Meltdown

By Bill McGuire

Even as thousands of XR foot soldiers bring London to a halt in the name of climate change sanity, the bad news keeps rolling in. The latest despatches from the climate breakdown front point to the last days of the world’s mountain glaciers and the marvellous ecosystems they support. In an earlier post (Asia – Climate Breakdown’s New Front Line), I revealed how the loss of Himalayan glaciers and ice fields feeding Asia’s mighty rivers could lead to widespread famine as they shrink to little more than trickles. Now, it appears, glaciers in western Europe look likely to suffer the same fate. Hardly surprising really, but nonetheless another nail in the coffin of our stable, pre-climate-breakdown world.

What makes the picture painted by the new study (Modelling the future evolution of glaciers in the European Alps under the EURO-CORDEX RCM ensemble) especially bleak, is that even if we act to drastically curtail greenhouse gas emissions, most of the ice locked up in the world’s mountains will not survive until the end of the century. Given a business as usual scenario, the European Alps will be effectively ice-free by 2100; the winter sports business a distant memory. But even if emissions are slashed, two thirds of the ice will still have melted away in a little over eight decades time. Even more dramatically, whatever action we take on the emissions reduction front fully half of the ice locked up in the four thousand or so Alpine glaciers will be gone within barely thirty years.

A second study (Key indicators of Arctic climate change: 1971–2017) for the first time draws together information from both physical and biological systems to show how rising air temperatures are fundamentally transforming the Arctic and the life it supports as the Earth continues to heat up. As the landmark study reveals, the Arctic region’s long stable climate is now following a path into the unknown. The consequences of this are likely to be widespread and catastrophic, not only for the region itself, but also across the world. What happens in the icy wastes of the north is already affecting the climate at more temperate latitudes, such as Europe and North America. Here, the knock-on effects of changes in airflow at high latitudes are driving persistent weather patterns in both winter and summer that result in extreme weather; big freezes and baking heatwaves. Rapid ice melting in the Arctic is also affecting the Gulf Stream and associated ocean currents and has the potential to bring them to a halt or at least precipitate a major slow down. This, in turn, threatens colder winters around the North Atlantic rim along with rapidly rising sea levels along the eastern seaboard of North America.

So, a message to our XR heroes in the London campaign and those bringing the truth about climate breakdown to cities all over the world. Hang on in there. Our planet needs you now more than ever.

Hothouse Earth, Here We Come

By Bill McGuire

More evidence has come to light to support the thesis that we are on a warming trajectory that will leave our planet unrecognisable from the one upon which human civilisation developed and thrived. Scientists congregated, this week, at Imperial College London for a Royal Meteorological Society meeting, which focused on the Earth’s climate during the Pliocene era, around three million years ago (the last time the Earth had >400ppm of atmospheric CO2). This is the last time that carbon dioxide levels were above 400ppm (parts per million). They are currently 412ppm; up from around 280ppm during pre-industrial times and climbing at two or three ppm a year.

The papers presented at the meeting transport us to a world that is similar to our own in the sense that carbon dioxide levels are comparable, but there the similarity ends. During the Pliocene, global average temperatures were 3°C – 4°C higher than they are today; a seemingly small difference, but big enough to drive changes that make Pliocene Earth dramatically different from that of the 21st century.

Evidence from plant fossils found in Antarctica show that during this part of the Pliocene, beech trees – and maybe conifers – grew on the continent, which had a drastically reduced ice cover surrounded by scrubby tundra. Summertime temperatures were around 5°C compared with minus 15°C – 20°C today. At the other end of the world, Greenland was completely ice-free. The vanished ice at both poles translates into global sea levels that are around 20m higher than they are today.

