Climate change – key terms
This resource provides explanations of some of the key terms and concepts encountered when learning about climate change. It includes references to New Zealand’s greenhouse gas profile.
Anomaly
An anomaly is a variation from a baseline measurement. The World Meteorological Organization recommends the 30-year reference period from 1961–1990 as the baseline for calculating anomalies for long-term climate change assessments. It is used for reporting purposes to show climate change over time.
Anomalies can also be measured against the current climate normal, for example, 1991–2020. These anomalies are presented as ‘normal’ for a daily weather report.
Anomalies and outliers
Gregor Macara and Bonnie Farrant work with climate datasets. They explain two key terms – anomalies and outliers – why they are of interest and how they inform reports like Our atmosphere and climate 2020.
Questions for discussion:
How do anomalies make it possible to compare data between different sites?
Why do data scientists need to investigate outliers?
Anthropogenic global warming
The rise in regional and global temperatures caused by human-produced greenhouse gas emissions, including burning of fossil fuels and intensive agriculture.
Carbon dioxide (CO
A naturally occurring gas in the Earth’s atmosphere. It is the principal greenhouse gas produced by human activities. Humans added about 42 gigatonnes (Gt) of carbon dioxide to the atmosphere in 2018 – more than 190 times the weight of all the people in the world.
New Zealand’s gross CO2 emissions in 2016 were about 35,000 kilotonnes.
Carbon footprint
A carbon footprint corresponds to the whole amount of greenhouse gases produced to (directly and indirectly) support a person’s lifestyle and activities. It can also refer to the amount of carbon emitted during an activity or the manufacturing of a product.
Carbon neutral
A process in which there is no net release of carbon dioxide. The amount of carbon taken out has to equal the amount of carbon released. An organisation can achieve carbon neutrality by offsetting – balancing emissions by funding an equivalent amount of carbon savings via tree planting and other projects.
Southern Ocean carbon sink
Dr Sara Mikaloff-Fletcher, an atmospheric modeller at NIWA, describes the role of the Southern Ocean in taking up carbon dioxide from the atmosphere. Some computer models suggest that this carbon sink is slowing, which might accelerate climate change. The Argo project is providing data to test this model.
Carbon sink
Anything that absorbs more carbon dioxide than it emits. Natural examples of carbon sinks are forests, soil and the oceans.
Use the Connected article Trees, seas and soil to discover more about carbon sinks and why they are so important.
Emissions
The release of greenhouse gases from a human activity such as coal-burning power stations, car exhaust or methane from farm animals. Emissions can also come from natural sources such as volcanoes.
Different approaches for estimating our emissionse include:
a production-based approach that counts any emissions produced within our borders
a consumption-based approach that counts emissions within our borders released to produce goods and services used here and import emissions (emissions released overseas to produce the goods and services we use in New Zealand).
The Ministry for the Environment generates New Zealand’s Greenhouse Gas Inventory annually. It is the key source of evidence on the country’s greenhouse gas emission trends.
Extreme weather
Any type of severe or unseasonal weather such as heavy rainfall, droughts, extended heat waves or cold spells that is much higher or lower than what is expected. Extreme weather events are predicted to become more common due to extra energy entering the atmosphere.
Burning fossil fuels
In fossil fuels, the carbon is stored in long-chain hydrocarbons, and then through combustion with oxygen in our cars or in factories, the carbon is converted to CO2, which is released to the atmosphere. And in addition, a number of other byproducts are also produced through inefficiencies in combustion like CO which are atmospheric pollutants.
Fossil fuels
Coal, oil and natural gas are examples of fossil fuels. They are called fossil fuels because they come from ancient carbon sources (plants and animals). When burned, fossil fuels release the carbon they once stored.
In New Zealand, road transport makes the largest contribution to our carbon dioxide emissions due to burning fossil fuels.
Greenhouse gases
Greenhouse gases are natural and human-produced gases that trap heat in the Earth’s atmosphere and warm the Earth’s surface. Water vapour is the most common greenhouse gas. Carbon dioxide, methane and nitrous oxide are the most common human-generated greenhouses gases.
