How farming has to change to stop climate change, according to scientists

Looking after the land will be vital for tackling climate change, a sprawling new report compiled by scientists from around the world says.

But Kiwi farmers say they're already leading the world in terms of sustainable farming. 

The UN's Intergovernmental Panel on Climate Change on Friday released its latest report on the climate, this one with a focus on how land use is driving change and what needs to be done to mitigate the negative impacts. 

More than 7000 studies were analysed for the report, Lincoln University associate professor of agribusiness and economics Anita Wreford, told The AM Show on Friday.

"The role of the IPCC is to synthesise all of the existing research that's emerging in this area, and condense it in a way that's accessible for policymakers... presenting them with their options and the consequences of the decisions that they make."

Dr Wreford was the only New Zealander to contribute to the report - for the first time in IPCC history, the majority of scientists who worked on it were from developing countries, which are most at risk from climate change. 

Anita Wreford.
Anita Wreford. Photo credit: The AM Show

"Roughly 500 million people live in areas that experience desertification" since the 1980s, the IPCC said in a statement. "Drylands and areas that experience desertification are also more vulnerable to climate change and extreme events including drought, heatwaves, and dust storms, with an increasing global population providing further pressure."

The report says agriculture, forestry and other types of land use account for 23 percent of human greenhouse gas emissions. More than 70 percent of all land that isn't covered in ice is used by humans in some capacity, it says.

Dr Wreford said the report has a big focus on sustainable land management, but farmers will be relieved to hear they're not the only ones in the firing line.

"The report is quite careful to not focus only on farming systems. So it does identify options for farmers to reduce their impacts on the environment, and New Zealand farmers are probably very well aware of lots of these mechanisms. 

"But what the report really also does is look at the food system as a whole, and emphasises that we all have a role to play in the food choices that we make, and the food that we waste as well. If we reduce the amount of food waste, it can take a lot of pressure off the land."

The report estimates as much as 30 percent of all food produced goes to waste - if this was cut, emissions would be reduced.

"Food security will be increasingly affected by future climate change through yield declines - especially in the tropics - increased prices, reduced nutrient quality, and supply chain disruptions," said Priyadarshi Shukla, co-chair of IPCC Working Group III.

"Some dietary choices require more land and water, and cause more emissions of heat-trapping gases than others," said Debra Roberts, co-chair of IPCC Working Group II. "Balanced diets  featuring plant-based foods, such as coarse grains, legumes, fruits and vegetables, and animal-sourced food produced sustainably in low greenhouse gas emission systems, present major opportunities for adaptation to and limiting climate change."

Federated Farmers vice-president Andrew Hoggard told The AM Show the IPCC's report effectively holds up New Zealand as a model to the world.

"Effectively they're suggesting New Zealand-style grazing management needs to be adopted around the world. It's not about going plant-based - it's about being more efficient."

Andrew Hoggard.
Andrew Hoggard. Photo credit: The AM Show

Dr Wreford said it's not just food choices that have an impact.

"The report isn't telling people what food choices they should make, but it does present the information that what we choose to eat... and purchase in terms of our timber and paper and things like that as well, all have implications on the land and the pressure that we put on the land." 

"Some food choices put less pressure on our land and water. In some areas that might be moving away from meat and dairy towards more plant-based diets, but it really does depend on the locally specific context."

The report says low population growth will also help, as will reducing inequality. 

Dr Wreford said New Zealand's Zero Carbon Bill is "on the right track", but "certainly not being too ambitious".

"We kind of know what we need to do, and delaying those actions is going to result in it being more costly in the long-term, and we'll run out of options... We only have a small window of time to avoid the worst impacts of climate change."

Graphs supplied in the IPCC report.
Graphs supplied in the IPCC report. Photo credit: IPCC

Hoggard said while the report notes what needs to be done globally, not all of it is relevant for New Zealand policymakers.

"These reports are focused on the globe, not any specific country. We've got to recognise that difference - that we're already doing quite well."

NIWA principal scientist Mike Harvey also said New Zealand is doing its bit

"We are already thinking about how to minimise our emissions, how the future of agriculture might look under a lower-emissions scenario," he told Newshub.

But he thinks a "more integrated approach to mitigation and adaptation" is possible. 

The full IPCC report can be read on its website, and a summary document is also available.