THE WEATHER MAKERS
HOW MAN IS CHANGING THE CLIMATE AND WHAT IT MEANS FOR LIFE ON EARTH
TIM FLANNERY
ATLANTIC MONTHLY PRESS 2005
PART II
Chapter 6: Born in the Deep Freeze
· The ice age in which we evolved covers the last 2.4 million years. 2,000 fertile adults were all that stood between us and extinction. 13,000 years ago as the ice waned for a final time, our numbers increased rapidly, we occupied new lands and even discovered the Americas.
· Antarctic ice cores allow us to glimpse how things stood 430,000 years ago – the last time that the Milankovitch cycles brought Earth into a position similar to that which it occupies today.
· The warm (interglacial) period was exceptionally long. Warm phases – even far briefer ones than the present – were however, anomalies during the ice age. More typical are cold periods, including the so-called glacial maxima, when the grip of the ice is at its greatest. The last time this happened was between 35,000 and 20,000 years ago when the sea level was more than 300 feet lower than it is today.
· North America and Europe’s most densely inhabited landscapes lay under miles of ice. Even regions south of the ice, such as central France, were treeless subarctic deserts with a growing season of 60 days.
· Around 20,000 to 10,000 years ago the overall surface temperature of Earth warmed by 9ºF – the fastest rise recorded in recent Earth history. If we pursue business as usual, an increase of 5ºF (give or take 3ºF) over the 21st century seems inevitable. The fastest warming recorded back then was a mere 2ºF per thousand years.
· In 2000, analysis of a core from Bonaparte Gulf in Australia’s tropical northwest revealed that 19,000 years ago, over a period of just 100 to 500 years, sea levels rose abruptly by 10 to 15 yards.
· In 2004 a second study in the Irish Sea Basin showed a similar but better-dated rise. The water, it transpired, had come from the collapse of a Northern Hemisphere ice sheet, which poured somewhere between one quarter and two Sverdrups’ worth of fresh water into the north Atlantic.
· A Sverdrup is 1.3 million cubic yards of water per second per 0.4 of a square mile, disrupting the Gulf Stream.
· The Gulf Stream transports vast amounts of heat northward from near the equator – almost a third as much as the sun brings to western Europe. As it gives up its heat, the water sinks, because, being salty, it is heavier than the water around it; and this sinking draws more warm, salty water northward. If the Gulf Stream’s saltiness is diluted with fresh water, it does not sink as it cools, and no more warm water is drawn northward in its wake.
· The Gulf Stream has stopped flowing in the past. Without its heat, the melting glaciers begin to grow again, and, as their white surface reflects the sun’s heat back to space, the land cools. Animals and plants migrate or die, and temperate regions such as central France are plunged into a Siberian chill.
· Heat pools around the equator and in the Southern Hemisphere, the Gulf Stream is established once more and the world enters another cycle of warming.
· About 2 Sverdrups of fresh water is required to significantly slow the Gulf Stream, and that happened repeatedly between 20,000 and 8,000 years ago.
· A well-documented sudden freeze began 12,700 years ago after warming caused the collapse of a massive ice-dammed lake of meltwater. The big freeze lasted for 1,000 years, and much of Europe was plunged into full ice age conditions, leaving many parts of the continent uninhabitable. A further cooling event occurred 8,200 years ago, and this one caused temperatures over Greenland to drop around 9ºF for 200 years.
· Climatic madness gave way to serene calm. All over the world people who had been living hand to mouth began to grow crops, domesticate animals, and live in settled towns.
Chapter 7: Making the Long Summer
· The long summer that has been the last 8,000 years is without doubt the crucial event in human history. Before our long summer was 5,000 years old, cities had sprung up in western Asia, East Asia, Africa, and Central America.
· Just how extraordinary is the cosmic fluke that created a period of warmth and stability of unprecedented length becomes apparent when we compare the previous four warm periods where we see not stability but a long, unsteady cooling until a point is reached where Earth plunges into another frigid spell.
· Nobel Laureate Paul Crutzen marked the dawn of the Anthropocene at AD 1800 when the Industrial Revolution first began to influence Earth’s climate.
· Bill Ruddiman argues that wet agriculture, such as rice paddies, tipped the balance. Over the last 8,000 years atmospheric carbon dioxide rose from around 160 ppm to its preindustrial high of 280 ppm, due to cutting and burning forests.
· The shift in the Earth’s orbit between 10,000 and 4,000 BC brought 7% to 8% more sunlight to the Northern Hemisphere, enhancing the rainfall of Mesopotamia by 25% to 30%. What was once desert was transformed into a verdant plain that supported dense farming communities.
