Climate Change and Human Conflict in the Sahel

2021 ◽  
pp. 268-284
Author(s):  
Tor A. Benjaminsen
Keyword(s):  
Climate Change ◽  
Land Use ◽  
Climate Models ◽  
State Policies ◽  
Resource Scarcity ◽  
Minor Role ◽  
Armed Groups ◽  
Entire Region ◽  
Human Conflict ◽  
A Minor

Most climate models predict more rain in the future in the Sahel, but with more concentrated rainfall. Since the droughts of the 1980s, rains have increased, which has led to a regreening of the entire region. There is, however, a dominant narrative postulating that climate change will lead to drier conditions and desertification in the Sahel, which again will lead to resource scarcity, widespread migration, and more conflicts. This chapter critically investigates this narrative based on a review of international research. It considers conflict between farmers and herders, between the state and armed groups, in addition to jihadi violence that has increased in region in recent years. It concludes that the droughts in the 1980s only played a minor role in explaining conflicts, while the root causes were political and historical. State policies tend to lead to the marginalization of pastoralists. In areas where pastoralism and farming overlap as the main forms of land use, there are continuous conflicts of varying scale and intensity. These conflicts are primarily caused by politics, not climate change.

scholarly journals What can we learn from long-term groundwater data to improve climate change impact studies?

2011 ◽  
Vol 8 (4) ◽  
pp. 7621-7655 ◽  
Author(s):  
S. Stoll ◽  
H. J. Hendricks Franssen ◽  
R. Barthel ◽  
W. Kinzelbach
Keyword(s):  
Climate Change ◽  
Land Use ◽  
Climate Change Impact ◽  
Large Scale ◽  
Climate Models ◽  
Groundwater Resources ◽  
Groundwater Dynamics ◽  
Impact Studies ◽  
Change Impact

Abstract. Future risks for groundwater resources, due to global change are usually analyzed by driving hydrological models with the outputs of climate models. However, this model chain is subject to considerable uncertainties. Given the high uncertainties it is essential to identify the processes governing the groundwater dynamics, as these processes are likely to affect groundwater resources in the future, too. Information about the dominant mechanisms can be achieved by the analysis of long-term data, which are assumed to provide insight in the reaction of groundwater resources to changing conditions (weather, land use, water demand). Referring to this, a dataset of 30 long-term time series of precipitation dominated groundwater systems in northern Switzerland and southern Germany is collected. In order to receive additional information the analysis of the data is carried out together with hydrological model simulations. High spatio-temporal correlations, even over large distances could be detected and are assumed to be related to large-scale atmospheric circulation patterns. As a result it is suggested to prefer innovative weather-type-based downscaling methods to other stochastic downscaling approaches. In addition, with the help of a qualitative procedure to distinguish between meteorological and anthropogenic causes it was possible to identify processes which dominated the groundwater dynamics in the past. It could be shown that besides the meteorological conditions, land use changes, pumping activity and feedback mechanisms governed the groundwater dynamics. Based on these findings, recommendations to improve climate change impact studies are suggested.

The Annual Cycle of Fractional Atmospheric Shortwave Absorption in Observations and Models: Spatial Structure, Magnitude, and Timing

2019 ◽  
Vol 32 (20) ◽  
pp. 6729-6748 ◽  
Author(s):  
M. Schwarz ◽  
D. Folini ◽  
S. Yang ◽  
M. Wild
Keyword(s):  
Water Vapor ◽  
Biomass Burning ◽  
Annual Cycle ◽  
Climate Models ◽  
Global Scale ◽  
Shortwave Radiation ◽  
Minor Role ◽  
Annual Cycles ◽  
Regional Feature ◽  
A Minor

