As world leaders arrive in Paris to try and reach a binding agreement on climate change, RNZ looks into what it's all about and what it means for New Zealand.
There is no doubt temperatures are slowly rising in New Zealand and throughout the world, glaciers are melting and sea levels are rising.
Last year was the hottest on record, but this year is expected to be even hotter, which means just one thing according to the World Meteorological Organisation: "Bad news".
So what is causing all of these changes and what is being done to slow the effects of climate change?
More on the talks in Paris
Activists around the world gathered in 2000 locations, including 35 in New Zealand, at the weekend to call for more action - saying world leaders aren't doing enough in the face of climate change.
The exact leaders they want action from, including Prime Minister John Key, are meeting in Paris this week at the COP21 conference to try to form a binding agreement to mitigate climate change.
But will they be able to reach an agreement, and will it be enough to prevent irreversible damage if they do?
An estimated 7000 people marched in Wellington to the steps of Parliament, demanding more action to address climate change, on Saturday. Photo: RNZ / Johnny Blades
Climate change - what causes it
Gases in the atmosphere trap heat that radiates from the surface of the Earth, causing warmer temperatures.
Global warming is expected to raise sea levels. Photo: 123rf
The increased concentration of greenhouse gases has largely been driven by human activity, mainly the burning of fossil fuels.
The Ministry for the Environment and Statistics New Zealand released a state of the environment report last month - Environment Aotearoa 2015 - which showed New Zealand's greenhouse gas emissions increased 42 percent between 1990 and 2013.
The five biggest contributors to this were carbon dioxide from road transport and electricity generation (from coal and gas), nitrous oxide from agricultural soils, hydrofluorocarbons from industrial and household refrigeration and air conditioning systems, and methane from farm animals.
New Zealand's greenhouse gas emissions in 2013 (by sector, in million tonnes of CO2 equivalent). Graphic: Ministry for the Environment
The agriculture sector is the largest contributor to New Zealand's greenhouse gas emissions, making up 48 percent in the 13-year period.
The emissions from agriculture are mainly methane from animals and nitrous oxide from fertiliser in soils. Methane and nitrous oxide do not stay in the atmosphere as long as carbon dioxide, but they retain more heat.
Prime Minister John Key is in Paris for the talks. Photo: RNZ
The energy sector, which includes electricity generation and road transport, is the country's second-biggest emitter, contributing 39 percent of emissions between 1990 and 2013.
Emissions from electricity generation can fluctuate depending on how much rain falls, because New Zealand's energy is largely driven by hydro. When hydro inflows are low because of a lack of rain, energy is generated from other sources such as coal and gas.
It can also be influenced by economic conditions; a downturn will reduce the number of trucks out on the road.
Emissions from industrial processes and the products New Zealanders use contributed 6 percent. This included hydrofluorocarbons used in industrial and household refrigeration and air-conditioning systems, and carbon dioxide from mineral, chemical and metal production.
The waste New Zealanders produced, including landfill waste and industrial and domestic wastewater, made up the final 6 percent of the country's emissions profile.
How does New Zealand fit into the global picture?
Between 1990 and 2011, global net emissions of greenhouse gases rose 33 percent.
New Zealand contributed about 0.1 percent of global emissions. By comparison, the United States contributed an average of 16 percent, and China 15 percent.
Estimated net emission of greenhouse gases by major emitting countries from 1990-2011. Graphic: Ministry for the Environment
It might seem small, but New Zealand's contribution is high on a per capita basis, coming in as the fifth highest emitter in the Organisation for Economic Co-operation and Development (OECD).
The OECD earlier this year gave New Zealand a poor mark for the amount of greenhouse gas emissions produced not only per capita, but also relative to its economic production.
New Zealand's greenhouse gas intensity and its greenhouse gas per capita measurements were improving, but not as fast as some other countries, it reported.
Transport emission intensities were also high, reflecting low use of public transport and poor average vehicle fuel economy, the report said.
When carbon dioxide emissions - those stemming from the burning of fossil fuels and the manufacture of cement - are considered, New Zealand performance is average, when compared to other countries.
OPINION: What do key NZ players have to say about the talks in Paris?
What is being done about it?
The conference in Paris, which is expected to attract 50,000 people over two weeks, is expected to be a make-or-break moment. Countries are being urged to agree on a binding deal on emissions that would restrict global warming to no more than 2°C above pre-industrial levels.
If they don't then irreversible climate change damage, including the melting of Greenland's ice sheet and an outpouring of greenhouse gases from permafrost thawing, could occur.
To reach the target would require a cut in emissions of between 40 and 70 percent over the next 35 years.
Greenpeace protesters at Parliament earlier this year Photo: RNZ / Alexander Robertson
The New Zealand government announced in July a target of reducing emissions to 30 percent below 2005 levels by 2030, which is another way of saying an 11 percent reduction on 1990 levels.
New Zealand's target has been slammed as "inadequate" by Climate Action Tracker, which produces independent scientific analysis by four research organisations,
If most other countries followed the New Zealand approach, global warming would exceed 3-4°C, the tracker report said.
Scientists say the higher the warming, the greater and more severe extreme weather events will become; sea levels will rise, along with the number of climate refugees and threats to food security and biodiversity.
If no effort is made to reduce emissions, temperatures could rise by as much as 4.8° by the end of the century, according to the Intergovernmental Panel on Climate Change.
The COP21 conference gets underway on Monday morning in France (Monday evening in New Zealand).
