At least 22 people were killed and more than 270 injured when the southern city of Kaohsiung, Taiwan’s second largest, was rocked by blasts that sent flames surging into the streets.
HONG KONG — Under pressure to reduce smog and greenhouse gas emissions, the Chinese government is considering a mandatory cap on coal use, the main source of carbon pollution from fossil fuels. But it would be an adjustable ceiling that would allow coal consumption to grow for years, and policy makers are at odds on how long the nation’s emissions will rise.
Senior officials are debating these issues as they formulate a new five-year development plan, to be finalized by the end of next year. China emits more carbon dioxide than any other country, so what President Xi Jinping and his colleagues decide will have far-reaching consequences for efforts to contain climate change.
China’s leaders have not detailed their views on coal or carbon emission limits. But there is robust support among senior policy advisers for a firm national cap on coal starting in 2016, Wang Yi, a professor at the Chinese Academy of Sciences in Beijing who studies environmental policy, said in a telephone interview.
Photo
A tourist wore a face mask in Tiananmen Square in February as heavy air pollution shrouded Beijing.CreditMark Ralston/Agence France-Presse — Getty Images
“I think there’s a broad consensus on this, and it’s a question of how to implement it,” said Professor Wang, who is a senior member of China’s legislature, the National People’s Congress. “If we can have a cap on coal, that would almost be equivalent to a cap on carbon, because coal is such a dominant source of pollution and emissions.”
Professor Wang and others say a coal ceiling would be easier to enforce than a cap on carbon emissions from all fossil fuels, which some expertshave proposed. China accounts for half of global coal consumption.
The coal cap would be stricter than current limits, which are not mandatory and are only loosely enforced. But it would be pegged to expected economic growth and energy demand, so coal use could keep rising for years.
Chinese policy advisers remain divided about how quickly the country should move to cut coal consumption. Some officials fear stricter limits would drag down the economy. They cite the prospect of mine closings, job losses and energy shortfalls if alternative sources of energy, such as nuclear, hydroelectric and solar power, fail to deliver in time.
“The main difficulty is the time it takes to develop the substitutes for coal, and the uncertainties of bringing them online,” said Lin Boqiang, director of the China Center for Energy Economics Research at Xiamen University in eastern China. “The government is now more focused on cleaning up smog, but if the economy falters, then it’s possible the government’s focus could shift back to economic growth.”
Strict limits are also likely to face opposition from the powerful coal industry and allied officials, said Ailun Yang, a senior associate at the World Resources Institute in Washington who works on emissions and energy policy in China. Growth in coal use has slowed markedly in the past couple of years, but the China National Coal Association said last year that it expected the country to consume 4.8 billion metric tons annually by 2020.
“The real debate is about how to engage the big state-owned fossil-fuel companies, and also the big provinces whose economies are very, very dependent on these industries,” Ms. Yang said.
On the other side, some economists argue that bold efforts to reduce coal consumption would be an economic and environmental boon in the long term by encouraging new, clean modes of growth.
And, experts say, there is new pressure on the government from rising domestic anger over smog. Coal burned in power plants, boilers and furnaces is a main source of the grimy pollution that swamps Beijing and other cities, and many steps to cut smog would also cut carbon emissions.
“The whole air pollution situation has changed the debate dramatically,” Ms. Yang said. “There’s a lot more political space to argue for control measures.”
A dozen provinces and major cities, including Beijing and Shanghai, have already set firm limits on coal use or goals to reduce consumption.
Yet the most worrisome new threat to China’s carbon-cutting efforts could come from coal gasification plants, which officials have promoted as a way to reduce particulate air pollution, said Barbara A. Finamore, the Asia director at the Natural Resources Defense Council.
Those plants can feed gas to big cities, cutting coal demand in those cities, but producing the gas emits large quantities of carbon dioxide. A report issued by Greenpeace East Asia this week said local governments in China had proposed 48 such plants, in addition to two already running.
“Without a national cap, there is a real danger that coal production and air pollution will simply move to other parts of China,” Ms. Finamore said.
China’s National Energy Administration called this year for research proposals for “caps for total energy and coal consumption for 2020, and a practical path for implementing caps on energy and coal consumption.”
