碳阻迹
2020-05 07
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Carbon footprint hotspots: Mapping China's export-driven emissions

Date:2020-05

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The coronavirus pandemic has highlighted just how reliant the United States and other countries are on Chinese manufacturing, with widespread shortages of protective medical gear produced there. But U.S. dependence on China extends far beyond surgical masks and N95 respirators. China is the largest producer of many industrial and consumer products shipped worldwide, and about one-quarter of the country's gross domestic product comes from exports. It is also the world's largest emitter of climate-altering carbon dioxide gas, generated by the burning of fossil fuels. A new study details the links between China's exports and its emissions by mapping the in-country sources of carbon dioxide emissions tied to products consumed overseas. University of Michigan researchers and their Chinese collaborators tracked these emissions to a small number of coastal manufacturing hubs and showed that about 1% of the country's land area is responsible for 75% of the export-linked CO2 emissions. The study, scheduled for publication May 7 in Nature Communications, provides the most detailed mapping of China's export-driven CO2 emissions to date, according to corresponding author Shen Qu of the U-M School for Environment and Sustainability. The findings, which are based on 2012 emissions data, offer insights that can guide policymakers, he said. "Developing localized climate mitigation strategies requires an understanding of how global consumption drives local carbon dioxide emissions with a fine spatial resolution," said Qu, a Dow Sustainability Postdoctoral Fellow at SEAS who combines the tools of input-output analysis and network analysis to uncover the role of international trade in global environmental impacts. "The carbon footprint hotspots identified in this study are the key places to focus on collaborative mitigation efforts between China and the downstream parties that drive those emissions," he said. The study found that the manufacturing hubs responsible for most of the foreign-linked emissions are in the Yangtze River Delta (including Shanghai, China's top CO2-emitting city), the Pearl River Delta (including Dongguan) and the North China Plain (including Tianjin). These cities have, or are close to, ports for maritime shipping. The modeling study uses data from large-scale emissions inventories derived from 2012 surveys of individual firms in all Chinese industries that generate carbon dioxide emissions. Emissions levels have likely changed in response to recent U.S.-China trade disputes and the COVID-19 pandemic, which has significantly impacted Chinese manufacturing and exports. Chinese CO2 emissions driven by foreign consumption totaled 1.466 megatons in 2012, accounting for 14.6% of the country's industrial-related carbon dioxide emissions that year. If the Chinese manufacturing hubs identified in the U-M study constituted a separate country, their CO2 emissions in 2012 would have ranked fifth in the world behind China, the United States, India and Russia, according to the authors. The study also found that: Exports to the United States, Hong Kong and Japan were responsible for the biggest chunks of Chinese foreign-linked CO2 emissions, contributing about 23%, 10.8% and 9%, respectively. About 49% of the U.S.-linked CO2 emissions were driven by the production of consumer goods for the household. About 42% of the export-driven CO2 emissions in China are tied to electricity generation, with notable hotspots in the cities of Shanghai, Ningbo, Suzhou (Jiangsu Province) and Xuzhou. Much of that electricity is produced at coal-fired power plants. China is the world's largest steel producer and exporter. Cities that manufacture large amounts of iron and steel—and that use large amounts of coal in the process—were hotspots for export-driven CO2 emissions. Cement plants and petroleum refineries were also big contributors. In the study, U-M researchers and their collaborators used carbon footprint accounting—i.e., consumption-based accounting—to track greenhouse gas emissions driven by global supply chains. They mapped those emissions at a spatial resolution of 10 kilometers by 10 kilometers, a level of detail that enabled them to identify specific source cities. "Previous studies have linked greenhouse gas emissions to final consumption of products, but primarily at national or regional levels," said study co-author Ming Xu of the U-M School for Environment and Sustainability and the Department of Civil and Environmental Engineering. "Given the increasing importance of non-state actors—provinces, states, cities and companies—in climate mitigation, it becomes increasingly important to be able to explicitly link the final consumers of products to the subnational actors that have direct control over greenhouse gas emissions." Source: phys.org Author: University of Michigan Date: MAY 7, 2020

