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International audience ; At last year's 26th UN Climate Change Conference of the Parties (COP26) in Glasgow, 141 countries committed to halt and reverse forest loss and land degradation by 2030 (1). It was part of one of several side deals designed to keep the objectives of the Paris agreement within reach. The UK government boasted that these nations had made a landmark pledge to end deforestation (2). Yet, one crucial detail was left out: whether that deforestation will be gross or net. The distinction matters, because differing interpretations of how countries can "end deforestation" significantly impact future carbon dioxide emissions. Put simply, ending gross deforestation would be a major step forward for the climate. But considering only net deforestation could be anecdotal and even be detrimental to biodiversity. Overall, human activities related to land use emit 4 gigatonnes (Gt) of carbon dioxide (CO 2) per year to the atmosphere (3). These are net emissions, comprising both carbon losses and carbon gains. On the loss side, the destruction of tree biomass during deforestation, for large-scale agriculture, cattle ranching, or shifting cultivation (cycles of cutting forest for agriculture, then abandoning to recover soil fertility, then returning), and the legacy emissions from harvested wood products, form the bulk of gross emissions, totaling 14 Gt CO 2 per year (3). On the gain side, secondary forest regrowth after reforestation, agricultural abandonment, or during shifting cultivation form the bulk of the gross carbon Differing interpretations as to how countries can "end deforestation" will have significant impacts on future carbon dioxide emissions. Only ending gross deforestation would be a major step forward for the climate. Image credit: Shutterstock/guentermanaus.

International audience ; At last year's 26th UN Climate Change Conference of the Parties (COP26) in Glasgow, 141 countries committed to halt and reverse forest loss and land degradation by 2030 (1). It was part of one of several side deals designed to keep the objectives of the Paris agreement within reach. The UK government boasted that these nations had made a landmark pledge to end deforestation (2). Yet, one crucial detail was left out: whether that deforestation will be gross or net. The distinction matters, because differing interpretations of how countries can "end deforestation" significantly impact future carbon dioxide emissions. Put simply, ending gross deforestation would be a major step forward for the climate. But considering only net deforestation could be anecdotal and even be detrimental to biodiversity. Overall, human activities related to land use emit 4 gigatonnes (Gt) of carbon dioxide (CO 2) per year to the atmosphere (3). These are net emissions, comprising both carbon losses and carbon gains. On the loss side, the destruction of tree biomass during deforestation, for large-scale agriculture, cattle ranching, or shifting cultivation (cycles of cutting forest for agriculture, then abandoning to recover soil fertility, then returning), and the legacy emissions from harvested wood products, form the bulk of gross emissions, totaling 14 Gt CO 2 per year (3). On the gain side, secondary forest regrowth after reforestation, agricultural abandonment, or during shifting cultivation form the bulk of the gross carbon Differing interpretations as to how countries can "end deforestation" will have significant impacts on future carbon dioxide emissions. Only ending gross deforestation would be a major step forward for the climate. Image credit: Shutterstock/guentermanaus.

International audience ; At last year's 26th UN Climate Change Conference of the Parties (COP26) in Glasgow, 141 countries committed to halt and reverse forest loss and land degradation by 2030 (1). It was part of one of several side deals designed to keep the objectives of the Paris agreement within reach. The UK government boasted that these nations had made a landmark pledge to end deforestation (2). Yet, one crucial detail was left out: whether that deforestation will be gross or net. The distinction matters, because differing interpretations of how countries can "end deforestation" significantly impact future carbon dioxide emissions. Put simply, ending gross deforestation would be a major step forward for the climate. But considering only net deforestation could be anecdotal and even be detrimental to biodiversity. Overall, human activities related to land use emit 4 gigatonnes (Gt) of carbon dioxide (CO 2) per year to the atmosphere (3). These are net emissions, comprising both carbon losses and carbon gains. On the loss side, the destruction of tree biomass during deforestation, for large-scale agriculture, cattle ranching, or shifting cultivation (cycles of cutting forest for agriculture, then abandoning to recover soil fertility, then returning), and the legacy emissions from harvested wood products, form the bulk of gross emissions, totaling 14 Gt CO 2 per year (3). On the gain side, secondary forest regrowth after reforestation, agricultural abandonment, or during shifting cultivation form the bulk of the gross carbon Differing interpretations as to how countries can "end deforestation" will have significant impacts on future carbon dioxide emissions. Only ending gross deforestation would be a major step forward for the climate. Image credit: Shutterstock/guentermanaus.

