ALBERT

Description: Globally increasing temperatures may have unmanageable impacts on terrestrial, aquatic and marine ecosystems. Quantifying impacts worldwide and systematically as a function of global warming is critical to substantiate the ongoing international negotiations on climate mitigation targets. Here we present a macro-scale analysis of climate change impacts on terrestrial ecosystems based on newly developed sets of climate scenarios featuring a step-wise sampling of global mean temperature increase between 1.5 and 5 K by 2100. These are processed by a biogeochemical model (LPJmL) to derive an aggregated metric of simultaneous biogeochemical and structural shifts in land surface properties which we interpret as a proxy for the risk of shifts and possibly disruptions in ecosystems. Our results show a substantial risk of climate change to transform terrestrial ecosystems profoundly. Nearly no area of the world is free from such risk, unless strong mitigation limits warming to around 2 degrees above preindustrial level. Even then, most climate models agree that up to one fifth of the land surface may experience at least moderate change, primarily at high latitudes and high altitudes. If countries fulfill their current emissions pledges, resulting in roughly 3.5 K of warming, this area expands to cover half the land surface, including the majority of tropical forests and savannas and the boreal zone. Due to differences in regional patterns of climate change the area potentially at risk of severe ecosystem change considering all AOGCMs is up to 2.5 times as large as for a single AOGCM.

Description: Globally increasing temperatures are likely to have impacts on terrestrial, aquatic and marine ecosystems that are difficult to manage. Quantifying impacts worldwide and systematically as a function of global warming is fundamental to substantiating the discussion on climate mitigation targets and adaptation planning. Here we present a macro-scale analysis of climate change impacts on terrestrial ecosystems based on newly developed sets of climate scenarios featuring a step-wise sampling of global mean temperature increase between 1.5 and 5 K by 2100. These are processed by a biogeochemical model (LPJmL) to derive an aggregated metric of simultaneous biogeochemical and structural shifts in land surface properties which we interpret as a proxy for the risk of shifts and possibly disruptions in ecosystems. Our results show a substantial risk of climate change to transform terrestrial ecosystems profoundly. Nearly no area of the world is free from such risk, unless strong mitigation limits global warming to around 2 degrees above preindustrial level. Even then, our simulations for most climate models agree that up to one-fifth of the land surface may experience at least moderate ecosystem change, primarily at high latitudes and high altitudes. If countries fulfil their current emissions reduction pledges, resulting in roughly 3.5 K of warming, this area expands to cover half the land surface, including the majority of tropical forests and savannas and the boreal zone. Due to differences in regional patterns of climate change, the area potentially at risk of major ecosystem change considering all climate models is up to 2.5 times as large as for a single model.

Description: In the ongoing political debate on climate change, global mean temperature change (ΔTglob) has become the yardstick by which mitigation costs, impacts from unavoided climate change, and adaptation requirements are discussed. For a scientifically informed discourse along these lines, systematic assessments of climate change impacts as a function of ΔTglob are required. The current availability of climate change scenarios constrains this type of assessment to a narrow range of temperature change and/or a reduced ensemble of climate models. Here, a newly composed dataset of climate change scenarios is presented that addresses the specific requirements for global assessments of climate change impacts as a function of ΔTglob. A pattern-scaling approach is applied to extract generalised patterns of spatially explicit change in temperature, precipitation and cloudiness from 19 Atmosphere–Ocean General Circulation Models (AOGCMs). The patterns are combined with scenarios of global mean temperature increase obtained from the reduced-complexity climate model MAGICC6 to create climate scenarios covering warming levels from 1.5 to 5 degrees above pre-industrial levels around the year 2100. The patterns are shown to sufficiently maintain the original AOGCMs' climate change properties, even though they, necessarily, utilise a simplified relationships between ΔTglob and changes in local climate properties. The dataset (made available online upon final publication of this paper) facilitates systematic analyses of climate change impacts as it covers a wider and finer-spaced range of climate change scenarios than the original AOGCM simulations.

