CHAPTER ONE

The Weather Makers: Right or Wrong?

Whether we and our politicians know it or not, Nature is party to all our deals and decisions, and she has more votes, a longer memory, and a sterner sense of justice than we do.

WENDELL BERRY

WHEN I wrote The Weather Makers, I laid out the state of climate science as it was understood in 2005. The book received much acclaim, but it was also criticised by climate-change sceptics as extremist and alarmist. One critic even wrote his own book in search of any faults or exaggerations. I was pleased that he found only a handful of errors, none of great consequence: no wide-ranging science book can hope for 100 per cent accuracy. Here I wish to be my own critic, for it’s only with the passing of time that it has become possible to test whether claims about climate change have come to pass.

Since The Weather Makers was published, the Intergovernmental Panel on Climate Change (IPCC) has completed two major summaries, in the form of its fourth and fifth assessment reports, and thousands of scientific publications have added to our understanding of how Earth’s climate system responds to carbon pollution. The IPCC does not do its own research. Under the auspices of the UN it provides a report card based on an enormously thorough examination of the published scientific literature. As a result, many details of climate science have been clarified. Not only are the scientific projections of major trends more certain than ever, but today many of us also have firsthand experience of living in a strongly shifted climate. With climate change an experienced reality, and the science verified, the room for climate change denialism keeps shrinking.

Another thing that has changed over the past decade is the accessibility of climate science to the general public. Ten years ago I had to comb the scientific literature and textbooks for explanations of how our gossamer-thin atmosphere interacts with the oceans and land to create components of the climate system. Indeed I found that books written a century earlier by luminaries such as Alfred Russel Wallace were more poetically eloquent on the subject and more informative than many recent works. Today, a great wealth of material is available to anyone curious enough to look, much of it online (including on the excellent website scepticalscience.com). Sadly, the misleading blogs by sceptics have also proliferated, though an increasingly sophisticated public is less easily deceived by them.

Some of the tools that climate scientists use have also changed enormously. Our capacity to model the climate system in time and space, for example, has been transformed. The models used in the 1990s could operate across four orders of magnitude in time and space, while current ones operate across five orders of magnitude. By way of illustration, four orders of magnitude in space extends from a millimetre to 10,000 millimetres (10 metres), while five orders extends from a millimetre to 100,000 millimetres (100 metres). The capacity of the climate models continues to grow at a rate of around an order of magnitude per decade, with each decadal increase involving 10,000 times more calculations for space alone than were required previously. When climate models are able to operate across 14 orders of magnitude—from milliseconds to millennia, and millimetres to thousands of kilometres,—they will be able fully to model Earth’s climate system.¹

Despite their vast increase in computational power, the models remain consistent in telling us that our Earth is warming, and will continue to warm in proportion to the volume of fossil fuel we burn. What has changed is the detail they reveal about the things that will unfold. While no climate model can predict the future—simply because the future is impossible to predict—the increasing computational power of the models means that they are becoming ever more useful at explaining how climatic changes are being influenced by humanity.

Studies of past climates are also becoming ever more informative. One that examines over 1000 years of temperature records has shown that climate trends have sometimes differed markedly in the northern and southern hemispheres. One example of hemispheric difference, which the sceptics used to cast doubt on the fact that CO₂ causes warming, concerns the medieval warm period. The new study demonstrates unequivocally that this warm period was restricted to the northern hemisphere.² But such is the unprecedented volume of greenhouse gases that humans have released into the atmosphere that the climate system is being overwhelmed, and today warming is occurring in both hemispheres.

The contemporary world is changing fast; few changes have been as profound or disturbing as the increases in extreme weather experienced right across the planet. For that dwindling band who continue to deny anthropogenic climate change, this is the new battleground—albeit one which is becoming ever more difficult for them to defend. When, in late 2013, Australian Prime Minister Tony Abbott and his environment minister Greg Hunt argued that there is no link between the warming trend and extreme bushfires, they were arguing not only against science, but also contrary to common sense.³

The link between extreme weather and climate change is a critical area for public understanding, because it’s the devastating extremes, rather than a shift in averages, that have the greatest impact. To deny the link also permits people to believe that climate change is something only for future generations to worry about. It is not. Our climate has already changed, and over the last decade we have begun to witness more frequently the consequences of our profligate burning of coal, oil and gas. Very recent advances have allowed scientists to quantify the human impact on individual extreme weather events.⁴ Extremes in the weather are therefore a good place to begin looking at what has changed in climate science over the past decade.

