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  • 1
    Online Resource
    Online Resource
    Dordrecht :Springer Netherlands,
    Keywords: Climatic changes--Africa. ; Climatic changes--Social aspects--Africa. ; Klimaänderung. swd. ; Afrika. swd. ; Aufsatzsammlung. ; Electronic books.
    Type of Medium: Online Resource
    Pages: 1 online resource (209 pages)
    Edition: 1st ed.
    ISBN: 9789048138425
    Series Statement: Advances in Global Change Research Series ; v.43
    DDC: 551.696
    Language: English
    Note: Intro -- Contents -- Contributors -- Introduction -- 1 General Background -- 2 Uncertainty over Climate Change -- 3 Reasons for Particularly High Vulnerability of Africa -- 4 Expected Impacts of Climate Change on Africa -- 5 Options for Reducing Vulnerability -- 6 Structure of Book -- References -- Large Scale Features Affecting Ethiopian Rainfall -- 1 Introduction -- 2 Data and Methods -- 2.1 Data -- 2.1.1 Rain Gauge Data -- 2.1.2 Other Data -- 2.2 Methods -- 3 Large Scale Features Associated with Kiremt Rainfall Anomalies -- 3.1 Upper Level Tropospheric Wind and Tropical Easterly Jet (TEJ) -- 3.2 Stratospheric Influence - Quasi Biennial Oscillation (QBO) -- 3.3 African Easterly Jet (AEJ) -- 3.4 Inter-Tropical Convergence Zone (ITCZ) -- 3.5 Low Level Humidity -- 3.6 Low Level wind -- 3.7 Low Level Pressure -- 3.8 ENSO -- 3.9 Discussion on Kiremt Large Scale Features -- 4 Large Scale Features Associated with Belg Rainfall Anomalies -- 4.1 Sub-Tropical Westerly Jet (STWJ) -- 4.2 Low Level Humidity -- 4.3 Low Level Wind -- 4.4 Low Level High Pressures -- 4.5 ENSO -- 4.6 Indian Ocean Related Teleconnections -- 4.7 Discussion on Belg Season Large Scale Features -- 5 Summary and Conclusions -- References -- Ethiopian Rainfall in Climate Models -- 1 Introduction -- 2 Models, Observations and Methodologies -- 3 Ethiopian Rainfall in HadAM3 and HiGAM -- 3.1 The Geographical Distribution of Kiremt Rainfall -- 3.2 The Seasonal Cycle of Rainfall in Ethiopia -- 4 Interannual Variability of Ethiopian Rainfall -- 4.1 Kiremt Rainfall Time-Series -- 4.2 Kiremt Rainfall and Atmospheric Circulation Anomalies -- 5 Conclusions and Discussion -- References -- Extreme Rainfall Events over Southern Africa -- 1 Introduction -- 2 Data and Model Details -- 2.1 Satellite-Derived and Reanalysis Data -- 2.2 Model Details. , 3 Definition and Identification of Extremes, Associated SST Anomalies and Model Experiments -- 3.1 Definition and Identification of Extremes -- 3.2 Rainfall, Pressure and SST Anomalies Associated with Extremes -- 3.3 Model Experiments -- 4 Model Experiment Results: HadAM3 -- 4.1 Rainfall Spatial Averages and Daily Rainfall Extremes -- 4.2 Pixel-by-Pixel Temporal Averages -- 4.2.1 Mean Daily Rainfall and Rainfall Variability -- 4.2.2 Large-Scale Atmospheric Associations with Daily Rainfall Means -- 5 Model Experiment Results: PRECIS -- 5.1 Rainfall Spatial Averages and Daily Rainfall Extremes -- 5.2 Pixel-by-Pixel Temporal Averages of Daily Rainfall -- 6 Conclusions -- References -- Understanding the Large Scale Driving Mechanisms of Rainfall Variability over Central Africa -- 1 Introduction/Rationale -- 2 Review of the Main Drivers of Central African Climatology -- 2.1 Convective Systems -- 2.2 The ITCZ -- 2.3 Sea Surface Temperature -- 2.4 Central African Jets -- 3 Teleconnections -- 3.1 EL Nino Southern Oscillation (ENSO) -- 3.2 Large-Scale Circulation -- 4 Methodology -- 4.1 Data Sources -- 4.2 Regions -- 4.3 Composite Analysis -- 5 Analysis of Rainfall Variability over Central Africa -- 5.1 Region B (0--6S, 18--32E) -- Rainfall Seasonal Cycle and Time Series Analysis -- 5.2 Analysis of Region B's Wet and Dry Year Composites During the Primary Rainy Season (MAM) -- 5.3 Analysis of Region B's Wet and Dry Year Composites During the Secondary Rainy Season (SON) -- 5.4 Region E (3--5--N, 15--22E and 5--7--N, 22--32E) -- Rainfall Seasonal Cycle and Time Series Analysis -- 5.5 Cause of Extreme and Deficit Rainfall During the Apr--Oct Rainy Season -- 6 Summary of Findings -- References -- Climate Change Impacts on Hydrology in Africa: Case Studies of River Basin Water Resources -- 1 Introduction -- 2 Summary of Changes to the Hydrological Cycle in Africa. , 2.1 Historical Observations -- 2.2 Future Projections -- 2.3 Uncertainty in Projected Climate Change Impacts -- 3 Case Study I: The Okavango River System -- 3.1 Hydro-Climate and Development Context -- 3.2 Hydrological Modeling Tools -- 3.3 Methodology for Climate Impacts Simulation -- 3.4 Simulated Future Climate Change -- 3.5 Summary of Results from Okavango River Case Study -- 4 Case Study II: The Mitano River Basin, Uganda -- 4.1 The Hydro-Climate and Development Context -- 4.2 Hydrological Modeling -- 4.3 Methodology for Climate Impacts Simulation -- 4.4 Simulated Future Climate Change -- 4.5 Summary of Results from Mitano River Case Study and Implications for