2010 Diary week 36
Global warming, climate change and weather extremes
Book Review
Below is the review of Part IV of With Speed and Violence: Why Scientists Fear Tipping Points in Climate Change by Fred Pearce. These are some snippets: “Reason to fear truly does lurk in the frozen bogs of western Siberia. There, beneath a largely uninhabited wasteland of permafrost, lies what might reasonably be described as nature’s own doomsday device, primed to be triggered by global warming. That device consists of thick layers of frozen peat containing tens of billions of tons of carbon.” “The entire western Siberia peat bog covers approaching 400,000 square miles – an area as big as France and Germany combined. In fetid swamps and lakes devoid of oxygen, that will produce methane. Methane is a powerful and fast-acting greenhouse gas, potentially a hundred times more potent than carbon dioxide.” “Released quickly enough in such quantities it would create an atmospheric tsunami, swamping the planet in warmth. But we have to change tense here. For ‘would create,’ read ‘is creating.’” “I went to northern Sweden to visit what is almost certainly the longest continually monitored Arctic peat bog in the world. The lake freezes a month later than it did only a couple of decades ago.” “The average annual temperature here over the past century has been 30.7°F, but in recent years it has sometimes crept above 32°.” “’The bog is changing very fast,’ said Torben Christensen. Below our feet, the permafrost was still as deep as 30 feet, but a step away it was gone.” “Half the bog permafrost in the north of Finland has disappeared since 1975. The rest will be gone by 2030.” “As temperatures rise, methane emissions grow exponentially.” The highest emissions are in western Siberia and Alaska, where big temperature rises are taking place.”
WITH SPEED AND VIOLENCE
WHY SCIENTISTS FEAR TIPPING POINTS IN CLIMATE CHANGE
FRED PEARCE
BEACON PRESS 2007
PART IV
Chapter 14: The Doomsday Device. A lethal secret stirs in the permafrost
• Reason to fear truly does lurk in the frozen bogs of western Siberia. There, beneath a largely uninhabited wasteland of permafrost, lies what might reasonably be described as nature’s own doomsday device, primed to be triggered by global warming. That device consists of thick layers of frozen peat containing tens of billions of tons of carbon.
• The entire western Siberia peat bog covers approaching 400,000 square miles – an area as big as France and Germany combined. In fetid swamps and lakes devoid of oxygen, that will produce methane. Methane is a powerful and fast-acting greenhouse gas, potentially a hundred times more potent than carbon dioxide.
• Released quickly enough in such quantities it would create an atmospheric tsunami, swamping the planet in warmth. But we have to change tense here. For “would create,” read “is creating.”
• One degree of global warming could unleash enough methane to raise temperatures several more degrees.
• I went to northern Sweden to visit what is almost certainly the longest continually monitored Arctic peat bog in the world. The lake freezes a month later than it did only a couple of decades ago.
• The average annual temperature here over the past century has been 30.7°F, but in recent years it has sometimes crept above 32°.
• “The bog is changing very fast,” said Torben Christensen. Below our feet, the permafrost was still as deep as 30 feet, but a step away it was gone.
• Half the bog permafrost in the north of Finland has disappeared since 1975. The rest will be gone by 2030.
• “As temperatures rise, methane emissions grow exponentially.” The highest emissions are in western Siberia and Alaska, where big temperature rises are taking place.
• Current emissions of methane are probably still below 50 million tons a year. But that is still the warming equivalent of more than a billion tons of carbon dioxide.
• With lakes forming everywhere, and climate models predicting that 90% of the Arctic permafrost will have melted to a depth of at least 3 yards by 2012, there is “alarming potential for positive feedback to climate from methane,” says Christensen
Chapter 15: The Acid Bath. What carbon dioxide does to the oceans
• The oceans are the ultimate sink for most of the heat from the sun and also for most of the greenhouse gases we are pouring into the atmosphere. At any one time, there is 50 times as much carbon dioxide dissolved in ocean waters as there is in the atmosphere.
• Currently the oceans absorb in excess of 2 billion tons more a year than they release. Much of that surplus finds its way to the ocean floor after being absorbed by growing marine organisms.
• Ocean surfaces absorb more carbon dioxide when the waters are cold. Warmer oceans are likely to release large amounts of carbon dioxide into the air. It would take only a very small change to turn the oceans from a carbon sink into a potentially very large carbon source.
• Since the beginning of the Industrial Revolution, the oceans have absorbed about 130 billion tons of carbon resulting from human activities. While much of it has fallen to the seabed, a considerable amount remains dissolved in ocean waters – with a singular and rather remarkable effect: it is making the oceans more acid.
• The carbonic acid produced by dissolving carbon dioxide is corrosive and especially damaging to organisms that need calcium carbonate for their shells or skeletons.
• Acidity, measured as the amount of hydrogen ions in the water, is already up by 30%. To put it another way, the pH has dropped by 0.1 points, from 8.2 to 8.1.
