The climate is changing and sea level is rising - and humans must continue to adapt to the conditions.
An expert in such changes, Victoria University of Wellington professor of physical geography James Renwick, is giving a talk on the matter in Taupō next week.
James was involved in writing the sixth assessment report from the intergovernmental panel on climate change, which came out in August.
"I'm going to be giving a bit of an overview of the headlines of that report. The chapter I was working on was all about the water cycle - hydrology, river flows - so I'll cover some of the points from that chapter.
"I may get into some of the policy as well, in terms of the New Zealand response and what it means for adaptation and mitigation in this country."
He says anyone interested in climate change - which "should be everyone" - should attend the talk.
"It's impossible to overstate how big the issue is. The climate defines pretty much every part of our lives. Every mouthful of food we eat, every glass of water comes from the climate system.
"If it's changing and becoming more extreme, making it harder for us to produce food and changing water availability, it threatens our lifestyle, it threatens the lifestyle the whole world has gotten used to.
"If we allow the climate to change too much more, it could wreck the global economy and it could undermine the rule of law and the way society operates worldwide. It doesn't get much bigger than that."
James says society got used to a climate that hardly changed for thousands of years, but now it is changing rapidly.
"Where we used to grow the crops that we like to eat are no longer the best places to grow those crops. All of our effort around agriculture has to move as the climate changes, and the costs are huge.
"The costs if we don't respond are also huge. Climate change is the biggest problem there is really and something we really need to get on top of."
Public talk on climate change: science, response and energy.
5pm, Thursday, February 17.
Lakes and Waterways, Acapulco Motel, 19 Rifle Range Rd, Taupō.
Register with Lakes and Waterways secretary Jane Penton at email@example.com.