International audience ; At last year's 26th UN Climate Change Conference of the Parties (COP26) in Glasgow, 141 countries committed to halt and reverse forest loss and land degradation by 2030 (1). It was part of one of several side deals designed to keep the objectives of the Paris agreement within reach. The UK government boasted that these nations had made a landmark pledge to end deforestation (2). Yet, one crucial detail was left out: whether that deforestation will be gross or net. The distinction matters, because differing interpretations of how countries can "end deforestation" significantly impact future carbon dioxide emissions. Put simply, ending gross deforestation would be a major step forward for the climate. But considering only net deforestation could be anecdotal and even be detrimental to biodiversity. Overall, human activities related to land use emit 4 gigatonnes (Gt) of carbon dioxide (CO 2) per year to the atmosphere (3). These are net emissions, comprising both carbon losses and carbon gains. On the loss side, the destruction of tree biomass during deforestation, for large-scale agriculture, cattle ranching, or shifting cultivation (cycles of cutting forest for agriculture, then abandoning to recover soil fertility, then returning), and the legacy emissions from harvested wood products, form the bulk of gross emissions, totaling 14 Gt CO 2 per year (3). On the gain side, secondary forest regrowth after reforestation, agricultural abandonment, or during shifting cultivation form the bulk of the gross carbon Differing interpretations as to how countries can "end deforestation" will have significant impacts on future carbon dioxide emissions. Only ending gross deforestation would be a major step forward for the climate. Image credit: Shutterstock/guentermanaus.

International audience ; At last year's 26th UN Climate Change Conference of the Parties (COP26) in Glasgow, 141 countries committed to halt and reverse forest loss and land degradation by 2030 (1). It was part of one of several side deals designed to keep the objectives of the Paris agreement within reach. The UK government boasted that these nations had made a landmark pledge to end deforestation (2). Yet, one crucial detail was left out: whether that deforestation will be gross or net. The distinction matters, because differing interpretations of how countries can "end deforestation" significantly impact future carbon dioxide emissions. Put simply, ending gross deforestation would be a major step forward for the climate. But considering only net deforestation could be anecdotal and even be detrimental to biodiversity. Overall, human activities related to land use emit 4 gigatonnes (Gt) of carbon dioxide (CO 2) per year to the atmosphere (3). These are net emissions, comprising both carbon losses and carbon gains. On the loss side, the destruction of tree biomass during deforestation, for large-scale agriculture, cattle ranching, or shifting cultivation (cycles of cutting forest for agriculture, then abandoning to recover soil fertility, then returning), and the legacy emissions from harvested wood products, form the bulk of gross emissions, totaling 14 Gt CO 2 per year (3). On the gain side, secondary forest regrowth after reforestation, agricultural abandonment, or during shifting cultivation form the bulk of the gross carbon Differing interpretations as to how countries can "end deforestation" will have significant impacts on future carbon dioxide emissions. Only ending gross deforestation would be a major step forward for the climate. Image credit: Shutterstock/guentermanaus.

International audience ; At last year's 26th UN Climate Change Conference of the Parties (COP26) in Glasgow, 141 countries committed to halt and reverse forest loss and land degradation by 2030 (1). It was part of one of several side deals designed to keep the objectives of the Paris agreement within reach. The UK government boasted that these nations had made a landmark pledge to end deforestation (2). Yet, one crucial detail was left out: whether that deforestation will be gross or net. The distinction matters, because differing interpretations of how countries can "end deforestation" significantly impact future carbon dioxide emissions. Put simply, ending gross deforestation would be a major step forward for the climate. But considering only net deforestation could be anecdotal and even be detrimental to biodiversity. Overall, human activities related to land use emit 4 gigatonnes (Gt) of carbon dioxide (CO 2) per year to the atmosphere (3). These are net emissions, comprising both carbon losses and carbon gains. On the loss side, the destruction of tree biomass during deforestation, for large-scale agriculture, cattle ranching, or shifting cultivation (cycles of cutting forest for agriculture, then abandoning to recover soil fertility, then returning), and the legacy emissions from harvested wood products, form the bulk of gross emissions, totaling 14 Gt CO 2 per year (3). On the gain side, secondary forest regrowth after reforestation, agricultural abandonment, or during shifting cultivation form the bulk of the gross carbon Differing interpretations as to how countries can "end deforestation" will have significant impacts on future carbon dioxide emissions. Only ending gross deforestation would be a major step forward for the climate. Image credit: Shutterstock/guentermanaus.

