Q&A: Documenting climate change threats

Climate scientist Jim Salinger has launched a new book, Living in a Warmer World. Photo / APN

Nature is giving us many signals about warming up of the world which must be heeded, says scientist author

What compelled you to write this book and what does it seek to achieve?

As I have been watching climate change since the mid-1970s, watching the world warm up, I decided it was time to document the changes and the likely projections of what will occur. Over this period the world has warmed by almost 0.5C and is projected to warm a further 3C or more during the 21st century, if we act on climate change. But current pledges from governments put the world on a track to reach 3.5C to 4C by 2100. Nature is now giving many signals: globally, our water, food systems and health are changing and are going to change dramatically.

What in your book is being presented for the first time?

Perhaps the most interesting new information for New Zealand is the rate at which our glaciers are shrinking. From 1977 to 2008, the glaciers in the Southern Alps shrank by 16 per cent. While researching my chapter, written with Trevor Chinn, we found that the loss has almost doubled. We have lost 14 per cent of our Southern Alps glaciers in just four years (30 per cent since 1977). Our section on the news media shows they have largely framed the issue of climate change as a matter of emissions reductions and political negotiations - and largely ignored the direct physical risks to national populations, environments and economies.

Have this century's severe weather events raised awareness?

Yes. Since 2000 there have been the 2003 Western Europe and 2010 Russian heat waves killing an extra 30,000 and 56,000 people, the 2010 Pakistani floods and many others, and Superstorm Sandy smashing into New Jersey and New York. The polls in the US are showing these severe weather events are definitely raising awareness as people see the evidence before their very eyes.

Scientists talk about a no-action, end-game scenario of 4C by 2100. What would this mean for the globe?

With the emissions cut pledges made by governments right now, we are heading to a 3.5 to 4C world. This would be a world of unprecedented heat waves, severe drought and major floods in many regions. Ocean acidity would increase one and half times, which would have extreme adverse effects on all marine life, on top of warming and overfishing, with regional extinction of entire coral reef systems. Sea levels would rise in the order of 1m by 2100 with metres more in following centuries resulting in major impacts on highly vulnerable cities, especially in the developing world, inundation of some small island states and river delta regions. As 12 of New Zealand's 15 largest towns and cities are coastal, places especially at risk are Christchurch, Hokitika and Invercargill. There are also huge implications for human health.

How would biodiversity be affected - which species are most at risk?

As the globe warms, species generally are extending their ranges poleward and up in elevation. Species on every continent are already shifting in the timing of various events; primarily those occurring in spring, but also to some extent in the autumn. Birds are arriving from their spring migratory travel more than three weeks earlier than in the 1960s. Wild species are shifting their ranges poleward and upwards in elevation. If the temperature increases by 4C as many as half the identified species could become extinct.

What are the implications for food production and water resources?

Food supplies would be challenged with a significant risk to the global food basket. Crop yields are likely to fall significantly, especially in India, Africa, the US and Australia, by as much as 30 per cent for wheat. Livestock face more heat stress and disease, reducing their productivity. The number of humans affected by water stress will grow to a range of 50 million to 160 million by 2050.

There are interesting possibilities for viticulture and wine. What can we expect here?

Canterbury and Otago vineyards may have to move to higher elevations with wine styles migrating south (for example, sauvignon blanc to Otago). The eastern North Island will be very suitable for red wine styles. Winters may become too warm in Auckland for viable wine production and pinot noir would be pushed out.

What political upheaval is possible?

When combined with climate model projections of future temperature trends, the historical response to temperature suggests a roughly 55 per cent increase in armed conflict incidence by 2030, or an additional 393,000 battle deaths. India and China share similar rivers - as the glaciers in the Himalayas melt, there will eventually be less water for the massive populations. That will be a potential source of conflict.

What extreme weather events could we expect in a world 4 degrees warmer?

Recent extreme heat waves such as in Europe in 2003 and Russia in 2010 are likely to become the new normal summer in a 4C world. Tropical South America, central Africa and all tropical islands in the Pacific are likely to regularly experience heat waves of unprecedented magnitude and duration. Droughts will become more frequent. For New Zealand a one in 20-year drought will become a one in two to five-year drought, so droughts like that of last summer will become much more common.

What can New Zealand expect socially, industrially and environmentally?

The largest environmental effects will be on our mountain environments, with glacier ice shrinking to a mere 14 km3, or less than 10 per cent of the 19th century mantle by 2100. More droughts in eastern areas are expected to constrain farming, with severe impacts on the economy. Cropping and horticultural ranges will move south and to higher elevations with cereal cropping widespread in Otago and Southland. Changes in sea temperatures and currents will shift the commercial fisheries around, with cool-water species such as blue cod likely to reduce and warmer water species such as snapper move south. Sea level rise is likely to increase damage to infrastructure and our coastal settlements. We'll have more extreme rainfall, winds and storm surges.

What will the average Kiwi notice?

Much warmer winters, like the last one, with dramatically fewer frosts. For ski enthusiasts, a rise in snow line will reduce the ski areas in the North Island dramatically and push the South Island areas to far higher elevations. Flash flooding in our towns will be much more common. And those with beach front hideaways will be more prone to storm surges and king tides. And we could see many of our Pacific Island neighbours looking for help.

How can governments avert this - is it too late?

This will require reducing fossil fuels dramatically by the 2050s. It is still possible to keep global warming below 2C, but we have to start now. It is already too late to avoid a certain level of warming, but had we begun a few decades ago, the job of remaining below dangerous levels of warming would have been easier and far less costly. Uncertainty, given the high stakes, is no longer a responsible rationalisation for delay. It is up to us now to help avoid a bleak future for our grandchildren.