Understanding Climate Change Helps us Face the Future

20 July 2016

Professor James Renwick teaches climate change at Victoria University. When he isn’t teaching, he is conducting research. At the moment, he is trying to understand what is going on with Antarctic sea ice.

“Over the last couple of decades, the amount of sea ice formed in Antarctica in winter, between June and September, has been increasing. This is very counter-intuitive. Given what we know about global warming, it should be going the other way.”

What the research is showing is that these patterns are a consequence of natural variability.

“It comes down to elements like wind direction, and kinks in the jet stream,” Dr Renwick says.

The value of the research is in obtaining a clearer and more comprehensive picture of climate change. It is another piece in a complicated puzzle, and means we can be better prepared for what lies ahead.

“Having a better understanding is an end in itself but it also means better foundations for the future,” he says.

Dr Renwick started his career more than 30 years ago as a weather forecaster and researcher at the MetService. Currently, he holds a teaching and research role at the School of Geography, Environment and Earth Sciences at Wellington’s Victoria University. He is a member of the World Climate Research Programme Joint Scientific Committee, and the chair of the Royal Society of New Zealand Climate Expert Panel.

With all his knowledge and experience, he and other scientists cannot predict exactly the future course of the climate system. The catch is that we need to know what future emissions of greenhouse gases will be, to know just how much the climate will change. But some aspects of climate change are expected to change in predictable ways, almost independent of future emissions.

“Sea level rise is the most predictable component. Whatever we do, we’re still going to get a 30-centimetre rise in sea levels over the next 40 or so years.”

“The wild card is what the big ice sheets in Antarctica are doing, the extent to which they will melt, and how fast. We may soon be committing the globe to 10 or 20 metres of sea level rise.”

The uncertain future of our planet was the focus of the 2015 Paris climate conference, where 195 countries adopted the first ever universal global climate deal. These countries agreed to limit global warming to well below 2°C.

“If we honour the Paris agreement and move away from fossil fuels quite quickly, there may not be that much more change in New Zealand. It may not look that different,” Dr Renwick says. “If the international agreement falls over or isn’t lived up to, that would have bigger implications.”

One of the challenges of climate change is that people are not always confronted with its effects, which are already happening, and this can make them lose sight of the urgency of the issue. New Zealand has a temperate climate and has been relatively spared when it comes to extreme weather patterns, Dr Renwick says.

Yet if we want to avoid high-risk levels of climate change, including large rises in sea level, we need to start reducing emissions globally right away, and take them to zero over the next 50 years or so. The time lag between the cause and the effects of climate change can make it hard for members of the public to grasp the urgency of action.

The effects of climate change on New Zealand, particularly as it relates to outdoor recreation in coastal and mountainous areas, will be the subject of a talk Dr Renwick is giving in Wellington in September. His presentation will outline the latest scenarios for climate change here.

“In alpine locations, it’s likely for example that temperatures will increase faster than in the lowlands. In coastal areas, rising sea levels and stronger storms means an increased risk of inundation.”

Information on the impact of climate change will be important to outdoor organisations, and also to planners and policymakers. The more they know, the better they can understand, prepare and adapt to changing circumstance.

In the international climate change community, information sharing is vital. Given the global nature of the climate system, the more experts know and share, the better, Dr Renwick says. Luckily, he says, that exchange is happening all the time.

“With climate science and weather predictions, the observational networks are global, the data is shared in a number of ways. It’s a worldwide collaboration.”

Dr James Renwick will speak at the Outdoors Forum, held in Wellington from 1-2 September and the NZRA National Conference, held in Queenstown from 9-11 November.

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