So, forget the widely touted idea that we can keep the global average temperature rise below 1.5°C or 2°C. It is now clear that the atmospheric carbon levels we have already are compatible – in the longer term – with temperatures 3°C – 4°C higher than they are now. The climate system is relatively slow to respond to change, so it will take some time for temperatures to catch up with greenhouse gas levels. But catch up they will, almost certainly by the end of the century. In other words, whatever actions we take to reduce emissions, we cannot avoid a hothouse planet scenario that will see our society torn apart by a combination of extreme heat, wild weather and catastrophically rising sea levels. And remember, there is still no sign of rising greenhouse levels being brought under control. Given current inaction, carbon dioxide concentrations in the atmosphere could quite feasibly top 500ppm and keep going, dragging global temperatures ever higher.

I hope to God that it never happens, but it is worth keeping in mind that burning most fossil fuel reserves is projected to lead – ultimately – to a global average temperature rise of a staggering 16°C. This would bring the mean temperature of our world to a furnace-like 30°C. This would likely – to all intents and purposes – be an extinction-level event as far as the human race is concerned. Some might say, quite justifiably in view of our appallingly bad stewardship of the planet, good riddance too!

Bill McGuire is Professor Emeritus of Geophysical & Climate Hazards at UCL and author of Waking the Giant: How a Changing Climate Triggers Earthquakes, Tsunamis and Volcanic Eruptions. He was a contributor to the IPCC 2012 report on Climate Change & Extreme Events and Disasters.

Burning coal, oil and gas may cause sudden, extreme climate change

By Zeeshan Hasan

It is scientifically established that our burning of fossil fuels and the resultant carbon dioxide emissions will result in global warming, and ultimately may cause dangerous climate change. But how fast can that happen? The Two-Mile Time Machine: Ice Cores, Abrupt Climate Change And Our Future by climatologist Richard B. Alley, explores climate scientists’ answers to these questions. The author is Professor of Geo-sciences at the Pennsylvania State University in the USA.

Alley is one of the climate scientists who has spent years collecting and analysing ice cores; these are long samples of ancient ice which have been extracted from the two mile thick Greenland ice cap. This massive layer of ice has been forming for over 100,000 years, and is an repository of historical evidence to climate scientists. The snow deposited each year is still visible as layers in the ice, and these annual layers preserve much chemical information from which scientists can extract a record of past snowfall and temperature. Of particular importance is what the ice cores have revealed of the end of the “Younger Dryas” ice age.

‘At the beginning of this book, we met the Younger Dryas, the last cold gasp of the ice age between about 12,800 and 11,500 years ago… Standing in the science trench in Greenland, I measured how thick the annual layers were in the [ice] core across the end of the Younger Dryas. I found that… many thick layers were followed by one slightly thinner layer, one scarcely more than half as thick, one scarcely more than half as thick, another slightly thinner than that, then a lot of similarly thin ones grouped around a spike of thicker ones. This is most directly explained as a twofold change in three years, with most of that change in one year… So I cannot insist that the climate changed in one year, but it certainly looks that way.’ (pages 110-111).

So science tells us that very significant climate change can occur in just a handful of years. Similar warming may well be in store for us, given that our carbon emissions are changing the atmosphere far more rapidly than any natural process has in the past. Alley proceeds to give details of the sudden, extreme temperature change that occurred at the end of Younger Dryas ice age:

The most direct interpretation… is that the surface of Greenland warmed by about 15 F (8 degrees Celsius) in a decade or less. (page 112)

This should frighten us. This sort of warming today would mean the end of the world as we know it. Climatologists estimate global warming of 5 to 6 degrees Celsius today would render most of the world too hot for agriculture (except a narrow northern band comprising Canada, northern Europe, Russia and Siberia). Widespread famine, starvation and war would be the norm. The vast majority of humanity would almost certainly perish.

