Limiting global warming to less than 2ºC will need significant improvements to land use through changes such as switching to plant-based food, the Intergovernmental Panel on Climate Change (IPCC) said on Thursday.
A special report on the relationship between climate change and land found that better management of land is required to ensure food supplies are not disrupted by the rise of extreme weather.
For example, the use of biofuels such as wood or crop waste needs to be carefully managed to avoid land degradation, it said.
The report was prepared by 107 experts from 52 countries as part of the IPCC's work on the impacts of climate change. It is the first such report where a majority of the authors (53%) are from developing countries. Women accounted for 40% of the lead authors.
The UN's body on assessing the science related to climate change warned last year that the world was off track for limiting global temperature rise to below 1.5ºC.
The 2015 Paris agreement aimed to limit the increase of global average temperature to "well below 2ºC above pre-industrial levels and pursuing efforts to limit the temperature increase to 1.5ºC above pre-industrial levels".
Land becoming less productive
Climate change is adding to water scarcity, soil erosion, vegetation loss, wildfire damage, permafrost thawing, coastal degradation, and tropical crop yield decline, the IPCC report said.
"Agriculture, forestry and other types of land use account for 23% of human greenhouse gas emissions," said Jim Skea, a co-chair of one of the IPCC's three working groups on the topic.
When land is degraded, the new IPCC report says, it becomes less productive. It impacts the soil's ability to absorb carbon which in turn exacerbates climate change.
"New knowledge shows an increase in risks from dryland water scarcity, fire damage, permafrost degradation and food system instability, even for global warming of around 1.5°C,” said Valérie Masson-Delmotte, one of the IPCC working group co-chairs. At 2°C of warming, the risks are even higher.
Recent wildfires in the Arctic circle have been emitting high levels of carbon dioxide into the atmosphere. Greenpeace Russia recently estimated that the wildfires in Siberia spanned 4.3 million hectares.
Humans affect more than 70% of the global ice-free land surface, the report summary said, and the expansion of agriculture and forestry have contributed to emissions and loss of the natural ecosystems and wildlife.
Eating different food
Higher carbon dioxide levels are expected to lower the "nutritional quality of crops," the report said. Cereal prices could increase by 7.6% in price by 2050, it estimated.
Food yield will also change and agricultural diseases will increase in some areas.
"Certain types of diet have a lower carbon footprint" and reduced meat consumption would ensure more food is available overall, Skea told a news conference.
He said the IPCC was not telling people to change their diet, but instead it was up to policymakers to decide how to use evidence.
"25-30% of food produced is lost or wasted," he added.
"Food security will be increasingly affected by future climate change through yield decline — especially in the tropics — increased prices, reduced nutrient quality, and supply chain disruptions,” said Priyadarshi Shukla, co-chair of one of the IPCC working groups.
“We will see different effects in different countries, but there will be more drastic impacts on low-income countries in Africa, Asia, Latin America and the Caribbean,” he said.
Trade-offs on land use might be required in the future if people don't create more sustainable methods of food and land production.
IPCC co-chair Dr Debra Roberts said an upcoming report would examine the impact of urban design on climate change because cities have a disproportionate effect on climate change.
“Land is part of the solution but land cannot do it all,” she said