2020-04 30
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Transition to low-carbon energy may accelerate after crisis: Shell

Date:2020-04

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LONDON (Reuters) - The ongoing transition to low-carbon energy sources may accelerate as economies recover from the impact of the coronavirus crisis, the head of oil and gas company Royal Dutch Shell said on Thursday. Chief Executive Ben van Beurden said while Shell was not ringfencing its low-carbon Integrated Gas and New Energies division from spending cuts to weather the crisis, those businesses would be shielded from the worst of the reductions. “Where possible, we try to spare (New Energies) a little bit and that is basically because we still believe that there is an energy transition underway which may even pick up speed in the recovery phase of this crisis and we want to be well positioned for it,” he said after Shell announced first-quarter results. Under pressure from a slide in oil prices, Shell slashed its dividend by two-thirds on Thursday having already announced a $5 billion cut to its 2020 investment budget to $20 billion last month. About 45% of the spending cuts will hit Shell’s upstream - or exploration and production - business, with 30% for downstream which includes the refining and marketing of oil products, van Beurden said. He said the other 25% in cuts would come from Integrated Gas and New Energies but added that the crisis would not distract the company from its shift to low-carbon energy as it braces for a complete overhaul over the next 30 years. The head of the world’s energy watchdog, Fatih Birol, told Reuters this week that global efforts to minimise the fallout from the pandemic presented an historic opportunity to scale up the technologies needed to move to cleaner energy. The European Union, meanwhile, is working on a revised work plan for its climate policies because of the crisis which is set to include new, more ambitious targets for 2030, according to a draft seen by Reuters. Shell’s low-carbon energy division, which includes wind and solar energy and retail power distribution, was due to receive investment of up to $2 billion in 2020 and then up to $3 billion a year thereafter. Chief Financial Officer Jessica Uhl said the fundamental outlook for Shell’s focus on shifting from liquid fuels to generating and distributing electricity had not changed. “Companies growing low-carbon businesses should eventually be rewarded by the market, and ultimately we see this as the most likely way for Shell to rebuild its ambition to be a world- class investment case over the longer term,” Barclays equities analysts said in a note. Source:REUTERS Author: Shadia Nasralla, Ron Bousso Date:APRIL 30, 2020

2020-04 09
View 98
Long-living tropical trees play outsized role in carbon storage

