NZ to be devastated by continuing climate change

A woman walks past a map showing the elevation of the sea in the last 22 years during COP21 (Reuters)
A woman walks past a map showing the elevation of the sea in the last 22 years during COP21 (Reuters)

An in-depth report by the Royal Society of New Zealand has outlined the effect continuing climate change will have on New Zealand, and the result is likely to be devastating.

It found six key areas New Zealand was particularly vulnerable to:

Unless serious action is taken to remove global emissions of greenhouse gases, it's almost certain climate change will accelerate over the century.

As an ocean-bound nation with a large proportion of the population living in coastal or flood-prone areas, New Zealand is very vulnerable to the projected changes, says Professor James Renwick.

Prof Renwick is the chair of the expert panel who wrote the reports and he says even little alterations in averages can have a huge difference in how often extreme events occur.

"With a 30cm rise in sea level, the current 'one in 100 years' extreme sea event would be expected to occur once every year or so in many coastal regions. Along the Otago coast for example, the difference between a two-year and 100-year storm surge is about 32cm of sea level."

Rainfall and heatwaves are likely to be affected in the same way -- if carbon dioxide levels continue to rise, a number of regions will see double to quadruple the number of days per year above 25degC by 2100.

Across the northeast South Island and the north and eastern North Island, annual rainfall is expected to decrease, but increase in some other regions.

It's predicted fire risk across many parts of the country will rise, and the frequency of droughts in eastern and northern New Zealand is expected to double or triple by 2040.

Combined with urban expansion, competition for freshwater is going to get heated, the report says.

Ocean levels are forecast to rise in a future with high carbon emissions, threatening coastal populations and eroding land.

The report also found evidence of acidification in waters surrounding New Zealand, which can damage the exoskeleton of many marine organisms such as paua and mussels.

"International research suggests that fish may also be affected by ocean acidification, and new work is underway to characterise impacts on fish in the New Zealand region," the report says.

As ocean levels rise and rainfall increases, both rural and urban flood-prone areas, including those near the coast, are expected to suffer.

"Flooding is the most frequent natural disaster in New Zealand and the second-most costly one after earthquakes," the report says, placing around two-thirds of Kiwis as living in areas prone to flooding.

But while things look bad for the humans, it's even worse for our unique ecosystem. More than half of New Zealand's 50,000 species can't be found anywhere else in the world.

"New Zealand's native plants and animals already face pressure from habitat loss and fragmentation, introduced mammalian predators and herbivores and invasive plants," the report says.

"Climate change will increase the stress on many of these already stressed systems."

Part of the problem with Government and societal responses to climate change is the fact it's still so unsure -- it's known heavy rainfall will become more frequent, the average sea level will rise and droughts will increase in intensity and frequency, but to what extent is uncertain.

The uncertainties hold groups and individuals from making decisions. But the report compares the risks of climate change to preparing in case of a house fire.

"Having your house burn down is not likely, but the consequences would be devastating. So, we are proactive and fit smoke alarms and take out house insurance, just in case.

"Taking action on the basis of climate change risk helps ensure that New Zealand’s society and environment can be resilient by responding flexibly to changing climatic as well as social, economic and environmental conditions."

It also highlights the frailty of Antarctica's ice, warning a melt could contribute to several metres of global sea level rise.

"The exact amount of warming required to trigger irreversible melting is unknown, but may be as little as one more degree."

The report predicts dangers to come based on climate change in the coming years, but the Green Party says we're already seeing it.

Last year's floods in Whanganui were a prime example, party co-leader James Shaw says.

"Victoria University did a study on that, but found that drought was as long and as deep as it was because of climate change. So we've already had droughts, but the thing is they're getting more frequent, longer and deeper."

It's proof damage from climate change is coming whether we like it or not, he says, and the evidence is overwhelming.

"This is going to take place gradually over the course of the coming decade and a half, so we really need to get ahead of this and start planning for it.

"It's time for us to get together and develop a plan that actually reduces New Zealand's contribution to global warming."