The Australian Open Tennis Championships are Melbourne’s moment in the sun, and during the fortnight of the competition there’s hardly another topic of conversation in the city. When, during the 2014 Open, a heatwave of unprecedented ferocity struck Melbourne, bringing a record-breaking four days in a row of temperatures over 41°C, as well as the city’s hottest-ever 24-hour period, the stadium built to host the event turned into a furnace. Despite the long and loud warnings of the climate scientists that extreme heatwaves were all but inevitable, Rod Laver Arena had not been built to cope with the threat, and lives and money were put at risk.

With millions of dollars at stake, the tournament organisers were reluctant to call an end to play. For day after scorching day the players slogged it out in 40°C+ temperatures on the courts. The fans stuck around too, though more than 1000 had to be treated for heat stress. Finally, the health risks to both players and spectators became too much, and the multi-million dollar tournament was suspended.⁵

Australia’s growing heatwave crises rarely make global news, but the suspension of the Australian Open made page one in newspapers around the world. The Australian Climate Commission, which I headed until it was closed by the Abbott government in September 2013, had led in warning that heatwaves were becoming more severe in Australia, so I was not surprised when the BBC World Service approached me to explain the relationship between the tennis-cancelling heatwave and climate change.

I told the journalist how the small shift in average temperatures caused by emissions of greenhouse gases was influencing the extreme temperatures across Australia, and indeed the world. The reporter said he’d call me back. When he did, it was to apologise that the interview had been called off. His bosses had told him that unless I could prove that climate change had caused the heatwave they were not interested in the story. I was astonished. In a system as complex as Earth’s climate, single factors are rarely the sole cause of anything, so it’s usual to talk in terms of influence rather than cause.

But when it comes to the question of climate change’s influence on the Australian heatwaves of 2013–14, we do have a definitive answer. In late 2014 Dr Thomas Knutson of the US Geophysical Fluids Dynamics Laboratory at Princeton University, New Jersey, and colleagues published an analysis demonstrating that it is virtually impossible that the extreme heat experienced over Australia in 2013 could have occurred without the influence of human-emitted greenhouse gases.⁶ The analysis used a large series of computer models, some of which exclude human influence, while others include it. The Australian heat of 2013 was so extreme that in the 12,000 simulations generated by the models that included only natural factors, in all but one simulation it lay outside the range of probabilities. Moreover, human influence tripled the odds that heatwaves that year would occur as frequently as they did, and doubled the odds that they would be as intense as they were. Our ability to link some kinds of extreme weather to climate change in this way is very new, and is likely to revolutionise our understanding of how we are influencing Earth’s climate system.

The average temperature of Earth’s lower atmosphere has risen by just under 1°C during the past 200 years. How, you might ask, can such a small average increase have a large effect on extreme weather? There are several aspects that must be considered. One is that, because around 90 per cent of the extra heat captured by greenhouse gases is transferred to the oceans, the oceans are warming dramatically. This alters evaporation, which influences the intensity of rainfall as well as the intensity of cyclones, and indeed the water cycle as a whole. But a second, more important, answer lies in the simple observation that if you plot weather for any location it looks like a bell curve. As you can see from the diagram below, you need only shift the average temperature a little to have a huge effect at the extremes. The graph, incidentally, is a realistic reflection of the extent to which climate change has shifted the average temperature at many locations in the northern hemisphere over the last half century.⁷

As the bell curve shows, we will still experience some cold days in our warmer climate. But we will get many more hot days, as well as a number of record-breaking hot days. During the summer of 2013, more than 3000 weather records were broken in the US, while 123 such records were broken in Australia (which has far fewer weather stations). In 2014 a further 156 records were broken in Australia.⁸ We’re seeing the climate change before our eyes.

So, how serious have things got with a global average of less than 1°C of warming? There’s no better place to begin investigating than heatwaves, which are defined as prolonged periods of above-average temperature at a location that last days to weeks. They are, increasingly, the most fatal of all changes flowing from the increase in average temperatures.

A well-documented heatwave experienced in Melbourne, Australia, in January 2009 shows in detail how heat affects health. After four days of high night-time as well as daytime temperatures, many people’s bodies had become overstressed and unable to shed the excess heat. Mortality records reveal that, on average, around 90 people die annually in Melbourne between January 26 and February 1. But during the heatwave of 2009, 374 ‘excess deaths’ were recorded, the great majority occurring after four days of the extreme heat.⁹ Bushfires and hurricanes might gain the headlines, but it’s easy to understand why doctors have come to dread what they call ‘the silent killer’.