Water -- 5 Discussion and Conclusions -- References -- Adaptation to Climate Change and Variability: Farmer Responses to Intra-seasonal Precipitation Trends in South Africa -- 1 Introduction -- 2 Climate Variability, Uncertainty and Change -- 2.1 Climate Variables: Informing Adaptation Research -- 3 Investigating Climate Variability Through Self Organising Mapping -- 3.1 Study Region Characteristics -- 4 Living with Risk and Uncertainty -- 5 Recognising Changes in Climate -- 5.1 Changing Climate Risk -- 6 Strategies in Response to Disturbance and Change -- 6.1 Changes to Farming Practices: Short-Term Coping -- 6.2 Exploiting the Spatial and Temporal Diversity of the Landscape -- 6.3 Commercialising Livelihoods Through Individual and Collective Action -- 7 Discussion -- 8 Conclusion -- References -- Climate Change and Migration: A Modelling Approach -- 1 Introduction -- 2 Climate Change Migration Modelling -- 3 Proactive Conceptual Development -- 4 Bounded Rationality -- 5 Reactive Conceptual Development -- 6 Conceptual Model Development -- 7 Translation into An Agent-Based Model -- 8 Model Validation -- 9 Conclusion -- References -- Index.
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  • 2
    Publication Date: 2021-07-01
    Description: The modeling of paleoclimate, using physically based tools, is increasingly seen as a strong out-of-sample test of the models that are used for the projection of future climate changes. New to the Coupled Model Intercomparison Project (CMIP6) is the Tier 1 Last Interglacial experiment for 127 000 years ago (lig127k), designed to address the climate responses to stronger orbital forcing than the midHolocene experiment, using the same state-of-the-art models as for the future and following a common experimental protocol. Here we present a first analysis of a multi-model ensemble of 17 climate models, all of which have completed the CMIP6 DECK (Diagnostic, Evaluation and Characterization of Klima) experiments. The equilibrium climate sensitivity (ECS) of these models varies from 1.8 to 5.6 ∘C. The seasonal character of the insolation anomalies results in strong summer warming over the Northern Hemisphere continents in the lig127k ensemble as compared to the CMIP6 piControl and much-reduced minimum sea ice in the Arctic. The multi-model results indicate enhanced summer monsoonal precipitation in the Northern Hemisphere and reductions in the Southern Hemisphere. These responses are greater in the lig127k than the CMIP6 midHolocene simulations as expected from the larger insolation anomalies at 127 than 6 ka. New synthesis for surface temperature and precipitation, targeted for 127 ka, have been developed for comparison to the multi-model ensemble. The lig127k model ensemble and data reconstructions are in good agreement for summer temperature anomalies over Canada, Scandinavia, and the North Atlantic and for precipitation over the Northern Hemisphere continents. The model–data comparisons and mismatches point to further study of the sensitivity of the simulations to uncertainties in the boundary conditions and of the uncertainties and sparse coverage in current proxy reconstructions. The CMIP6–Paleoclimate Modeling Intercomparison Project (PMIP4) lig127k simulations, in combination with the proxy record, improve our confidence in future projections of monsoons, surface temperature, and Arctic sea ice, thus providing a key target for model evaluation and optimization.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
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  • 3
    Publication Date: 2022-05-01
    Description: Despite tectonic conditions and atmospheric CO2 levels (pCO2) similar to those of present-day, geological reconstructions from the mid-Pliocene (3.3-3.0 Ma) document high lake levels in the Sahel and mesic conditions in subtropical Eurasia, suggesting drastic reorganizations of subtropical terrestrial hydroclimate during this interval. Here, using a compilation of proxy data and multi-model paleoclimate simulations, we show that the mid-Pliocene hydroclimate state is not driven by direct CO2 radiative forcing but by a loss of northern high-latitude ice sheets and continental greening. These ice sheet and vegetation changes are long-term Earth system feedbacks to elevated pCO2. Further, the moist conditions in the Sahel and subtropical Eurasia during the mid-Pliocene are a product of enhanced tropospheric humidity and a stationary wave response to the surface warming pattern, which varies strongly with land cover changes. These findings highlight the potential for amplified terrestrial hydroclimate responses over long timescales to a sustained CO2 forcing.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
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  • 4
    Publication Date: 2021-08-25
