Context – Climate Change Impacts – Land and Food

1. Introduction

The purpose of this Context article is to provide a basic explainer of the climate change impacts on weather and weather extremes. The Article utilises key selected extracts from reputable sources as well as from UNFCCC’s most recent benchmark IPCC’s 6^th Assessment Report, Working Group 1 – Climate Change 2011: the Physical Science Basis (6^thAR-WG1) which are all fully referenced at the start of the extract – direct extracts are copied in italics and highlighted in maroon for emphasis.

The aim is to set out in summary, the climate change drivers as well as the effects and impacts on land and food currently experienced as well as the likely committed changes and possible future consequences, depending on the climate change pathway into the future.

This future pathway is itself dependent on the global Greenhouse Gas (GHG) emissions trajectory particularly from Carbon Dioxide (CO2) and Methane (CH4) and whether these continue to increase, level off or are reduced and at what speed committing the world to warming of 2.7 degrees on current trajectories as outlined in this article or other outcomes; what happens is essentially in our hands.

At the end a number of the article a number of links to recent articles are listed which provides further information and evidence of the impacts, this list will be updated from time to time to keep current. A basic outline of greenhouse gases, emissions and temperature rise is provided in the short Impacts – Introduction Context article

2. Climate Change Impacts – Land

Extracts From Land – the planet’s carbon sink | United Nations

The world’s land — including its mountains, hills, plateaus and plains — provides vital services, such as oxygen, food and water, that are essential for life. Land is also home to much of the world’s biodiversity.

Land “plays a key role in the climate system” as an essential carbon sink because its surfaces, such as forests, regulate the planet’s temperature and help to store carbon. In the last decade alone, land-based ecosystems absorbed around 30 per cent of the carbon emissions generated by human activities, such as the burning of fossil fuels.

But our land is under increasing pressure from deforestation, urbanization, industrial development, agricultural expansion and unsustainable farming practices that are undermining its ability to sustain food production, maintain freshwater and forest resources, as well as regulate the climate and air quality.

And a changing climate, in turn, exacerbates land degradation through drought, desertification and other extreme weather events that are increasing in frequency and intensity as the planet gets warmer.

State of our land

Today, up to 40 per cent of the world’s land surface has been degraded including 30 per cent of its cropland and 10 per cent of its pastureland.

In the last fifty years, the area of drylands in drought has increased on average by more than 1 per cent per year — affecting mostly countries in Africa and Asia. If we continue to misuse our land, we could degrade a surface area as vast as the size of South America by 2050.

When land is degraded, it impacts food security, water availability and ecosystem health, directly affecting half of humanity, and causing a loss of about US$40 trillion worth of ecosystem services each year — nearly half of the global GDP of $93 trillion in 2021.

Land degradation is also considered “the single greatest cause of terrestrial biodiversity loss,” resulting in the destruction of the habitats of many animals and plants. Severe degradation such as drought and desertification can also devastate communities, leading to social and economic instability. Up to 250 million people could be displaced by 2050 as a result of climate change-induced desertification.

Land and climate change

How does land degradation impact climate change? It decreases the soil’s ability to store carbon. Moreover, when forests are cleared or burnt, they release the carbon they have stored. A 2018 UN report found that deforestation alone contributed about 10 per cent of all human-induced greenhouse gas emissions.

Between 2000 and 2009, annual greenhouse gas emissions from degraded land accounted for up to 4.4 billion tonnes of carbon dioxide (CO2) emissions — in comparison, the global energy-related CO2 emissions were considered to reach their highest ever level in 2021 at 36.3 billion tonnes.

And as the planet warms, extreme weather events, including longer and more intense droughts, heavier rainfall leading to floods and landslides, and more frequent and intense tropical storms, worsen land degradation.

Projected length of drought with every 0.5°C temperature increase. SOURCE: UNFCCC

The IPCC warns that droughts will lead to soil erosion as well as reduced crop yields, while floods and landslides can destroy agricultural lands and infrastructure. Tropical storms can uproot trees and damage crops.

Heatwaves have caused significant agricultural losses, including in the world’s major breadbasket regions in the last few decades, with major consequences for global food security.