Alley’s conclusions regarding the climate change which ended the Younger Dryas ice age should serve as a wake-up call. The reason that no action has been taken by governments to reduce carbon dioxide emissions and stop global warming is that climate change is assumed to be something that will happen very slowly, and thus only impact the distant future. However, this assumption is questionable given the findings of the 2018 UN IPCC report, which said that there was only 12 years left to drastically reduce fossil fuel use to prevent global warming of more than 1.5C. The scientific record of the Greenland ice cores shows that when climate change does occur, it can be both quick and extreme. In that case it is not just nameless future generations that our carbon emissions endanger. Rather, our addiction to fossil fuels like oil, coal and gas may well sacrifice the lives of our own children and grandchildren. All of us who wish for a better future than this need to start lobbying our governments and continuously demanding that elected officials quickly replace fossil fuels with solar and wind power.

An Alarmist’s Guide To Climate Change

By Bill McGuire

First posted on Scientists for Global Responsibility

Have you noticed how the term ‘alarmist’ has been high-jacked? In the context of climate breakdown, habitat and wildlife loss and other environmental issues, it has become synonymous with scaremongering; with the voice of doom. In certain circles it is frowned upon and judged to be a hindrance to getting the global heating argument across. Iconic broadcaster David Attenborough is the latest to express the view that ‘alarmism’ in the context of the environment can be a ‘turn-off’ rather than a call to action. But are such viewpoints justified, especially when our world and our society teeter on the edge of catastrophe? After all, the simplest, most straightforward, meaning of an ‘alarmist’ is someone who raises the alarm. Is this not what we need now more than ever; to be told the whole story – warts and all? The alternative, it seems to me, is to play down the seriousness of our predicament; to send a message that is incomplete, and to conveniently avoid or marginalise predictions and forecasts that paint a picture regarded as too bleak for general consumption. Surely, this is the last thing we need at this critical time?

No-one could ever accuse the IPCC (Inter-governmental Panel on Climate Change) of being alarmist. Because every sentence of IPCC report drafts is pored over by representatives of national governments – some of whom are luke-warm or even antagonistic to the whole idea of climate change – the final versions are inevitably conservative. The closest the IPCC has come to sounding an alarm bell can be found in its latest report Global Warming of 1.5ºC, published last month. Here it warns that emissions must be slashed within 12 years (by 2030) if there is to be any chance whatsoever of keeping the global average temperature rise (since pre-industrial times) below 1.5ºC, and fall to zero by 2050.

Notwithstanding the unlikelihood of achieving net zero global emissions in a little more than three decades, the pace and degree of climate change are about more than just anthropogenic emissions. They are also influenced by tipping points and positive feedback loops; sudden changes in the behaviour of ice sheets, carbon sources and sinks, and ocean currents, which can accelerate warming and its consequences way beyond the expected. Depressingly, but perhaps not surprisingly, the latest IPCC report’s Summary for Policymakers1 – let’s face it, the only bit likely to be read by the movers and shakers – includes just one brief mention of feedbacks and has nothing at all to say about tipping points. The justification for this appears to be that because it is not possible to assign levels of confidence to such known unknowns, they cannot be included. But it is difficult not to conclude that the real reason is to tone down the threat in order to appease those governments that view climate change as a nuisance that they would like to go away.

The decision to bury concerns over tipping points and feedbacks in the depths of the full report rather than flagging them in the Summary is nonsensical. Touting the critical importance of drastic action while at the same time soft peddling the threat has the potential to backfire, providing the obvious get out: well, if the situation is not so bad, maybe the response doesn’t need to be that urgent. If drastic, life-changing, action is being mooted, people need to know – have a right to know – why. They need to be presented with a complete picture showing how bad things might get – however scary or poorly constrained.

