Mid-21st Century Research Articles

Near-term impact of climate variability on yam rot incidence over a humid tropical region: projections in CORDEX-Africa scenarios

AbstractThe global population is projected to be enormous by the mid-21st century, whereas, most essential crops being sustained by the rain-fed agriculture are threatened by climate change. Therefore, the study investigated the projected near-future effect of rainfall variability on rot incidence and yam production in humid tropical Nigeria. Production data from the Food and Agriculture Organization and the Nigeria National Bureau of Statistics showed the significant increasing trend in the annual yam output. The field survey conducted in 2018 showed that the maximum percentage of rot incidence occurred in July. Climate Research Unit observational rainfall data from 1979 to 2018 showed the nonsignificant trend in the interannual rainfall variability; however, it showed low variability and a significant decreasing trend in the July rainfall. A pathogenicity test on yam samples confirmed rot by fungi, bacteria and nematodes as virulent pathogens, whereas, the nutritional qualities of the rotted yams were indicated. Monthly rainfall and rot incidence showed positive correlation (r = 0.84, significant at 99% from t-test). The positive characteristic impact values indicated that increase (decrease) in the monthly rainfall corresponds to increase (decrease) in the magnitude of monthly percentage rot incidence. Thus, the significantly decreasing rainfall reduced the quantity of rot incidence and consequently increased the annual yam production for the period. Selected CoOrdinated Regional Downscaling EXperiment-Africa models and the ensemble mean showed a good measure of agreement with observational rainfall in the historical experiments. The efficiencies of the bias-corrected outputs in the representative concentration pathway (RCP) 4.5 and 8.5 indicated improved ‘reasonable’ performances. Bias-corrected projections of the July rainfall showed an increasing trend in both the RCPs, which indicate a potential increase in rot incidence and the consequent decline in annual yam production. The findings are imperative in sustaining the global food supply.

Assessing Future Impacts of Climate Change on Streamflow within the Alabama River Basin

Global climate change is expected to impact future precipitation and surface temperature trends and could alter local hydrologic systems. This study assessed the likely hydrologic responses and changes in streamflow due to future climate change within the Alabama River Basin (ARB) for the mid-21st century 2045 (“2030–2060”) and end-21st century 2075 (“2060–2090”). Using an integrated modeling approach, General Circulation Model (GCM) datasets; the Centre National de Recherches Météorologiques Climate Model 5 (CNRM-CM5), the Community Earth System Model, version 1–Biogeochemistry (CESM1- BGC.1), and the Hadley Centre Global Environment Model version 2 (HADGEM2-AO.1), under medium Representative Concentration Pathway (RCP) 4.5, and based on World Climate Research Program (WCRP)’s Couple Model Intercomparison Phase 5 (CMIP5), were assimilated into calibrated Soil and Water Assessment Tool (SWAT). Mann–Kendall and Theil Sen’s slope were used to assess the trends and magnitude of variability of the historical climate data used for setting up the model. The model calibration showed goodness of fit with minimum Nash–Sutcliffe Efficiency (NSE) coefficient values of 0.83 and Coefficient of Determination (R2) of 0.88 for the three gages within the ARB. Next, the research assessed changes in streamflow for the years 2045 and 2075 against that of the reference baseline year of 1980. The results indicate situations of likely increase and decrease in mean monthly streamflow discharge and increase in the frequency and variability in peak flows during the periods from the mid to end of the 21st century. Seasonally, monthly streamflow increases between 50% and 250% were found for spring and autumn months with decreases in summer months for 2045. Spring and summer months for 2075 resulted in increased monthly streamflow between 50% and 300%, while autumn and spring months experienced decreased streamflow. While the results are prone to inherent uncertainties in the downscaled GCM data used, the simulated dynamics in streamflow and water availability provide critical information for stakeholders to develop sustainable water management and climate change adaptation options for the ARB.

Differential responses in anti-predation traits of the native oyster Ostrea edulis and invasive Magallana gigas to ocean acidification and warming

Ocean acidification and warming (OAW) pose a threat to marine organisms, with particular negative effects on molluscs, and can jeopardize the provision of associated ecosystem services. As predation is an important factor shaping populations in the marine environment, the ability of organisms to retain traits valuable in predation resistance under OAW may be decisive for future population maintenance. We examine how exposure to seawater temperature (control: 16.8°C and warm: 20°C) and atmosphericpCO2(ambient [~400], ~750, and ~1000 ppm) conditions affects traits linked to predation resistance (adductor muscle strength and shell strength) in two ecologically and economically important species of oysters (Magallana gigasandOstrea edulis) and relate them to changes in morphometry and fitness (condition index, muscle and shell metrics). We show thatO. edulisremained unimpacted following exposure to OAW scenarios. In contrast, the adductor muscle ofM. gigaswas 52% stronger under elevated temperature and ~750 ppmpCO2, and its shell was 44% weaker under combined elevated temperature and ~1000 ppmpCO2.This suggests greater resistance to mechanical predation toward the mid-21stcentury, but greater susceptibility toward the end of the century. For both species, individuals with more somatic tissue held an ecological advantage against predators; consequently, smaller oysters may be favoured by predators under OAW. By affecting fitness and predation resistance, OAW may be expected to induce shifts in predator-prey interactions and reshape assemblage structure due to species and size selection, which may consequently modify oyster reef functioning. This could in turn have implications for the provision of associated ecosystem services.

