Allocating China's 2025 CO2 emission burden shares to 340 prefecture cities: methods and findings

Peak emission is an important policy/scheme for all the countries to respond greenhouse gas mitigation. The key is how to distribute the emission burden shares to its sub-regions. This study aims to develop a prefecture city leveled CO₂ emission allocation model by integrating multi-indicators method and benchmark method so that China's 2025 (end year of 14th Five-Year Plan, FYP) CO₂ emission burdens can be allocated to its prefecture cities and provinces. Results show that China's total CO₂ emission will reach 12 billion tons in 2025. The majority of such emission will occur in the east China due to its more developed economy and dense population. Cities with high emissions are usually allocated more emission quotas, such as Shanghai, Tianjin, Chongqing, Tangshan, Yulin, Suzhou, and Ningbo. The top five provinces with higher CO₂ emission quotas are traditionally high-emission and energy-intensive provinces, including Shandong, Jiangsu, Inner Mongolia, Henan, and Hebei. The national CO₂ emission intensity will decrease by 69.35% in 2025 compared to the 2005 level. The CO₂ emission intensity reduction rates among the 340 Chinese cities is found to be fluctuating significantly from 16 to 74% during the 14th FYP. Finally, policy recommendations are raised for mitigating city level CO₂ emissions by considering the local realities.

Allocating and mapping ecosystem service demands with spatial flow from built-up areas to natural spaces

Co-urbanized areas around large cities in developing countries face the problem of spatial disconnection between supply and demand areas of ecosystem services (ES). To explore the reflection of human needs in the nonadjacent surrounding natural spaces and identify the response of the existing natural space system to the ES demand in terms of total amount and spatial distribution, a new method for ES demand mapping in co-urbanized areas was proposed. Based on the theory of the ES delivery chain, urban built-up areas are identified as service benefiting areas (SBAs) and the sources where demands are generated, natural spaces are regarded as service provision areas (SPAs) and the sinks and destinations where demands are satisfied, and ES spatial flow is considered as the delivery mechanism and ecological process that promotes the demand flow from sources to sinks. An indicator cluster composed of four multidimensional indicators, including flow quantity, flow boundary, flow direction and allocation mode along the distance, was used to characterize the spatial flow and represent the four key links in the technical path of allocating ES demand from built-up areas to natural spaces with spatial flow to intuitively reflect the spatial characteristics of human social demands projected in them. We quantified and mapped the distribution of three ES demands in built-up areas and surrounding natural spaces. In the former, the high-demand spaces are concentrated in the areas with high population density or high aging degree; while in the latter, the high-demand spaces are mainly adjacent to the built-up areas or the large-scale natural spaces. By controlling the flow quantity, expanding the flow area, increasing the flow directions and improving the ES supply capacity of SPAs within a given distance, the high ES demands in the above spaces can be effectively regulated.

The energetics of social signaling during roost location in Spix's disc-winged bats

Long-term social aggregations are maintained by multiple mechanisms, including the use of acoustic signals, which may nonetheless entail significant energetic costs. To date, however, no studies have gauged whether there are significant energetic costs to social call production in bats, which heavily rely on acoustic communication for a diversity of social tasks. We measured energetic expenditure during acoustic signaling in Spix's disc-winged bats (Thyroptera tricolor), a species that commonly uses contact calls to locate the ephemeral furled leaves that they use for roosting. To determine the cost of sound production, we measured oxygen consumption using intermittent-flow respirometry methods, with and without social signaling. Our results show that the emission of contact calls significantly increases oxygen consumption; vocal individuals spent, on average, 12.42 kJ more during social signaling trials than they spent during silent trials. We also found that as resting metabolic rate increased in males, there was a decreasing probability that they would emit response calls. These results provide support to the 'allocation model', which predicts that only individuals with lower self-maintenance costs can afford to spend energy in additional activities. Our results provide a step forward in our understanding of how physiology modulates behavior, specifically how the costs of call production and resting metabolic rate may explain the differences in vocal behavior among individuals.