Bringing the potential consequences of tipping points and feedbacks into the equation inevitably transforms perceptions of the dangers we face. Suddenly, climate change ceases to be something vaguely inconvenient that we can leave future generations to deal with. Instead, it becomes far more of an immediate threat capable of tearing our world apart. Take sea level, for example. The IPCC’s 5th Assessment Report, published in 2013 and 2014, predicts – for a worst case scenario – that global mean sea level could be about a metre higher by the end of the century. Bad enough for millions of coastal dwellers, but nothing compared to what our descendants might experience if a tipping point is crossed that sees the Greenland and/or West Antarctic ice sheets start to disintegrate in earnest. Models that incorporate this point to sea level rising far more rapidly. One suggests that the ice loss in Antarctica could occur at a much faster rate than expected, leading to global average sea level being more than 3 metres higher at the end of the century (Le Bars, D. et al. 2017 A high-end sea-level rise probabilistic projection including rapid Antarctic Ice Sheet mass loss. Environmental Research Letters 12). Another, based upon correlations between temperature and sea levels during the last interglacial, which ended around 115,000 years ago, proposes that sea level – in theory at least – could climb by as much as 5m by 2100 (Hansen, J. et al. 2016 Ice melt, sea level rise and superstorms: evidence from paleoclimate data, climate modeling, and modern observations that 2 °C global warming could be dangerous. Atmos. Chem. Phys., 16, 3761-3812).

Worrying evidence that we might be at a tipping point in Antarctica comes from a very recent study on the rate of ice loss from 2012 to 2017. During this five-year period, Antarctic ice loss shot up threefold, from 76 billion tonnes annually, to a colossal 219 billion tonnes (The IMBIE Team 2018 Mass balance of the Antarctic Ice Sheet 1992 – 2017. Nature, 558, 219-222). In total, more than 2.7 trillion tonnes of Antarctic ice has melted in the last quarter century, adding three quarters of a centimetre to global sea level. At the new rate, the contribution over the next 25 years would be 1.5cm. Not enough to worry about in its own right. If, however, the rate of increase is maintained over this period, then the annual rise by 2043 would be close to a catastrophic five centimetres a year. And this is without the growing contribution from Greenland and from the increasing expansion of sea water as the oceans warm.

And there are other causes for serious concern too. None more so than the behaviour of the Gulf Stream and associated currents (together making up the AMOC – Atlantic Meridional Overturning Circulation) that warm north-west Europe and also have a big influence on global weather patterns. In the distant past, surges of meltwater from shrinking ice sheets have caused the Gulf Stream to shut down. Now, it looks as if it might be in danger of doing so again as huge volumes of freshwater from the crumbling Greenland Ice Sheet pour into the North Atlantic, forming a so-called ‘cold blob’. The IPCC’s official line is that another complete shutdown is ‘very unlikely’, but this is not the same as ruling it out. And there are certainly some worrying signs. The Gulf Stream has slowed by 15 – 20 percent since the middle of the 20th century and is now at its weakest for at least 1600 years (Caesar, L. et al. 2018 Observed fingerprint of a weakening Atlantic Ocean overturning circulation. Nature 556, 191 – 196). The Gulf Stream has a tipping point, and – evidence from the past shows – can shut down in just a few years when this is crossed. The problem is that no-one knows when – or even if – this will happen. If it does, the ramifications will be sudden and widespread. The North Atlantic region will cool dramatically, particularly across the UK, Iceland and North West Europe, while sea ice will expand southwards. Sea-levels along the eastern seaboard of North America could rise at three to four times the global average rate. Further afield, changes to weather patterns are forecast to include a weakening of Indian and east Asian monsoons, which could have devastating consequences for crop yields. No-one is saying that the Gulf Stream is in imminent danger of collapse. Nonetheless, the threat is not insignificant, and as such should be soberly touted, not wilfully ignored.