International audience Widely present in boreal regions, peatlands contain large carbon stocks because of their hydrologic properties and high water content, which makes primary productivity exceed decomposition rates. We have enhanced the global land surface model ORCHIDEE by introducing a hydrological representation of northern peatlands. These peatlands are represented as a new plant functional type (PFT) in the model, with specific hydrological properties for peat soil. In this paper, we focus on the representation of the hydrology of northern peatlands and on the evaluation of the hydrological impact of this implementation. A prescribed map based on the inventory of Yu et al. (2010) defines peatlands as a fraction of a grid cell represented as a PFT comparable to C 3 grasses, with adaptations to reproduce shallow roots and higher photosynthesis stress. The treatment of peatland hy-drology differs from that of other vegetation types by the fact that runoff from other soil types is partially directed towards the peatlands (instead of directly to the river network). The evaluation of this implementation was carried out at different spatial and temporal scales, from site evaluation to larger scales such as the watershed scale and the scale of all northern latitudes. The simulated net ecosystem exchanges agree with observations from three FLUXNET sites. Water table positions were generally close to observations, with some exceptions in winter. Compared to other soils, the simulated peat soils have a reduced seasonal variability in water storage. The seasonal cycle of the simulated extent of inundated peatlands is compared to flooded area as estimated from satellite observations. The model is able to represent more than 89.5 % of the flooded areas located in peatland areas, where the modelled extent of inundated peatlands reaches 0.83 × 10 6 km 2. However, the extent of peatlands in northern latitudes is too small to substantially impact the large-scale terrestrial water storage north of 45 • N. Therefore, the ...

The central role of land-use change in the Earth System and its implications for food security, biodiversity and climate has spurred the development of global models that combine economical and agro-ecological drivers and constraints. With such a development of integrated approaches, evaluating the performance of global models of landuse against observed historical changes recorded by agricultural data becomes increasingly challenging. The Nexus Land-Use model is an example of land-use model integrating both biophysical and economical processes and constraints. This paper is an attempt to evaluate its ability to simulate historical agricultural land-use changes over 12 large but economically coherent regions of the world since 1961. The evaluation focuses on the intensification vs. extensification response of crop and livestock production in response to changes of socio-economic drivers over time, such as fertiliser price, population and diet. We examine how well the Nexus model can reproduce annual observation-based estimates of cropland vs. pasture areas from 1961 to 2006. Food trade, consumption of fertilisers and food price are also evaluated against historical data. Over the 12 regions considered, the total relative error on simulated cropland area is 2%yr?1 over 1980-2006. During the period 1961-2006, the error is larger (4%yr?1) due to an overestimation of the cropland area in China and Former Soviet Union over 1961-1980. Food prices tend to be underestimated while the performances of the trade module vary widely among regions (net imports are underestimated in Western countries at the expense of Brazil and Asia). Finally, a sensitivity analysis over a sample of input datasets provides some insights on the robustness of this evaluation.

France is a major crop producer, with a production share of approx. 20% within the European Union. Yet, a discussion has recently started whether French yields are stagnating. While for wheat previous results are unanimously pointing to recent stagnation, there is contradictory evidence for maize and few to no results for other crops. Here we analyse a data set with more than 120,000 yield observations from 1900 to 2016 for ten crops (barley, durum and soft wheat, maize, oats, potatoes, rapeseed, sugar beet, sunflower and wine) in the 96 mainland French departements (NUTS3 administrative division). We dissect the evolution of yield trends over time and space, analyse yield variation and evaluate whether growth of yields has stalled in recent years.Yields have, on average across crops, multiplied four-fold over the course of the 20th century. While absolute yield variability has increased, the variation relative to the mean has halved - mean yields have increased faster than their variability. But growth of yields has stagnated since the 1990's for winter wheat, barley, oats, durum wheat, sunflower and wine on at least 25% of their areas. Reaching yield potentials is unlikely as a cause for stagnation. Maize, in contrast, shows no evidence for stagnation.

International audience ; France is a major crop producer, with a production share of approx. 20% within the European Union. Yet, a discussion has recently started whether French yields are stagnating. While for wheat previous results are unanimously pointing to recent stagnation, there is contradictory evidence for maize and few to no results for other crops. Here we analyse a data set with more than 120,000 yield observations from 1900 to 2016 for ten crops (barley, durum and soft wheat, maize, oats, potatoes, rapeseed, sugar beet, sunflower and wine) in the 96 mainland French departements (NUTS3 administrative division). We dissect the evolution of yield trends over time and space, analyse yield variation and evaluate whether growth of yields has stalled in recent years.Yields have, on average across crops, multiplied four-fold over the course of the 20th century. While absolute yield variability has increased, the variation relative to the mean has halved - mean yields have increased faster than their variability. But growth of yields has stagnated since the 1990's for winter wheat, barley, oats, durum wheat, sunflower and wine on at least 25% of their areas. Reaching yield potentials is unlikely as a cause for stagnation. Maize, in contrast, shows no evidence for stagnation.