Description: In the ongoing political debate on climate change, global mean temperature change (ΔTglob) has become the yardstick by which mitigation costs, impacts from unavoided climate change, and adaptation requirements are discussed. For a scientifically informed discourse along these lines systematic assessments of climate change impacts as a function of ΔTglob are required. The current availability of climate change scenarios constrains this type of assessment to a narrow range of temperature change and/or a reduced ensemble of climate models. Here, a newly composed dataset of climate change scenarios is presented that addresses the specific requirements for global assessments of climate change impacts as a function of ΔTglob. A pattern-scaling approach is applied to extract generalized patterns of spatially explicit change in temperature, precipitation and cloudiness from 19 AOGCMs. The patterns are combined with scenarios of global mean temperature increase obtained from the reduced-complexity climate model MAGICC6 to create climate scenarios covering warming levels from 1.5 to 5 degrees above pre-industrial levels around the year 2100. The patterns are shown to sufficiently maintain the original AOGCMs' climate change properties, even though they, necessarily, utilize a simplified relationships between ΔTglob and changes in local climate properties. The dataset (made available online upon final publication of this paper) facilitates systematic analyses of climate change impacts as it covers a wider and finer-spaced range of climate change scenarios than the original AOGCM simulations.

Description: Burkina Faso has a high socio-economic dependency on agriculture, a sector which is strongly influenced by weather-related factors and increasingly challenged by the impacts of climate change. Currently, only limited information on climate risks and its impacts is available for the agricultural sector in the country. Therefore, this study aims to provide a comprehensive climate risk analysis including a thorough evaluation of four potential adaptation strategies that can guide local decision makers on adaptation planning and implementation in Burkina Faso. The impact assessment consists of several steps including climate projections based on two emissions scenarios (SSP3-RCP7.0 and SSP1-RCP2.6), hydro-logical modelling on water availability changes, modelling and comparison of future yields of four widely used crops (maize, sorghum, millet and cowpeas) and an assessment of livestock production under future climate conditions. Based on the projected climate change impacts on agricultural production, four different adapta-tion strategies ((1) Integrated soil fertility ma-nagement (ISFM), (2) irrigation, (3) improved seeds and (4) climate information services (CIS)) suggested and selected by different national stakeholders were analysed regarding their potential to risk mitigation, (cost-)effectiveness and suitability for local conditions. The analyses have been further complemented by expert- and literature-based assessments, semi-structured key informant interviews and two stakeholder work-shops. The results show that the mean daily temperature is on the rise and projected to increase further by 0.6°C (2030) up to 1.1°C (2090) under SSP1-RCP2.6 and by 0.5°C (2030) up to 3.6°C (2090) under SSP3-RCP7.0 in reference to 2004, dependent on future greenhouse gas emissions. Some un-certainty exists for annual precipitation projections, with slight increases until 2050 followed by a slight decrease under SSP1-RCP2.6 and continuous increase under SSP3-RCP7.0 with high year-to-year variability. Projected impacts of cli-mate change on yields vary between regions and show partly opposing trends. Some regions in the north show increasing yields (up to +30% in SSP1-RCP2.6 and up to +20% in SSP3-RCP7.0), while few regions in the south present decreasing yields (down to -30% in SSP1-RCP2.6 and down to -20% in SSP3-RCP7.0). Crop models show that the areas suitable for cowpeas will decrease in Burkina Faso under future climate change conditions while the suitability for maize, millet and sorghum will remain stable. Moreover, the potential to produce multiple crops will become more and more difficult, which limits farmers’ diversification options. Regarding the livestock sector, it seems very likely that the grazing potential will decrease under both climate change scenarios with higher decreases under SSP1-RCP2.6 than under SSP3-RCP7.0. All four adaptation strategies were found to be economically beneficial, can have a high potential for risk mitigation and entail different co-benefits. Particularly, ISFM can be highly recommended for smallholder farmers, resulting in very positive effects for societies and environment. Irrigation and improved seeds have a high potential to improve livelihoods especially in Northern Burkina Faso, but are also complex, costly and support-intensive adaptation strategies. Lastly, CIS can support farmers to make informed decisions and thereby reduce the impact of climate risks. Generally, a combination of different adaptation strategies can entail additional benefits and active stakeholder engagement as well as participatory approaches are needed to ensure the feasibility and long-term sustainability of adaptation strategies. The findings of this study can help to inform national and local adaptation and agricultural development planning and investments in order to strengthen the resilience of the agricultural sector and especially of smallholder farmers against a changing climate.