Of the many and varied feedback loops and tipping points linked with rapid anthropogenic warming, perhaps the most disquieting involves the vast tracts of permafrost at high latitudes – both on land and beneath the sea. Trapped beneath this frozen crust are colossal quantities of methane, a greenhouse gas that has a warming effect 86 times greater than carbon dioxide. Fortunately, methane has a relatively short residence time in the atmosphere and breaks down to carbon dioxide within a few decades. Nonetheless, major outbursts of methane from the rapidly thawing permafrost are capable of causing climate mayhem with little or no warning. The geographic region of most concern is probably the submarine permafrost that floors the East Siberian Continental Shelf, where an estimated 1400 billion tonnes of carbon, in the form of methane, is lurking beneath a frozen carapace that is thawing rapidly. According to Natalia Shakhova and colleagues (Shakhova N. E. 2008 Anomalies of methane in the atmosphere over the East Siberian shelf. Geophysical Research Abstracts10, EGU2008-A-01526. Abstract), as much as 50 billion tonnes of this is available for sudden release at any time, which would – at a stroke – hike the methane content of the atmosphere 12 times. According to a study published in 2013 (Whiteman, G., Hope, C. and Peter Wadhams. 2013 Vast costs of Arctic change. Nature499, 401–403), a discrete methane ‘burp’ on this scale, could advance global warming by 30 years and cost the global economy USD60 trillion – a figure close to four times the US national debt. Once again, the occurrence of such an outburst is far from a certainty and there are other issues to consider, including how much methane is absorbed by the ocean as it bubbles upwards. Notwithstanding this, there is a potential danger here that needs to be promulgated rather than hidden away, so that the scale of the climate change threat is clear to everyone.

So – to conclude – be alarmed; be very alarmed. But don’t let alarm feed inertia. Use it instead to galvanise action. For your children’s and their children’s sake, stand up and do something about it. Drastically change your life style; become an activist; vote into power a government that will walk the walk on climate change, not just talk the talk. Or – preferably – all three.

The science of global warming

By Zeeshan Hasan
Unfortunately, many people still doubt the dangers of global warming and climate change. In particular, elected politicians intent on avoiding unpopular carbon taxes and higher fuel prices continue to assert that the relevant scientific issues are doubtful. The fact is that the non-scientist public has been deceived by a large number of books and newspaper articles by ‘skeptics’ of climate change who themselves often have no understanding of the science involved. Fortunately, a glimpse into the real world of climate science is available through Global Warming: Understanding The Forecast by David Archer, an ocean chemistry professor at the University of Chicago. Archer’s book is an introductory climate science text which aims to make the basics of climate science comprehensible to any one with a high school background in science.
The basic science of how carbon dioxide emissions raise global temperatures is outlined by Archer. On the one hand, the earth is constantly being heated by sunlight. On the other hand, the Earth is also cooled by loss of heat into space as infrared radiation. These two continuous mechanisms of heat gain and heat loss by the Earth result in a thermal equilibrium at the average global temperatures which we experience.
Heat gain from the sun is relatively constant, varying only slowly over time; however, heat loss into space has been reduced significantly by humans over the last century. Atmospheric ‘greenhouse gases’ such as carbon dioxide have the property of absorbing the infrared radiation which carries heat from the earth into space, and thus reduce the cooling of the earth. This effect of carbon dioxide is called the Greenhouse effect; it was discovered over a century ago and is undisputed. Since the Industrial Revolution, humans have been continuously burning fossil fuels such as coal, oil and gas, and thus adding huge amounts of carbon dioxide to the atmosphere. This has resulted in an increase of the carbon dioxide concentration in the atmosphere from 320 parts per million in 1960 to about 400 parts per million today, or about 20%. This additional carbon dioxide functions like a blanket or greenhouse around the planet, slowing down loss of heat into space. If the same amount of solar heat comes into the Earth, while simultaneously heat loss from the Earth to space is reduced by additional carbon dioxide, then the Earth has to get warmer. At a higher temperature the Earth’s heat loss by radiation into space increases, because hotter objects lose more heat through infrared radiation than cooler ones; and the planet once more reaches a stable temperature.
A good analogy to the above is a pot of food simmering on an oven above a low flame; putting the lid on the pot does not change heat gain from the oven, but reduces heat loss through evaporation from the open pot and thus makes the food cook at a higher temperature. Our carbon dioxide emissions are effectively putting a lid on the earth, making heat from the sun ‘cook’ the planet at a higher temperature.
The question is whether a hotter stable temperature of the globe would be one capable of sustaining human life as we know it. Climate scientists have evidence from ancient ocean sediments that increasing the level of greenhouses gases in the atmosphere can cause temperatures to rise. Such an event took place 55 million years ago, when thousands of billions of tons of greenhouses gases were released into the atmosphere (probably because of a peak in volcanic activity). This event is known as the Permian Eocene Thermal Maximum (PETM). During the PETM, global average temperature rose by about 5 degrees C and 90% of life on the planet perished. Such an increase in global average temperature today would have terrible consequences, rendering much of tropical and sub-tropical Asia, Africa, central America and southern Europe too hot and dry for agriculture. The consequences would be famine on a scale never seen before, and billions of deaths.
Dangerous global heating events like the PETM may seem distant and irrelevant. But as a comparison, burning all world’s known reserves of coal would release about 5000 billion tons of carbon dioxide, comparable to the surge in greenhouse gases which caused the PETM. Our current course is to exploit not only existing coal reserves but also oil and gas. So it is entirely within our power to destroy our planet.
Continuing our current policies of exploiting all fossil fuels available will literally ensure the end of the Earth as we know it. The only way to stop it is to keep fossil fuels in the ground and switch to solar, wind or nuclear power, none of which emit carbon dioxide. This will require worldwide imposition of carbon taxes to raise fuel prices and make investment in alternative energy feasible. The leaders of all countries need to make some hard decisions, which they have failed to do in 20 years of climate negotiations. They will only do so now if the public demands it of them. The public now needs to make their voices heard loudly and persistently to force politicians to reduce fossil fuel use.

