Calcination of carbonate rocks during the manufacture of cement produced 5% of global CO₂ emissions from all industrial process and fossil-fuel combustion in 2013^1, 2. Considerable attention has been paid to quantifying these industrial process emissions from cement production^2, 3, but the natural reversal of the process—carbonation—has received little attention in carbon cycle studies. Here, we use new and existing data on cement materials during cement service life, demolition, and secondary use of concrete waste to estimate regional and global CO₂ uptake between 1930 and 2013 using an analytical model describing carbonation chemistry. We find that carbonation of cement materials over their life cycle represents a large and growing net sink of CO₂, increasing from 0.10 GtC yr⁻¹ in 1998 to 0.25 GtC yr⁻¹ in 2013. In total, we estimate that a cumulative amount of 4.5 GtC has been sequestered in carbonating cement materials from 1930 to 2013, offsetting 43% of the CO₂ emissions from production of cement over the same period, not including emissions associated with fossil use during cement production. We conclude that carbonation of cement products represents a substantial carbon sink that is not currently considered in emissions inventories^1, 3, 4.

Climate change driven by anthropengic carbon emissions is one of the most serious challenges facing human development. China is currently the world’s largest developing country, primary energy consumer, and carbon emitter. The nation releases one quarter of the global total of carbon dioxide (9.2 Gt CO2 in 2013), 1.5 times that from the US. Nearly three-quarters (73%) of the growth in global carbon emission between 2010 and 2012 occurred in China. Without mitigation, China’s emissions could rise by more than 50% in the next 15 years. Given the magnitude and growth rate of China’s carbon emissions, the country has become a critical partner in developing policy approaches to reduce global CO2 emissions.

China is a country with significant regional differences in terms of technology, energy mix, and economic development. 1 Understanding the characteristics and state of regional carbon emissions within China is critical for designing geographically appropriate mitigation policies, including the provincial cap and trade system that is projected to be lanuched in 2017. In this study, I summarize the key features and drivers of China’s regional carbon emissions and conclude with suggestions for a low carbon policy for China.

The principal findings are:

1. Provincial aggregated CO2 emissions increased from 3 billion tons in 2000 to 10 billion tons in 2016. During the period, Shandong province contributed most to national emissions, followed by Liaoning, Hebei, and Shanxi provinces. Most of the CO2 emissions were from raw coal, which is primarily burned in the manufacturing and the thermal power sectors.
2. Significant differences exist among provinces in terms of CO2 emissions. Analyses of per capita emissions and emission intensity indicate that provinces located in the northwest and north had higher per capita. CO2 emissions and greater emission intensities than the central and southeast coastal regions. Developing areas have intensive resource use and their economic structure is dominated by heavy industries with higher sectoral emission intensity. These areas contribute to most of the growth in national emissions and are the main drivers of China’s carbon intensive economic structure.
3. An analysis of the factors that affect China’s CO2 emissions shows that technology heterogeneity is directly connected to China’s carbon growth. The dissimilar rate of adoption of energy efficient technologies among regions is a major barrier to China’s CO2 mitigation, and thus needs more attention from researchers and policy makers.

International trade separates regions consuming goods and services from regions where goods and related aerosol pollution are produced. Yet the role of trade in aerosol climate forcing attributed to different regions has never been quantified. Here, we contrast the direct radiative forcing of aerosols related to regions’ consumption of goods and services against the forcing due to emissions produced in each region. Aerosols assessed include black carbon, primary organic aerosol, and secondary inorganic aerosols, including sulfate, nitrate and ammonium. We find that global aerosol radiative forcing due to emissions produced in East Asia is much stronger than the forcing related to goods and services ultimately consumed in that region because of its large net export of emissions-intensive goods. The opposite is true for net importers such as Western Europe and North America: global radiative forcing related to consumption is much greater than the forcing due to emissions produced in these regions. Overall, trade is associated with a shift of radiative forcing from net importing to net exporting regions. Compared to greenhouse gases such as carbon dioxide, the short atmospheric lifetimes of aerosols cause large localized differences between consumption- and production-related radiative forcing. International efforts to reduce emissions in the exporting countries will help alleviate trade-related climate and health impacts of aerosols while lowering global emissions.