Additionally, climate change causes sea levels to rise, leading to coastal flooding and erosion. Such impacts have serious economic, social and environmental impact on countries and communities around the world, and scientists caution that these impacts will only become more severe in the future.

Without efforts to restore and protect land, nearly 70 gigatonnes more carbon would be emitted by 2050 due to land use change and soil degradation, representing approximately 17 per cent of current annual greenhouse gas emissions.

3. Climate Change Impacts – Food.

Climate Change impacts food security and is itself impacted by food production. Both aspects will be looked at in this section

Food Security

Extracts from IPCC Special Report on Climate Change and Land –Chapter 5 : Food Security — Special Report on Climate Change and Land

The current food system (production, transport, processing, packaging, storage, retail, consumption, loss and waste) feeds the great majority of world population and supports the livelihoods of over 1 billion people. Since 1961, food supply per capita has increased more than 30%, accompanied by greater use of nitrogen fertilisers (increase of about 800%) and water resources for irrigation (increase of more than 100%). However, an estimated 821 million people are currently undernourished, 151 million children under five are stunted, 613 million women and girls aged 15 to 49 suffer from iron deficiency, and 2 billion adults are overweight or obese. The food system is under pressure from non-climate stressors (e.g., population and income growth, demand for animal-sourced products), and from climate change. These climate and non-climate stresses are impacting the four pillars of food security (availability, access, utilisation, and stability). {5.1.1, 5.1.2}

Observed climate change is already affecting food security through increasing temperatures, changing precipitation patterns, and greater frequency of some extreme events (high confidence). Studies that separate out climate change from other factors affecting crop yields have shown that yields of some crops (e.g., maize and wheat) in many lower-latitude regions have been affected negatively by observed climate changes, while in many higher-latitude regions, yields of some crops (e.g., maize, wheat, and sugar beets) have been affected positively over recent decades. Warming compounded by drying has caused large negative effects on yields in parts of the Mediterranean. Based on indigenous and local knowledge (ILK), climate change is affecting food security in drylands, particularly those in Africa, and high mountain regions of Asia and South America. {5.2.2}

Food security will be increasingly affected by projected future climate change (high confidence). Across Shared Socio-economic Pathways (SSPs) 1, 2, and 3, global crop and economic models projected a 1–29% cereal price increase in 2050 due to climate change (RCP 6.0), which would impact consumers globally through higher food prices; regional effects will vary (high confidence). Low-income consumers are particularly at risk, with models projecting increases of 1–183 million additional people at risk of hunger across the SSPs compared to a no climate change scenario (high confidence). While increased CO₂ is projected to be beneficial for crop productivity at lower temperature increases, it is projected to lower nutritional quality (high confidence) (e.g., wheat grown at 546–586 ppm CO₂ has 5.9–12.7% less protein, 3.7–6.5% less zinc, and 5.2–7.5% less iron). Distributions of pests and diseases will change, affecting production negatively in many regions (high confidence). Given increasing extreme events and interconnectedness, risks of food system disruptions are growing (high confidence). {5.2.3, 5.2.4}

Vulnerability of pastoral systems to climate change is very high (high confidence). Pastoralism is practiced in more than 75% of countries by between 200 and 500 million people, including nomadic communities, transhumant herders, and agropastoralists. Impacts in pastoral systems in Africa include lower pasture and animal productivity, damaged reproductive function, and biodiversity loss. Pastoral system vulnerability is exacerbated by non-climate factors (land tenure, sedentarisation, changes in traditional institutions, invasive species, lack of markets, and conflicts). {5.2.2}

Fruit and vegetable production, a key component of healthy diets, is also vulnerable to climate change (medium evidence, high agreement). Declines in yields and crop suitability are projected under higher temperatures, especially in tropical and semi-tropical regions. Heat stress reduces fruit set and speeds up development of annual vegetables, resulting in yield losses, impaired product quality, and increasing food loss and waste. Longer growing seasons enable a greater number of plantings to be cultivated and can contribute to greater annual yields. However, some fruits and vegetables need a period of cold accumulation to produce a viable harvest, and warmer winters may constitute a risk. {5.2.2}