Researchers are warning that unless the world lowers its carbon dioxide (CO2) emissions, New Zealand is on track to have a tropical climate.

Waikawa Beach, New Zealand. Source: istock.com

The prediction comes off the back of a new study from scientists at Bristol University, who have been examining what the world's climate looked like 56 million years ago.

Back then, New Zealand was much more hot and humid, with high C02 levels.

In fact, the levels during that period are similar to those predicted for the end of this century, sparking a warning from experts.

Currently, it's estimated that the world produces at least 32 gigatons of carbon dioxide annually, with that number forecast to grow.

Professor Rich Pancost, co-author of the study, said "our work adds to the evidence for a very hot climate under potential end-of-century carbon dioxide levels".

The research has also revealed that annual land temperatures in Western Europe as well as New Zealand were actually higher millions of years ago than previously thought.

The next step for scientists is to examine whether life could have survived back then.

Dr Naafs, the research leader, said "did the tropics, for example, become ecological dead zones because temperatures in excess of 40 degrees were too high for most form of life to survive?"

"Some climate models suggest this, but we currently lack critical data."

- By Andrew Macfarlane