Heatwaves have, of course, always occurred. The dustbowl-era American heatwave of 1936 was the hottest on record until 2012. The great Chicago heatwave of 1995, which killed about 600 people, occurred as greenhouse gas concentrations were beginning to climb, and so may have been influenced by climate change. But it was only with the arrival of the twenty-first century that our shifting climate began to influence heatwaves strongly. Humanity’s first intimation of just how great a threat to health heatwaves could become arrived in the summer of 2003. Europe’s summer that year was the hottest since records began in 1540.¹⁰ The most severe conditions were felt in France, and by August—the traditional time for summer holidays—parts of the country were sweltering in record heat. With their families at the seaside, many elderly people had little support for coping with the extreme conditions, a situation made worse by the lack of preparedness by authorities.

Because heatwaves had not been considered a major threat, many aged-care facilities lacked air conditioning. Remarkably, though, the residents of nursing homes did better than the more capable elderly living alone at home. With nobody to help them, it was the ‘fit elderly’ who experienced the worst mortality rate, succumbing to overheating, dehydration and heart and lung failure. In France, nearly 15,000 heat-related deaths resulted in a severe overload of mortuary facilities, and a refrigerated warehouse outside Paris was used as temporary storage. Across Europe, more than 70,000 people died of the heat.¹¹ At current rates of warming, by mid-century the conditions seen in the 2003 European heatwave are set to become the annual summer average.¹²

In July–August 2010, another heatwave caused an estimated 56,000 deaths, this time in western Russia. The extreme conditions were part of a larger phenomenon, the period April–June 2010 being the warmest on record for land areas in the northern hemisphere.¹³

In Australia, heatwaves are hotter, last longer and come earlier than ever before. The number of hot days (above 35°C) across the country per year has doubled in the last 50 years, and the annual number of heatwaves has doubled in Perth. In Adelaide, heatwaves last an average of two days longer than they did 50 years ago, while in Melbourne the heatwave season is starting 17 days earlier.¹⁴ In 2014, Adelaide experienced 13 days over 40°C (the average is currently two), a number expected for the average summer by 2030.

In the last few years, record-breaking heatwaves have been felt from Shanghai to Texas. In the US in 2011–2012, the number of intensive heatwaves was almost three times the long-term average, with the 2011 Texas heatwave and the 2012 heatwave in the Midwest both breaking temperature records.¹⁵ Akin in their extremity to the Russian heatwave of 2010, they give some intimation of the conditions scientists predict are likely to be felt towards the end of this century in the US if we don’t rein in emissions.¹⁶

At the same time that unprecedented heatwaves are being felt across the planet, recent winters in some densely populated areas of the northern hemisphere have been unusually cold relative to the average of the previous two decades. So what’s going on? Some scientists are investigating the possibility that the polar vortex is being weakened by the rapid warming of the poles. The polar vortex is a strong current in the atmosphere that separates the frigid air lying over the Arctic from the warmer air to the south. With a diameter of about 1000 kilometres, it is a persistent and powerful cyclone centred on the North Pole, the strength of which varies seasonally and annually, as it is influenced by many factors.

A weak polar vortex is associated with cold winters in the northern hemisphere. Like a top losing momentum, when a weakened polar vortex encounters intense low-pressure systems, it can’t push through, but instead flows around them to the north or south. In effect it develops the wobbles. When it’s diverted to the south, as during recent winters over North America, great masses of frigid air push south, while over parts of the Arctic, lobes of warm air penetrate deep over the normally frigid ice cap, melting sea ice and permafrost.

It’s easy to see how a decreasing temperature gradient can weaken a cyclone like the polar vortex, which feeds on temperature differences. But many other influences are felt on this complex and variable system, and years of study will be required before firm conclusions can be drawn. For the moment, the default position of many scientists is that the recent cold winters are just part of natural variability. Even as Earth warms, we will continue to experience some cold days and cold seasons.

As heatwaves become hotter, longer and more frequent, there’s an inevitable impact on forest fires, or bushfires as they’re known in Australia. While the relationship is not as simple as that between rising average temperatures and heatwaves, it is clear enough. Three things are necessary for a forest fire to rage—enough fuel, a source of ignition, and the right weather. Sufficient fuel exists much of the time at many locations, and sources of ignition, from dropped cigarette butts to lightning strikes, are ever present. So, as common sense suggests, the right weather conditions are the key factor in determining how severe a bushfire will become. Few places are as bushfire prone as southeastern Australia, and the most severe and damaging fire in the nation’s history provides a clear picture of how climate change is influencing fire risk.

