NZ heating up faster than predicted
New Zealand may be in for a much hotter future than previously thought, say the international authors of leading climate change research presented at GNS in Avalon last Wednesday.
The findings are the conclusion of a 15-year collaborative project looking at geological markers that record evidence of climate changes. The project focused on a period with a comparable climate to ours, the last time greenhouse gases rose significantly - 50 million years ago.
Lower Hutt-based GNS paleontoglogist and paleoclimate scientist Chris Hollis says since 1998 the team has compiled a comprehensive pool of geological data from this era, from both onshore and offshore in Marlborough and Canterbury.
Evidence from more than 5000 mineral and organism deposits the team collected records evidence of past environmental changes, and the data has been pieced together to help the scientists understand how different factors, such as the level of different atmospheric gases, contributed to vast climate systems.
The research has helped to shed light on the "South West Pacific temperature anomaly," a pattern of "extreme warming seen in our sea surface temperature estimates," Mr Hollis says.
The new data has been used by international climate modelling scientists participating in the project to re-examine the existing models.
"These models of past climate are the same kinds of models that are used to predict future climate.
"Our studies help to test and refine predictions of the climatic consequences of increasing greenhouse gas levels."
The patterns shown by the new geological evidence point to "extreme warming", he says.
"Our main finding has been that greenhouse climate models appear to underestimate the degree of warming that occurs in higher latitudes, such as the New Zealand region."
The research touches on one of the bigger problems now facing climate scientists - discrepancies in the understanding of the relationship between greenhouse gases and temperature.
"The commonly cited value is temperature increases by about 2 degrees Celsius for each doubling of CO2," Dr Hollis says.
"However, the geological record suggests it could be higher and may not be constant, temperatures may increase at a greater rate at higher CO2."
The relationship is termed "climate sensitivity", and the New Zealand research will help scientists work towards a better understanding of the very complex systems.
The presentation last week was delivered by Dr Hollis, along with professor Gerald Dickens of Rice University, Texas, and visiting professor Matt Huber of Purdue University, Indiana.
It is internationally significant, and a serious warning about our future, Dr Hollis says.
"The research suggests at the current level of CO2 increase, the planet is already committed to significant climate change.
"Mitigation is still important to reduce the long-term impact but we need to be thinking more about adaptation."