We use the best currently available in situ and satellite-derived surface and top-of-the-atmosphere (TOA) shortwave radiation observations to explore climatological annual cycles of fractional (i.e., normalized by incoming radiation at the TOA) atmospheric shortwave absorption [Formula: see text] on a global scale. The analysis reveals that [Formula: see text] is a rather regional feature where the reported nonexisting [Formula: see text] in Europe is an exception rather than the rule. In several regions, large and distinctively different [Formula: see text] are apparent. The magnitudes of [Formula: see text] reach values up to 10% in some regions, which is substantial given that the long-term global mean atmospheric shortwave absorption is roughly 23%. Water vapor and aerosols are identified as major drivers for [Formula: see text] while clouds seem to play only a minor role for [Formula: see text]. Regions with large annual cycles in aerosol emissions from biomass burning also show the largest [Formula: see text]. As biomass burning is generally related to human activities, [Formula: see text] is likely also anthropogenically intensified or forced in the respective regions. We also test if climate models are able to simulate the observed pattern of [Formula: see text]. In regions where [Formula: see text] is driven by the annual cycle of natural aerosols or water vapor, the models perform well. In regions with large [Formula: see text] induced by biomass-burning aerosols, the models’ performance is very limited.

scholarly journals Assessing Climate Change and Land-Use Impacts on Drinking Water Resources in Karstic Catchments (Southern Croatia)

2021 ◽  
Vol 13 (9) ◽  
pp. 5239
Author(s):  
Matko Patekar ◽  
Ivona Baniček ◽  
Josip Rubinić ◽  
Jasmina Lukač Reberski ◽  
Ivana Boljat ◽  
...  
Keyword(s):  
Climate Change ◽  
Land Use ◽  
Air Temperature ◽  
Climate Models ◽  
Anthropogenic Factors ◽  
Anthropogenic Activity ◽  
Land Use Impacts ◽  
Water Losses ◽  
Freshwater Resources ◽  
Southern Croatia

The Mediterranean freshwater resources, mostly represented by groundwater, are under increasing pressure due to natural and anthropogenic factors. In this study, we investigated possible negative effects of climate change and land-use practices on water quality and availability from five springs in the karstic catchments in southern Croatia. The investigated springs are used in the regional public water supply system. Firstly, we employed hydrogeochemical field and laboratory analyses to detect possible traces of anthropogenic activity originating from specific land use. Additionally, we performed hydrological and climate modeling to detect changes in the air temperature, precipitation, and runoff. In particular, we used three regional climate models (Aladin, RegCM3, and Promes). The results estimated an increase in the mean annual air temperature, changes in the precipitation patterns, and reductions in runoff in the study area. Hydrochemical analyses showed standard ion concentrations for karst groundwaters, elevated sulfates due to evaporite deposits in the hinterland, surprisingly low nitrate levels which disproved expected agricultural pollution, and high microbiological activity. Significant water losses are expected in the near future which require immediate attention in order to develop adaptation strategies that focus on sustainable utilization and resilience of freshwater resources. This paper was based on the Interreg Central Europe PROLINE-CE project research in the South Dalmatia.

Warmer climate projections in CMIP6: the role of changes in the greenhouse gas concentrations from CMIP5 to CMIP6

2020 ◽  
Author(s):  
Klaus Wyser ◽  
Erik Kjellström ◽  
Torben Koenigk ◽  
Helena Martins ◽  
Ralf Döscher
Keyword(s):  
Radiative Forcing ◽  
Climate Models ◽  
Climate Impact ◽  
Earth Model ◽  
Minor Role ◽  
Climate Projections ◽  
First Results ◽  
Effective Radiative Forcing ◽  
A Minor ◽  
New Generation

<p>Many modelling groups have contributed with CMIP6 scenario experiments to the CMIP6 archive. The analysis of CMIP6 future projections has started and first results indicate that CMIP6 projections are warmer than their counterparts from CMIP5. To some extent this is explained with the higher climate sensitivity of many of the new generation of climate models. However, not only have models been updated since CMIP5 but also the forcings have changed from RCPs to SSPs. The new SSPs have been designed to have the same instantaneous radiative forcing at the end of the 21st century. However, we find that in the EC-Earth3 model the effective radiative forcing differs substantially when the GHG concentrations from the SSP are replaced by those from the corresponding RCP with the same nameplate RF. We estimate that for the SSP5-8.5 and SSP2-4.5 scenarios 50% or more of the stronger warming in CMIP6 than CMIP5 for the EC-Earth model can be explained by changes in GHG gas concentrations. Other changes in the forcing datasets such as aerosols only play a minor role for the additional warming. The discrepancy between RCP and SSP forcing datasets needs to be accounted for when comparing CMIP5 and CMIP6 climate projections and should be properly conveyed to the climate impact, adaptation and mitigation communities.</p>

