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Climate Change Pressures Land and Food Resources, Report Warns

There is a window of time to act now before threats increase further and solutions become less effective, a new report from the Intergovernmental Panel on Climate Change states.

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Climate change is putting increased pressure on land and food resources while poor land use and food management are also contributing to climate change, according to a new report issued today, 8 August, by the Intergovernmental Panel on Climate Change (IPCC).

The special report on climate change and land details these impacts and outlines near- and long-term actions that can help to mitigate and stave off far worse impacts.

The report “provides a road map for governments to think about these issues,” said Pamela McElwee, a lead author of the report and an associate professor in the Department of Human Ecology at Rutgers University, New Brunswick, N.J., at a briefing prior to the report’s release.

Policy makers need to act soon to make a difference, according to the document, Climate Change and Land: An IPCC Special Report on Climate Change, Desertification, Land Degradation, Sustainable Land Management, Food Security, and Greenhouse Gas Fluxes in Terrestrial Ecosystems. The report follows an October 2018 IPCC Special Report: Global Warming of 1.5 °C.

A delay in taking action now means more difficulties later, according to the report.

“Delayed action across sectors leads to an increasing need for widespread deployment of land-based adaptation and mitigation options and can result in a decreasing potential for the array of these options in most regions of the world and limit their current and future effectiveness,” the report states.

The report paints a better picture if actions are taken. “Prompt action on climate mitigation and adaptation aligned with sustainable land management and sustainable development depending on the region could reduce the risk to millions of people from climate extremes, desertification, land degradation and food and livelihood insecurity.”

Climate Change and Land

Among the impacts that climate change is having on land are increases in the frequency and intensity of weather and climate extremes; threats to food security, human health, and terrestrial ecosystems; contributions to desertification; and effects on land degradation through actions such as increased rainfall intensity, flooding, heat stress, and sea level rise.

In addition, the report notes that data available since 1961 show that global population growth and changes in per capita consumption of food, feed, fiber, timber, and energy “have caused unprecedented rates of land and freshwater use” and that agriculture currently accounts for about 70% of global freshwater use. The report states that the expansion of areas under agriculture and forestry has supported consumption and food availability for a growing population but that with large regional variation, these changes have contributed to increasing net greenhouse gas emissions, loss of natural ecosystems, and declining biodiversity.

In addition, although efforts continue to try to limit the global mean surface temperature to a 1.5°C increase above the preindustrial period, the observed mean land surface air temperature already has increased about that much, according to the report.

“When we talk about 1.5 degrees warming, in the [IPCC] 1.5 report, for example, that was average global air temperature. Keep in mind that the planet is 70% ocean and 30% land, and land and water behave very differently with respect to how they absorb energy,” said Louis Verchot, a lead author of the report and director of the Soils and Landscapes for Sustainability Research Area at the International Center for Tropical Agriculture in Cali, Colombia, at the 7 August briefing.

“We can just consider that the land is warming at twice the speed of the average temperature of the Earth that scientists express when we talk about 1.5 or 2 degrees C,” Verchot said. He added that at some locations, warming has increased as much as 4°C.

In addition, the report points out that land is both a source and a sink of greenhouse gases. Between 2007 and 2016, agriculture, forestry, and other land use activities accounted for about 13% of carbon dioxide (CO2), 44% of methane, and 82% of nitrous oxide emissions from human activities globally.

“Land plays an important role in the climate system,” noted Jim Skea, cochair of IPCC Working Group III and professor at Imperial College London’s Centre for Environmental Policy, in press materials from IPCC. “Agriculture, forestry and other types of land use account for 23% of human greenhouse gas emissions. At the same time natural land processes absorb carbon dioxide equivalent to almost a third of carbon dioxide emissions from fossil fuels and industry.”

The report cautions, however, that “future net increases in CO2 emissions from vegetation and soils due to climate change are projected to counteract increased removals due to CO2 fertilization and longer growing seasons.”

Climate Change and Food

The report also looks at food from a number of perspectives, including soil erosion, fertilizer use, domestic livestock, food waste, and even individual diets. The report notes, for instance, that climate change affects food security because of warming, changing precipitation patterns, and greater frequency of some extreme events. It states that 25%–30% of total food produced currently is either lost or wasted and that if this amount could be reduced, it could take some pressure off of the need to convert additional land for agriculture.

In addition, the report says that “the total technical mitigation potential of dietary changes” by having more people adopt plant-based diets could be as much as 8 gigatons of CO2 equivalent by 2050.

“With diets with less meat, you’re not only getting reductions in methane and nitrous oxide emissions from livestock and the fertilizer to grow the feed for them,” Cynthia Rosenzweig, a coordinating lead author of the report and senior research scientist and head of the Climate Impacts Group at the NASA Goddard Institute for Space Studies in New York, said at the briefing. “At the same time, [there is] an increase in soiled carbon sequestration on the land that is spared.”

—Randy Showstack (@RandyShowstack), Staff Writer

Citation: Showstack, R. (2019), Climate change pressures land and food resources, report warns, Eos, 100, https://doi.org/10.1029/2019EO130813. Published on 08 August 2019.
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