WILDFIRES UPON THE DEEP

Bill McGuire

Another week – another bombshell; this time exploding out of the world’s oceans. Covering more than seventy percent of our world’s surface, the oceans form an integral part of the climate system, interacting in many and complex ways with the atmosphere and cryosphere (polar ice). Because they are so closely aligned with the atmosphere they are also intimately linked to climate breakdown and increasingly impacted by it.

More than anything else, as the world has warmed, the oceans have protected us from overwhelming heat that would – by now – have otherwise likely wiped us out. The results of a study published in January reveal that, over the last 150 years, the oceans have absorbed a staggering 90 percent of the heat arising from increasing concentrations of greenhouse gases in the atmosphere. This is the equivalent of the energy produced by between around 1.5 Hiroshima-sized atomic bombs exploding every second over the entire period. Impressive enough; recently, however, the rate of heating has climbed to the energy equivalent of between three and six Hiroshima detonations a second. Another way of looking at it, is that over the last century and a half, the oceans have taken up about one thousand times the annual energy use of global society.

The huge quantities of heat sucked up by the oceans leave just a few percent to heat the land, atmosphere and ice caps – which is very lucky for us. The bad news is that the warmer oceans are starting to drive more powerful, and potentially more destructive, hurricanes and typhoons. Furthermore, ocean heating also drives rising sea levels as the warmer waters expand.

Another study, the results of which were published just this week paints a terrifying picture of the devastating impact of ocean heating on marine life. The authors of this latest study describe ocean heatwaves spreading like the wildfires that, on land, take out vast tracts of bush. In the oceans, instead, great swathes of coral reef, seagrass meadow and kelp forest are being wiped out – along with the sea-life that depends and thrives upon them. Following a similar trend to heatwaves on land, ocean heatwaves have tripled in frequency in just the last couple of decades, raising huge concerns about the survival of marine ecosystems as further heating occurs. Fish stocks, in particular, already seem to be suffering, with global stocks down by at least four percent since 1930, and by as much as 35 percent in some parts of the world.

The bottom line is that, while the oceans are shielding us from the worst of the heating caused by human activities, they can’t continue to do this forever. In addition, as they absorb more and more heat, so the life they contain is coming under increasing pressure. If we continue with business as usual, we will be left with oceans hugely depleted of life, and menus from which fish are permanently excluded. Yet another reason – as if we need one – for net zero emissions by 2025. Let’s do it.

