scholarly journals Water availability in +2°C and +4°C worlds

2011 ◽  
Vol 369 (1934) ◽  
pp. 99-116 ◽  
Author(s):  
Fai Fung ◽  
Ana Lopez ◽  
Mark New
Keyword(s):  
Climate Change ◽  
Population Growth ◽  
Water Availability ◽  
Climate Models ◽  
Population Change ◽  
Spatial Coherence ◽  
World Population ◽  
Policy Objective ◽  
Positive Effects ◽  
Run Off

While the parties to the UNFCCC agreed in the December 2009 Copenhagen Accord that a 2°C global warming over pre-industrial levels should be avoided, current commitments on greenhouse gas emissions reductions from these same parties will lead to a 50 : 50 chance of warming greater than 3.5°C. Here, we evaluate the differences in impacts and adaptation issues for water resources in worlds corresponding to the policy objective (+2°C) and possible reality (+4°C). We simulate the differences in impacts on surface run-off and water resource availability using a global hydrological model driven by ensembles of climate models with global temperature increases of 2°C and 4°C. We combine these with UN-based population growth scenarios to explore the relative importance of population change and climate change for water availability. We find that the projected changes in global surface run-off from the ensemble show an increase in spatial coherence and magnitude for a +4°C world compared with a +2°C one. In a +2°C world, population growth in most large river basins tends to override climate change as a driver of water stress, while in a +4°C world, climate change becomes more dominant, even compensating for population effects where climate change increases run-off. However, in some basins where climate change has positive effects, the seasonality of surface run-off becomes increasingly amplified in a +4°C climate.

scholarly journals Skewed temperature dependence affects range and abundance in a warming world

2018 ◽  
Author(s):  
Amy Hurford ◽  
Christina A. Cobbold ◽  
Péter K. Molnár
Keyword(s):  
Climate Change ◽  
Population Growth ◽  
Climate Warming ◽  
Synergistic Effects ◽  
Climate Change Impacts ◽  
Integrodifference Equation ◽  
Positive Effects ◽  
Growth Metrics ◽  
Fitness Curve ◽  
Warming World

AbstractPopulation growth metrics such asR0are usually asymmetric functions of temperature, with cold-skewed curves arising when the positive effects of a temperature increase outweigh the negative effects, and warm-skewed curves arising in the opposite case. Classically, cold-skewed curves are interpreted as more beneficial to a species under climate warming, because cold-skewness implies increased population growth over a larger proportion of the species’ fundamental thermal niche than warm-skewness. However, inference based on the shape of the fitness curve alone, and without considering the synergistic effects of net reproduction, density, and dispersal may yield an incomplete understanding of climate change impacts. We formulate a moving-habitat integrodifference equation model to evaluate how fitness curve skewness affects species’ range size and abundance during climate warming. In contrast to classic interpretations, we find that climate warming adversely affects populations with cold-skewed fitness curves, positively affects populations with warm-skewed curves and has relatively little or mixed effects on populations with symmetric curves. Our results highlight the synergistic effects of fitness curve skewness, spatially heterogeneous densities, and dispersal in climate change impact analyses, and that the common approach of mapping changes only inR0may be misleading.

scholarly journals Skewed temperature dependence affects range and abundance in a warming world

2019 ◽  
Vol 286 (1908) ◽  
pp. 20191157 ◽  
Author(s):  
Amy Hurford ◽  
Christina A. Cobbold ◽  
Péter K. Molnár
Keyword(s):  
Climate Change ◽  
Population Growth ◽  
Climate Warming ◽  
Synergistic Effects ◽  
Climate Change Impacts ◽  
Integrodifference Equation ◽  
Positive Effects ◽  
Growth Metrics ◽  
Fitness Curve ◽  
Warming World

Population growth metrics such as R 0 are usually asymmetric functions of temperature, with cold-skewed curves arising when the positive effects of a temperature increase outweigh the negative effects, and warm-skewed curves arising in the opposite case. Classically, cold-skewed curves are interpreted as more beneficial to a species under climate warming, because cold-skewness implies increased population growth over a larger proportion of the species's fundamental thermal niche than warm-skewness. However, inference based on the shape of the fitness curve alone, and without considering the synergistic effects of net reproduction, density and dispersal, may yield an incomplete understanding of climate change impacts. We formulate a moving-habitat integrodifference equation model to evaluate how fitness curve skewness affects species’ range size and abundance during climate warming. In contrast to classic interpretations, we find that climate warming adversely affects populations with cold-skewed fitness curves, positively affects populations with warm-skewed curves and has relatively little or mixed effects on populations with symmetric curves. Our results highlight the synergistic effects of fitness curve skewness, spatially heterogeneous densities and dispersal in climate change impact analyses, and that the common approach of mapping changes only in R 0 may be misleading.

