On the eve of the United Nations Cop26 climate conference, New Zealand vowed to decrease its net greenhouse gas emissions by half by 2030, upping its initial goals to limit global warming.

"While we are a small contributor to global emissions, we are not immune to the impact of climate change as a country surrounded by oceans and an economy reliant on our land, so it's critical we pull our weight," Prime Minister Jacinda Ardern said in a statement on Sunday.

"New Zealand's increased contribution to the global effort to combat climate change now represents our fair share, and it is in line with what is required to avoid the worst effects of global warming on New Zealand."

"Climate change is a government priority because it poses a threat to our economy, environment, and daily lives."

At the Cop26 summit, which begins on Sunday evening in Glasgow, Scotland, leaders of the world's 20 wealthiest countries are expected to accept the existential threat of climate change and take actions to reduce global warming.

New Zealand's contribution to global greenhouse gas emissions is minor, but its gross emissions per capita are high, and it is one of the poorest performers in terms of emissions growth. New Zealand's emissions increased by 57% between 1990 and 2018, the second-highest increase among industrialized countries. According to data released earlier this year, New Zealand's emissions grew by 2% in 2018-19.

In a joint statement, Ardern and climate change minister James Shaw said the earlier objective was incompatible with global efforts to keep global warming to 1.5 degrees Celsius above pre-industrial levels.

New Zealand's primary goal was to reduce emissions by 30% by 2030 compared to 2005 levels.

Each country selects an international objective known as a nationally determined contribution under the 2015 Paris Agreement, which pledged signatories to keep global warming "well below" 2 degrees Celsius above pre-industrial levels, preferably 1.5 degrees Celsius (NDC).

The new NDC for New Zealand aims to reduce net emissions by 50% below gross 2005 levels by 2030. Using an "emissions budget" method translates to a 41 percent reduction from 2005 levels.

"The improved NDC reflects our increased investment in climate aid, particularly in the Pacific, and represents a significant step forward in New Zealand's role in addressing climate change," Ardern said.

According to Shaw, the next ten years will be a "make or break" for the planet. "The science shows we now have about eight years to almost halve global greenhouse gas emissions in order to limit global warming to 1.5 degrees Celsius," he said.

"That gives countries eight years to make the necessary plans, put policies in place, implement them, and finally deliver the cuts."

"The priority in meeting our new NDC will be to reduce emissions at home – and to do so fairly and equitably." The emissions reduction strategy we'll release next year will be the driving force behind this."

During its second term, the New Zealand government has proposed various initiatives to reduce emissions, including a pledge to make the public sector carbon-neutral by 2025 and purchase entirely zero-emission public vehicles by the middle of this decade.