Change now or endanger food and climate

Geneva: Humanity faces increasingly painful trade-offs between food security and rising temperatures within decades unless it curbs emissions and stops unsustainable farming and deforestation, a landmark climate assessment said on Thursday.

The UN´s Intergovernmental Panel on Climate Change (IPCC) warned that efforts to limit global warming while feeding a booming population could be wrecked without swift and sweeping changes to how we use the land we live off.

Its report on land use and climate change highlighted the need to protect remaining tropical forests as a bulkhead against future warming.

But in a stark warning to those who may hope that vast reforestation and biofuel schemes alone can offset mankind´s environmental damage, the report cautioned that these mega-projects could endanger food security, underlining that reducing emissions will be central to averting disaster.

"This is a perfect storm. Limited land, an expanding human population, and all wrapped in a suffocating blanket of climate emergency," said Dave Reay, Professor of Carbon Management at the University of Edinburgh.

Land is intimately linked to climate. With its forests, plants and soil it sucks up and stores around a third of all man-made emissions.

Intensive exploitation of these resources also produces huge amounts of planet-warming CO2, methane and nitrous oxide, while agriculture guzzles up 70 percent of Earth´s freshwater supply.

As the global population balloons towards 10 billion by mid-century, how land is managed by governments, industry and farmers will play a key role in limiting or accelerating the worst excesses of climate change.

With humanity´s failure to live within Earth´s natural boundaries, every future choice facing policymakers struggling to limit emissions throws up trade-offs elsewhere.

The IPCC is the world´s leading authority on climate change. Last year it warned that limiting global warming to 1.5C -- the optimal level aimed for in the Paris climate deal -- would be impossible without a drastic drawdown in greenhouse gas emissions.

The report emphasises that any measure taken to stave off climate disaster while shoring up food supply cannot be taken without "rapid reductions" in emissions.

Any delay in this -- across industry, transport, agriculture and infrastructure -- "would lead to increasingly negative impacts on land and reduce the prospect of sustainable development," its summary said.

Forests, an enormous carbon sink, can be regenerated to cool the planet. But with industrial farming covering a third of land today, there´s limited space.

Bioenergy in the form of vegetation used to sequester carbon also has potential. But room for that must be carved from crop land, pastures or existing forests.

The report said that a "limited" allocation of land for bioenergy schemes could indeed benefit the climate.

It warned however that deployment at a scale needed to draw down billions of tonnes of CO2 from the atmosphere each year "could increase risks for desertification, land degradation, food security and sustainable development."

Linda Schneider, senior programme officer of International Climate Policy at the Heinrich Boll Foundation, told AFP the report left "no doubt about the devastating impacts large-scale bioenergy and afforestation would have on water availability, biodiversity, food security (and) livelihoods."