Anthropogenic climate change driven by human induced carbon emissions, is one of the most serious challenges facing human development. China is currently the world largest developing country, top primary energy consumer and carbon emitter. The nation releases one quarter of the global total (9.2 Gt CO2 in 2013), 1.5 times that from US. Nearly three-quarters (73 %) of the growth in global carbon emission between 2010 and 2012 occurred in China. Without mitigation, China’s emissions could rise by more than 50 % in the next 15 years. Given the magnitude and growth rate of China’s carbon emissions, the country has become a critical partner in developing policy approaches to reducing global CO2 emissions. Supported by a 5-year joint research programme among more than 100 research institutes globally to investigate carbon emissions in China (Jiao and Stone, 2011), this study presents a systematically evaluation of China’s carbon emission from fossil fuel combustion and cement manufacturing process. The main contributions of the study are listed as: (1) This study was conducted with 4243 mine investigation and 602 site experiments to comprehensively test the qualities of different fuels in China. For the first time the “Measurable, reportable, verifiable” carbon emission factors and total carbon emission inventories are reported for nation, provinces, cities and invidual sectors. (2) The feature, pattern and driving forces of China’s carbon emissions are analyzied. Results show that China’s carbon emissions are mainly the result of fossil fuel combustion (90 %) and cement production (10 %). Manufacturing and power generation are the major sectors contributing to total carbon emissions, together these sectors accounted for 85 % of China’s total carbon emissions. The results also uncovered significant differences of sectoral emission intensity among provinces, implying a huge disparity of technology level among regions. Less developed provinces with much higher energy intensive technologies, contribute to most of national emission increment since 2000s and cause the whole country’s economic structure to become carbon intensive. vii (3) The study explored China’s emission embodied in international trade: the carbon footprints. By analyzing the carbon footprints by nations, Chinese trade represents 34 % of all emissions embodied in trade, and these traded emissions are growing each year. About twenty-five percent of China’s carbon footprints are caused by manufacturing products that are consumed abroad. These, so-called virtual emissions, which are “embodied” in international trade, lead to China having the world’s most unbalanced virtual emissions trade with its emissions associated to exports being eight times higher than its emissions associated with imports. This study provides basic understanding of China’s carbon emissions and further proposes a basis to support global mitigation efforts and low-carbon development. Keywords Sustainability China Climate change Carbon Emissions Carbon footprint

Natural ventilation (NV) is a key sustainable solution for reducing the energy use in buildings, improving thermal comfort, and maintaining a healthy indoor environment. However, the energy savings and environmental benefits are affected greatly by ambient air pollution in China. Here we estimate the NV potential of all major Chinese cities based on weather, ambient air quality, building configuration, and newly constructed square footage of office buildings in the year of 2015. In general, little NV potential is observed in northern China during the winter and southern China during the summer. Kunming located in the Southwest China is the most weather-favorable city for natural ventilation, and reveals almost no loss due to air pollution. Building Energy Simulation (BES) is conducted to estimate the energy savings of natural ventilation in which ambient air pollution and total square footage at each city must be taken into account. Beijing, the capital city, displays limited per-square-meter saving potential due to the unfavorable weather and air quality for natural ventilation, but its largest total square footage of office buildings makes it become the city with the greatest energy saving opportunity in China. Our analysis shows that the aggregated energy savings potential of office buildings at 35 major Chinese cities is 112 GWh in 2015, even after allowing for a 43 GWh loss due to China’s serious air pollution issue especially in North China. 8–78% of the cooling energy consumption can be potentially reduced by natural ventilation depending on local weather and air quality. The findings here provide guidelines for improving current energy and environmental policies in China, and a direction for reforming building codes.

Nearly three-quarters of the growth in global carbon emissions from the burning of fossil fuels and cement production between 2010 and 2012 occurred in China^1, 2. Yet estimates of Chinese emissions remain subject to large uncertainty; inventories of China’s total fossil fuel carbon emissions in 2008 differ by 0.3 gigatonnes of carbon, or 15 per cent^1, 3, 4,5. The primary sources of this uncertainty are conflicting estimates of energy consumption and emission factors, the latter being uncertain because of very few actual measurements representative of the mix of Chinese fuels. Here we re-evaluate China’s carbon emissions using updated and harmonized energy consumption and clinker production data and two new and comprehensive sets of measured emission factors for Chinese coal. We find that total energy consumption in China was 10 per cent higher in 2000–2012 than the value reported by China’s national statistics⁶, that emission factors for Chinese coal are on average 40 per cent lower than the default values recommended by the Intergovernmental Panel on Climate Change⁷, and that emissions from China’s cement production are 45 per cent less than recent estimates^1, 4. Altogether, our revised estimate of China’s CO2emissions from fossil fuel combustion and cement production is 2.49 gigatonnes of carbon (2 standard deviations = ±7.3 per cent) in 2013, which is 14 per cent lower than the emissions reported by other prominent inventories^1, 4, 8. Over the full period 2000 to 2013, our revised estimates are 2.9 gigatonnes of carbon less than previous estimates of China’s cumulative carbon emissions^1, 4. Our findings suggest that overestimation of China’s emissions in 2000–2013 may be larger than China’s estimated total forest sink in 1990–2007 (2.66 gigatonnes of carbon)⁹ or China’s land carbon sink in 2000–2009 (2.6 gigatonnes of carbon)¹⁰.