· After 3800 BC, Earth’s orbit reverted to its former pattern and rainfall dropped off, forcing many farmers to abandon their fields and wander in search of food. By 3100 BC Mesopotamia’s southern cities, a key human adaptation to drier climatic conditions, had become the world’s first civilizations.
· Ruddiman sees a clear correlation with times of low atmospheric carbon dioxide and plagues such as the black plague of medieval times, which were global in their reach and killed so many people that forests were able to grow back on deserted farmland, lowering atmospheric carbon dioxide concentrations by 5 to 10 ppm. Global temperatures then fell, and periods of relative cold ensured in places such as Europe.
· Ruddiman’s thesis implies that, by adding sufficient greenhouse gases to keep earth ‘just right’ to delay another ice age yet not overheating the planet, the ancients performed an act of chemical wizardry.
· But it was a damn close thing. Haloes of dead lichen around Baffin Island’s ice caps tell of stillborn ice ages, because what killed these growths was an accumulation of snow that, even a century ago had conditions been fractionally cooler, would have turned to ice and begun the slide into a frigid world.
· Had the snow not melted, much of the interior of northeast Canada today would host a cloak of ice that each year would grow farther southward.
· The new ice core from Dome C challenges Ruddiman’s theory because it reveals that although our current interglacial is different from the past four, it is similar in some ways to the fifth before our own which occurred around 430,000 years ago.
· Then the confluence of Milankovich’s cycles and levels of carbon dioxide was similar to the present, and the warm spell was exceptionally long – 26,000 years, as opposed to 12,000 for the others.
· Today there are unmistakable signs that the Anthropocene is turning ugly. So great are the changes scientists are detecting in our atmosphere that time’s gates appear once again to be opening. Will the Anthropocene become the shortest geological period on record?
Chapter 8: Digging Up the Dead
· When we burn wood, we release carbon that has been out of atmospheric circulation for a few decades; when we burn fossil fuels we release carbon that has been out of circulation for eons.
· In 2002, the burning of fossil fuels released a total of 23 billion tons of CO2 into the atmosphere. Of this, coal contributed 41%, oil 39%, and gas 20%. The efficiency with which power is generated by burning a fuel is an important factor in determining how much CO2 is produced.
· Coal is our planet’s most abundant and widely distributed fossil fuel. Brown coal is the most polluting of all fuels. 249 coal-fired power plants are projected to be built worldwide between 1999 and 2009, 483 in the decade to 2019, and 710 between 2020 and 2030.
· By the beginning of the 21st century gas had surplanted coal in importance, and, if current trends continue, by 2025 it will have overtaken oil as the world’s most important fuel source.
· The 20th century opened on a world that was home to little more than a billion people and closed on a world of 6 billion, and every one of those 6 billion is using on average four times as much energy as their forefathers did 100 years before. The burning of fossil fuels has increased sixteenfold over that period.
· In 1961 there was still room to maneuver. There were just 3 billion people and they were using only half of the total resources that our global ecosystem could sustainably provide.
· In 1986 we reached a watershed when our population topped 5 billion and we were using all earth’s sustainable production. Ever since 1986 we have been running the environmental equivalent of a deficit budget, which is sustained by plundering our capital base.
· By 2001 humanity’s deficit had ballooned to 20%, and our population to over 6 billion. By 2050, when the population is expected to level out at around 9 billion, we will be using – if they can still be found – nearly two planet’s worth of resources.
· Most of the increase in the burning of fossil fuels has occurred over the last few decades, and nine out of the ten warmest years ever recorded have occurred since 1990.
PART 2: ONE IN TEN THOUSAND
Chapter 9: The Unraveling World
· Global warming changes climate in jerks, during which climate patterns jump from one stable state to another. The best analogy is that of a finger on a light switch. Nothing happens for a while, but if you slowly increase the pressure, a certain point is reached, a sudden change occurs, and conditions swiftly alter from one state to another.
· Climatologist Julia Cole refers to the leaps made by climate as “magic gates,” and she argues that since temperatures began rising rapidly in the 1970s, our planet has seen two such events – in 1976 and 1998.
· The 1976 magic gate originated on the coral atoll of Maiana in the Pacific nation of Kiribati, where El Niňos are first detected, and manifested as a sudden and sustained increase in sea surface temperature of 1°F, and a decline in the ocean’s salinity of 0.8%.