Issues in the interpretation of climate model ensembles to inform decisions

2007 ◽  
Vol 365 (1857) ◽  
pp. 2163-2177 ◽  
Author(s):  
David A Stainforth ◽  
Thomas E Downing ◽  
Richard Washington ◽  
Ana Lopez ◽  
Mark New
Keyword(s):  
Climate Change ◽  
Climate Models ◽  
Climate Model ◽  
Global Scale ◽  
Climate Modelling ◽  
Large Ensembles ◽  
Recent Developments ◽  
Climate Model Simulations ◽  
Model Ensembles ◽  
A Minor

There is a scientific consensus regarding the reality of anthropogenic climate change. This has led to substantial efforts to reduce atmospheric greenhouse gas emissions and thereby mitigate the impacts of climate change on a global scale. Despite these efforts, we are committed to substantial further changes over at least the next few decades. Societies will therefore have to adapt to changes in climate. Both adaptation and mitigation require action on scales ranging from local to global, but adaptation could directly benefit from climate predictions on regional scales while mitigation could be driven solely by awareness of the global problem; regional projections being principally of motivational value. We discuss how recent developments of large ensembles of climate model simulations can be interpreted to provide information on these scales and to inform societal decisions. Adaptation is most relevant as an influence on decisions which exist irrespective of climate change, but which have consequences on decadal time-scales. Even in such situations, climate change is often only a minor influence; perhaps helping to restrict the choice of ‘no regrets’ strategies. Nevertheless, if climate models are to provide inputs to societal decisions, it is important to interpret them appropriately. We take climate ensembles exploring model uncertainty as potentially providing a lower bound on the maximum range of uncertainty and thus a non-discountable climate change envelope. An analysis pathway is presented, describing how this information may provide an input to decisions, sometimes via a number of other analysis procedures and thus a cascade of uncertainty. An initial screening is seen as a valuable component of this process, potentially avoiding unnecessary effort while guiding decision makers through issues of confidence and robustness in climate modelling information. Our focus is the usage of decadal to centennial time-scale climate change simulations as inputs to decision making, but we acknowledge that robust adaptation to the variability of present day climate encourages the development of less vulnerable systems as well as building critical experience in how to respond to climatic uncertainty.

scholarly journals What can we learn from long-term groundwater data to improve climate change impact studies?

2011 ◽  
Vol 15 (12) ◽  
pp. 3861-3875 ◽  
Author(s):  
S. Stoll ◽  
H. J. Hendricks Franssen ◽  
R. Barthel ◽  
W. Kinzelbach
Keyword(s):  
Climate Change ◽  
Land Use ◽  
Climate Change Impact ◽  
Large Scale ◽  
Climate Models ◽  
Groundwater Resources ◽  
Groundwater Dynamics ◽  
Impact Studies ◽  
Change Impact

Abstract. Future risks for groundwater resources, due to global change are usually analyzed by driving hydrological models with the outputs of climate models. However, this model chain is subject to considerable uncertainties. Given the high uncertainties it is essential to identify the processes governing the groundwater dynamics, as these processes are likely to affect groundwater resources in the future, too. Information about the dominant mechanisms can be achieved by the analysis of long-term data, which are assumed to provide insight in the reaction of groundwater resources to changing conditions (weather, land use, water demand). Referring to this, a dataset of 30 long-term time series of precipitation dominated groundwater systems in northern Switzerland and southern Germany is collected. In order to receive additional information the analysis of the data is carried out together with hydrological model simulations. High spatio-temporal correlations, even over large distances could be detected and are assumed to be related to large-scale atmospheric circulation patterns. As a result it is suggested to prefer innovative weather-type-based downscaling methods to other stochastic downscaling approaches. In addition, with the help of a qualitative procedure to distinguish between meteorological and anthropogenic causes it was possible to identify processes which dominated the groundwater dynamics in the past. It could be shown that besides the meteorological conditions, land use changes, pumping activity and feedback mechanisms governed the groundwater dynamics. Based on these findings, recommendations to improve climate change impact studies are suggested.