    Description: El Niño–Southern Oscillation (ENSO) is the strongest mode of interannual climate variability in the current climate, influencing ecosystems, agriculture, and weather systems across the globe, but future projections of ENSO frequency and amplitude remain highly uncertain. A comparison of changes in ENSO in a range of past and future climate simulations can provide insights into the sensitivity of ENSO to changes in the mean state, including changes in the seasonality of incoming solar radiation, global average temperatures, and spatial patterns of sea surface temperatures. As a comprehensive set of coupled model simulations is now available for both palaeoclimate time slices (the Last Glacial Maximum, mid-Holocene, and last interglacial) and idealised future warming scenarios (1 % per year CO2 increase, abrupt four-time CO2 increase), this allows a detailed evaluation of ENSO changes in this wide range of climates. Such a comparison can assist in constraining uncertainty in future projections, providing insights into model agreement and the sensitivity of ENSO to a range of factors. The majority of models simulate a consistent weakening of ENSO activity in the last interglacial and mid-Holocene experiments, and there is an ensemble mean reduction of variability in the western equatorial Pacific in the Last Glacial Maximum experiments. Changes in global temperature produce a weaker precipitation response to ENSO in the cold Last Glacial Maximum experiments and an enhanced precipitation response to ENSO in the warm increased CO2 experiments. No consistent relationship between changes in ENSO amplitude and annual cycle was identified across experiments.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
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  • 5
    Publication Date: 2021-08-25
    Description: The mid-Holocene (6000 years ago) is a standard time period for the evaluation of the simulated response of global climate models using palaeoclimate reconstructions. The latest mid-Holocene simulations are a palaeoclimate entry card for the Palaeoclimate Model Intercomparison Project (PMIP4) component of the current phase of the Coupled Model Intercomparison Project (CMIP6) – hereafter referred to as PMIP4-CMIP6. Here we provide an initial analysis and evaluation of the results of the experiment for the mid-Holocene. We show that state-of-the-art models produce climate changes that are broadly consistent with theory and observations, including increased summer warming of the Northern Hemisphere and associated shifts in tropical rainfall. Many features of the PMIP4-CMIP6 simulations were present in the previous generation (PMIP3-CMIP5) of simulations. The PMIP4-CMIP6 ensemble for the mid-Holocene has a global mean temperature change of −0.3 K, which is −0.2 K cooler than the PMIP3-CMIP5 simulations predominantly as a result of the prescription of realistic greenhouse gas concentrations in PMIP4-CMIP6. Biases in the magnitude and the sign of regional responses identified in PMIP3-CMIP5, such as the amplification of the northern African monsoon, precipitation changes over Europe, and simulated aridity in mid-Eurasia, are still present in the PMIP4-CMIP6 simulations. Despite these issues, PMIP4-CMIP6 and the mid-Holocene provide an opportunity both for quantitative evaluation and derivation of emergent constraints on the hydrological cycle, feedback strength, and potentially climate sensitivity.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
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  • 6
    Publication Date: 2021-09-06
    Description: The mid-Pliocene warm period (mPWP; ∼3.2 million years ago) is seen as the most recent time period characterized by a warm climate state, with similar to modern geography and ∼400 ppmv atmospheric CO2 concentration, and is therefore often considered an interesting analogue for near-future climate projections. Paleoenvironmental reconstructions indicate higher surface temperatures, decreasing tropical deserts, and a more humid climate in West Africa characterized by a strengthened West African Monsoon (WAM). Using model results from the second phase of the Pliocene Modelling Intercomparison Project (PlioMIP2) ensemble, we analyse changes of the WAM rainfall during the mPWP by comparing them with the control simulations for the pre-industrial period. The ensemble shows a robust increase in the summer rainfall over West Africa and the Sahara region, with an average increase of 2.5 mm/d, contrasted by a rainfall decrease over the equatorial Atlantic. An anomalous warming of the Sahara and deepening of the Saharan Heat Low, seen in 〉90 % of the models, leads to a strengthening of the WAM and an increased monsoonal flow into the continent. A similar warming of the Sahara is seen in future projections using both phase 3 and 5 of the Coupled Model Intercomparison Project (CMIP3 and CMIP5). Though previous studies of future projections indicate a west–east drying–wetting contrast over the Sahel, PlioMIP2 simulations indicate a uniform rainfall increase in that region in warm climates characterized by increasing greenhouse gas forcing. We note that this effect will further depend on the long-term response of the vegetation to the CO2 forcing.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
