It is difficult to adapt to climate variability even if it is easy to adapt to changes in mean climate. Authors assume that the primary problem with climate change for farmers is extreme events. But extreme events are rare and they have changed very little.  They have confused the increased damage from extreme events with an actual change in the events themselves.

Other weather related topics include discussions of weather forecasting and weather insurance.  Paper argues for more reliance on weather forecasting.  Although short term weather forecasts (1 week) have made huge progress, long term weather forecasts (next season) remain unreliable.  This discussions, however, remains focused on the weather and not climate change. Index based insurance should help farmers cope with the uncertainty of weather.  Curiously, farmers have been unwilling to buy fair insurance. The lack of interest in fair insurance suggests that either the programs are too difficult to administer or that farmers do not actually care about the uncertainty of weather. 

The climate smart program has the lofty goal of 1) increasing yields, 2) increasing net revenue 3) increasing resilience to climate change and 4) reducing GHG emissions.  Although there are many activities which can achieve one or two of these objectives, the number of activities which can do all four are few. This is the real test of their synergy argument. As the authors note, almost every activity aimed at 1) and 2) will fail at 4). The one exception that they hail is by Tilman (and others) who suggest intensifying crop production. This is in fact one mitigation activity that might reduce aggregate emissions, raise farmer incomes, and also be a good adaptation to climate. However, a closer examination suggests that this is particularly good for commercial farmers in mid and high latitudes on good land.  They will produce a lot more food.  Subsistence farmers on poor land are assumed to go bankrupt in this scenario and so release their land back to forestry. The forest then accumulates carbon which is why the program reduces GHG emissions.  This program is not aimed at helping subsistence farmers. It is not clear that the authors understand this.      

All crops are climate sensitive. Farmers have traditionally matched their climate with the crop that grows in that climate.  Suggesting that scientists develop crops that are not climate sensitive is both hard to do and not obviously useful.

The paper does not address why the African program to get farmers to adopt new varieties failed whereas such programs worked well elsewhere.         

Warming does not imply that all cropland deteriorates. Where would cropland tend to deteriorate and where would warming be helpful?

They list examples where a particular adaptation has been applied. This is one place in the manuscript that is not vague but is quite clear and specific. This section should be expanded. Can they be more specific about when one would use one adaptation versus another?  What issue is the adaptation trying to overcome- high temperature, low precipitation, weather, economies to scale? Where would you use it?  It is not random. 

What is the relationship between cultural or political regime change and adaptation to climate or mitigation?

Figure 3 addresses who will import and who will export cereals. This does not necessarily address something that needs to be fixed.

Author Response

Point 1:“Food and earth systems: Priorities for climate change adaptation and mitigation for small and family farms” has been edited but the changes do not really address the problems of this paper.  The paper claims to be focused on farms but it cannot help itself and try to address all the problems of the world that are vaguely related to food. This shotgun approach has something for everyone but the paper is totally scattered and ends up making many claims it cannot support. The major themes of the paper such as a synergy between adaptation and mitigation or even what farms can and cannot do are lost and distorted.  The many sweeping statements have little support and are often misleading.

Response 1: Following the academic editor suggestion, we changed the title of the paper to the following: “Food and earth systems: Priorities for climate change adaptation and mitigation for agriculture and food systems” and we removed the mention of focusing on small-farms in the abstract, but in the introduction, we included an extra sentence on the focus of the paper. It now reads, “While many of the adaptation and mitigation options are relevant globally, our focus is on small and family farms in developing countries, for it is that sector that will face the greatest challenges with respect to climate change. Some of the key mitigation options, e.g. reducing loss at the demand end of the supply chain and changes in consumption, are more relevant to developed countries, but will become global priorities as countries develop.”

Point 2: The paper is largely qualitative and vague. The parts that are clear and precise are too small. It is not clear that the qualitative insights have empirical foundation or what they actually mean.

Response 2: We could easily add references to these if we knew which ones were a problem to the reviewer.

Point 3: One serious deficiency is that the paper treats all farmers, small and family farms as a group.  But the critical small farmers in this paper are subsistence farmers and the other group are commercial farmers. Many of the sweeping statements of this paper are relevant to one group or the other but not both. Commercial farms practice intensive farming, these farmers are generally wealthy, they produce most of the world’s food, and they are responsible for most of the direct GHG emissions from agriculture. In contrast, subsistence farmers are poor, they have low quality land, they use little inputs, and they generate few emissions.  Subsistence farming’s primary contribution to warming is through deforestation. 

