IPCC: Climate change begins to bite
Global warming is already impacting food security, human health, and the natural world – and it only gets worse from here. James Mitchell Crow reports.
It’s no longer a problem we can leave to our grandchildren. According to the latest report of the Intergovernmental Panel on Climate Change (IPCC), released in Yokohama, Japan, on 31 March, the impact of climate change is already evident. Our oceans, forests, agriculture, human health, water supplies, and people’s livelihoods are all being damaged. Impacts “are occurring from the tropics to the poles, from small islands to large continents, and from the wealthiest countries to the poorest,” the authors write.
“We live in an era of man-made climate change,” says Vicente Barros who co-chaired the IPCC working group. “The report has a lot of bad news in it,” admits ecologist Chris Field, the other co-chair of the group.
In September 2013, the IPCC predicted how carbon emissions would change the climate over the next century. This week it released the follow-up chapter: how will climate change affect us and how might we adapt?
What’s immediately clear is that dealing with climate change is no longer something we can leave until tomorrow. Until now the natural world has born the brunt of the impact of warming, especially in hotspots where temperature rises have been much higher than the average. But people are beginning to feel the pinch too.
Food production needs to increase dramatically over the next four
decades to feed a population that could reach 10.9 billion.
Take the oceans, for example. Since the last IPCC report in 2007, scientists have refined their understanding of how they respond to climate change. The latest report singles out the Great Barrier Reef as being under particular threat. But further south along Australia’s eastern seaboard, an accelerating ocean current is pulling more warm water down from the tropics and the impact of this warming hotspot could be dire too, with potentially disastrous consequences for people.
As the oceans off Australia warm, tropical fish usually found on the Great Barrier Reef are turning up as far south as Sydney Harbour. Their arrival threatens the New South Wales kelp forests with overgrazing. This could ultimately lead to the collapse of crucial commercial fisheries, as has already happened in southern Japanese waters. As kelp forests there disappeared, so did the valuable abalone. “It’s like desertification, and we are seeing the very first signs of this happening in Australia,” says University of New South Wales ecologist Adriana Vergés. That might be a wake-up call. Keen to protect their livelihoods, fishermen in Japan’s remaining kelp regions have become the ecosystem’s strongest protectors, she says.
Land-based agriculture is also beginning to feel the pinch. Food production needs to increase dramatically over the next four decades if we are to feed a population of up to 10.9 billion. But increasingly extreme heatwaves, droughts and floods are already “putting a brake” on the decades-long trend of increasing crop yields, especially for the staples of wheat and maize, Field says. And while some reports have suggested that crop yields could rise in the short term as a result of increased CO2 concentrations, the majority of recent scientific papers conclude that crop yields will decline by the end of the century. A quarter of the studies predict falls of more than 50% by 2100, says Field.
It becomes quite frightening how many times there will be
major flooding events in Sydney alone.
Irrigation areas are at particular risk. Take Australia’s Murray Darling river system, which provides water for the region that produces more than half the country’s grain cereals. With the IPCC predicting southern Australia will become even drier due to climate change, the system could be drained, destroying the agriculture that depends on it.
Cities aren’t immune to climate change damage either, says Brian Walker, an honorary research fellow at CSIRO and an expert in system resilience. The IPCC predicts sea-level rises of up to a metre by 2100. Combined with an increased chance of high intensity storms, this means the coastal cities will flood more often. The number of major flooding events in Sydney alone "becomes quite frightening", Walker says. Around the country, $226 billion worth of infrastructure is at risk if sea levels rise 1.1 m, says CSIRO scientist Kathleen McInnes, a lead author on the “Coastal and Low-lying Areas” section of the report.
With such dire projections, it is not surprising the IPCC is emphasising the vital need to curb greenhouse emissions as soon as possible. The faster the climate changes, the more likely it will exceed our ability to adapt.
But Field is also keen to emphasise the report’s positive side, its exploration of the “solution space”.
Lauren Rickards, a human geographer at Melbourne University’s Sustainable Society Institute, shares this hope. “Climate change causes you to pause, and it can open up new opportunities,” she says. Agriculture has shown an example of this. The drought that desiccated many parts of Australia last decade put farmers under such economic pressure that they drastically reduced their use of inputs such as fertilisers and herbicides. After the drought was broken, they realised they could farm effectively without returning to high inputs. That in turn cuts the carbon emissions that would otherwise have come from manufacturing and applying the chemicals.
“Climate change is about managing risk and building more resilient societies,” says Field. For farmers that might mean diversifying their crops or, instead of buying the plot of land next to an existing farm, buying one 100 km south where the weather might be kinder.
And when it comes to the Great Barrier Reef, resilience planning could place greater limits on fishing and the fertiliser run-off that promotes algal blooms and chokes the coral, although Walker warns, “there will be limits to the amount we can do".
Some people are starting to think about resilience planning for things like sea level rise, says Walker. “It’s one of the encouraging things, that people are beginning to understand,” he says. “But it doesn’t guarantee you will always be able to sort the problem out.”
Inaction is now inexcusable, concludes Michel Jarraud, secretary-general of the World Meteorological Organization. Previously people could have damaged the Earth's climate out of ignorance, he says. "Ignorance is no longer a good excuse.”