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  • 7
    Publication Date: 2022-01-10
    Description: The mid-Pliocene warm period (3.264–3.025 Ma) is the most recent geological period during which atmospheric CO2 levels were similar to recent historical values (∼400 ppm). Several proxy reconstructions for the mid-Pliocene show highly reduced zonal sea surface temperature (SST) gradients in the tropical Pacific Ocean, indicating an El Niño-like mean state. However, past modelling studies do not show these highly reduced gradients. Efforts to understand mid-Pliocene climate dynamics have led to the Pliocene Model Intercomparison Project (PlioMIP). Results from the first phase (PlioMIP1) showed clear El Niño variability (albeit significantly reduced) and did not show the greatly reduced time-mean zonal SST gradient suggested by some of the proxies. In this work, we study El Niño–Southern Oscillation (ENSO) variability in the PlioMIP2 ensemble, which consists of additional global coupled climate models and updated boundary conditions compared to PlioMIP1. We quantify ENSO amplitude, period, spatial structure and “flavour”, as well as the tropical Pacific annual mean state in mid-Pliocene and pre-industrial simulations. Results show a reduced ENSO amplitude in the model-ensemble mean (−24 %) with respect to the pre-industrial, with 15 out of 17 individual models showing such a reduction. Furthermore, the spectral power of this variability considerably decreases in the 3–4-year band. The spatial structure of the dominant empirical orthogonal function shows no particular change in the patterns of tropical Pacific variability in the model-ensemble mean, compared to the pre-industrial. Although the time-mean zonal SST gradient in the equatorial Pacific decreases for 14 out of 17 models (0.2 ∘C reduction in the ensemble mean), there does not seem to be a correlation with the decrease in ENSO amplitude. The models showing the most “El Niño-like” mean state changes show a similar ENSO amplitude to that in the pre-industrial reference, while models showing more “La Niña-like” mean state changes generally show a large reduction in ENSO variability. The PlioMIP2 results show a reasonable agreement with both time-mean proxies indicating a reduced zonal SST gradient and reconstructions indicating a reduced, or similar, ENSO variability.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
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  • 8
    Publication Date: 2022-01-10
    Description: The mid-Pliocene (∼3 Ma) is one of the most recent warm periods with high CO2 concentrations in the atmosphere and resulting high temperatures, and it is often cited as an analog for near-term future climate change. Here, we apply a moisture budget analysis to investigate the response of the large-scale hydrological cycle at low latitudes within a 13-model ensemble from the Pliocene Model Intercomparison Project Phase 2 (PlioMIP2). The results show that increased atmospheric moisture content within the mid-Pliocene ensemble (due to the thermodynamic effect) results in wetter conditions over the deep tropics, i.e., the Pacific intertropical convergence zone (ITCZ) and the Maritime Continent, and drier conditions over the subtropics. Note that the dynamic effect plays a more important role than the thermodynamic effect in regional precipitation minus evaporation (PmE) changes (i.e., northward ITCZ shift and wetter northern Indian Ocean). The thermodynamic effect is offset to some extent by a dynamic effect involving a northward shift of the Hadley circulation that dries the deep tropics and moistens the subtropics in the Northern Hemisphere (i.e., the subtropical Pacific). From the perspective of Earth's energy budget, the enhanced southward cross-equatorial atmospheric transport (0.22 PW), induced by the hemispheric asymmetries of the atmospheric energy, favors an approximately 1∘ northward shift of the ITCZ. The shift of the ITCZ reorganizes atmospheric circulation, favoring a northward shift of the Hadley circulation. In addition, the Walker circulation consistently shifts westward within PlioMIP2 models, leading to wetter conditions over the northern Indian Ocean. The PlioMIP2 ensemble highlights that an imbalance of interhemispheric atmospheric energy during the mid-Pliocene could have led to changes in the dynamic effect, offsetting the thermodynamic effect and, hence, altering mid-Pliocene hydroclimate.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
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