The dilemma of agriculture under climate change: 3% yield reduction due to warming and 27% of greenhouse gas emissions

Key takeaways:

• 1

  Climate change, which is characterized by warming, is an indisputable fact, and the impact of human activities is at the heart of the warming.

• 2

  Agriculture is both a victim and an enabler of the climate crisis. Warming could reduce global food production by about 3%, while agriculture accounts for about 27% of global greenhouse gas emissions each year.

• 3

  The impact of climate change on agricultural production is a multidimensional and complex complexity, which is beneficial in specific regions and sectors, but also has negative impacts.

• 4

  If we do some active adaptation, there will probably be an average of 8-11% reduction in "reduced yield" by mid-century on top of existing farmland management.

It is well known that climate change threatens agrifood production, food quality and supply. What is often overlooked is that agricultural production also exacerbates climate change.

During the just-concluded 28th United Nations Climate Change Conference (COP 28), FAO has been calling for a significant reduction in global greenhouse gas emissions through agrifood systems transformation, protecting natural resources and biodiversity, and effectively tackling climate change.

Why does farming exacerbate climate change? How does global warming affect our tables, and how should agriculture adapt to climate change in the face of a range of systemic risks?

In the face of the above problems, Ye Tao explained at the Gates Foundation's Global Health and Development Media Seminar.

Narrator: Ye Tao丨Professor of Beijing Normal University, Director of the Secretariat of the United Nations Asia-Pacific Committee on Science and Technology for Disaster Reduction

1. The contribution behind the "hottest decade" - greenhouse gas emissions account for 27% of total emissions

First, climate change, characterized by warming, is an indisputable fact. There have been debates in the past, but now it is getting hotter and hotter, both in terms of instrumental measurements and the actual feelings of each person, the IPCC (Editor's Note: The Intergovernmental Panel on Climate Change, that is, the Intergovernmental Panel on Climate Change, is an intergovernmental organization affiliated with the United Nations, which was established in 1988 by the World Meteorological Organization, The United Nations Environment Programme (UNEP) has been set up to study human-induced climate change) in recent years, as the phrase has been "the hottest decade since we had instrumental records".

At the heart of this rising reality is the impact of human activities. In fact, the global temperature can be affected by many different natural or anthropogenic factors, and in general, human activities are overwhelmingly dominant in it, which is also divided into two parts. The first part is that greenhouse gas emissions will bring about warming, and the other part is that aerosols will bring some blocking and cooling effects.

There are five major elements in human activities, and agricultural production is a very important source of greenhouse gas emissions, ranking second among them, accounting for about 27% of the world's total annual emissions.

So in this context, agriculture is also an important source of emission reductions, such as the use of large amounts of fertilizers, and emissions from the livestock sector, especially ruminants.

In fact, climate change has a comprehensive, systemic, and even irreversible impact on the world, including the physical systems of our atmosphere and surface, as well as our ecosystems, as well as human-managed systems, such as agricultural or food production, and then our livelihoods, economic activities, and so on.

Second, carbon dioxide is good for agricultural production, and global warming is still a negative effect on the whole

The red part in the picture on the lower left is the part related to our agriculture and livelihoods, and the things related to agriculture and livelihoods are lighter in color, and the boxes are not all solid, does this mean that the impact is smaller?

For example, if we look at crop production related to agriculture, let's say the first column in the red box, the middle column is livestock production, and fisheries production, and you will find that there are plus and minus signs in different regions of the world. The minus sign indicates that the overall is negative, and it will have a positive impact in a specific region and a specific industry, but it will also have a negative impact. The core is that there are so many determinants of agricultural production, and there are many ways in which climate change can affect agricultural production, and here are some of the main ones.

First, the most direct high temperature stress after the temperature rise, which is a negative impact. In addition, precipitation variability will increase, which means that we may have more heavy rains, floods and drought events, which can lead to disaster losses.

Second, the growth period of crops is equivalent to growing faster after being hot, and shortening the growth period will actually have some adverse effects on the formation of dry matter, so that the yield and quality of crops will be reduced. Warming also increases pests and diseases, as well as supportive ecosystem services around farmland, which can also have indirect impacts.

The more clear positive effect is carbon dioxide, which we know is the main source of greenhouse gases for global warming, but it can be said to be positive for most sectors of agricultural production.