Date:2020-04

View:09

A group of trees that grow fast, live long lives and reproduce slowly account for the bulk of the biomass -- and carbon storage -- in some tropical rainforests, a team of scientists says in a paper published this week in the journal Science. The finding that these trees, called long-lived pioneers, play a much larger role in carbon storage than previously thought may have implications in efforts to preserve forests as a strategy to fight climate change. "People have been arguing about whether these long-lived pioneers contribute much to carbon storage over the long term," said Caroline Farrior, an assistant professor of integrative biology at The University of Texas at Austin and a primary investigator on the study. "We were surprised to find that they do." It is unclear the extent to which tropical rainforests can help soak up excess carbon dioxide in the atmosphere produced by burning fossil fuels. Nonetheless, the new study provides insights about the role of different species of trees in carbon storage. Using more than 30 years' worth of data collected from a tropical rainforest in Panama, the team has uncovered some key traits of trees that, when integrated into computer models related to climate change, will improve the models' accuracy. With the team's improved model, the scientists plan to begin answering questions about what drives forest composition over time and what factors affect carbon storage. Most existing Earth system models used to forecast global climate decades from now, including those used by the Intergovernmental Panel on Climate Change, represent the trees in a forest as all basically the same. "This analysis shows that that is not good enough for tropical forests and provides a way forward," Farrior said. "We show that the variation in tropical forest species's growth, survival and reproduction is important for predicting forest carbon storage." The project was led by Nadja Rüger, research fellow at the German Centre for Integrative Biodiversity Research (iDiv), Halle-Jena-Leipzig. In addition to the finding about long-lived pioneers, the team found the composition of a tropical forest over time depends on how each tree species balances two different sets of trade-offs: growth versus survival (for example, one type of tree might grow fast but die young) and stature versus reproduction (another might grow tall but reproduce leisurely). Plotting every species as a point on a graph based on where they fall along these two different axes allowed the scientists to have a more sophisticated and accurate model than prior ones, which usually focused exclusively on the first of these two trade-offs or parametrized the groups by different means. "To really appreciate that there is this second trade-off between stature and reproduction, and that it's important in old-growth forests, is a big deal biologically," Farrior said. The team also discovered that the nearly 300 unique tree species that live on Barro Colorado Island, which sits in the middle of the Panama Canal, can be represented in their computer model by just five functional groups and still produce accurate forecasts of tree composition and forest biomass over time. It's not possible to directly verify the forecasts of a forest model in future decades. So the researchers did the next best thing: They seeded their model with forest composition data collected at their site in Panama during the 1980s and then ran the model forward to show that it accurately represents the changes that occurred from then until now. This is called "hindcasting." Next, they plan to explore how a warming world might benefit trees with certain traits over others, shifting forest composition and the potential of forests to store carbon. "One of the biggest unknowns in climate forecasting is: What are trees going to do?" said Farrior. "We really need to get a handle on that if we're going to accurately predict how climate will change and manage forests. Right now, they're absorbing some of the excess carbon we're producing and delaying climate change, but will they keep doing it?" The other coauthors on the paper are Richard Condit at the Field Museum of Natural History in Chicago and the Morton Arboretum; Daisy H. Dent at the Smithsonian Tropical Research Institute (STRI) in Panama and the University of Stirling in the U.K.; Saara J. DeWalt at Clemson University; Stephen P. Hubbell at STRI and the University of California, Los Angeles; Jeremy W. Lichstein at the University of Florida, Gainesville; Omar R. Lopez at STRI and Instituto de Investigaciones Científicas y Servicios de Alta Tecnología in Panama; and Christian Wirth at iDiv, University of Leipzig and Max Planck Institute for Biogeochemistry in Germany. Funding was provided by the U.S. National Science Foundation, Deutsche Forschungsgemeinschaft and Secretaría Nacional de Ciencia, Tecnología e Innovación. Source:University of Texas at Austin Date:April 9, 2020

2020-04 08
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Forecast: U.S. greenhouse gas emissions to fall 7.5-percent in 2020

Date:2020-04

View:08

I think it’s safe to say nobody wants to see greenhouse gasses reduced this way. But one major COVID-19 impact so far is a dramatic reduction in fossil fuel use. Global liquid fuels use Global liquid fuels useU.S. Energy Information Administration The U.S. Energy Information Administration tracks energy use. The report released this week forecasts a historic reduction in fossil fuel use in 2020. The agency predicts a 7.5-percent reduction in energy-related carbon dioxide (CO2) emissions in the U.S. this year. That follows a 2.7-percent drop last year. U.S. Carbon Dioxide emissions  U.S. Carbon Dioxide emissions U.S. Energy Information Administration After decreasing by 2.7% in 2019, EIA forecasts that energy-related carbon dioxide (CO2) emissions will decrease by 7.5% in 2020 as the result of the slowing economy and restrictions on business and travel activity related to COVID-19. The agency also predicts a 9-percent decrease in gasoline consumption and a 10-percent decrease in jet fuel use this year. In 2020, EIA forecasts that U.S. motor gasoline consumption will average 8.4 million b/d, a decrease of 9% compared with 2019, while jet fuel and distillate fuel oil consumption will fall by 10% and 5%, respectively over the same period. Historic drop The decrease in fossil fuel use this year could be the biggest drop since the Great Depression. It may also be a boost to renewables, often the cheapest form of electricity in many areas. And coal may take another big hit this year according to this Associated Press piece. Globally, “we’re seeing radical declines in transportation emissions and drops in other sectors of the economy,” said Stanford University’s Rob Jackson, who heads a group of independent scientists who monitor global carbon pollution. “We haven’t seen anything like this since the Great Depression.” The energy agency projects Americans will burn 9% less gasoline and diesel and 10% less jet fuel, and that the electricity sector will generate 3% less power overall, among other declines. Solar and wind power — which get scant attention from Trump, other than his statements of loathing for wind turbines — will account for the majority of the country’s new electricity generation, the report says. As marketplace competition reshapes how Americans get their energy, power plants will use 11% more renewables and 20% less coal this year. U.S. renewable energy trends U.S. renewable energy trendsU.S. Energy Information Administration There is little doubt the many widespread and unpleasant impacts from COVID-19 will be studied closely. One question I will be asking is; how much of the greenhouse gas reductions can we retain, while our economy gets back to something approaching normal? And how many people that are working from home now can continue to do so in the future? That’s a big opportunity for reducing our commuter carbon footprints. Source:MPRnews Author:Paul Huttner Date:April 8, 2020

