“In the past 30 years - the period the world has been talking about fixing climate change - we have made it twice as big a problem," Victoria University climate scientist Professor James Renwick says. Photo / Supplied
Here’s what’s happened to our planet since a young James Renwick began his career as a weather researcher, some 44 years ago.
The global temperature has climbed by an average 0.18C each decade, to the point we’ve seen a doubling in the number of days where the mercury soars past 50C.
Sea levels have similarly risen with quickening pace: from about 2.5mm each year in the early 1990s, compared about 3.9mm today.
Our Southern Alps have lost a third of their ice volume and our coastal waters have been warming by an average 0.2C every 10 years.
For Renwick – now arguably our most visible climate scientist – one trend sticks out more than any other.
“In the past 30 years – the period the world has been talking about fixing climate change – we have made it twice as big a problem,” he said.
“Half of the total human emissions of carbon dioxide since the 1700s have occurred since about 1990 – and the emissions are still going up.”
Climate change was now “pervading everything”, he said, its extreme influence implicated in heatwaves, warm seas, droughts, fires, floods and devastation across the globe.
Take February’s Cyclone Gabrielle.
In the aftermath of our century’s worst weather disaster, scientists concluded that extreme deluges had become up to four times more common, unleashing up to 30 per cent more rain, in the East Coast regions it hit hardest.
“We now have wildfires in Siberia and Greenland,” Renwick said.
“I remember a few years ago looking at a map of wildfires in Alaska and I could hardly see the map for all the fire markers.
“This is such a shift. It really does feel like it is affecting everything, everywhere, all at once.”
Given what we’re already witnessing, it’s difficult to ponder some of the bleak scenarios laid out in the UN’s recently-issued 7700-page Sixth Assessment Report, on which Renwick served as co-author.
According to its mid-range scenario – in which CO2 levels peak around 2040, then hit the 2C point sometime between 2041 and 2060 – this century might finish up being some 2.7C hotter than pre-industrial years.
What does that mean?
With even 2C of warming, the hottest day in a decade will be 2.6C warmer, relative to the climate as it was 150 years ago, while droughts will occur three times more than they once did each decade.
With 4C, a decade’s hottest day could be 5.1C warmer than it was, droughts will grow more than five times more frequent, intense tropical cyclones will become 30 per cent more frequent, and the planet’s snow cover extent will shrink by a quarter.
In New Zealand, particularly, we can expect major climate shifts such as wetter summers in the east of both islands, or rainier winters and springs in the west and south.
Baked-in impacts on our oceans and ice sheets also mean unavoidable sea-level rise over millennia.
Just last month, the World Meteorological Organisation warned that a forming El Nino could push global warming past the symbolic threshold of 1.5C, within only five years.
In the face of these dire projections, Renwick carefully described himself as “optimistic and pessimistic” about the world averting the very worst consequences.
“As a global community I think we have missed the boat on 1.5C,” he said.
“Unless there are miraculous emissions reductions in the next two to three years, we will lock in 1.5C soon.
“Individual years may cross the 1.5C warming threshold before the end of the 2020s and average temperatures will be at that level in the early 2030s.
“We may get to 1.7C or 1.8C warming before the problem is brought under control, but I think we can avoid 2C or more warming – if we move quickly.”
But will we?
Renwick thinks back to the sluggish progress made to combat climate change since humanity woke up to its greatest existential threat.
During his school and study years throughout the 1970s, global warming wasn’t even on his radar.
“Climate change was already understood by many in the climate research community, but it wasn’t a topic of popular interest and indeed many in the weather and climate community were not working on it, or thinking too much about it,” he said.
“I think it was recognised as a possible problem, but something for the future.”
It was when former Nasa scientist James Hansen issued a warning to the United States Congress in the 1980s that Renwick, by then working as a MetService weather forecaster, began to grasp the danger.
“It gained wide coverage, and the discovery of the ozone hole and the signing of the Montreal Protocol in 1987 showed what was possible in the policy sphere when the science was clear.”
Some other watershed moments: the US National Academy of Sciences’ influential report in 1979; the 1980 and 1985 Villach climate conferences; and the birth of the UN’s Intergovernmental Panel on Climate Change in 1988.
“So, I’d say most in the climate research community were well aware of the reality and the dangers of climate change by 1990,” he said.