Description: Niger has a high socio-economic dependency on agriculture which is strongly influenced by weather-related factors and highly vulnerable to climate change. Currently, only limited information on climate risks and its impacts is available for the agricultural sector in the country. Therefore, this study aims to provide a comprehensive climate risk analysis including a thorough evaluation of four potential adaptation strategies that can guide local decision makers on adaptation planning and implementation in Niger: (1) agroforestry and farmer managed natural regeneration (FMNR) of trees, (2) integrated soil fertility management (ISFM), (3) irrigation and (4) improved fodder management for livestock. The impact assessment includes climate projections based on two future emissions scenarios (SSP3-RCP7.0 and SSP1-RCP2.6), hydrological modelling on water availability, modelling and comparison of future yields of four dominant crops (sorghum, millet, maize and cowpeas) and an as-sessment of livestock production under future climate conditions. Based on the projected climate change impacts on agricultural production, the four adaptation strategies suggested by different national stakeholders were analysed regarding their potential to risk mitigation, cost-effectiveness and suitability for local conditions. The analyses have been complemented by expert- and literature-based assessments, semi-structured interviews and two stakeholder workshops. The results show that the mean daily temperature is projected to increase further in Niger, up to +1.3 °C (SSP1-RCP2.6) and +4.2 °C (SSP3-RCP7.0) by 2090, in reference to 2004. The mean annual precipitation sum is also projected to increase until 2050 under both emissions scenarios, with a slight decrease in the interannual variability. In the second half of the century, this trend in precipitation is likely to continue (SSP3-RCP7.0) or decrease slightly (SSP1-RCP2.6), while the year-to-year variability would increase. Greater annual rates of groundwater recharge due to increasing precipitation amounts and higher annual mean river discharge are expected until mid-century. Sorghum yields would decline in general, by 20-50% (SSP1-RCP2.6) or 40-75% (SSP3-RCP7.0) by 2090, compared to 2005. Crop models hinted at an increase in the suitability of sorghum and millet, and no significant change for maize and cowpeas in Niger under both emissions scenarios. In addition, the potential for multiple cropping would de-crease from mid-century, limiting farmers’ diversification options. Regarding the livestock sector, the grazing potential is likely to decrease in the south and increase in the central regions of Niger, under SSP1-RCP2.6, while it is expected to increase in the whole country under SSP3-RCP7.0. All four adaptation strategies were found to be economically beneficial, risk-independent, with a medium to high risk mitigation potential, and can bring about various co-benefits. FMNR practice can be highly recommended, as the upscaling potential is high and the climate resilience of local livelihoods will be strengthened. ISFM can help to improve water use efficiency and benefit from positive environmental and social outcomes. Irrigation has a medium potential to improve livelihoods of smallholder farmers but is also a support-intensive adaptation strategy that needs to be carefully implemented in order to avoid overexploitation of local water resources. Lastly, improved fodder management, especially al-falfa production, contributes to building up resilience of livestock farming systems and affects women and youth employment positively. Gener-ally, a combination of different adaptation strategies can yield additional benefits and active stake-holder engagement as well as participatory ap-proaches are needed to ensure the feasibility and sustainability of adaptation strategies. The findings of this study can help to inform national and local adaptation as well as development planning and investments in order to strengthen the climate resilience of the Nigerien agricultural sector and especially of smallholder farmers.