2020-04 06
View 83
The ocean's 'biological pump' captures more carbon than expected

Date:2020-04

View:06

Every spring in the Northern Hemisphere, the ocean surface erupts in a massive bloom of phytoplankton. Like plants, these single-celled floating organisms use photosynthesis to turn light into energy, consuming carbon dioxide and releasing oxygen in the process. When phytoplankton die or are eaten by zooplankton, the carbon-rich fragments sinks deeper into the ocean, where it is, in turn, eaten by other creatures or buried in sediments. This process is key to the "biological carbon pump," an important part of the global carbon cycle. Scientists have long known that the ocean plays an essential role in capturing carbon from the atmosphere, but a new study from Woods Hole Oceanographic Institution (WHOI) shows that the efficiency of the ocean's "biological carbon pump" has been drastically underestimated, with implications for future climate assessments. In a paper published April 6 in Proceedings of the National Academy of Sciences, WHOI geochemist Ken Buesseler and colleagues demonstrated that the depth of the sunlit area where photosynthesis occurs varies significantly throughout the ocean. This matters because the phytoplankton's ability to take up carbon depends on amount of sunlight that's able to penetrate the ocean's upper layer. By taking account of the depth of the euphotic, or sunlit zone, the authors found that about twice as much carbon sinks into the ocean per year than previously estimated. The paper relies on previous studies of the carbon pump, including the authors' own. "If you look at the same data in a new way, you get a very different view of the ocean's role in processing carbon, hence its role in regulating climate," says Buesseler. Scientists have long known that the ocean plays an essential role in capturing carbon from the atmosphere, but a new study shows that the efficiency of the ocean's "biological carbon pump" has been drastically underestimated. Credit: Elise Hugus, UnderCurrent Productions, © Woods Hole Oceanographic Institution "Using the new metrics, we will be able to refine the models to not just tell us how the ocean looks today, but how it will look in the future," he adds. "Is the amount of carbon sinking in the ocean going up or down? That number affects the climate of the world we live in." In the paper, Buesseler and his coauthors call on their fellow oceanographers to consider their data in context of the actual boundary of the euphotic zone. Marine chemist Ken Buesseler (right) deploys a sediment trap from the research vessel Roger Revelle during a 2018 expedition in the Gulf of Alaska. Buesseler's research focuses on how carbon moves through the ocean. Buesseler and co-authors of a new study found that the ocean's biological carbon pump may be twice as efficient as previously estimated, with implications for future climate assessments. Credit: Alyssa Santoro, © Woods Hole Oceanographic Institution "If we're going to call something a euphotic zone, we need to define that," he says. "So we're insisting on a more formal definition so that we can compare sites." Rather than taking measurements at fixed depths, the authors used chlorophyll sensors —indicating the presence of phytoplankton— to rapidly assess the depth of the sunlit region. They also suggest using the signature from a naturally-occuring thorium isotope to estimate the rate at which carbon particles are sinking. Buesseler is a principal investigator with WHOI's Ocean Twilight Zone project, which focuses on the little-understood but vastly important mid-ocean region. In a commentary published in Nature on March 31, Buesseler and colleagues call on the international marine research community to intensify their studies of the twilight zone during the upcoming United Nations Decade of the Ocean (2021-2030). Increased understanding of the twilight zone ecosystem and its role in regulating climate, the authors say, will lead to global policy to protect the area from exploitation. Source: phys.org Author: Woods Hole Oceanographic Institution Date: APRIL 6, 2020