How uncertain are climate model projections of water availability indicators across the Middle East?

2010 ◽  
Vol 368 (1931) ◽  
pp. 5117-5135 ◽  
Author(s):  
Debbie Hemming ◽  
Carlo Buontempo ◽  
Eleanor Burke ◽  
Mat Collins ◽  
Neil Kaye
Keyword(s):  
Middle East ◽  
Water Availability ◽  
Large Scale ◽  
Drought Index ◽  
Climate Models ◽  
Climate Model ◽  
Regional Climate ◽  
General Distribution ◽  
The North ◽  
Run Off

The projection of robust regional climate changes over the next 50 years presents a considerable challenge for the current generation of climate models. Water cycle changes are particularly difficult to model in this area because major uncertainties exist in the representation of processes such as large-scale and convective rainfall and their feedback with surface conditions. We present climate model projections and uncertainties in water availability indicators (precipitation, run-off and drought index) for the 1961–1990 and 2021–2050 periods. Ensembles from two global climate models (GCMs) and one regional climate model (RCM) are used to examine different elements of uncertainty. Although all three ensembles capture the general distribution of observed annual precipitation across the Middle East, the RCM is consistently wetter than observations, especially over the mountainous areas. All future projections show decreasing precipitation (ensemble median between −5 and −25%) in coastal Turkey and parts of Lebanon, Syria and Israel and consistent run-off and drought index changes. The Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment Report (AR4) GCM ensemble exhibits drying across the north of the region, whereas the Met Office Hadley Centre work Quantifying Uncertainties in Model ProjectionsAtmospheric (QUMP-A) GCM and RCM ensembles show slight drying in the north and significant wetting in the south. RCM projections also show greater sensitivity (both wetter and drier) and a wider uncertainty range than QUMP-A. The nature of these uncertainties suggests that both large-scale circulation patterns, which influence region-wide drying/wetting patterns, and regional-scale processes, which affect localized water availability, are important sources of uncertainty in these projections. To reduce large uncertainties in water availability projections, it is suggested that efforts would be well placed to focus on the understanding and modelling of both large-scale processes and their teleconnections with Middle East climate and localized processes involved in orographic precipitation.

scholarly journals Climate, CO<sub>2</sub>, and demographic impacts on global wildfire emissions

2015 ◽  
Vol 12 (17) ◽  
pp. 15011-15050 ◽  
Author(s):  
W. Knorr ◽  
L. Jiang ◽  
A. Arneth
Keyword(s):  
Climate Change ◽  
Population Density ◽  
Population Growth ◽  
Biomass Burning ◽  
Human Population ◽  
Population Change ◽  
Future Climate Change ◽  
Burned Area ◽  
Human Population Density ◽  
Semi Empirical

Abstract. Wildfires are by far the largest contributor to global biomass burning and constitute a large global source of atmospheric traces gases and aerosols. Such emissions have a considerable impact on air quality and constitute a major health hazard. Biomass burning also influences the radiative balance of the atmosphere and is thus not only of societal, but also of significant scientific interest. There is a common perception that climate change will lead to an increase in emissions as hot and dry weather events that promote wildfire will become more common. However, even though a few studies have found that the inclusion of CO2 fertilization of photosynthesis and changes in human population patterns will tend to somewhat lower predictions of future wildfire emissions, no such study has included full ensemble ranges of both climate predictions and population projections, including the effect of different degrees of urbanisation. Here, we present a series of 124 simulations with the LPJ-GUESS-SIMFIRE global dynamic vegetation – wildfire model, including a semi-empirical formulation for the prediction of burned area based on fire weather, fuel continuity and human population density. The simulations comprise Climate Model Intercomparison Project 5 (CMIP5) climate predictions from eight Earth system models using two Representative Concentration Pathways (RCPs) and five scenarios of future human population density based on the series of Shared Socioeconomic Pathways (SSPs), sensitivity tests for the effect of climate and CO2, as well as a sensitivity analysis using two alternative parameterisations of the semi-empirical burned-area model. Contrary to previous work, we find no clear future trend of global wildfire emissions for the moderate emissions and climate change scenario based on the RCP 4.5. Only historical population change introduces a decline by around 15 % since 1900. Future emissions could either increase for low population growth and fast urbanisation, or continue to decline for high population growth and slow urbanisation. Only for high future climate change (RCP8.5), wildfire emissions start to rise again after ca. 2020 but are unlikely to reach the levels of 1900 by the end of the 21st century. We find that climate warming will generally increase the risk of fire, but that this is only one of several equally important factors driving future levels of wildfire emissions, which include population change, CO2 fertilisation causing woody thickening, increased productivity and fuel load, and faster litter turnover in a warmer climate.

