A just-released major UN report on climate change has big implications for agricultural New Zealand, scientists and researchers say.
After two years in the making, the Intergovernmental Panel on Climate Change (IPCC) released it wide-ranging special report Climate Change and Land this evening.
Its key takeaways included:
• The temperature over land has risen considerably more than the global average, rising 1.53C since pre-industrial times compared with 0.87C globally.
• Farming, forestry and other land-use activities combined accounted for around a quarter of human-caused greenhouse gas emissions.
• Since 1961, the consumption of meat has more than doubled, while emissions of methane from cattle and manure had increased by 1.7 times in the same period.
The warming of the global temperature has already affected global food security through greater frequency of droughts, floods, storms and other extreme weather events and has led to shifts of climate zones for many plant and animal species.
About a quarter of the planet's ice-free land mass was now subject to human-induced degradation.
The University of Canterbury's Associate Professor Bronwyn Hayward called the report a "stark reminder" that everything we do affected our climate.
"For New Zealanders, one immediate and striking recommendation is to change our diets, traditionally high in meat and dairy to ones more balanced around more plant-based food choices that require less land and water to produce and involve the emission of fewer greenhouse gases," she said.
"The report also notes the value of moving towards more sustainable, less intensive farming in the global north."
Associate Professor Anita Wreford, of Lincoln University, said the report was highly relevant to New Zealand as it grappled for trade-offs with reducing emissions – around half of which were contributed by agriculture.
"The report highlights the importance of carefully designed policies that do not contradict each other or lead to unintended consequences, and careful planning and consideration of the long term in decision-making," she said.
"Early action will be less costly than delaying action, and will generate opportunities to address wider issues beyond climate, including sustainable livelihoods, maintaining biodiversity, addressing societal inequalities and improving our health.
"However, the report emphasises that while better land management can help to tackle climate change, it cannot do it all – we still need steep greenhouse gas reductions across all sectors."
Climate scientist Professor Jim Salinger argued the agriculture sector could not ignore calls for maximum reductions in methane and nitrous oxide emissions, "as the international focus will now be on New Zealand's response".
"Both methane and nitrous oxide have increased, and the main culprit is livestock farming globally."
The globally averaged atmospheric concentration of methane showed a steady increase between the mid-1980s and early 1990s, slower growth thereafter until 1999, a period of no growth between 1999-2006, followed by a resumption of growth in 2007.
Biological sources made up a larger proportion of emissions than they did before 2000, Salinger noted, and ruminant animals like cows and sheep, and the expansion of rice cultivation, were important contributors to the rising concentration.
The Government is proposing a Zero Carbon Act that would carry a split target - aiming to reduce all greenhouse gas emissions, aside from biogenic methane, to net zero by 2050.
Biogenic methane – the emissions created from livestock such as sheep and cattle – is not completely exempt as the bill commits to reducing it to 10 per cent below the 2017 levels by 2030.
The Government has also put to the public two recommendations on how the sector could ultimately be managed under the Emissions Trading Scheme.