by Ashley Hay
Climate change raises temperatures and, in some parts of Australia, leads to drier conditions. When it gets hotter or drier, bushfire risk increases. In southern Australia, increases in temperature and a decrease in spring rainfall in recent years have created a perfect storm of bushfire danger conditions.
Severe fire danger conditions, marked by an unusually high Forest Fire Danger Index, have increased particularly in the south-east since the 1970s. Not only is the danger becoming more intense, severe fire danger days are beginning to appear not just in summer but also in spring and autumn. In other words, the fire season is lengthening. The fire season is projected to continue to grow longer in coming decades, with even more days of extreme fire danger each year.
The bushfires that ravaged New South Wales in 2013 were striking, not just because of the magnitude of the blazes, but because they began unusually early, in September. A contributor to the early bushfire season was the fact that the state experienced its hottest September on record along with unusually dry conditions.
Perhaps paradoxically, global warming leads not only to an increased risk of fires but also to more intense rainfall. As heat builds up in our climate system, this accelerates evaporation of water from the ground and from water sources. This leads to more moisture in the atmosphere. But what goes up must come down, and one consequence is more heavy downpours. Since 1990, scientists have been predicting an intensification of the water cycle – both evaporation and rainfall – due to global warming. These predictions have been borne out by subsequent observations.
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Over the past four decades, the amount of moisture in the atmosphere has increased by 4 per cent. Globally, that’s equivalent to 900 Sydney Harbours’ worth of extra water in the air. Consequently, consistent with scientists’ expectations, we have experienced an increase in heavy rainfall, particularly in north-western Australia.
Flooding can have a devastating impact on infrastructure and human lives. The Queensland floods in 2011 resulted in the deaths of 35 Queenslanders and cost the state $12 billion. The forces driving the floods were complex, with heavier than normal rainfall conditions accompanying La Niña conditions in the Pacific. At the same time, there were record high sea surface temperatures around Queensland. As with heatwaves and bushfires, global warming is increasing the risk from floods.
But in addition to more floods, we are also experiencing intensified drought. As it gets warmer and evaporation increases, the ground gives up moisture to the atmosphere. This means that drier regions become even drier, while wet areas are getting wetter. Global warming intensifies the water cycle.
While rainfall has overall increased across Australia, different regions have shown varying responses to global warming. North-western Australia has seen a strong increase in rain but in Australia’s south and east, rainfall levels have decreased. The decline in the south has led to severely reduced water supplies in south-western Australia and the Murray Darling basin.
The change in rainfall patterns has several flow-on effects. Key food-growing areas in Australia’s south-west and south-east are likely to experience more drought in coming decades, which will have consequences for agriculture. Drier conditions in the south-east, along with increased heatwaves, will combine to increase bushfire danger.
As cyclones travel across the sea surface, they scoop up energy from the ocean water. The warmer the water, the more energy cyclones build up. Ocean heat is fuel for cyclones. Scientists project that as global warming continues and oceans continue to warm, cyclones will grow more intense.
Cyclone Yasi, which struck North Queensland in 2011, was a Category 5 cyclone and caused $1.4 billion damage. In November 2013, Cyclone Haiyan devastated large sections of the Philippines when it recorded the highest ever wind speeds of any tropical cyclone to hit landfall. The stronger winds were fuelled by unusually warm ocean temperatures as the cyclone passed over the west Pacific.
With over 90 per cent of global warming going into the oceans, ocean waters are building up heat. As the oceans warm, the water thermally expands, leading to rising sea levels. In addition, glaciers all over the world are shrinking at an accelerating rate and melting ice sheets are sliding faster into the oceans. The Greenland ice sheet is currently shedding over 300 billion tonnes of ice each year. The result is that over the last century, global sea levels rose by 21 centimetres. Of even greater concern is the fact that the rate of sea-level rise is accelerating. This means that over the next century, we can expect to see substantially more than a 21-centimetre sea-level rise.
Australia is considered by many climate scientists to be the ‘frontline of climate change’ and ‘the canary in the coal-mine’, with certain impacts such as rising sea levels more severe here compared to other parts of the world. This is particularly pertinent given that 85 per cent of Australians live near the coast. In northern Australia the rise in sea level is among the highest on the planet, up to 1 centimetre per year – more than three times the global average.
The 2013 United Nation’s Intergovernmental Panel on Climate Change (IPCC) report projects that sea levels will rise between 45 and 82 centimetres under a business-as-usual scenario. To put this in perspective, a sea-level rise of 50 centimetres will result in a 75-fold increase in the frequency of coastal flooding; in many regions, the increase is over 1000 times.
Because the world’s oceans absorb most of the CO2 we emit into the atmosphere, we are starting to pay a very heavy price. Coral reefs, the havens of biodiversity that act as the rainforests of the oceans, are being threatened by the one–two punch of warming and acidification.
When waters get too warm, corals expel the algae that live in their tissues. These algae live symbiotically with the coral, feeding it nutrients and giving the corals their bright colours. After the algae are expelled, the coral dies and is bleached white. In 1998, when the Pacific Ocean experienced an unusually warm El Niño, it is estimated to have bleached 16 per cent of the world’s reefs.