scholarly journals Future challenges of representing land-processes in studies on land-atmosphere interactions

2012 ◽  
Vol 9 (9) ◽  
pp. 3587-3599 ◽  
Author(s):  
A. Arneth ◽  
L. Mercado ◽  
J. Kattge ◽  
B. B. B. Booth
Keyword(s):  
Climate Change ◽  
Land Use ◽  
Air Pollution ◽  
Land Surface ◽  
Climate Models ◽  
Human Land Use ◽  
Process Understanding ◽  
Exchange Processes ◽  
Terrestrial Biota ◽  
Future Challenges

Abstract. Over recent years, it has become increasingly apparent that climate change and air pollution need to be considered jointly for improved attribution and projections of human-caused changes in the Earth system. Exchange processes at the land surface come into play in this context, because many compounds that either act as greenhouse gases, as pollutant precursors, or both, have not only anthropogenic but also terrestrial sources and sinks. And since the fluxes of multiple gases and particulate matter between the terrestrial biota and the atmosphere are directly or indirectly coupled to vegetation and soil carbon, nutrient and water balances, quantification of their geographic patterns or changes over time requires due consideration of the underlying biological processes. In this review we highlight a number of critical aspects and recent progress in this respect, identifying in particular a number of areas where studies have shown that accounting for ecological process understanding can alter global model projections of land-atmosphere interactions substantially. Specifically, this concerns the improved quantification of uncertainties and dynamic system responses, including acclimation, and the incorporation of exchange processes that so far have been missing from global models even though they are proposed to be of relevance for our understanding of terrestrial biota-climate feedbacks. Progress has also been made regarding studies on the impacts of land use/land cover change on climate change, but the absence of a mechanistically based representation of human response-processes in ecosystem models that are coupled to climate models limits our ability to analyse how climate change or air pollution in turn might affect human land use. A more integrated perspective is necessary and should become an active area of research that bridges the socio-economic and biophysical communities.

scholarly journals Decomposition responses to climate depend on microbial community composition

2018 ◽  
Vol 115 (47) ◽  
pp. 11994-11999 ◽  
Author(s):  
Sydney I. Glassman ◽  
Claudia Weihe ◽  
Junhui Li ◽  
Michaeline B. N. Albright ◽  
Caitlin I. Looby ◽  
...  
Keyword(s):  
Climate Change ◽  
Microbial Community ◽  
Community Composition ◽  
Microbial Community Composition ◽  
Current Theory ◽  
Minor Role ◽  
Transplant Experiment ◽  
Reciprocal Transplant Experiment ◽  
Bacteria And Fungi ◽  
A Minor

Bacteria and fungi drive decomposition, a fundamental process in the carbon cycle, yet the importance of microbial community composition for decomposition remains elusive. Here, we used an 18-month reciprocal transplant experiment along a climate gradient in Southern California to disentangle the effects of the microbial community versus the environment on decomposition. Specifically, we tested whether the decomposition response to climate change depends on the microbial community. We inoculated microbial decomposers from each site onto a common, irradiated leaf litter within “microbial cages” that prevent microbial exchange with the environment. We characterized fungal and bacterial composition and abundance over time and investigated the functional consequences through litter mass loss and chemistry. After 12 months, microbial communities altered both decomposition rate and litter chemistry. Further, the functional measurements depended on an interaction between the community and its climate in a manner not predicted by current theory. Moreover, microbial ecologists have traditionally considered fungi to be the primary agents of decomposition and for bacteria to play a minor role. Our results indicate that not only does climate change and transplantation have differential legacy effects among bacteria and fungi, but also that bacterial communities might be less functionally redundant than fungi with regards to decomposition. Thus, it may be time to reevaluate both the role of microbial community composition in its decomposition response to climate and the relative roles of bacterial and fungal communities in decomposition.

scholarly journals Investigation of the effective peak supersaturation for liquid-phase clouds at the high-alpine site Jungfraujoch, Switzerland (3580 m a.s.l.)