“That’s only two years before the Rio Summit and the development of the UN Framework Convention on Climate Change.”
Around that time, Renwick shifted to Niwa, and then to Victoria University, where he discovered he had a knack for explaining science in a way the rest of us could understand.
Having given hundreds of public presentations since, on top of countless media interviews, he’s become one of the country’s leading science communicators – often fronting for the camera in one of his signature waistcoats.
All of that effort has culminated in a new book, Under the Weather, which offers a “future forecast” for New Zealand.
He pulls out some eye-opening highlights.
With 2C of warming, places like Canterbury, Hawke’s Bay and Northland will see a five to 10 per cent drop in average rainfall – and perhaps a doubling or tripling in droughts.
In Northland, heat stress will likely shift dairy cows indoors, while Canterbury may need to revert to more dryland-style agriculture.
Crops grown in the southern North Island may become viable in Southland, and in Northland, bananas could become a staple crop.
Even pineapples might become an option within a few decades, while other crops might struggle – and we could say goodbye to apples, apricots, peaches and even kiwifruit in places they currently thrive.
Our land and sea will become hospitable to new and destructive pests, excessive heat may lead to more shorting and brown-outs in power networks, and ski-fields in the central North Island could be marginal in just 20 or 30 years.
Atmospheric rivers, which have been relentless over summer, will deliver more rain than snow to the Southern Alps, causing our glaciers to shrink even further, and add even more water to river flows.
“This is a book about climate change, about my understanding of it, what it means for me, and what it means for all of us in Aotearoa,” Renwick said.
“I was inspired to write it for the same reason I give a lot of public talks and media interviews – I want to get ideas about climate change in front of as many people as possible.
“We are in the fight of our lives, and I want everyone to be armed with information.”
Compared with even 20 years ago, it is reassuring to him that most Kiwis now have a high awareness about climate change – and accept our own activity is fuelling it.
IAG’s latest annual survey, for instance, indicated three-quarters of us feel we are seeing more frequent floods – up from 57 per cent only five years ago – while eight in 10 see climate change as an issue personally important.
More Kiwis are looking to the Government for direction, and to councils to invest in smarter infrastructure and prevent development in risky places.
Another recent Herald poll found nearly 60 per cent of Kiwis think the country should take stronger action – with around a quarter “strongly” agreeing New Zealand should be bolder.
Although younger people are more likely than older Kiwis to back stronger action, that sentiment fell generally evenly across age groups.
The wettest summer in recorded history for many North Island locations has only brought the reality of climate change extremes closer to home – if only temporarily.
“I think that right after Gabrielle and the big floods in Auckland, there was a lot of concern and awareness,” he said.
“But humans have short attention spans, and if the extremes go away, that concern can lapse, unfortunately.
“I don’t like the idea that further extreme events, with harm to many, are what’s required to focus our minds to action, but that does seem to be the way it works.”
Is New Zealand moving fast enough?
Not according to the global Climate Action Tracker, which grades our policy as “highly insufficient”, or global rankings that show our emissions footprint to be comparably small, yet high per capita.
“I think the policy moves in the past few years, with the Zero Carbon Act, the Climate Change Commission, and the Government’s Emissions Reduction Plan, put us on a good footing for climate action,” said Renwick, who serves on the commission.
“The commission showed it is possible and affordable to get to net-zero carbon dioxide emissions by or before 2050, and the Government has been accepting that advice.
“But now, we need action. We need investment in public transport, in renewable electricity generation and so on.
“It is starting to happen, so I think we’re on a good track, provided the momentum keeps up.”
If ever he needs cause for optimism, he turns to the thousands of young Kiwis who took to the streets in nationwide marches just a week ago.
“There is real activism in the community these days, with groups like the Climate Strike movement and Extinction Rebellion,” he said.
“Those Climate Strike school students will be in positions of power soon – some already are – and that will accelerate action.
“So, what gives me hope, is that humanity holds all the power in its hands, and are the ones driving this problem, and adding the greenhouse gases to the air.
“When we stop doing that, we will stop global warming. It’s a race against time, but, can we stop emissions before the changes become overwhelming?
“I hope so and I believe it can be done. For all our sakes, we had better give it our best shot.”
Under the Weather: A Future Forecast for New Zealand (RRP $39.99) releases on June 7.
Allegations - raised after former student’s suicide - relate to former Murupara teacher.