Then there is ocean acidification. Ocean waters absorb much of our CO2 emissions, converting it to carbonic acid. Since the Industrial Revolution, the ocean’s acidity has increased 30 per cent. This acidity makes it harder for corals to form calcified skeletons. This combination of bleaching and acidification is impacting corals all around the world.
Many Australians do not know that half of the Great Barrier Reef has already lost its coral cover over the last 27 years. It has experienced multiple bleaching events over recent decades, caused by underwater heatwaves. This trend is expected to continue, and Australia is in danger of irrevocably losing one of its national treasures.
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In 1908, Dorothea Mackellar characterised our country as a land ‘of droughts and flooding rains’. Australia has always been vulnerable to climate extremes, and global warming is making us more vulnerable. As bushfires, floods and drought intensify, our country is becoming further exposed to extreme weather.
We are handing over to our children a world more dangerous than the world our parents gave us. If our planet warms more than 2° Celsius, we will move beyond the threshold of what is considered ‘safe’ global warming. The likelihood of the Greenland ice sheet disintegrating, which would contribute metres of sea-level rise, increases to more than 50 per cent. If we carry on at the present rate, we will see as much as 4° Celsius to 6° Celsius warming. This will take our climate to conditions not seen in millions of years, when sea levels were tens of metres higher than they are now.
But just as we human beings are the cause of the problem, we are also the solution. We are already committed to 1.5° Celsius warming from pre-industrial times: we’re currently at 0.8°. We will experience some climate impacts based on our emissions already.
The question is just how intense and dangerous are we willing to let it become. We already possess a range of technologies involving energy efficiency, solar power, biomass, wind power and a range of other options that can reduce the impacts of climate change. Wha
t is missing is the will to act, from our political leaders and from the Australian public. The choice to commit our children and grandchildren to a perilous world, or to work to transition our society towards a clean and safe future, is in our hands.
Weathering the storm
Firefront
Weather and mind games
Tom Griffiths
As a teenager I read Charles Darwin’s Voyage of the Beagle and was intoxicated by the glimpse of a young questing mind wrestling with experience, evidence and argument. In my final year at school we studied Alan Moorehead’s Darwin and the Beagle and learned how this voyage came to change our understanding of the world. Darwin’s insight into the origin of species and the process of natural selection was carefully and anxiously developed over decades in his home at Down House in Kent and then forced into the open by Alfred Russel Wallace’s 1858 letter from the feverish jungles of Malaya. Two great and very different offspring of competitive, industrial Britain had arrived at the same idea. It was at heart a beautifully simple concept but its full scientific implications are still unfolding today. As I read Darwin’s account of his South American excursions and learned of Thomas Huxley’s eloquent defence of On the Origin of Species, I yearned to live at a time when a grand and transformative scientific idea burst upon the world.
Be careful what you wish for.
Even while I was at school, a revolutionary new idea was already emerging, but its power remained hidden. It was a scientific insight that was eventually to reveal itself as even more radical and challenging than Darwin’s. The science of climate change had its foundations in the mid-19th century with the discovery of ice ages, and it had a breakthrough moment in the year of the publication of On the Origin of Species, 1859, when Darwin’s friend, John Tyndall, discovered the influence of greenhouse gases on the temperature of the planet. A century later, in the late 1950s, Charles Keeling began to measure a steady, relentless upward trend in atmospheric CO2, and by the final decades of the 20th century, ice cores from both Greenland and Antarctica delivered a sense of urgency and crisis about global warming. The ice core data revealed the historical delicacy and instability of Earth’s climate and confirmed that CO2 levels, which have risen rapidly since the Industrial Revolution, are the highest for at least three million years and therefore new in human history. Scientific alarm began to influence public debate and in 1988 the Intergovernmental Panel on Climate Change was established to distil complex, emerging scientific information for government and business.
The theories of evolution and of anthropogenic climate change both had a long, slow gestation followed by a sudden crystallisation, rapid scientific acceptance and some trenchant public resistance. In the early 19th century, the link between animals and humans became a subject of dangerous fascination, for it raised questions about ‘the mode of creation’, about organic origins and spiritual destiny, and therefore about the relationship between science and religion. The beak of a finch thus seemed connected to the salvation of a human. In popular discourse, Darwin’s idea became condensed into a contest between apes and angels.
Charles Darwin delayed publication of his insight into the transformation of species because he feared its effect on the religious beliefs of his society, and those of his devout wife, Emma. We have a compelling picture of Darwin as a tortured soul, bunkered down with his barnacles in Kent, and meticulously gathering a fortress of detail with which to defend his idea when the time came to reveal his secret. It was, he wrote, ‘like confessing a murder’. He applied scientific scepticism to his theory with the double force of his critical faculties and his emotional fears. In his wife’s religious faith he had the loving embodiment of all that he wished not to upset. If you visit the museum that was once Darwin’s home, you can open a hall cupboard and see a replica of the securely wrapped parcel labelled by Darwin: ‘Only to be opened in the event of my death’. It was the first account of his great idea, a 200-page manuscript completed in 1844, a ticking time-bomb at the centre of the elegant Georgian home.
