Synopsis :
Unusual book
Extrait:
CHAPTER ONE
WHAT GOES UP MUST COME DOWN
Human civilization and the earth's ecological system are colliding, and the climate crisis is the most prominent, destructive, and threatening manifestation of this collision. It is often lumped together with other ecological crises, such as the destruction of ocean fisheries and coral reefs; the growing shortages of freshwater; the depletion of topsoil in many prime agricultural areas; the cutting and burning of ancient forests, including tropical and subtropical rain forests rich in species diversity; the extinction crisis; the introduction of long-lived toxic pollutants into the biosphere and the accumulation of toxic waste from chemical processing, mining, and other industrial activities; air pollution; and water pollution.
These manifestations of the violent impact human civilization has on the earth's ecosystem add up to a worldwide ecological crisis that affects and threatens the habitability of the earth. But the deterioration of our atmosphere is by far the most serious manifestation of this crisis. It is inherently global and affects every part of the earth; it is a contributing and causative factor in most of the other crises; and if it is not quickly addressed, it has the potential to end human civilization as we know it.
For all its complexity, however, its causes are breathtakingly simple and easy to understand.
All around the world, we humans are putting into the atmosphere extraordinary amounts of six different kinds of air pollution that trap heat and raise the temperature of the air, the oceans, and the surface of the earth.
These six pollutants, once emitted, travel up into the sky quickly. But all six of them eventually come back down to earth, some quickly, others very slowly. And as a result, the oft-cited aphorism "What goes up must come down" will work in our favor when we finally decide to solve the climate crisis.
Indeed, the simplicity of global warming causation points toward a solution that is equally simple, even if difficult to execute: we must sharply reduce what goes up and sharply increase what comes down. That's what this book is about.
The biggest global warming cause by far--carbon dioxide--comes primarily from the burning of coal for heat and electricity, from the burning of oil- based products (gasoline, diesel, and jet fuel) in transportation, and from the burning of coal, oil, and natural gas in industrial activity. Carbon dioxide produced in the burning of these fossil fuels accounts for the single largest amount of the air pollution responsible for the climate crisis. That is why most discussions of how to solve the climate crisis tend to focus on producing energy in ways that do not at the same time produce dangerous emissions of CO2.
At this point, however, the burning of coal, oil, and natural gas is not only the largest source of CO2 but also far and away the most rapidly increasing source of global warming pollution.
After fossil fuels, the next largest source of human-caused CO2 pollution-- almost a quarter of the total--comes from land use changes--predominantly deforestation, the burning of trees and vegetation. Since the majority of forest burning is in relatively poorer developing countries and the majority of industrial activity is in relatively wealthier developed countries, the negotiators of proposed global agreements to solve the climate crisis generally try to strike a balance between measures that sharply reduce the burning of fossil fuels on the one hand and sharply reduce deforestation on the other.
excess natural gas is flared off at a gas platform off the coast of thailand. flaring produces co2, but minimizes the release of methane, an even more potent greenhouse gas. it is wasteful not to capture the methane.
WHAT GOES UP: GREENHOUSE GASES
The pollutants that produce global warming come from many different activities, especially electricity generation, industry, agriculture, deforestation, and transportation. Carbon dioxide, the most prevalent greenhouse gas, enters the atmosphere from the processing and burning of coal (and other fossil fuels) for electricity and heat; burning forests and agricultural waste; land, air, and sea transportation; and frozen carbon just beginning to be released from the thawing of permafrost, to name just a few sources. The best scientists say we must reduce CO2 to 350 parts per million in the atmosphere. Methane, which is less abundant but has a much stronger greenhouse effect, comes from sources such as livestock, rice cultivation, decaying waste in landfills, and "fugitive emissions" from coal, oil, and gas processing. Black-carbon pollution, now believed to be an extremely important contributor to global warming, is produced by burning forests and grasslands, cooking fires, and other man-made sources. Some industries and businesses emit very powerful greenhouse gases known as halocarbons, some of which are thousands of times more powerful molecule per molecule than CO2. Industrial agriculture is also the largest source of nitrous oxide, carbon monoxide, and volatile organic com£ds (VOCs).