Bill McGuire is Professor Emeritus of Geophysical & Climate Hazards at UCL and author of Waking the Giant: How a Changing Climate Triggers Earthquakes, Tsunamis and Volcanic Eruptions. He was a contributor to the IPCC 2012 report on Climate Change & Extreme Events and Disasters.

Global warming and mass extinction of life on Earth

By Zeeshan Hasan

underagreensky

Climate change is usually pictured in terms of rising sea levels and increased storm and drought; but science has revealed that it bears further threats. These previously unknown dangers of climate change are the focus of Peter D. Ward’s book, “Under a Green Sky: Global warming, the mass extinctions of the past, and what they can tell us about our future”. Ward is a professor of biology and earth and space sciences at the University of Washington at Seattle, and also works at Nasa. He is one of the biologists whose analysis of the fossil record has helped scientists understand what caused the numerous mass extinctions that have occurred during the history of life on earth.

The most famous of earlier mass extinctions was the one which wiped out the dinosaurs; thirty years ago, scientists confirmed it was the result of an asteroid hitting the earth. Following that great discovery, scientists for years assumed that all the other mass extinctions were similarly the result of asteroid impacts. However, geologists were ultimately unable to find any evidence for those supposed asteroids. Apparently, the extinction of the dinosaurs was unique, and a different explanation was necessary for the remaining mass extinctions. This was ultimately found to be global warming due to excess carbon dioxide in the atmosphere. It turns out that large quantities of carbon dioxide can be released by volcanic activity; this is especially likely in major tectonic events such as when the Indian subcontinent collided with Eurasia (creating the Himalayas).

Ward’s book investigates the mechanism by which global warming caused mass extinctions such as the end-Permian extinction event, which destroyed 95% of life on earth 250 million years ago. Scientists have found that most mass extinctions were marked by the release of huge amounts of hydrogen sulphide gas, which is the smelly, poisonous gas released by rotten eggs. The hydrogen sulphide would have been created by an oxygen-free “Canfield ocean” (named after the scientist who discovered it), a condition similar to that which now exists in the Black Sea. Canfield oceans occur when global warming melts too much polar ice, releasing so much cold water that the normal ocean currents which circulate water from deep to shallow and keep the oceans oxygen-rich are disrupted. Once this happens, the oxygen-breathing fish and other sea creatures quickly consume all the oxygen left in the water and then suffocate. The remaining oxygen-free water can sustain only anaerobic purple bacteria which require no oxygen to live; by filling up the ocean, these bacteria would also turn the ocean purple.

Anaerobic purple bacteria in a Canfield ocean produce massive quantities of hydrogen sulphide gas, which then bubbles to the surface and poisons animals on land. Hydrogen sulphide also damages the ozone layer, exposing the remaining animals and plants to deadly levels of ultraviolet rays from the sun (as a minor side effect, hydrogen sulphide from a Canfield ocean would also turn the sky green; hence the title of the book). Thus global warming has caused mass extinctions on both land and sea which can only be described as apocalyptic.

How far away is this? We don’t know exactly how much polar ice has to melt to create a Canfield ocean and another mass extinction, but we do know the following:
“Using [current carbon dioxide emission] rates, which work out to about 120 parts per million per century, we might expect carbon dioxide levels to hit 500 to 600 parts per million by the year 2100. That would be the same carbon dioxide levels that were most recently present sometime in the past 40 million years — or more relevant, it would be equivalent to times when there was little or no ice even at the poles.” (Pages 164-5)

In other words, by the year 2100, within two or three generations, carbon dioxide levels will be high enough to virtually ensure another polar melt. This could possibly set into motion a Canfield ocean and mass extinction which humanity may not survive.

Our only chance to avoid this apocalyptic future is to stop using fossil fuels like coal, petroleum and gas, and replace them completely within a few decades with nuclear, wind and solar. This is the only way to prevent further polar ice melting and a Canfield ocean-created mass extinction. Unfortunately politicians and the public are in a state of scientific ignorance and denial of climate change. Anyone who cares about the survival of humanity beyond the next century needs to take action to stir the public from it’s state of inertia.