New Zealand has an unusual greenhouse gas profile for a developed country. Almost half of our greenhouse gas emissions come from agriculture, and only a small proportion comes from electricity generation, which is the opposite to many other developed countries.
Gross greenhouse gas emissions
Gross greenhouse gas emissions are the total emissions from energy, industrial processes and product use, agriculture and waste. They do not include natural sources of emissions such as those from biological processes or volcanoes.
In New Zealand, gross greenhouse gas emissions were about 24% higher in 2018 than in 1990. From 2008–2018, emissions have changed little despite increases in gross domestic product (GDP) and population .
Methane (CH
Methane is a gas that is naturally emitted from wetlands and wildfires. It is also associated with agriculture, landfills and coal mining. Methane warms the climate about 25 times more than an equivalent amount of carbon dioxide.
About 86% of New Zealand’s methane emissions come from ruminant livestock – sheep, cattle, goats and deer.
Net greenhouse gas emissions
Net greenhouse gas emissions include gross emissions combined with emissions and removals from land use, land-use change and forestry. Land-use change is the conversion of land from one purpose to another.
New Zealand’s net emissions have increased by 57% since 1990.
Nitrous oxide
Dr Selai Letica explains some of the causes of nitrous oxide emissions in agricultural soils and why it is important to limit them.
Points of interest:
Nitrous oxide (N2O) occurs naturally in the environment, but human activities increase its concentration in the atmosphere.
One unit of N2O is equivalent to 310 units of CO2, making nitrous oxide a more potent greenhouse gas than CO2.
Nitrous oxide (N
Nitrous oxide is a gas that is a natural part of the nitrogen cycle. However, about 40% of total nitrous oxide emissions come from human activities. Nitrous oxide is emitted from agricultural soils (via animal urine patches), fossil fuels and industrial activities. Nitrous oxide warms the climate about 300 times more than an equivalent amount of carbon dioxide.
Most of New Zealand’s nitrous oxide emissions come from the soil – microbes convert nitrate in urine patches to nitrogen gases.
Parts per million (ppm)
A unit of measurement for the concentration of greenhouse gases in the atmosphere. Atmospheric carbon dioxide concentrations have been monitored continuously at Mauna Loa Observatory in Hawaii. In March 1958, the CO2 concentration was 313 ppm by volume. In May 2020, the concentration reached a seasonal peak of 417 ppm by volume.
Baring Head, a monitoring station at the southern end of the North Island, has been recording atmospheric CO2 concentrations since 1972 – the longest continuous record in the southern hemisphere. It has also documented the rise of CO2 from around 320 ppm in 1972 to well over 409 ppm in September 2019.
Related content
Find out some of the ways in which scientists measure greenhouse gases.
Activity ideas
Use food dye to visualise parts per million.
Content curation
Collections
Climate change – this focuses on the science of change and associated socio-scientific issues – including melting ice and sea level rise.
Climate change (HoS) – this collection supports the House of Science e Change Kit – but it is also useful for anyone exploring what is change, ocean acidification, sea and land water, how change affects Māori, the Earth's interacting systems and ideas to tackle these wicked problems in the classroom.
Our atmosphere and climate 2020 – The Our Atmosphere and e 2020 report was released to all New Zealanders in October 2020. In collaboration with the Ministry for the Environment and Stats NZ we developed a suite of teaching and learning resources around this important report.
Find our more about using our Collection tool, including tips on making one of these collections your own to amend to your own needs, collaborate with and more.
Pinterest boards
We have curated a range of supporting resources in these Pinterest boards: Climate change and Methane – a potent greenhouse gas.
Acknowledgement
This resource has been produced with the support of the Ministry for the Environment and Stats NZ. (c) Crown Copyright.
Our atmosphere and climate 2020
The Ministry for the Environment and Stats NZ produce New Zealand’s Environmental Reporting Series. Our atmosphere and climate 2020 focuses on climate change, with an overview of what is happening to our climate and how this affects many of the things we care about.
