Goodbye frosts, hello droughts and bush fires.

That's among the less frightening ramifications that a rise of up to 3C in our average climate by the next century would hold for New Zealand, according to Victoria University climate scientist Dr James Renwick.

"Middle-earth may go back to existing only in books, for most of the world's population."

Frosts would likely vanish in areas near sea level and the country would experience a much higher frequency of hot days and heat waves, with more frequent bush fires, especially in the east of the country.


"A more seasonal climate is likely, summers much more often like the one we've had this year but winters likely to stay relatively wet and stormy."

Less snow stored in the mountains in winter and spring would hold ramifications for winter tourism and hydro-lake management.

Gardeners and farmers could expect to see a greater prevalence of plant and insect pest species, many coming from more tropical locations.

It might mean we can grow crops that find our present climate too cold, though many cooler-climate crops such as apples could in turn find most of the country too warm.

There would be a greater risk of flooding and heavy rainfalls, even in places that become drier over time, while sea levels were likely to climb by around 1m by the end of the century, and keep rising.

"This would mean many low-lying areas - Takapuna, Kilbirnie, New Brighton - would be at much greater risk of coastal inundation and may become uninhabitable."

Globally, there was a risk Kiwis could see huge disruption to global food supplies as rain bands shifted and temperature extremes changed.

A dramatic change could even lead to regional competition over food, agricultural land, and water resources turn to armed conflict, he said.


"New Zealand is likely to be seen as a safe haven for many, so there are likely to be political, diplomatic, and even military implications for us."

As the risks to global agriculture implied the risk of global financial instability, New Zealand's economy would be affected regardless of how agriculture was performing locally.

Dr Renwick said sea level rise alone was likely to drive migration, at least from low-lying areas such as some of the Pacific island nations, potentially bringing much larger numbers of Pacific Islanders to New Zealand.

If the drying trend continued across southern Australia, as it was forecast to do, cities such as Melbourne might not be sustainable as places to live unless large-scale desalination of sea water came into play.

The Great Barrier Reef would die through a mix of warming water and increasing acidity of the ocean, with obvious effects on tourism.

Whether international tourist travel to far-flung places such as New Zealand was sustainable in future remained an open question, he said.

"Should a realistic price be placed on carbon emissions ... air travel is likely to become much more expensive." Rising fuel prices would also boost the cost.