The scope of our report was determined by the framework for environmental reporting set out in legislation (the Environmental Reporting Act 2015), which requires us to report on the pressures on and state of the atmosphere and climate, and the impacts of changes to the state of the atmosphere and climate. In line with our focus on changes to the environment from human pressures, we also focus on long-term, human-induced climate change rather than the natural climate variability that is a prominent feature of New Zealand’s climate.
For environmental reporting purposes, we differentiate the shallow gas layer that is closest to Earth – the air that we breathe – from the rest of the atmosphere. We report on air quality as a separate domain, with an updated report on air due in October 2018.
While reducing emissions (mitigation) and adaptation are critical factors in how climate change will affect New Zealanders, they are largely outside the scope of this report, and we do not discuss them in detail. New Zealand’s action on climate change is reported under the United Nations Framework Convention on Climate Change in national communications (every four years) and biennial reports (every two years). The next editions of both reports are due at the end of 2017.
We also do not cover features of weather, such as daily weather forecasts or recent weather events experienced around New Zealand. Weather information is regularly updated by and available from sources such as NIWA or Meteorological Service of New Zealand Ltd (MetService). NIWA also provides comprehensive annual reports on climate variability and long-term climate change.
We use our own national data and international data to report on climate change and UV sunlight exposure. Our national data are based on datasets that have passed our Environmental Reporting Programme’s quality standards. The datasets are available on our data service.
We have assessed all trends described in this report at the 95 percent confidence level. For more information about our trend assessments, see Trend assessment – technical information.
In many instances, our data are collected from 30 regionally representative climate stations around the North and South islands. We selected stations that:
- are currently open and likely to remain open for the foreseeable future
- have a long record of reliable, good-quality data
- are situated near a large city (eg at an airport site) so they are representative of the climate where many people in the region live.
We aimed to collect data from at least one station for each region – although we also selected two or three stations to represent a large region.
We advise you to be cautious when comparing results presented in Our atmosphere and climate 2017 with those from other reports, which might use data from a range of locations or cover different lengths of time. For further detail on data and methodologies, see Environmental indicators Te taiao Aotearoa – Atmosphere and climate.
We do not have adequate data to report on the more remote land masses of our realm, including the Chatham Islands and extending from the Ross Dependency in Antarctica in the south and north to the Cook Islands, Niue, and Tokelau.
The Intergovernmental Panel on Climate Change (IPCC) is an independent international scientific authority set up in 1988 by the World Meteorological Organization and the United Nations to provide objective analysis of global climate change. Where we do not yet have suitable national data for some issues, we have supported our discussion with information from the IPCC and other reports and scientific literature, which we reference within the text.
Box 1 Whether it’s weather or whether it’s not
Climate is different from weather. Weather relates to current atmospheric conditions, such as rainfall, temperature, and wind, at a specific time in a particular location or region. Weather changes from day to day.
Climate is the average weather conditions for a particular location or region over at least three decades. In a wider sense, it relates to the complex interactions between the world’s atmosphere, water bodies (such as oceans, rivers, and lakes, including frozen water bodies), land areas, and the ecosystems and organisms that live in the climate system.
Climate variability is the natural, normal variations in the world’s climate patterns. It relates to seasonal and yearly variations around a long-term average. For example, some summers are warmer or cooler than average, and some years are wetter, drier, or windier than average. These changes are not long term or permanent.
Climate change is an adjustment in climate that persists for even longer periods, typically decades or more (see figure 2). Climate change can occur naturally, for example, through large-scale ocean circulation changes or changes in Earth’s orbit. However, increasing greenhouse gas concentrations in the atmosphere resulting from human activities are the key driver of the climate change that has been occurring since the 19th century.
This figure shows timescales for weather conditions, climate variability and climate change.