The publication of On the Origin of Species 15 years later did indeed unleash a storm – but it was ultimately not quite as bad as Darwin had feared. By the time Darwin died, 23 years after the publication of Origin, he was celebrated enough to be buried in Westminster Abbey and he was hailed as a hero and icon. As Iain McCalman’s compelling collective biography, Darwin’s Armada, reminds us, the key battles within Victorian Britain for acceptance of Darwin’s theory and its associated scientific culture ‘were over in a surprisingly short time’. By 1868, Joseph Hooker could address the British Association, as president, and conclude that few scientists now openly rejected the theory.
Of course, the idea of natural selection continued to be refined by scientists and, in the 20th century, was challenged and ultimately strengthened by the discovery of the gene. And religious resistance to evolutionary theory continued; indeed, at times it has even grown. In the United States today, polls keep telling us that up to 40 per cent of Americans reject the theory of evolution and believe that the Earth was created less than 10 000 years ago. Since the 1960s, ‘creation science’ has become active and politically powerful, challenging not only Darwin but also the scientific method, and seeking ‘equal time’ in the US school curriculum.
During a Q&A discussion on ABC TV in 2011, an audience member disparaged climate change science as ‘just a theory – like gravity’. Inadvertently, he was making a good parallel. Our understanding of anthropogenic climate change is indeed a theory – like gravity, electricity, germs, the heliocentric solar system, evolution, relativity and plate tectonics. But in science, ‘theory’ is a very strong word. It does not mean an untested hypothesis; it does not mean a vague, esoteric concept. Rather, it describes a consistent form of scientific knowledge not yet disproved by experiment. Resilient scientific theories describe complex phenomena extremely well, continue to be refined and improved by experimentation and observation, and have impressive explanatory and predictive power.
Good scientists subject their own work, and that of others, to rigorous scepticism: it is the scientific method. Darwin’s methodical analysis of the possible weaknesses of his theory gave him the structure of his book. ‘I have felt these difficulties far too heavily during many years to doubt their weight,’ he wrote near the end of Origin. And at the beginning of the book he explained: ‘No one ought to feel surprise at much remaining as yet unexplained in regard to the origin of species and varieties, if he make due allowance for our profound ignorance in regard to the mutual relations of the many beings which live around us.’ A good theory is fertile and identifies uncertainty; it can remain true at the same time as it generates new and exciting research into areas of weakness. ‘The theory of evolution is not just getting older, it is getting better,’ declared the palaeontologist Steven Stanley in 1981. And the theory of climate change is also getting older and better – and more forbidding. It has accurately predicted many observed manifestations of global warming – from sea-level rises to increased temperatures to acidification of the oceans – although sometimes these changes have come about a little more quickly than had been estimated. Caution – of which Darwin at Down is the exemplar – is another hallmark of good science.
The theory of evolution opened up a new worldview, chiefly of the past but also with implications for the future. Family history – across deep time – became natural history. Natural selection was radical in its vision of a totally contingent natural world, one ruled by chance and improbability rather than by a steady and progressive purpose or a predetermined set of stages. People who resisted or rejected the theory of evolution argued about origins, creation, history and natural history. But they also felt the future was at stake – the prospect of a godless world and their personal destinies in heaven. At the end of Origin, Darwin argued eloquently that there is ‘grandeur in this view of life’, that ‘from so simple a beginning endless forms most beautiful and most wonderful have been, and are being, evolved’. And he
also finished the book with words of confident hope about the earthly future of humanity: ‘Hence we may look with some confidence to a secure future of great length’, he wrote, because humanity under the influence of natural selection ‘will tend to progress towards perfection’. Here the scientist begins to look for a way of selling his idea to Victorian industrial society, and allows the chaos at the heart of his theory to be conceived as ‘progress’. Thus Darwin succumbed to the progressive culture that his own theory undermined.
Today, climate scientists are like Darwin: the implications of their science frighten them, and the politics of their society can intimidate them. The theory of anthropogenic climate change met with swift scientific acceptance but has been followed by a sustained and strengthening public counterattack. The backlash has been deep and powerful because this new idea does not have the reassuring ethic of progress on its side; instead it requires a critical reassessment of the implications of the Industrial Revolution. And the balance of the problem it poses lies more in the future than in the past. It does not promise ‘a secure future of great length’; it threatens it. It demands political action, which the theory of evolution did not. And for that action to have significant effect, it must be global. Competition will need to be moderated by co-evolution. Further refinement of Darwin’s theory awaits humanity’s decisions this century about its own evolutionary fate.
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You are sitting at the dinner table with old friends you haven’t seen for a while. The atmosphere is warm, friendly and celebratory. Then, suddenly, climate change slips into the conversation. The mention of global warming immediately precipitates a light frost. There is some wariness and a sounding-out of positions. Then one old friend leans forward, slightly conspiratorially but also with the conviction that he is delivering some welcome information, and tells you that a friend of his uncle’s is an absolute whiz with computers and has crunched the numbers of the climate scientists and found that they have made a basic error that changes everything. What do you say? This kind of conversation is happening – or dying – at dinner tables, barbecues and pub bars around the country.