scholarly journals Climate Adaptation in the Water Sector in India

2019 ◽  
pp. 498-518
Author(s):  
Veena Srinivasan
Keyword(s):  
Climate Change ◽  
Water Availability ◽  
Climate Models ◽  
Climate Adaptation ◽  
Hydrologic Cycle ◽  
Rainfall Trends ◽  
Droughts And Floods ◽  
Regional Redistribution ◽  
Short Term Variability

Climate change is likely to affect both the short-term variability of water resources through increased frequency and intensity of droughts and floods, and long-term changes in mean renewable water supply. Both models and historical data suggest that temperatures have increased in most parts of India, affecting the hydrologic cycle through decreased Himalayan snowpack, increased evaporation, and evapotranspirative demand by vegetation. In contrast, there are uncertainties about the climate–rainfall relationship. While most climate models predict intensification of the Indian monsoon, past rainfall trends suggest a weakening and a regional redistribution, perhaps due to local factors such as aerosols, land use change, and sea surface temperatures. Translating these uncertain projections to water availability is complicated by sparse hydrologic records and human modifications of catchments. Empirical research suggests that climate change is not the only stressor. As climate and socio-economic futures are interlinked, this requires participatory, adaptive management and mainstreaming of adaptation across agencies.

Modelling population displacement: both climate change and population growth heighten displacement risk due to river floods. 

2021 ◽  
Author(s):  
Pui Man Kam
Keyword(s):  
Climate Change ◽  
Climate Models ◽  
Climate Adaptation ◽  
Population Change ◽  
Hydrological Cycle ◽  
Well Being ◽  
Vulnerable Groups ◽  
Physical And Mental Health ◽  
Population Displacement ◽  
Displaced People

&lt;p&gt;Disaster displacements create hardships, particularly for socio-economically vulnerable groups. Displaced people face heightened risks to their well-being, including their physical and mental health and personal security. Assisting displaced people is an important part of any humanitarian response to disasters.&lt;/p&gt;&lt;p&gt;Among weather-related disasters, river flooding is responsible for a large part of population displacement. River flood risk is expected to increase due to climate change and its effects on the hydrological cycle. At the same time, socioeconomic development scenarios indicate substantial increases of population in many regions that experience flood-induced displacement.&lt;/p&gt;&lt;p&gt;We have modelled projected changes to flood-driven population displacement in the 21&lt;sup&gt;st&lt;/sup&gt; Century with the CLIMADA (CLIMate ADAptation) platform, in collaboration with the Internal Displacement Monitoring Centre.&lt;/p&gt;&lt;p&gt;We show that both climate and population change are projected to lead to an increase of relative global flood displacement risk by roughly 350% by the end of the century. If we keep the population fixed at present levels, we find a roughly 150% increase in relative global flood displacement risk by the end of the century, or a 50% increase of risk per degree of global warming. We model displacement probabilities as a function of population density, flood depth and flood fraction.&lt;/p&gt;&lt;p&gt;Although the resolution of the global model is limited, the effect of climate change is robust across greenhouse gas concentration scenarios, climate models and hydrological models. Our work potentially enables the creation of a displacement early warning system.&lt;/p&gt;

scholarly journals Should climate change make us think more about the economics of forest management?

2015 ◽  
Vol 91 (01) ◽  
pp. 23-31 ◽  
Author(s):  
Jing Yang ◽  
Daniel W. McKenney ◽  
Alfons Weersink
Keyword(s):  
Climate Change ◽  
Forest Management ◽  
Net Present Value ◽  
Climate Models ◽  
Global Climate ◽  
Economic Thought ◽  
Global Climate Models ◽  
Management Problem ◽  
Policy Objective ◽  
Intertemporal Efficiency

Forest management agencies have budget constraints and continually face difficult questions regarding how much to invest in silviculture and when to harvest forests. Economic thought suggests these decisions should be guided by the pursuit of economic efficiency and tools like net present value (NPV) analysis. In forestry this would make use of the so-called Faustmann model and generally result in shorter rotation ages than the Maximum Sustained Yield (MSY) criterion, which is often used as a policy objective in forest management. The two approaches have caused tension and controversy between foresters and economists. Climate change is adding yet another uncertainty dimension to the forest management challenge. Global climate models suggest massive changes in climate this coming century that will surely affect forests. Here we use climate change as a backdrop to compare the MSY and Faustmann results for black spruce (Picea mariana) and white pine (Pinus strobus) in Ontario. Climate change is adding new risks to silvicultural investments. Our intent is not to “resolve” the management problem but highlight some issues and differences between the two approaches. We suggest that climate change could, or should, cause a resurgence of the debate over pursuit of intertemporal efficiency in forest management.