Response 3: We of course agree with reviewer 2 that it is much more complex, that one needs to distinguish a range of different types of farmers (and not only subsistence vs. commercial), that some options are more relevant than others depending on the farmer type, and that all options need to consider context to be successfully applied. However, doing this in a single paper would double the size of the paper. In Section 6, the paper clarifies that we are only trying to facilitate thinking of a global audience and have up-front stated that we recognize that priorities will and should be very different in different parts of the world and for different types of farmers.

Point 4: Both mitigation and adaptation for these two distinct groups of farmers is different. Lumping these two groups together leads to nothing but confusion. For example, the authors are concerned about global food supply. How much of this will be met by subsistence farmers versus commercial farmers? Commercial farmers have produced more food by increasing inputs. This leads to more GHG emissions. There is a tradeoff between more food and fewer emissions. This is not a synergy.  More inputs on the poor quality land of subsistence farmers will actually reduce their net income. To grow more food, all subsistence farmers can do is farm more land.  If the only new land available is forested, that means they must cut down forests which will increase carbon emissions. So whether the topic is supplying more food to global agriculture, mitigation of GHG emissions, reduction of deforestation, adaptation to climate, or implications for rural poverty, it is very important to distinguish between commercial and subsistence farmers.  

Response 4: We acknowledge what the reviewer says about distinct types of farmers and mitigation, but even here, note that context matters, e.g. mitigation actions are important to consider for small-scale rice producers and small-scale cattle/dairy producers.

Point 5: Authors go back and forth between a global mitigation program and what can be done in agriculture. An examination of any of the global programs to reduce greenhouse gases to reach a low temperature target reveals that agriculture can remove only a relatively small percentage of global emissions. The most important mitigation activity involving agriculture is bioenergy from crops. This dramatically increases the price of food which falls heavily on the poor.  It also requires a great deal more crop production which will lead to more emissions. A serious deficiency of crop bioenergy is that it provides an incentive to do more deforestation. The paper does not address crop bioenergy at all. 

Response 5: The focus is on global mitigation in food systems, including globally direct non CO2 emissions from agriculture, avoided deforestation due to agriculture, food loss and waste, and dietary shifts.  We believe this is consistent and clear in the text.

Agriculture contributes 10-12% of global emissions, already a significant source of emissions, and when land use change is considered, agriculture is accountable for about 22% of global emissions. This is comparable or larger than the transport sector.  As stated in the paper, if the entire food system is considered, food systems contribute 19%–29% of GHGs global emissions. So agricultural and food-related emissions are significant by multiple measures.  Regarding mitigation, while it is true that current levels of mitigation in agriculture are low, the potential is high and the need to mitigation in the sector is urgent. The IPCC 5th Assessment Report (2014) reports that agriculture can provide mitigation of 0.3 to 4.6 GtCO2eq/yr in 2030.  By 2030, when emissions from the energy sector have hopefully reached carbon neutrality, to reach global targets, the largest remaining source of emissions will be in the agriculture sector. See also Bajzelj B, Richards KS, Allwood JM, Smith P, Dennis JS, Curmi E, Gilligan CA (2014) Importance of food -demand management for climate mitigation. Nature Climate Change, 4, 924–929.  Furthermore, the NDCs demonstrate that demand for mitigation in agriculture is there.

Thank you for urging us to address the point in relation to bioenergy. We have added the following text:

Bioenergy crops play a potentially important role in the transition to renewable energy and can contribute to the mitigation of emissions from fossil fuels in fertilizer production, farm mechanization, and the food supply chain.  However, issues related to competition with food crops, the role of bioenergy crops as a driver of land use change, the life cycle emissions and efficiency of biofuels, site-specific outcomes, differential impacts on the poor, and sustainable cultivation practices have made bioenergy controversial as a mitigation measure (Smith et al. 2014).

Point 6: The discussion of food safety nets, food distribution, food waste, and food consumption may address diverse sustainability goals but they have nothing to do with farmers. Title suggests the paper is about farmers but they cannot help themselves and talk about these topics. Authors travel over these topics quickly because to actually address them would require a lot deeper discussion. This only adds to the sense that there is no substance to this paper.  The global poor who might not be able to buy food and are not necessarily rural or farmers.  How is food distributed today?  What food programs work?  How do these food programs affect subsistence and commercial farmers? Although these are an important issues for sustainable development goals, these topics are not adequately developed and are clearly outside the scope of this paper.