International audience ; France is a major crop producer, with a production share of approx. 20% within the European Union. Yet, a discussion has recently started whether French yields are stagnating. While for wheat previous results are unanimously pointing to recent stagnation, there is contradictory evidence for maize and few to no results for other crops. Here we analyse a data set with more than 120,000 yield observations from 1900 to 2016 for ten crops (barley, durum and soft wheat, maize, oats, potatoes, rapeseed, sugar beet, sunflower and wine) in the 96 mainland French departements (NUTS3 administrative division). We dissect the evolution of yield trends over time and space, analyse yield variation and evaluate whether growth of yields has stalled in recent years.Yields have, on average across crops, multiplied four-fold over the course of the 20th century. While absolute yield variability has increased, the variation relative to the mean has halved - mean yields have increased faster than their variability. But growth of yields has stagnated since the 1990's for winter wheat, barley, oats, durum wheat, sunflower and wine on at least 25% of their areas. Reaching yield potentials is unlikely as a cause for stagnation. Maize, in contrast, shows no evidence for stagnation.

International audience ; France is a major crop producer, with a production share of approx. 20% within the European Union. Yet, a discussion has recently started whether French yields are stagnating. While for wheat previous results are unanimously pointing to recent stagnation, there is contradictory evidence for maize and few to no results for other crops. Here we analyse a data set with more than 120,000 yield observations from 1900 to 2016 for ten crops (barley, durum and soft wheat, maize, oats, potatoes, rapeseed, sugar beet, sunflower and wine) in the 96 mainland French departements (NUTS3 administrative division). We dissect the evolution of yield trends over time and space, analyse yield variation and evaluate whether growth of yields has stalled in recent years.Yields have, on average across crops, multiplied four-fold over the course of the 20th century. While absolute yield variability has increased, the variation relative to the mean has halved - mean yields have increased faster than their variability. But growth of yields has stagnated since the 1990's for winter wheat, barley, oats, durum wheat, sunflower and wine on at least 25% of their areas. Reaching yield potentials is unlikely as a cause for stagnation. Maize, in contrast, shows no evidence for stagnation.

International audience ; France is a major crop producer, with a production share of approx. 20% within the European Union. Yet, a discussion has recently started whether French yields are stagnating. While for wheat previous results are unanimously pointing to recent stagnation, there is contradictory evidence for maize and few to no results for other crops. Here we analyse a data set with more than 120,000 yield observations from 1900 to 2016 for ten crops (barley, durum and soft wheat, maize, oats, potatoes, rapeseed, sugar beet, sunflower and wine) in the 96 mainland French departements (NUTS3 administrative division). We dissect the evolution of yield trends over time and space, analyse yield variation and evaluate whether growth of yields has stalled in recent years.Yields have, on average across crops, multiplied four-fold over the course of the 20th century. While absolute yield variability has increased, the variation relative to the mean has halved - mean yields have increased faster than their variability. But growth of yields has stagnated since the 1990's for winter wheat, barley, oats, durum wheat, sunflower and wine on at least 25% of their areas. Reaching yield potentials is unlikely as a cause for stagnation. Maize, in contrast, shows no evidence for stagnation.

International audience ; France is a major crop producer, with a production share of approx. 20% within the European Union. Yet, a discussion has recently started whether French yields are stagnating. While for wheat previous results are unanimously pointing to recent stagnation, there is contradictory evidence for maize and few to no results for other crops. Here we analyse a data set with more than 120,000 yield observations from 1900 to 2016 for ten crops (barley, durum and soft wheat, maize, oats, potatoes, rapeseed, sugar beet, sunflower and wine) in the 96 mainland French departements (NUTS3 administrative division). We dissect the evolution of yield trends over time and space, analyse yield variation and evaluate whether growth of yields has stalled in recent years.Yields have, on average across crops, multiplied four-fold over the course of the 20th century. While absolute yield variability has increased, the variation relative to the mean has halved - mean yields have increased faster than their variability. But growth of yields has stagnated since the 1990's for winter wheat, barley, oats, durum wheat, sunflower and wine on at least 25% of their areas. Reaching yield potentials is unlikely as a cause for stagnation. Maize, in contrast, shows no evidence for stagnation.