There's good news and bad news about CO2. Here is the good news: if we stopped producing excess CO2 tomorrow, about half of the man-made CO2 would fall out of the atmosphere (to be absorbed by the ocean and by plants and trees) within 30 years.
Here is the bad news: the remainder would fall out much more slowly, and as much as 20 percent of what we put into the atmosphere this year will remain there 1,000 years from now. And we're putting 90 million tons of CO2 into the atmosphere every single day!
The good news should encourage us to take action now, so that our children and grandchildren will have reason to thank us. Although some harmful consequences of the climate crisis are already under way, the most horrific consequences can still be avoided. The bad news should embolden us to a sense of urgency, because--to paraphrase the old Chinese proverb--a journey of a thousand years begins with a single step.
The second most powerful cause of the climate crisis is methane. Even though the volume of methane released is much smaller than the volume of CO2, over a century-long period, methane is more than 20 times as potent as CO2 in its ability to trap heat in the atmosphere--and over a 20-year period, it is about 75 times as potent.
Methane is different from CO2 in one other key respect: it is chemically active in the atmosphere. CO2, for the most part, does not interact with other molecules in the atmosphere, but methane does--and it plays a big role in its interactions with ozone, particulates, and other components of the atmosphere. Methane interacts with other chemicals in the atmosphere that break it down over a 10-to 12-year period into CO2 and water vapor, both of which trap heat, though less powerfully molecule for molecule than methane before it is broken into its component parts. The global warming effect of methane is also magnified by these interactions in ways that make it a somewhat larger cause of the problem than scientists used to believe. Overall, it is now considered to have contributed about two thirds as much to global warming as CO2.
syncrude tar sands processing plant, alberta, canada. over its life cycle, fuel made from tar sands emits much more co2 than either coal or oil. a toyota prius running on gasoline made from tar sands has the carbon footprint of a hummer.
feedlot near bakersfield, california. about half of our diet-related greenhouse gas emissions come from the production of meat.
More than half of human-caused methane releases occur in agriculture. Most of the methane from agricultural operations comes from livestock, livestock waste, and rice cultivation. And most of the remaining methane emissions come from oil and gas production, coal-mining operations, landfills, waste treatment, and fossil fuel combustion.
There is some good news about methane: since it has inherent economic value, there are powerful incentives driving efforts to capture it and prevent it from being released into the atmosphere wherever that is possible. For example, the "natural gas" that heats many homes is primarily methane, so captured methane can be put to good use. In addition, almost a quarter of the methane releases come from leaks and evaporation during the processing, transportation, handling, and use of the gas. And as a result, some of these releases may prove easier to stop.
However, there is also bad news about methane: continued warming of the frozen permafrost in the land surrounding the Arctic Ocean (and from warming seabed sediments) is beginning to release large amounts of methane into the atmosphere as the frozen structures containing it melt, and as microbes digest the thawing carbon buried in the tundra. The only practical way to prevent these releases is to slow and then halt global warming itself--while there is still time.
burning sugarcane, brazil. burning agricultural land and vegetation is a major source of black-carbon pollution and of carbon dioxide.
The third largest source of the climate crisis is black carbon, also called soot. Black carbon is different from the other air pollutants that cause global warming. First, unlike the others, it is technically not a gas but is made up of tiny carbon particles like those you can see in dirty smoke, only smaller. That is one reason it only recently became a major focus for scientists, who discovered the surprisingly large role it was playing in warming the planet. Second, unlike the other five causes of global warming, which absorb infrared heat radiated by the earth back toward space, black carbon absorbs heat from incoming sunlight. It is also the shortest lived of the six global warming culprits.
