About Climate Change | What is Climate Change?
When we're talking about climate change, we're talking about changes in long-term averages of daily weather. In most places, weather can change from minute-to-minute, day-to-day and season-to-season. Climate, however, is how weather behaves over long time scales.
We've known for over a century that greenhouse gases like carbon dioxide and methane trap heat in the atmosphere. Releasing them causes polar ice caps to melt, sea temperatures to increase, oceans to expand and sea levels to rise. Human activity – burning greenhouse gases and cutting down trees – is the main cause of climate change.
Atua Māori attempt to maintain balance. As controllers or personifications of natural forces, they also make themselves known in the form of giant storms and massive tides. Climate change is already having drastic impacts across our planet and these will get worse. How fast it gets worse depends on whether we stop using fossil fuels and find ways to take carbon dioxide back out of the atmosphere.
Nevertheless, a certain amount of change has already been “locked in”. Our ancestors are changing. Now we have to figure out how to change with them.
Over the centuries, Māori have developed extensive knowledge about local weather and climate conditions. These learnings have formed the bases of traditional and modern practices of agriculture, fishing, medicine and education.
Seasonal tohu (indicators), along with knowledge of local māramataka (lunar calendars), have always supported Māori to plan for the seasons ahead.
Kaumātua have intimate knowledge of how the climate is changing, and point to stark differences in the climate of their childhoods and today's climate. Researchers are also closely examining the impact of climate change on the māramataka and on traditional indicators and taonga species.
You can use these resources to explore how others are reconnecting with their environment to understand and manage the risks associated with changing weather and climate conditions.
Antarctica, the Southern Ocean and the atmosphere above them have a significant influence on our Southern Hemisphere climate and our weather here in Aotearoa.
Improving our understanding of these systems helps us improve climate models and better predict the future of the global climate.
While no single iwi claims mana whenua over Antarctica, Polynesians were the first to navigate the Southern Ocean. The navigator Hui te Rangiora travelled to the Southern Ocean some 700 years ago, resting half-way at the mouth of the Riuwaka River in Motueka.
Mātauranga about the Southern Ocean is held in kōrero tuku iho, a comprehensive system of knowledge – including science and guidance about values and behaviour – which Western climate science is yet to properly reckon with.
Our research is trying to uphold the mana of both knowledge systems as well as building bridges between them.
Climate models calculate how carbon dioxide and other greenhouse gases affect the flow of heat, energy and water around the planet.
Our climate is extremely complex. Advanced climate models – earth system models – combine this atmospheric and oceanic information with chemical and biological data.
We use earth system models to tell us what will happen to our planet if we release more (or less) greenhouse gas into the atmosphere. These models also inform international climate assessments, such as the Intergovernmental Panel on Climate Change (IPCC) reports.
Overseas models generally focus on the Northern Hemisphere climate, and our climate in the Southern Hemisphere is often poorly represented. This is most obvious for Antarctica and the Southern Ocean, which has serious consequences for the quality of projections over Aotearoa. We are investing in the New Zealand Earth System Model (NZESM), and investigating key processes that influence Antarctic sea ice, clouds above the Southern Ocean and the way heat is transported in the ocean.
These resources set out New Zealand's latest global and regional climate projections and also explore the science underway in New Zealand to improve our own NZESM.
Of all the carbon dioxide we produce from fossil fuels, only about half stays in the atmosphere. So where does the other half go? Papatūānuku, Earth, is maintaining balance, absorbing it into the land and the oceans.
The carbon cycle is nature's way of reusing carbon atoms, which travel from the atmosphere into organisms on land and sea and then back into the atmosphere over and over again.
Most carbon is stored in rock and sediment, while the rest is stored in the ocean, atmosphere and in living organisms. These are known as carbon sinks, through which carbon cycles.
The Southern Ocean is the most important of these “carbon sinks”, taking up more carbon dioxide than any region of the world. But we don't know whether it's ability to absorb carbon dioxide is increasing or decreasing.
What drives the uptake of carbon into these sinks, and how might this change? Could these sinks “fill up”, causing global warming to accelerate?
This century, climate change will alter New Zealand’s water cycle significantly.
It will change how much rain and snow we receive, and when. It will change how much water is stored in the soil, snow, glaciers and aquifers. It will change how much water evaporates back to the atmosphere and how much flows through streams and rivers to the coast. And it will change the severity of droughts, floods and power shortages.
In New Zealand, fresh water is central to our natural environment, economy and way of life. It has shaped our landscapes and wildlife, supports farming, tourism and other industries, supplies over 50% of our electricity through hydropower, and is integral to our heritage and sense of place.
We are investigating where New Zealand’s water cycle is most vulnerable to change and developing new approaches to calculating the likelihood and severity of future floods.