In 1988, international concern about global warming led to the establishment of the Intergovernmental Panel on Climate Change (IPCC). This group was to assess all the latest scientific, technical and socio-economic research on the topic. The IPCC’s Fifth Assessment Report in 2014 identified sufficient evidence to blame global warming on human activities. A strong conclusion was drawn: ‘Warming of the climate system is unequivocal, and since the 1950s, many of the observed changes are unprecedented over decades to millennia’. Scientists had carried out extensive modelling to understand the global climate, but were unable to reproduce the warming observed since 1950 without increasing carbon dioxide concentrations. Neither the natural variability of weather systems nor changes in incoming solar radiation were sufficient to cause the observed changes.
New Zealand’s position
New Zealand, together with many other developed countries, is taking action to minimise greenhouse gas emissions and reduce the effects of climate change. The Paris Agreement is an international agreement to reduce climate change. New Zealand has ratified the 2015 Paris Agreement. The government passed the Climate Change Response (Zero Carbon) Amendment Act in 2019, and many local and regional councils are developing their own plans to reduce emissions and adapt to the impact of a changing climate.
The prediction by scientists in the 1970s of an impending ice age is often raised by sceptics to discredit global warming. However, the cooling was expected to occur gradually, reaching glacial conditions in 20,000 years’ time. This long-term cooling would be due to natural variations in the earth’s orbit around the sun. By contrast, global warming is largely a consequence of human activity.
Just under half of New Zealand’s total greenhouse gases are produced by agriculture in the form of methane and nitrous oxide. The agricultural sources of methane are ruminant animals, including sheep, cattle, deer, and goats. Nitrous oxide is produced in the soil by bacterial breakdown of animal excreta and nitrogenous fertilisers. Forty-one per cent of emissions come from carbon dioxide produced by the energy sector (mainly transport and electricity generation). Industrial processes and waste account for 11%. On the upside, New Zealand's abundant forests absorb carbon dioxide from the atmosphere. However, New Zealand's total emission of greenhouse gases is estimated to have increased by about 23% between 1990 and 2017. This figure is even higher when the volume of timber harvested from New Zealand’s plantation forests is taken into account.
The Paris Agreement
The Paris Agreement is the current global agreement on climate change. It was adopted at the United Nations Framework Convention on Climate Change (UNFCCC) in 2015 and commits all signatories to take action on climate change. New Zealand is one of nearly 200 countries that have ratified the agreement, which aims to limit the increase in global average temperature to well below 2°C above pre-industrial levels by reducing greenhouse gas emissions globally. The Paris Agreement takes effect from 2020 and New Zealand’s commitment (to reduce greenhouse gas emissions by 30% below 2005 levels by 2030) will apply from 2021.
Climate change research and strategies
Research conducted by New Zealand’s government, education and private sectors aims to understand how sensitive the country is to climate change and variability. In addition, there are a number of initiatives to reduce emissions. These include strategies to improve energy efficiency, increase renewable energy sources, use more energy-efficient transport, and reduce emissions from landfills.