The largest source of black carbon is the burning of biomass, especially the burning of forests and grasslands, mostly to clear land for agriculture. This problem is disproportionately concentrated in three areas: Brazil, Indonesia, and Central Africa. Forest fires and seasonal burning of ground cover in Siberia and Eastern Europe also produce soot that is carried by the prevailing winds into the Arctic, where it settles on the snow and ice and has contributed greatly to the progressive disappearance of the Arctic's sea ice cover. Indeed, one estimate is that black carbon is responsible for an estimated 1°C (1.8°F) of the 2.5°C (4.5°F) of warming that has already occurred in the Arctic. Large amounts of black carbon are also produced by forest fires in North America, Australia, Southern Africa, and elsewhere. In addition to biomass burning, as much as 20 percent of the black carbon comes from the burning of wood, cow dung, and crop residues in South Asia for cooking and heating homes, and from China, where the burning of coal for home heating is also a major source.
CLEANING THE AIR AFTER THE GREAT SMOG OF 1952
Daytime air quality in London's Trafalgar Square in 1952
In December 1952, a lethal smog descended on London, immersing the city in a thick blanket of pollution for five dark days. Four thousand people died that week, and 8,000 more in the following months, from respiratory infections as well as asphyxiation.
The tragedy was the result of increased coal burning prompted by a stretch of especially cold weather. The city's million-plus coal-heated households added pollutants to the already thick industrial smog produced by local factories. Unusual weather conditions--including a temperature inversion-- kept the hugely elevated levels of black soot and tar particles close to the ground, reducing visibility and bringing the city to a virtual standstill.
After this disaster, the government took action to improve the country's air quality. In 1956, the British Parliament introduced the Clean Air Act, outlawing the burning of coal in open-hearth fires and incentivizing the replacement of coal with cleaner sources of energy, such as electricity, gas, and oil. Soon thereafter, a determined environmental movement also emerged in the United States and beyond.
Black carbon also poses a particular threat to India and China, partly because of the unusual seasonal weather pattern over the Indian subcontinent, which typically goes without much rain for six months of the year between monsoon seasons. The temperature inversion that forms over much of South Asia during that period traps the black carbon above the glaciers and snow, causing air pollution high in the Himalayas and on the Tibetan Plateau. In some of these areas, air pollution levels are now comparable to those of Los Angeles. So much black carbon settles on the ice and snow that the melting already triggered by atmospheric warming has accelerated. By some estimates, 75 percent of all Himalayan glaciers less than 15 square kilometers could disappear in as little as 10 years.
BLACK CARBON AND HIMALAYAN GLACIERS
As much as 20 percent of the black carbon in our atmosphere comes from the burning of wood, dung, and crop residues for household cooking and heating in India, and from lumps of coal burned by households in China. Between monsoons, brown clouds of pollution are trapped above the Himalayas. The black carbon falls on the glaciers, darkening their surface and causing the ice and snow to absorb sunlight instead of reflecting it, accelerating the rate of melting. Partly as a result, scientists expect many Himalayan glaciers will disappear by 2020.
AMOUNT OF BLACK CARBON IN THE ATMOSPHERE
source: New York Times, "Third-World Soot Is Target in Climate Fight," April 15, 2009
a sooty haze from man-made sources blows eastward along the himalayas in nepal, india, and bhutan.
Since half of the drinking water and agricultural water in India and much of China and Indochina comes from the seasonal melting of these same glaciers, the human consequences could soon become catastrophic. For example, 70 percent of the water flowing in the Ganges River comes from the melting of ice and snow in the Himalayas.
Black carbon is also produced by the burning of agricultural waste, such as residue from sugarcane (bagasse) and residue from corn (stover), and from burning firewood throughout the world.
More than a third of the black carbon in the atmosphere comes from the burning of fossil fuels, primarily from diesel trucks not equipped with devices to trap emissions as they exit the tailpipe. Though these devices have recently been introduced, they are not yet widely used.
It is noteworthy that so much of the black-carbon pollution comes from activities that simultaneously produce CO2, including inefficient engines for small vehicles in Asia and wasteful coal-fired power plants. But this need not be the case. For example, coal burning in industrial countries produces CO2 without producing much black carbon due to measures taken in the past several decades to make fuel combustion more efficient and to curb local air pollution.
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