• Experiments are only getting under way, but one set of results is already in. James Orr of the Laboratoire des Sciences du Climate et de l’Environment put tiny sea snails called pteropods into an aquarium and exposed them to the kind of ocean chemistry expected later in this century.
• As well as being a major source of food for everything from fish to whales, pteropods are the biggest players in the biological pump there. Orr found that within hours, the acid pitted the pteropods’ shells. Within two days, the shells began to peel, exposing the soft flesh beneath. In the real world, predators would break through the weakened shells.
• We are seeing the start of an unexpected and frightening side effect of rising carbon dioxide levels.
Chapter 16: The Winds of Change. Tsunamis, megafarts, and mountains of the deep
• It was Earth’s biggest fart ever. 55 million years ago, more than a trillion tons of methane burst from the ocean, sending temperatures soaring by up to 18°F extinguishing two thirds of the species in the ocean depths, and causing a major evolutionary shock at the surface.
• The first whiff of this prehistoric megafart was unearthed in 1991, from a hole drilled about a mile into a submarine ridge just off Antarctica. This was clearly a global event – one of the largest extinctions in the history of the planet.
• There was a sudden change in the ratio of two oxygen types, known as oxygen-18 and oxygen-16 and also of isotopes of carbon. Earth’s organic matter suddenly contained a lot more carbon-12.
• There was only one source big enough and accessible enough to unleash a climatic eruption. Jerry Dickens, a biochemist at James Cook University, in Townsville, Australia, suggested that it had to be the vast stores of methane frozen in sediment beneath the oceans: methane clathrates.
• Methane clathrates are generally close to the surface of the ocean floor but frozen by high pressure and low temperatures, in a lattice of ice crystals rather like a honeycomb.
• They seem to arise when cold ocean water meets methane created by microbes living beneath the seabed.
• Dickens estimates that between 1 and 10 trillion tons of methane is tied up today in or beneath clathrates. Release the pressure or raise the temperature, and the lattices will shatter, pouring methane up through the sediment into the ocean and finally into the atmosphere.
• Deborah Thomas, of the University of North Carolina has analysed the event in detail. The oceans today may still be cooler than they were 55 million years ago, but they are warming faster. “The trigger on the clathrate gun will be a lot touchier than it was 55 million years ago.”
PART IV. REFLECTING ON WARMING
Chapter 17: What’s Watts? Planet Earth’s energy imbalance
• Jim Hansen says the sunlight reaching the face of Earth in recent centuries has been about 240 watts for every 10.8 square feet. Earth’s temperature is whatever is required to send back into space the same amount of energy that the planet absorbs.
• Thanks to our addition of greenhouse gases to the atmosphere, the planet is suffering what Hansen calls “a large and growing energy imbalance that has no known precedent.” The planet is warming, but it has not yet reached a new equilibrium.
• The net warming effect of man-made pollutants is about 1.8 watts per 10.8 square feet. Most of this goes into heating either the lower atmosphere or the oceans, but some provides the energy to melt ice.
• The critical term here is “albedo,” the measure of the reflectivity of the planet’s surface. On average, the planet’s albedo is 30% – which means that 30% of the sunlight reaching the surface is reflected back into space, and 70% is absorbed.
• In the Arctic, the albedo can rise above 90%, while over cloudless oceans, it can be less than 20%.
• According to the albedo expert Veerabhadran Ramanathan, of the Scripps Institution of Oceanography, if the planet’s albedo dropped by just a tenth from today’s level, to 27%, the effect would be comparable to a fivefold increase in atmospheric concentrations of carbon dioxide.
• Around the Arctic spring is coming earlier. Such is the power of the warming feedbacks that it is coming with ever-greater speed.
• As lakes crack open, rivers reawaken, and the ice and snow disappear, the landscape is suddenly able to trap heat.
• The “cold trap” of reflective white ice is sprung, and temperatures can rise by 18°F in a single day.
Chapter 18: Clouds From Both Sides. Uncovering flaws in the climate models
• The occasion was a workshop on climate change at the Hadley Centre for Climate Prediction, held in Exeter in mid-2004. If carbon dioxide in the atmosphere doubled from its pre-industrial levels, as James Murphy’s graph suggested, global warming would rise far above the widely accepted prediction of 2.7 to 8.1°F or even higher. It showed a very real chance that warming from a doubling of carbon dioxide would reach 10, 14, 18, or even 21°F.
• Carbon dioxide is widely expected to reach double its pre-industrial levels within a century if we carry on burning coal and oil in the business-as-usual scenario. But nobody has seriously tried to work out what 18 degrees of extra warming would mean for the planet or for human civilization. It would certainly be cataclysmic.
• The meeting also saw a projection by David Stainforth, of Oxford University, that suggested a plausible warming of 21°F.
• Unless the editors take fright, these figures will probably become part of the official wisdom, incorporated into the next report of the IPCC.
• Clouds, which have always been one of the weakest links in the models, are even more of a wild card than anyone had imagined. It is far from clear whether more clouds would damp down the greenhouse effect, as previously thought, or intensify it.