The people of Victoria will not soon forget the conditions they awoke to on 7 February 2009. For a decade, drought had ravaged Australia, and almost no rain had fallen in Victoria in the preceding two months. A heatwave had killed hundreds in the previous week, and temperatures were predicted to peak at 47°C that afternoon. Add to that a scorching southern-hemisphere northerly wind blowing at 100 kilometres per hour, and it was clear to everyone that this would be a day of dread.

Despite all the warnings and preparations, the thousand fires that broke out that day across the state would take 173 lives, almost half of them children. Under the extreme conditions that day, fire began to behave in ways never seen before. The speed of its spread and the intensity of its impact took almost everyone by surprise. The Black Saturday fires, as they became known, were Australia’s most deadly bushfires, and among the 10 worst ever recorded worldwide. In their wake, official advice about what to do when bushfires threaten has been drastically rewritten. Before Black Saturday, official advice was often to stay and defend your property. Afterwards, officials now warn residents to evacuate as soon as the announcement is made, which is often long before a fire reaches an area.

It turns out that at almost every step along the way, climate change had some influence on the severity of the Black Saturday bushfires. In Victoria, lightning strike typically accounts for about 25 per cent of all bushfire ignitions but, because bushfires started by lightning often burn in rugged areas and are difficult to put out, such fires account for around half of all land lost to bushfires in the state. And with every degree Celsius of warming experienced, lightning activity increases 5–6 per cent.¹⁷

The amount of fuel available to a fire can be influenced by climate cycles, which themselves are affected by climate change. Extreme rainfall can promote plant growth, and a long dry spell can then cure it and make it ready for burning. But by far the greatest influence of a changing climate on bushfires are short-term weather events, such as heatwaves. As one climate scientist put it, ‘climate change is increasing the frequency and severity of very hot days and driving up the likelihood of very high fire danger’.¹⁸

In regions as diverse as Spain, Greece, areas of Africa and parts of North America, increases in the extent and intensity of forest fires have been linked to climate change.¹⁹ In Canada, for example, the area of forest burned has increased in the last four decades as summer temperatures have risen. One study estimates that the boreal forests have not burned as extensively in the last 10,000 years.²⁰ In 2014 massive wildfires burned through the Northwest Territories, scorching an area six times greater than the 25-year average, yet in line with climate projections for increasing forest fires at high latitudes.²¹ Similar increases in forest fires have been seen in Spain, where the frequency of fire has doubled and the area burned annually increased tenfold since the 1970s.²²

How might forest fires play out in future? In Australia, while the projections regarding future bushfire activity are not detailed, most analyses indicate an increase in the fire danger index as temperatures increase.²³ Another issue that is likely to have a large impact is that, as the fire season lengthens, the opportunities to control fires through hazard-reduction burning are decreasing.²⁴ This leaves communities under threat of high fuel loads in an extended fire season. Fire crews are already finding the longer fire season a challenge. A few decades back they could work together and stage their efforts to meet the fire challenge as it unfolded sequentially across the continent from north to south. Now, they scramble to meet extreme conditions that may erupt in a number of states simultaneously.

Elsewhere, future trends are clearer. Even modest warming is projected to bring substantial increases in fire activity in the Rocky Mountains. Areas that have experienced fire every 200–300 years might see it every 30 years by 2050.²⁵ In California, increases of more than 100 per cent are expected in many forested areas, with the extreme fires of May 2014 offering yet another example of how rapidly the predictions of the scientists are being fulfilled.²⁶ In Alaska and western Canada too, conditions are set to worsen from their already severe state, with the average area burned by fires projected to double by mid-century and increase fivefold by the end of the century.²⁷ The age of the mega-fire, it seems, is about to arrive, if indeed it is not already here.

All of this puts the public at heightened risk of yet another silent killer. Each year, more than 300,000 people die worldwide from inhaling smoke from forest fires.²⁸ As the fire risk grows, the threat to life will worsen. In the western US, for example, organic carbon aerosol (a component of smoke) concentrations are expected to increase by 40 per cent by 2050.²⁹ Smoke from forest fires can threaten the health of people far from the fire front. During July 2002, forest fires in Quebec resulted in an up-to 30-fold increase in airborne fine particle concentrations in Baltimore, a city nearly 1600 kilometres downwind. These fine particles are extremely harmful to human health and affect both indoor and outdoor air quality.³⁰

