What is Climate change?
Climate change refers to long-term shifts in temperatures and weather patterns.
Climate is different from weather. The weather can change day to day, but climate is the usual weather found in a place, which includes the different seasons.
How does climate change happen?
Humans are taking fossil fuels (oil, natural gas and coal) out of the ground, where they have been stored for millions of years, and burning those fuels in vehicles, to produce electricity or to make stuff like fertiliser, clothes and plastics.
Burning of fossil fuels is causing lots of carbon dioxide (CO₂), to go into our atmosphere. CO₂ is a ‘greenhouse gas’ which acts like the roof of a greenhouse, letting heat from the sun in and trapping it, causing average temperatures to rise - this climate change is also called global warming.
The main greenhouse gases in the Earth’s atmosphere are water vapour (H₂O), carbon dioxide (CO₂), methane (CH₄), nitrous oxide (N₂O) and ozone (O₃), plus some fluorinated gases (e.g. hydrofluorocarbons, sulfur hexafluoride).
Without any greenhouse gases Earth would be very cold, about -18 °C on average.
Humans are causing a BIG increase in greenhouse gases. We’re burning petrol and diesel in our cars, boats and planes (CO₂); burning coal and natural gas to make electricity (CO₂); making products like iron, steel and cement (CO₂); burying food scraps in landfills instead of composting (CH₄); cutting down forests to create farmland (CO₂); using fertiliser (NO₂); and farming lots of cows, sheep, pigs and chickens (CH₄). All these activities cause an increase in greenhouse gases.
These gases affect the climate for years to come.
For example, methane stays in the atmosphere for about 10 years before decomposing to CO₂. CO₂ can stay in the atmosphere for more than 1000 years!
Want to learn more? Check out Bill Nye’s YouTube video.
A carbon footprint (or carbon inventory) is a measure of greenhouse gas emissions caused by you, your household, town, or country.
The amount of greenhouse gas created by an individual person isn’t much - you breathe out about 0.3 tonne of CO₂ per year. But the greenhouse gases associated with living i.e. heating or cooling your house, plane and car trips, food products you consume and products you buy and wear all add up to a lot more - basically, the more stuff you buy, the bigger your carbon footprint!
You can work out your personal carbon footprint by using the free online Future Fit tool.
Climate change alters weather extremes. We expect to see more extreme hot days (30+ °C), longer periods of dry weather, and higher risk of flooding when rain occurs.
We’re already seeing these extremes and expect these to increase and become more severe. Rare and extreme floods called a ‘one in 100-year event’, which means it has a 1% chance of occurring in any given year, will occur three times more often in Rotorua by 2090*.
Based on how much greenhouse gas we think is going to be added to our atmosphere each year we can estimate our future climate and risks.
’Hot days’ are days hotter than 25 °C. Between 1986-2005 Rotorua averaged about 10 hot days a year but is expected to increase to 30 – 72 days a year by 2090*.
Extremely hot days (30+ °C) are also expected to increase. Extremely hot days pose health risks and can cause difficulty growing things because soil moisture reduces.
Heat sensitive plants, insects and birds will struggle to survive, and numbers will reduce. We will also see an increase in pest species migrating to this area, which could cause further issues for our natural environment due to competition with native species.
Some fruit and vegetables need winter chilling so our horticultural industry may suffer with a reduction in cold days but other subtropical produce may grow better than currently. Warmer winters means pests like the Queensland fruit fly could become established in this area - which would be devastating for our horticulture industry.
Droughts in Rotorua and the Bay of Plenty are expected to be more frequent and severe, affecting our natural environment, tourism based around this environment, and mahinga kai (food-gathering) practices. Species that live in water habitats, like wetlands, rivers and streams, will be affected if their habitats dry up. Droughts also put pressure on agriculture and forestry.
Wildfires in forest or scrubland will become more prevalent in hotter, drier weather and could destroy our forest industry, infrastructure, our mountain biking network, and homes. Fires reduce air quality which affects our community, including those vulnerable to respiratory illnesses.
Rainfall and flooding
An expected reduction in annual rainfall in Rotorua will be spread between increased rainfall in winter and autumn, and declining spring and summer rainfall*.
Extreme rainfall events are expected to increase in intensity and frequency, increasing the risk of flooding land, streams and rivers.
Flooding can damage homes and infrastructure and is a risk to people’s health and safety. Rainfall events can also wash pollution into our waterways.