• The three biggest feedbacks in the climate models are ice, water vapor, and clouds. We have already looked at the effect of melting ice on the planet’s albedo. It explains why the Arctic is warming faster than elsewhere and giving an extra push to global warming.
• Water vapor, like carbon dioxide, is a potent greenhouse gas, without which our planet would freeze. A warmer world will certainly evaporate more water from soils and oceans, and this process is already increasing the amount of water vapor in the atmosphere, amplifying warming.
• A lot of water vapor in the air eventually forms clouds, whose temperature effects depend on their height, depth, color, and density, because different clouds have different optical properties.
• To make his graph, Murphy took a standard climate model and tweaked it to reflect the new range of uncertainties for cloud cover, lifetime, and thickness. His model responded by delivering much higher probabilities of greater-than-expected warming.
• Planet Earth is also becoming hazier as pollution spreads from the Northern Hemisphere and much of Asia, blotting out the sun. While some parts of the world are seeing temperatures soar, some of the world’s most densely populated countries have seen temperatures drop.
• Since the fall of the Berlin Wall, central Europe’s polluting heavy industries have mostly shut down and the air has cleared. More sun penetrates and central Europe has warmed correspondingly. In the past 15 years, temperatures there have risen at three times the global average rate.
Chapter 19: A Billion Fires. How brown haze could turn off the monsoon
• In India’s million villages, where most of its billion-strong population still live, the air is often scarcely better than it is in the cities, with smoke billowing from a hundred million cooking stoves, all burning wood, dried cow dung, and crop residues.
• This smoke is becoming a major climatic problem. It is merging into one giant cloud called India’s “brown haze” – a giant version of the old pea-soup smog that used to hit London in the days when the city was heated by coal fires.
• Delhi’s air is reportedly worse than ever, with thick smog preventing flights from its airport.
• In 1999 measurements were taken of the air over India and the Indian Ocean. Every winter, from November to April, a pall of smoke more than a mile thick covers 4 million square miles, an area 7 times the size of India.
• The cooling impact of the haze over the Indian land surface delays the heating of the land that stimulates the monsoon winds. It thus threatens the lifeblood of India: the monsoon rains. The country is entirely dependent on just 100 days of monsoon rains to water crops that feed a billion people.
• East Asia could be in the same boat – a situation that would threaten food production for the world’s most populous nation, China.
• When Yun Qian and Dale Kaiser, of the U.S. Government’s Northwest National Laboratory studied the records of Chinese meteorological sunshine recorders over the past 50 years, they found a decline in sunshine since 1980 of 5% to 6% in the most polluted south and east of the country.
• While global warming is evident across much of China, daytime temperatures in the most polluted regions has fallen by about 1°F. That in turn is altering rainfall patterns.
• In the south of the country, the monsoon rains are becoming stronger, with flooding in the great southern river, the Yangtze; whereas farther north, in the catchment of the Yellow River, there is now less rainfall.
• Chinese records, which are among the most meticulous in the world, suggest that this shift is the biggest alteration in the country’s rainfall patterns in a thousand years.
• Asian countries, with their huge populations, have the worst smog. But parts of Africa and the Brazilian Amazon are also shrouded when farmers clear land for crops by burning grasslands and forests. In Zambia, studies have found a 22% drop in sunlight as the savannah is burned.
• Modeling studies supervised by Jim Hansen suggest that soot emissions over India and China may trigger drought in the African Sahel and even warming in western Canada.
• Cooking stoves in India, it seems, could have global consequences.
Chapter 20: Hydroxyl Holiday. The day the planet’s cleaner didn’t show up for work
• Just one chemical – hydroxyl – is responsible for cleaning most of the pollution out of the atmosphere.
• Concentrations of hydroxyl are generally much higher in the warm air over the tropics, where ultraviolet radiation is most intense, but are close to nonexistent in the Arctic, where, despite ozone holes, there is usually little ultraviolet light to make more hydroxyl.
• Toxic chemicals that might survive for only a few days in the tropics will last for a year or more in Arctic air.
• It is virtually impossible to measure hydroxyl levels directly and suggestions that levels might be declining because of excess demands placed on it by rising tide of pollution have been rejected.
• Many urban areas are already sufficiently polluted that hydroxyl levels are locally suppressed; the volume of pollution consumes all the available hydroxyl and smog prevents ultraviolet radiation creating more.
• The oxidation processes that should clean the air virtually shut down in smog-bound cities like Athens and Mexico City and it takes a breath of fresh air from the countryside to revive them.
• If, in the future, large parts of the atmosphere are as polluted as these cities are today, then we could anticipate the collapse of hydroxyl on a global scale.
• If we repair the ozone layer, we will reduce hydroxyl production to the levels of the mid-twentieth century, at a time when the demands on hydroxyl’s services are considerably higher. That could be the moment when a threshold is crossed and oxidation processes go into sharp decline.
• I have no data, no models, and no peer-reviewed papers to justify this scenario. It is just that: a scenario and not a prediction. But it is plausible speculation. It could conceivably happen.