· Between 1945 and 1955, the temperature of the surface of the tropical Pacific commonly dipped below 66.5°F, but after the magic gate opened in 1976, it has rarely been below 77°F.
· The western tropical Pacific is the warmest area in the global ocean and is a great regulator of climate, for among other things it controls most tropical precipitation and the position of the jet stream, whose winds bring snow and rain to North America.
· The 1998 magic gate is also tied up with the El Niño-La Niña cycle, a two- to eight-year-long cycle that brings extreme climatic events to much of the world.
· During the La Niña phase, winds blow westward across the Pacific, accumulating the warm surface water off the coast of Australia and the islands lying to its north. With the warm surface waters blown westward, the cold Humboldt Current is able to surface off the Pacific coast of South America, carrying with it nutrients that feed the most prolific fishery in the world, the anchovetta.
· The El Niño part of the cycle begins with a weakening of topical winds, allowing the warm surface water to flow back eastward, overwhelming the Humboldt and releasing humidity into the atmosphere, which brings floods to the normally arid Peruvian deserts.
· Cooler water then upwells in the far western Pacific, and as it does not evaporate as readily as warm water, drought strikes Australia and Southeast Asia.
· When an El Niño is extreme enough, it can afflict two thirds of the globe with droughts, floods, and other extreme weather. The 1997-98 El Niño was the year the world caught fire. Drought had a stranglehold on a large part of the planet, and fires burned on every continent.
· In the normally wet rain forests of Southeast Asia the conflagrations reached their peak, with 25 million acres burning. Many of the burned forests will never recover on a time scale meaningful to human beings.
· The 1998 event released enough energy to “spike” the global temperature by around 0.5°F. Some of the changes spawned were permanent, for ever since then, the waters of the central western Pacific have frequently reached 86°F, while the jet stream has shifted toward the North Pole. The new climatic regime also seems prone to generating more extreme El Niños.
· Parmesan and Yohe found that since 1950, around the globe there has been a poleward shift in species’ distribution of around 4 miles per decade, a retreat up mountainsides of 20 feet per decade, and an advance of spring activity of 2.3 days per decade.
Chapter 10: Peril at the Poles
· Dr. Angus Atkinson and his colleagues examined records of krill catches from the fishing fleets of nine countries working in the southwest Atlantic sector of the Southern Ocean. The subantarctic seas are some of the richest on Earth and 60% to 70% of the krill reside there.
· While there was variation year to year for the period 1926-39, no overall upward or downward trend in abundance was evident. The Krill population was stable.
· A very different pattern was seen in the years following 1976. Ever since that date, the krill have been in sharp decline, reducing at the rate of nearly 40% per decade.
· With satellite coverage since the 1980s, annual changes in sea ice volume can be estimated. The extent of ice was stable from 1840 to 1950 but has decreased sharply since then.
· The northern boundary of the ice has shifted southward from 59.3°S to 60.8°S, corresponding to a 20% decrease in sea ice extent. The reduction in krill numbers coincided so closely with the reduction of sea ice over time as to leave little doubt that climate change is a profound threat to the world’s most productive ocean, and to the largest creatures that exist and feed there.
· The Arctic is almost a mirror image of the south. While the Antarctic is a frozen continent surrounded by an immensely rich ocean, the Arctic is a frozen ocean entirely surrounded by land. It is also home to 4 million people.
· In places such as southern Alaska, winters are 4°F to 5°F warmer than they were 30 years ago.
· A run of mild winters in recent years has seen the numbers of spruce bark beetle rage out of control. Over the past 15 years it has killed some 40 million trees in southern Alaska, more than any other insect in North America’s recorded history. The spruce budworm is another threat to the trees, with female budworms laying 50% more eggs at 77°F than at 59°F.
· The plight of the harp seals living in the Gulf of St. Lawrence gives a clear idea of the shape of things to come. They can raise no pups when there is little or no sea ice present – which happened to them in 1967, 1981, 2000, 2001, and 2002. When a run of ice-free years exceeds the reproductive life of a female – perhaps a dozen years at most – the population will become extinct.
· The great bears are slowly starving as each winter becomes warmer than the one before. They are already 15% skinnier than they were a few decades ago.
· The changes we’re witnessing at the Poles are of the runaway type. Scientists estimate that any gain by encroaching forests taking in CO2 will be more than offset by the loss of albedo, for a dark forest absorbs far more sunlight, and thus captures more heat, than does snow-covered tundra.
· The overall impact of foresting the world’s northern regions will thus be to heat our planet ever more swiftly, and, once this has happened, no matter what humanity does about its emissions, it will be too late for a reversal.