The frequency and severity of extreme weather events – and the resulting impacts on agricultural systems – will continue to increase as global temperatures rise, scientists tracking changes in the Earth’s climate say.
The latest Intergovernmental Panel on Climate Change (IPCC) report warns that climate change is not just about temperature, it is also intensifying the water cycle, which will bring more intense rainfall and associated flooding, as well as more intense drought in many regions.
Manaaki Whenua – Landcare Research senior scientist Dr Nick Craddock-Henry says the release of the report should be a clarion call of the dangers of widespread and rapid changes in atmospheric conditions.
He says the evidence is unequivocal: human activity has resulted in dramatic shifts in global temperature and precipitation patterns and is driving increased frequency and severity of extreme weather events.
“The physical science is clear and changes in the frequency and severity of extremes have particular relevance for Aotearoa New Zealand,” Craddock-Henry said.
He says in the seven years since the last IPCC assessment report, recurring drought has had a marked impact on primary industries.
“Drought is now Aotearoa New Zealand’s costliest hazard, with economic and social implications for rural communities,” he said.
“Our agricultural systems – including horticulture, viticulture, arable cropping and livestock – are sensitive to these changes, due to their dependence on stable, long-term climatic conditions in which current land-management and land-use decisions and practices were developed, and through impacts on production, quality and yield.
“Furthermore, primary economic activities such as agriculture are, in many instances, the basis for rural economies, supporting the social, cultural and economic vitality of our regional rural communities. These changes are expected to continue, with warming to mid-century of 1.5-2degC. These changes will have flow-on effects for local conditions, increasing the likelihood of drought, flood, and compounding hazard events,” he said.
Craddock-Henry says although an accounting of NZ’s vulnerability to climate change is not due until early next year, the scale and urgency of the problem is clear: warming will continue unless dramatic reductions in greenhouse gases are made and mitigation will be insufficient to address the changes outlined in the report.
“To ensure sustainable long-term futures for Aotearoa New Zealand, the report is a stark reminder of the need for adaptation. Adaptation will require strategic and even radical adjustments to practices, processes, capital, and infrastructure in response to climate change, and must begin now,” he said.
Niwa principal scientist of carbon, chemistry and climate Dr Sara Mikaloff-Fletcher says even with rapid emissions reductions, it will still take 20-30 years for global temperatures to stabilise.
However, it is still possible to limit the impacts of climate change.
“Every action we take to reduce our net emissions of carbon dioxide, methane and other greenhouse gases will help us towards a brighter future,” Mikaloff-Fletcher said.
“However, the IPCC report shows that the longer we wait to stabilise climate, the harder it will be.
“Models predict extreme temperatures and droughts brought on by climate change will weaken the ability of forests and other green spaces to absorb carbon dioxide.
“This is particularly significant for Aotearoa New Zealand, because our forests and land use offsets roughly a third of our total greenhouse gas emissions. We must begin to come to terms with how changes in climate impact our forests and their ability to absorb and store carbon.”
The report says the evidence is clear that carbon dioxide is the main driver of climate change even though other greenhouse gases and air pollutants also affect the climate.
IPCC Working Group 1 co-chair Panmao Zhai says stabilising the climate will require strong, rapid and sustained reductions in GHG emissions, and reaching net zero CO2 emissions.
“Limiting other greenhouse gases and air pollutants, especially methane, could have benefits for both health and the climate,” Zhai said.
Federated Farmers president and climate change spokesperson Andrew Hoggard says if enabled by the Government, science and innovation has the potential to boost on-farm performance while also cutting emissions.
He says breeding advances, a cutting-edge Kiwi-developed GMO ryegrass, the nitrification inhibitor DCD and livestock methane inhibitors such as 3-NOP are just some of the options available or showing great promise. But several of them have run into regulatory roadblocks that the Government needs to deal with.
“Methane is a short-lived greenhouse gas that needs to be slightly reduced, and nitrous oxide is a long-lived and potent greenhouse gas that we need to reduce to net zero by 2050, but the few tools available to reduce these GHGs are being held up by regulatory constraints,” Hoggard said.
Hoggard says the report makes it clear that NZ was right to show global leadership when adopting split long and short-lived GHG targets.
“We need to follow this up and adjust the current methane reduction targets to ones which are zero carbon equivalent. We also need to split out emissions budgets to make sure climate policy treats short and long-lived emissions differently in a manner consistent with the split gas targets,” he said.
University of Canterbury professor of political science and international relations Bronwyn Hayward says thinking that new technology can be relied on to save the situation must be avoided.
“This IPCC report clearly states in the frequently asked questions section that technologies like CO2 removal techniques are not yet ready or unable to achieve the scale of removal to compensate for current levels of emissions and most have undesirable side effects,” Hayward said.
“It’s critical that we stop hoping someone or something else will fix this if we hope to achieve the Paris Agreement of holding the increase in the global average temperature to well below 2degC above pre-industrial levels, let alone 1.5degC.
“Extreme weather events cannot be the future we leave for our children.”