Response 6: Following the academic editor suggestion, we changed the title of the paper to the following: “Food and earth systems: Priorities for climate change adaptation and mitigation for agriculture and food systems”. We disagree that the topics mentioned by the reviewer should not be part of the adaptation priorities; they have to be part and parcel of an adaptation program related to food security. With respect to mitigation, even though the emphasis of the paper is on farmers we believe that when thinking about priorities for mitigation the discussion should go beyond the agriculture sector. This is one of the key messages of the paper.

Point 7: Authors confuse weather effects (climate variability) with climate change (changes in mean climate).   Climate variability is a feature of the current climate.  It is difficult to adapt to climate variability even if it is easy to adapt to changes in mean climate. Authors assume that the primary problem with climate change for farmers is extreme events. But extreme events are rare and they have changed very little.  They have confused the increased damage from extreme events with an actual change in the events themselves.

Response 7: We believe that the reviewer is incorrect. For four years, the American Association of Meteorologists has produced special issues related to extreme events, which shows conclusively how they have increased in likelihood and strength as a result of climate change, so the easy distinction between climate variability and climate change is not as easy as the reviewer makes it to be.

The authors do not confuse weather effects with climate change. The following text taken from the manuscript and backed up with relevant references explains the issue: “There is growing recognition that adapting smallholder and family agriculture to climate change requires developing resilience to the risks associated with natural climate variability [22-26]. Because anthropogenic forcing interacts with natural climate variability, smallholder and family farmers experience climate change largely as shifts in the frequency and severity of extreme events.  Increasing risk from extreme events, such as drought, flooding from extreme precipitation and coastal storm surge, and heat waves, is projected across much of the developing world [26, 27]. Climate variability – through loss of productive assets and human capital resulting from extreme events [28-31], and the adverse effect that the resulting uncertainty has on investment in agricultural inputs and innovation [32-36] – frustrates the efforts of smallholder and family farmers in risk-prone environments to escape poverty and build a better life [37-39].”

What the paper is communicating is that there is relevant literature that supports the fact that increasing risk from extreme events is projected across much of the developing world. The authors do not assume that the primary problem with respect to climate change is extreme events but they acknowledge that the risk associated to extreme events will increase. Among the priorities for adaptation discussed in the paper, breeding for developing crop varieties that are tolerant or resistant to both biotic and abiotic climate change impacts and migration are also included. Both of them respond to climate change as well to weather effects.

Point 8: Other weather related topics include discussions of weather forecasting and weather insurance.  Paper argues for more reliance on weather forecasting.  Although short term weather forecasts (1 week) have made huge progress, long term weather forecasts (next season) remain unreliable.  This discussions, however, remains focused on the weather and not climate change. Index based insurance should help farmers cope with the uncertainty of weather.  Curiously, farmers have been unwilling to buy fair insurance. The lack of interest in fair insurance suggests that either the programs are too difficult to administer or that farmers do not actually care about the uncertainty of weather. 

Response 8: As mentioned in the paper index insurance builds resilience and contributes to adaptation both by protecting farmers’ assets in the face of major climate shocks, and by promoting access to credit, and adoption of improved farm technologies and practices. It is indeed a measure to respond to climate variability. Also according to the paper, evidence shows that demand for insurance is not fixed but can be enhanced by designing indexes that reduce basis risk, and that invest in farmers’ understanding and trust in insurance. Therefore, there are opportunities to increase the number of farmers benefiting from index insurance.  We wonder whether the reviewer is up to date. In Africa GIZ estimates that 650,000 farmers now are being insured and the number is growing as the indices and insurance products improve.

With respect to uncertainty around weather forecasting, “climate science has advanced markedly over the past two decades, with international coordination and collaboration, and it is now possible to predict both short term weather and longer-term climate patterns at specific sites with a certain degree of confidence (Klemm, 2017; IPCC, 2014). Coupled with climate and weather analysis, crop models have been improved to the point that a realistic prediction of crop performance under a range of climate conditions and management is possible (Challinor et al., 2018; Manatsa et al., 2012; Stone and Meinke, 2005). Thus, it is now possible to combine weather and climate prognosis with crop models and farmers´ knowledge so that farmers can evaluate cropping options in the light of likely weather and climatic conditions.” (Loboguerrero et al., 2018).