scholarly journals Competition for water for the food system

2010 ◽  
Vol 365 (1554) ◽  
pp. 2927-2940 ◽  
Author(s):  
Kenneth Strzepek ◽  
Brent Boehlert
Keyword(s):  
Climate Change ◽  
Water Availability ◽  
Food Systems ◽  
Food System ◽  
Temporal Distribution ◽  
Agricultural System ◽  
Agricultural Water ◽  
Run Off ◽  
Eastern Australia ◽  
To Come

Although the global agricultural system will need to provide more food for a growing and wealthier population in decades to come, increasing demands for water and potential impacts of climate change pose threats to food systems. We review the primary threats to agricultural water availability, and model the potential effects of increases in municipal and industrial (M&I) water demands, environmental flow requirements (EFRs) and changing water supplies given climate change. Our models show that, together, these factors cause an 18 per cent reduction in the availability of worldwide water for agriculture by 2050. Meeting EFRs, which can necessitate more than 50 per cent of the mean annual run-off in a basin depending on its hydrograph, presents the single biggest threat to agricultural water availability. Next are increases in M&I demands, which are projected to increase upwards of 200 per cent by 2050 in developing countries with rapidly increasing populations and incomes. Climate change will affect the spatial and temporal distribution of run-off, and thus affect availability from the supply side. The combined effect of these factors can be dramatic in particular hotspots, which include northern Africa, India, China, parts of Europe, the western US and eastern Australia, among others.

scholarly journals Assessment of future water availability under climate change, considering scenarios for population growth and ageing infrastructure

2018 ◽  
Vol 10 (1) ◽  
pp. 1-12 ◽  
Author(s):  
Erle Kristvik ◽  
Tone M. Muthanna ◽  
Knut Alfredsen
Keyword(s):  
Climate Change ◽  
Population Growth ◽  
Water Availability ◽  
Distribution Systems ◽  
Water Distribution ◽  
Hydrological Cycle ◽  
Climate Projections ◽  
Local Climate ◽  
The City ◽  
Impacts Of Climate Change

Abstract Climate change is likely to cause higher temperatures and alterations in precipitation patterns, with potential impacts on water resources. One important issue in this respect is inflow to drinking water reservoirs. Moreover, deteriorating infrastructures cause leakage in water distribution systems and urbanization augments water demand in cities. In this paper, a framework for assessing the combined impacts of multiple trends on water availability is proposed. The approach is focused on treating uncertainty in local climate projections in order to be of practical use to water suppliers and decision makers. An index for water availability (WAI) is introduced to quantify impacts of climate change, population growth, and ageing infrastructure, as well as the effects of implementing counteractive measures, and has been applied to the city of Bergen, Norway. Results of the study emphasize the importance of considering a range of climate scenarios due to the wide spread in global projections. For the specific case of Bergen, substantial alterations in the hydrological cycle were projected, leading to stronger seasonal variations and a more unpredictable water availability. By sensitivity analysis of the WAI, it was demonstrated how two adaptive measures, increased storage capacity and leakage reduction, can help counteract the impacts of climate change.

Vulnerability of Human Populations to Climate Change

2019 ◽  
pp. 22-40
Author(s):  
Abdelkrim Ben Salem ◽  
Souad Ben Salem ◽  
Kholoud Kahime ◽  
Mohammed Messouli ◽  
Mohammed Yacoubi Khebiza
Keyword(s):  
Climate Change ◽  
Water Availability ◽  
Integrated Assessment ◽  
Human Population ◽  
Vulnerability Index ◽  
Human Populations ◽  
Social Scientists ◽  
Socioeconomic Vulnerability ◽  
Run Off ◽  
Key Features

Moroccan ecosystems are considered endangered due to climate change that affects directly or indirectly different key features (biodiversity, snow cover, run-off processes, and water availability). The chapter describes the strategy for achieving collaboration between natural and social scientists, stakeholders, decision makers, and other societal groups in order to carry out an integrated assessment of climate change in the 12 Moroccan regions, with an emphasis on vulnerability and adaptation, and evaluate the vulnerability of human population to climate change applying the socioeconomic vulnerability index (SeVI) that measures socioeconomic vulnerability by regions. Result suggest that three southern and one north region are relatively more vulnerable, which are the most exposed to natural hazard. Furthermore, significant adaptive capacity scores are recorded in in the remaining regions, and average sensitivity for all. Therefore, societies and economies at all levels and on every region have to prepare for and adapt to impacts of climate change.

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