Human health can also be directly impacted by the burning of fossil fuels. In northern China, air pollution from the burning of fossil fuels, principally coal, is causing people to die on average 5.5 years sooner than they otherwise might.³¹ It’s not just the particles produced by burning coal that are deadly. As Earth warms, more ozone is created at ground level, and ozone, when combined with fumes from burning fossil fuels or from wildfires, creates photochemical smog. Almost anyone living in a city will be familiar with the brown haze that results, and those who are young, asthmatic, old or suffering from lung or heart disease will know firsthand of its health impacts. As Earth warms, the problem is bound to increase, and the health effects will be compounded by other factors, including allergies.³²

In North America, hayfever sufferers dread the ragweed pollen season. Courtesy of global warming, the season has increased in length by between 11 and 27 days in parts of the US and Canada. And when photochemical smog or other air pollutants are present, exposure to them can spark heightened episodes of allergic reactions and asthma.³³

The increase in heavy downpours resulting from climate change is also affecting health, through promoting an increase in the growth of mould. This compounds lung diseases, allergies and asthma. Heavy rains can also overwhelm drainage systems, causing exposure to sewerage and toxic chemicals that add to other climate-related health issues.³⁴

Diseases that are transmitted by insects are also affected by our changing climate. This is hardly surprising, as insects are exquisitely sensitive to the climate. The blacklegged tick, which carries Lyme disease, requires specific temperatures, rainfall and humidity to survive, and in North America the changing climate is delivering it a windfall. At present the tick’s range is restricted to eastern and southeastern US, but is predicted to have spread over most of the eastern half of the US and deep into eastern Canada by 2080. The only good news is that parts of Florida and the Gulf Coast will become too hot for it.³⁵ Similar trends in the spread of Lyme disease are evident in Europe, while in Australia as many as eight million people may become exposed to dengue fever by 2100 as the mosquito that carries it moves further south.³⁶

Just whose health is most at risk from such impacts has been assessed in a recent Australian report.³⁷ Those living in remote areas, including Indigenous communities, low-income earners, the elderly, children, those who work outdoors, those with existing medical conditions, and tourists (who do not appreciate how extreme local conditions can become) are all at elevated risk.

Perhaps the most surprising health impact of climate change was revealed by a study published in Nature. It documented how increasing atmospheric CO₂ was degrading the nutritional value of crops, especially in Asia. Zinc, iron and protein levels are all falling in wheat and rice, and at least two billion people depend on rice for their iron and zinc. The researchers compared the nutritional value of crops grown under varying CO₂ concentrations, and found that at concentrations of around 550 parts per million, the amount of zinc in wheat declines by 9.3 per cent, iron by 5.1 per cent and protein by 6.3 per cent.³⁸ This occurs because the increased CO₂ allows the plants to grow faster and larger than previously, but because there are no more nutrients and minerals, their concentration is reduced. Broadly similar declines were documented for rice, peas and soybeans. Lead author of the study, Samuel Myers, said that the finding was ‘possibly the most significant health threat that has been documented for climate change’.³⁹ Significantly, the article made page-one news in the China Daily. Given the Chinese government’s control of the media, the prominence granted to the story should be read as preparation for significant new measures in that country to reduce greenhouse gas emissions.

Finally, to all such impacts must be added the mental illnesses caused by stress. Losing your home to a bushfire supercharged by a warming climate is traumatic, as is being flooded out, or losing your crop. Health workers are noting an uptick in people whose mental health is being affected in many ways due to our changing climate.⁴⁰

How will health impacts play out in future? An excellent response to the question was published in 2014 by global health expert Dr Tony McMichael. He says:

Climate change over the next few decades will mainly act by exacerbating existing health problems. The greatest impacts will occur—indeed, are occurring—in populations already burdened by climate-sensitive health problems such as child diarrhoea, nutritional stunting and urban heat extremes. Human-driven warming has increased heat-related death and illness in many locations, while changes in temperature and rainfall have altered the distribution of some waterborne infectious diseases and reduced food yields in some food-insecure populations.

     These adverse health impacts will widen the existing health gap between regions and between rich and poor. Climate change, unabated, will erode development gains—an issue now of explicit concern to the World Bank and . . . the Asian Development Bank.⁴¹

Looking beyond 2050, it becomes more difficult to assess risks to human health. But one thing is clear. The impacts of increasing temperatures upon human health are not linear. In a world in which temperatures are 4°C warmer than the pre-industrial base, we are likely to see health impacts many times more severe than those which will prevail in a world 2ºC warmer.⁴² As a worst case, our current trajectory could even:

erode the essential foundations of human population health—food yields, water supplies and the constraints on infectious disease rates, population displacement, conflict and war.⁴³