Point 9: The climate smart program has the lofty goal of 1) increasing yields, 2) increasing net revenue 3) increasing resilience to climate change and 4) reducing GHG emissions.  Although there are many activities which can achieve one or two of these objectives, the number of activities which can do all four are few. This is the real test of their synergy argument. As the authors note, almost every activity aimed at 1) and 2) will fail at 4). The one exception that they hail is by Tilman (and others) who suggest intensifying crop production. This is in fact one mitigation activity that might reduce aggregate emissions, raise farmer incomes, and also be a good adaptation to climate. However, a closer examination suggests that this is particularly good for commercial farmers in mid and high latitudes on good land.  They will produce a lot more food.  Subsistence farmers on poor land are assumed to go bankrupt in this scenario and so release their land back to forestry. The forest then accumulates carbon which is why the program reduces GHG emissions.  This program is not aimed at helping subsistence farmers. It is not clear that the authors understand this.      

Response 9: We agree with the reviewer that what is climate smart for one type of farmer can be not climate smart for other type of farmer. This is the beauty of climate smart agriculture that it really depends on specific contexts. The latter is acknowledge in the text: “These critiques and others suggest a disconnection between principles and practice. The way some have suggested to remedy this is thorough clearer definition of what is and what is not CSA [146]. That however goes against the fundamental definition of resilience, time and location specificity which is core to CSA and the UNFCCC agenda which promotes continuous improvements. So what is CSA today may not be CSA tomorrow. Drawing boundaries would seemingly contradict part of what makes CSA attractive: its flexibility for different stakeholders with their own values to contribute to the same goals.”

There are many examples of technologies and practices showing synergies (Tilman is not the only case). Please refer to Table 4 in the manuscript.

Point 10: All crops are climate sensitive. Farmers have traditionally matched their climate with the crop that grows in that climate.  Suggesting that scientists develop crops that are not climate sensitive is both hard to do and not obviously useful.

Response 10: In the paper, there is no mention to developing crops that are not climate sensitive. We mention the development and promotion of new varieties, breeds and populations that are adapted (more tolerant or more resistant) to abiotic and biotic stresses.

Point 11: The paper does not address why the African program to get farmers to adopt new varieties failed whereas such programs worked well elsewhere.   

Response 11: The paper includes the lack of the following as reasons why some African countries did not adopt the new varieties: Parallel initiatives that address easy and timely access to improved germplasm, information on complementary production inputs, more capable and better resourced extension services and the provision of climate information and rural financial services.

Point 12: Warming does not imply that all cropland deteriorates. Where would cropland tend to deteriorate and where would warming be helpful?

Response 12: This falls beyond the scope of the paper.

Point 13: They list examples where a particular adaptation has been applied. This is one place in the manuscript that is not vague but is quite clear and specific. This section should be expanded. Can they be more specific about when one would use one adaptation versus another?  What issue is the adaptation trying to overcome- high temperature, low precipitation, weather, economies to scale? Where would you use it?  It is not random. 

Response 13: Surely, there are regional differences as well as farmers’ type differences when thinking about priorities for adaptation and mitigation. Of course, we agree that solutions are very context specific. Nevertheless, to do a regionally nuanced paper or to distinguish under which specific circumstances these solutions should be implemented would make the paper very long. In Section 6, the paper clarifies that we are only trying to facilitate thinking of a global audience and have up-front stated that we recognize that priorities will and should be very different in different parts of the world. In addition, Section 6 includes some figures that illustrate some of the regional nuances. The approach in the paper is to highlight the main challenges and propose ways forward to tackle these challenges for each one of the proposed topics. We believe that this is helpful given that we are providing a working agenda for starting addressing the main issues in relation to the solutions proposed in the paper. 

Point 14: What is the relationship between cultural or political regime change and adaptation to climate or mitigation?

Response 14: This falls beyond the scope of the paper.

Point 15: Figure 3 addresses who will import and who will export cereals. This does not necessarily address something that needs to be fixed.

Response 15: Figure 3 combines production gaps with the severity of impacts of climate change on maize, wheat and rice. By combining these two variables, the figure makes the point that different countries have different adaptation needs. This is the point that Section 6 is addressing. It is not related to needing to fix something.

Author Response File: Author Response.docx