A recent study that Professor Wang oversaw at the Chinese Academy of Sciences proposed that China aim for coal consumption to peak in 2025 around 4.5 billion metric tons. But other Chinese and foreign researchers say an earlier peak at a lower level is feasible and necessary.
Han Wenke, director general of the state Energy Research Institute in Beijing, has urged China to start cutting coal consumption around 2020. China’s “actual consumption of coal is already very close to four billion tons, which is at the limits of endurance for the domestic environment,” he wrote in a recent paper.
A parallel debate is whether China should set a date for a peak in its carbon emissions, and if so, what that date should be. Other governments have pressed China to set a date so they can better map out how global greenhouse gas levels could rise.
So far, the Chinese government has resisted doing so, partly out of fear that a deadline could become hostage to onerous international demands. But China’s chief climate talks negotiator, Xie Zhenhua, said this month that the government could “propose a peak year for carbon emissions” in the first half of 2015, reported Xinhua, the official Chinese news agency.
Governments negotiating a new climate change treaty have agreed to propose national contributions to emissions reduction as part of efforts to reach an agreement in Paris next year. Previous efforts have foundered in part because China and other large developing countries have refused to accept calls from rich nations to take on binding emission targets.
China has been the world’s biggest emitter of carbon dioxide from fossil fuels since around 2006, when it passed the United States, and most research indicates that its emissions are likely to keep rising for at least another decade, driven by industrialization, rising affluence and the growth of cities.
Just how long they will rise is a question that divides experts, even those close to the government.
“There is major controversy,” Pan Jiahua, an expert on global warming and greenhouse gas policy at the Chinese Academy of Social Sciences in Beijing, said in a telephone interview. “I’m personally more optimistic and believe that 2025 is a viable time for a carbon emissions peak, but others think that’s unrealistic and say we have to wait until 2030 or later.”
At international talks in Copenhagen in 2009, governments agreed to try to hold greenhouse gas concentrations below levels likely to cause the average global temperature to rise 3.6 degrees Fahrenheit above the preindustrial average during this century.
Virtually no country is acting fast enough to be on track to reach that target. Even if advanced countries do far more to cut carbon emissions, China’s must peak by the mid-2020s to keep hope alive for the Copenhagen goal, said Niklas Höhne, director of energy and climate policy at Ecofys, a consulting company. He and others said China could do that by around 2025, given the right industry, taxation and consumption policies.
“If a coal cap can help us reach a peak in coal in 2020, we can be confident that the CO2 peak will be about 2025,” said Yang Fuqiang, a former energy researcher for the Chinese government and now a senior adviser for the Natural Resources Defense Council in Beijing, referring to carbon dioxide.
But several experts at Chinese government institutes said it would be too economically perilous to peak so soon, and two recent Chinese studies have said that any attempt to do so before 2030 would be impractical.
“If you wanted a peak right now, China could do it by stopping economic growth,” said Professor Wang of the Chinese Academy of Sciences. “But the price would be that the ordinary people would go out onto the streets.”
紐約大學醫學院(New York University School of Medicine)傳染病專家、 人類微生物組計劃(Human Microbiome Program)負責人馬丁·J·布拉澤(Martin J. Blaser)博士在過去30多年間，一直研究細菌在疾病中發揮的作用。除傳染病外，他的研究範圍還囊括了自體免疫疾病，以及其他在世界範圍內急劇增加的疾病。
We may think of ourselves as just human, but we’re really a mass of microorganisms housed in a human shell. Every person alive is host to about 100 trillion bacterial cells. They outnumber human cells 10 to one and account for 99.9 percent of the unique genes in the body.
Katrina Ray, a senior editor of Nature Reviews, recently suggested that the vast number of microbes in the gut could be considered a “human microbial ‘organ’” and asked, “Are we more microbe than man?”
Our collection of microbiota, known as the microbiome, is the human equivalent of an environmental ecosystem. Although the bacteria together weigh a mere three pounds, their composition determines much about how the body functions and, alas, sometimes malfunctions.
Like ecosystems the world over, the human microbiome is losing its diversity, to the potential detriment of the health of those it inhabits.