2014 ◽  
Vol 14 (2) ◽  
pp. 1123-1139 ◽  
Author(s):  
E. Hammer ◽  
N. Bukowiecki ◽  
M. Gysel ◽  
Z. Jurányi ◽  
C. R. Hoyle ◽  
...  
Keyword(s):  
Climate Models ◽  
Cloud Condensation Nuclei ◽  
Radiation Budget ◽  
Minor Role ◽  
Research Station ◽  
Cumulus Clouds ◽  
Air Masses ◽  
The Difference ◽  
Aerosol Cloud Interactions ◽  
A Minor

Abstract. Aerosols influence the Earth's radiation budget directly through absorption and scattering of solar radiation in the atmosphere but also indirectly by modifying the properties of clouds. However, climate models still suffer from large uncertainties as a result of insufficient understanding of aerosol-cloud interactions. At the high altitude research station Jungfraujoch (JFJ; 3580 m a.s.l., Switzerland) cloud condensation nuclei (CCN) number concentrations at eight different supersaturations (SS) from 0.24% to 1.18% were measured using a CCN counter during Summer 2011. Simultaneously, in-situ aerosol activation properties of the prevailing ambient clouds were investigated by measuring the total and interstitial (non-activated) dry particle number size distributions behind two different inlet systems. Combining all experimental data, a new method was developed to retrieve the so-called effective peak supersaturation SSpeak, as a measure of the SS at which ambient clouds are formed. A 17-month CCN climatology was then used to retrieve the SSpeak values also for four earlier summer campaigns (2000, 2002, 2004 and 2010) where no direct CCN data were available. The SSpeak values varied between 0.01% and 2.0% during all campaigns. An overall median SSpeak of 0.35% and dry activation diameter of 87 nm was observed. It was found that the difference in topography between northwest and southeast plays an important role for the effective peak supersaturation in clouds formed in the vicinity of the JFJ, while differences in the number concentration of potential CCN only play a minor role. Results show that air masses coming from the southeast (with the slowly rising terrain of the Aletsch Glacier) generally experience lower SSpeak values than air masses coming from the northwest (steep slope). The observed overall median values were 0.41% and 0.22% for northwest and southeast wind conditions, respectively, corresponding to literature values for cumulus clouds and shallow-layer clouds. These cloud types are consistent with weather observations routinely performed at the JFJ.

scholarly journals Model-based scenarios of Mediterranean droughts

2007 ◽  
Vol 12 ◽  
pp. 145-151 ◽  
Author(s):  
M. Weiß ◽  
M. Flörke ◽  
L. Menzel ◽  
J. Alcamo
Keyword(s):  
Climate Change ◽  
General Circulation Model ◽  
North Africa ◽  
General Circulation ◽  
Climate Changes ◽  
Circulation Model ◽  
Hydrological Drought ◽  
Minor Role ◽  
A Minor ◽  
The Impact

Abstract. This study examines the change in current 100-year hydrological drought frequencies in the Mediterranean in comparison to the 2070s as simulated by the global model WaterGAP. The analysis considers socio-economic and climate changes as indicated by the IPCC scenarios A2 and B2 and the global general circulation model ECHAM4. Under these conditions today's 100-year drought is estimated to occur 10 times more frequently in the future over a large part of the Northern Mediterranean while in North Africa, today's 100-year drought will occur less frequently. Water abstractions are shown to play a minor role in comparison to the impact of climate change, but can intensify the situation.

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