We have a term called the fertilizing effect of carbon dioxide, that is, in the case of rising carbon dioxide concentration, photosynthesis will actually be better, so for crops, especially for carbon three (C3) crops, the rise of carbon dioxide will have a significant fattening effect.

In addition, for high-latitude, cold regions, areas that are not suitable for growing crops can now be expanded northward after global warming, and warming in those places will bring positive effects. So the impact is both positive and negative, and overall it is still a negative effect.

In terms of the impact of climate change on China's agriculture, the Fourth National Assessment Report on Climate Change says that the impact of climate change on China's agriculture that has been observed in the historical period is that the heat resources will increase, and the northern boundary of crop planting will move further northward; But at the same time, one of its negative effects is the increase in yield reduction caused by warming, the increase in pests and diseases, and the observed reduction in yield is about 2%-5%.

In the future, we will further estimate that in the case of 1.5 degrees Celsius and 2 degrees Celsius, the average yield reduction will be about 3.7-11.5%, so the overall impact is still negative.

China's climate change adaptation strategy in the agricultural sector looks like this:

First, breeding, improving and improving new varieties.

Second, do better work on water resources.

Third, the technology of water-saving farmland.

Fourth, climate services, including services for early warning, tracking, mitigation and prevention of agrometeorological disasters, are more of a solution from the perspective of disasters.

Meteorological forecasts in the agricultural field of the mainland (Source: China Meteorological Observatory)

3. How should agriculture adapt to climate change in the face of a series of systemic risks?

The previous discussion is more about the production side, but the impact of climate change on agriculture also includes the direction of rural and farmers' livelihoods, which is a series of systemic risks.

First of all, it may affect the output, but the reduction of the output will also bring about an increase in global or regional food prices; once the availability and availability of food change, it will bring about problems such as malnutrition and difficulty in obtaining food; it will further affect the income of farmers and the supply of labor; it will also affect people's intake of food, and finally affect their livelihood and quality of life, that is, the long-term development of people.

In fact, there are many ways and types of ways and types of climate change adaptation in agriculture.

First, plant breeding, and cultivating water-saving and drought-resistant rice is one of them.

Second, climate services, we have AI that can make better weather forecasts, and we can provide farmers with better climate services for precision agriculture to help them resist drought or heavy rainfall.

Third, adjust the growing area, for example, to a higher latitude.

Fourth, adjust the growth period.

Fifth, the change of varieties and conservation tillage, etc., as well as diversified planting in the field.

These are some of the active adaptation measures that are already being done in different regions of the globe for different crop types.

Why do we have to emphasize adaptation? The issue of adaptation has just been talked about to a greater or lesser extent, for example, the goal of the Paris Agreement is to limit the temperature rise by the end of the century to as little as possible to 2 degrees Celsius.

We have an ambition to limit it to 1.5 degrees Celsius, but even if we reach net zero emissions, that is, carbon neutrality, it will only mean that the concentration of carbon dioxide in the atmosphere will not increase. We will certainly live in a warmer world than we did before the Industrial Revolution, and we will have to prepare ourselves to live in a world that is hotter than we used to be, and we will probably stay there for many years.

So, in terms of global research, if we don't take any adaptation measures, how much impact will be there from warming and increasing carbon dioxide concentrations, these are all computer simulations based on some crop models. Even if we take into account the fertilizing effect of carbon dioxide, the yield of our four major staple crops will be reduced by 0.7%-3.3% in the case of a global temperature rise of 2 degrees Celsius, which is the result of multiple studies from around the world.

But if we do some aggressive adaptation, on top of existing farmland management, the adaptation potential is probably an average of 8%-11% reduction in "reduced yields" by mid-century. Because active adaptation can "reverse" the reduction in production, and the "reverse" part can offset the negative effects of climate change.

Adaptation measures taken into account in these studies include the renewal of varieties, the use of better fertilizers, better irrigation, regulation of growth periods, the management of soil organic matter, and conservation tillage.

In short, adaptation is a very important tool for agriculture, and we need to be prepared for this.

(The above is compiled from the sharing of the Gates Foundation's Global Health and Development Media Workshop)

Organizer: Wang Jiaxin