Dr. Martin J. Blaser, a specialist in infectious diseases at the New York University School of Medicine and the director of the Human Microbiome Program, has studied the role of bacteria in disease for more than three decades. His research extends well beyond infectious diseases to autoimmune conditions and other ailments that have been increasing sharply worldwide.
In his new book, “Missing Microbes,” Dr. Blaser links the declining variety within the microbiome to our increased susceptibility to serious, often chronic conditions, from allergies and celiac disease to Type 1 diabetes and obesity. He and others primarily blame antibiotics for the connection.
The damaging effect of antibiotics on microbial diversity starts early, Dr. Blaser said. The average American child is given nearly three courses of antibiotics in the first two years of life, and eight more during the next eight years. Even a short course of antibiotics like the widely prescribed Z-pack (azithromycin, taken for five days), can result in long-term shifts in the body’s microbial environment.
But antibiotics are not the only way the balance within us can be disrupted. Cesarean deliveries, which have soared in recent decades, encourage the growth of microbes from the mother’s skin, instead of from the birth canal, in the baby’s gut, Dr. Blaser said in an interview.
This change in microbiota can reshape an infant’s metabolism and immune system. A recent review of 15 studies involving 163,796 births found that, compared with babies delivered vaginally, those born by cesarean section were 26 percent more likely to be overweight and 22 percent more likely to be obese as adults.
The placenta has a microbiome of its own, researchers have discovered, which may also contribute to the infant’s gut health and help mitigate the microbial losses caused by cesarean sections.
Other studies have found major differences in the microorganisms living in the guts of normal-weight and obese individuals. Although such studies cannot tell which came first — the weight problem or the changed microbiota — studies indicate obese mice have gut bacteria that are better able to extract calories from food.
Further evidence of a link to obesity comes from farm animals. About three-fourths of the antibiotics sold in the United States are used in livestock. These antibiotics change the animals’ microbiota, hastening their growth.
When mice are given the same antibiotics used on livestock, the metabolism of their liver changes, stimulating an increase in body fat, Dr. Blaser said.
Even more serious is the increasing number of serious disorders now linked to a distortion in the microbial balance in the human gut. They include several that are becoming more common in developed countries: gastrointestinal ailments like Crohn’s disease, ulcerative colitis and celiac disease; cardiovascular disease; nonalcoholic fatty liver disease; digestive disorders like chronic reflux; autoimmune diseases like multiple sclerosis and rheumatoid arthritis; and asthma and allergies.
Some researchers have even speculated that disruptions of gut microbiota play a role in celiac disease and the resulting explosion in demand for gluten-free foods even among people without this disease. In a mouse model of Type 1 diabetes, treating the animals with antibiotics accelerates the development of the disease, Dr. Blaser said.
He and other researchers, including a team from Switzerland and Germany, have also linked the serious rise in asthma rates to the “rapid disappearance of Helicobacter pylori, a bacterial pathogen that persistently colonizes the human stomach, from Western societies.” Once, virtually everyone harbored this microbe, which European researchers have shown protected mice from developing hallmarks of allergic asthma.
H. pylori colonization in early life encourages production of regulatory T-cells in the blood, which Dr. Blaser said are needed to tamp down allergic responses. Although certain strains of H. pylori are linked to the development of peptic ulcer and stomach cancer, other strains are protective, his studies indicate.
Still, it is not always possible for researchers to tell whether disruptions in gut microbiota occur before or after people become ill. However, studies in laboratory animals often suggest the bacterial disturbances come first.
Dr. Blaser, among many others, cautions against the overuse of antibiotics, especially the broad-spectrum drugs now commonly prescribed. He emphasized in particular the importance of using fewer antibiotics in children.
“In Sweden, antibiotic use is 40 percent of ours at any age, with no increase in disease,” he said. “We need to educate physicians and parents that antibiotics have costs. We need improved diagnostics. Is the infection caused by a virus or bacteria, and if bacteria, which one?
“Then we need narrow-spectrum antibiotics designed to knock out the pathogenic bacteria without disrupting the health-promoting ones,” Dr. Blaser added. “This will make it possible to treat serious infections with less collateral effect.”
