Empirical estimates of regional carbon budgets imply reduced global soil heterotrophic respiration.

Resolving regional carbon budgets is critical for informing land-based mitigation policy. For nine regions covering nearly the whole globe, we collected inventory estimates of carbon-stock changes complemented by satellite estimates of biomass changes where inventory data are missing. The net land-atmospheric carbon exchange (NEE) was calculated by taking the sum of the carbon-stock change and lateral carbon fluxes from crop and wood trade, and riverine-carbon export to the ocean. Summing up NEE from all regions, we obtained a global 'bottom-up' NEE for net land anthropogenic CO2 uptake of -2.2 ± 0.6 PgC yr-1 consistent with the independent top-down NEE from the global atmospheric carbon budget during 2000-2009. This estimate is so far the most comprehensive global bottom-up carbon budget accounting, which set up an important milestone for global carbon-cycle studies. By decomposing NEE into component fluxes, we found that global soil heterotrophic respiration amounts to a source of CO2 of 39 PgC yr-1 with an interquartile of 33-46 PgC yr-1-a much smaller portion of net primary productivity than previously reported.

Impacts of environmental change on biodiversity and vegetation dynamics in Siberia.

Biological diversity is the basis for, and an indicator of biosphere integrity. Together with climate change, its loss is one of the two most important planetary boundaries. A halt in biodiversity loss is one of the UN Sustainable Development Goals. Current changes in biodiversity in the vast landmass of Siberia are at an initial stage of inventory, even though the Siberian environment is experiencing rapid climate change, weather extremes and transformation of land use and management. Biodiversity changes affect traditional land use by Indigenous People and multiple ecosystem services with implications for local and national economies. Here we review and analyse a large number of scientific publications, which are little known outside Russia, and we provide insights into Siberian biodiversity issues for the wider international research community. Case studies are presented on biodiversity changes for insect pests, fish, amphibians and reptiles, birds, mammals and steppe vegetation, and we discuss their causes and consequences.

Great Vasyugan Mire: How the world's largest peatland helps addressing the world's largest problems.

Peatlands cover 3% of the land, occur in 169 countries, and have-by sequestering 600 Gt of carbon-cooled the global climate by 0.6 °C. After a general review about peatlands worldwide, this paper describes the importance of the Great Vasyugan Mire and presents suggestions about its protection and future research. The World's largest peatland, the Great Vasyugan Mire in West-Siberia, forms the border between the Taiga and the Forest-Steppe biomes and harbours rare species and mire types and globally unique self-organizing patterns. Current oil and gas exploitation may arguably be largely phased out by 2050, which will pave the way for a stronger focus on the mire's role in buffering climate change, maintaining ecosystem diversity, and providing other ecosystem services. Relevant new research lines will benefit from the extensive data sets that earlier studies have gathered for other purposes. Its globally unique character as the 'largest life form on land' qualifies the Great Vasyugan Mire in its entirety to be designated as a UNESCO World Heritage Site and a Ramsar Wetland of International Importance.

A global dataset of CO2 emissions and ancillary data related to emissions for 343 cities.

We present a global dataset of anthropogenic carbon dioxide (CO2) emissions for 343 cities. The dataset builds upon data from CDP (187 cities, few in developing countries), the Bonn Center for Local Climate Action and Reporting (73 cities, mainly in developing countries), and data collected by Peking University (83 cities in China). The CDP data being self-reported by cities, we applied quality control procedures, documented the type of emissions and reporting method used, and made a correction to separate CO2 emissions from those of other greenhouse gases. Further, a set of ancillary data that have a direct or potentially indirect impact on CO2 emissions were collected from other datasets (e.g. socio-economic and traffic indices) or calculated (climate indices, urban area expansion), then combined with the emission data. We applied several quality controls and validation comparisons with independent datasets. The dataset presented here is not intended to be comprehensive or a representative sample of cities in general, as the choice of cities is based on self-reporting not a designed sampling procedure.

Temporal response of soil organic carbon after grassland-related land-use change.

The net flux of CO2 exchanged with the atmosphere following grassland-related land-use change (LUC) depends on the subsequent temporal dynamics of soil organic carbon (SOC). Yet, the magnitude and timing of these dynamics are still unclear. We compiled a global data set of 836 paired-sites to quantify temporal SOC changes after grassland-related LUC. In order to discriminate between SOC losses from the initial ecosystem and gains from the secondary one, the post-LUC time series of SOC data was combined with satellite-based net primary production observations as a proxy of carbon input to the soil. Globally, land conversion from either cropland or forest into grassland leads to SOC accumulation; the reverse shows net SOC loss. The SOC response curves vary between different regions. Conversion of cropland to managed grassland results in more SOC accumulation than natural grassland recovery from abandoned cropland. We did not consider the biophysical variables (e.g., climate conditions and soil properties) when fitting the SOC turnover rate into the observation data but analyzed the relationships between the fitted turnover rate and these variables. The SOC turnover rate is significantly correlated with temperature and precipitation (p < 0.05), but not with the clay fraction of soils (p > 0.05). Comparing our results with predictions from bookkeeping models, we found that bookkeeping models overestimate by 56% of the long-term (100 years horizon) cumulative SOC emissions for grassland-related LUC types in tropical and temperate regions since 2000. We also tested the spatial representativeness of our data set and calculated SOC response curves using the representative subset of sites in each region. Our study provides new insight into the impact grassland-related LUC on the global carbon budget and sheds light on the potential of grassland conservation for climate mitigation.