Climate change impact on streamflow in a tropical basin of Ghana, West Africa

Study regionPra River Basin, Ghana, West Africa. Study focusIn this study, variations of the future streamflow in the Pra River Basin (PRB), are projected using the Soil and Water Analysis Tool (SWAT) model with bias-corrected climate data from regional climate models (RCMs) for the near 21 st century (2010–2039), the mid 21 st century (2040–2069), and the end of the 21 st century (2070–2099), under two Representative Concentration Pathways (RCP4.5 and RCP8.5). Weighting, scaling and ranking techniques were applied to the data from each of the seventeen climate stations to select the climate models that best reproduced the observation dataset. New hydrological insights for the regionThe results from the calibration and validation (R2 and NSE > 0.75, and PBIAS within ±10 %), revealed good simulation of the PRB hydrology from the SWAT model. Annually, streamflow in the near and the mid-21st century is projected to increase within 4 % and 12 % while a reduction was projected at the end of the 21 st century with the RCP4.5 emission scenario. The simulation results from the RCP8.5 scenario showed increase streamflow throughout the 21 st century applying the best performing models. Monthly streamflow variations varied between -15 % and 23 % for RCP4.5, and -24 % to 24 % for RCP8.5. Generally, increasing streamflow was highest in the RCP4.5 emission scenario. In view of the model outcomes, the PRB is expected to experience upsurge in streamflow by the near and the mid of the 21 st century. This would require proper planning by applying cost-effective adaptative water management strategies to provide for the probable influence of climate change on the future water resources of the basin.

Climate variability affects water-energy-food infrastructure performance in East Africa

Summary The need to assess major infrastructure performance under a changing climate is widely recognized yet rarely practiced, particularly in rapidly growing African economies. Here, we consider high-stakes investments across the water, energy, and food sectors for two major river basins in a climate transition zone in Africa. We integrate detailed interpretation of observed and modeled climate-system behavior with hydrological modeling and decision-relevant performance metrics. For the Rufiji River in Tanzania, projected risks for the mid-21st century are similar to those of the present day, but for the Lake Malawi-Shire River, future risk exceeds that experienced during the 20th century. In both basins a repeat of an early-20th century multi-year drought would challenge the viability of proposed infrastructure. A long view, which emphasizes past and future changes in variability, set within a broader context of climate-information interpretation and decision making, is crucial for screening the risk to infrastructure.

Predicting U.S. Residential Building Energy Use and Indoor Pollutant Exposures in the Mid-21st Century.

The extent to which climate change and other factors will influence building energy use and population exposures to indoor pollutants is not well understood. Here, we develop and apply nationally representative residential energy and indoor pollutant model sets to estimate energy use, indoor pollutant concentrations, and associated chronic health outcomes across the U.S. residential building stock in the mid-21st century. The models incorporate expected changes in meteorological and ambient air quality conditions associated with IPCC RCP 8.5 and assumptions for changes in housing characteristics and population movements while keeping other less predictable factors constant. Site and source energy consumption for residential space-conditioning are predicted to decrease by ∼37-43 and ∼20-31%, respectively, in the 2050s compared to those in a 2010s reference scenario. Population-average indoor concentrations of pollutants of ambient origin are expected to decrease, except for O3. Holding indoor emission factors constant, indoor concentrations of pollutants with intermittent indoor sources are expected to decrease by <5% (PM2.5) to >30% (NO2); indoor concentrations of pollutants with persistent indoor sources (e.g., volatile organic compounds (VOCs)) are predicted to increase by ∼15-45%. We estimate negligible changes in disability-adjusted life-years (DALYs) lost associated with residential indoor pollutant exposures, well within uncertainty, although the attribution among pollutants is predicted to vary.

Variation of sea ice and perspectives of the Northwest Passage in the Arctic Ocean

The continued warming of the Arctic atmosphere and ocean has led to a record retreat of sea ice in the last decades. This retreat has increased the probability of the opening of the Arctic Passages in the near future. The Northwest Passage (NWP) is the most direct shipping route between the Atlantic and Pacific Oceans, producing notable economic benefits. Decadal variations of sea ice and its influencing factors from a high-resolution unstructured-grid finite-volume community ocean model were investigated along the NWP in 1988–2016, and the accessibility of the NWP was assessed under shared socioeconomic pathways (SSP245 and 585) and two vessel classes with the Arctic transportation accessibility model in 2021–2050. Sea ice thickness has decreased with increasing seawater temperature and salinity, especially within the Canadian Arctic Archipelago (CAA) in 1988–2016, which has facilitated the opening of the NWP. Complete ship navigation is projected to be possible for polar class 6 ships in August–December in 2021–2025, after when it may extends to July under SSP585 in 2026–2030, while open water ships will not be able to pass through the NWP until September in mid-21st century. The navigability of the NWP is mainly affected by the ice within the CAA. For the accessibility of the Parry Channel, the west part is worse than that of the eastern part, especially in the Viscount-Melville Sound.

The Mistake on the Snake: The Lower Snake River Dams

Congressman Mike Simpson’s proposal to remove the four federal dams on the Lower Snake River (LSR) has reenergized the longstanding debate over the future of those dams, their narrow benefits, and their substantial costs, particularly to Endangered Species Act-listed Snake River salmon. This article examines the LSR dams, their history and justification, their role in sending Snake River on a path toward extinction from which they have yet to recover, and their impending liabilities under the Endangered Species and Clean Water Acts. The Simpson proposal, while arresting, is so freighted with spending on replacement power and river navigation improvements, for example, that its estimated $33.5 billion price tag seems wholly unrealistic. And its dam license extensions throughout the Columbia Basin and the litigation moratorium it would impose until the mid-21st century have generated such substantial opposition that enactment by Congress, in anything resembling its current form, will have to overcome the longest of odds. Still, given the imperiled nature of Snake River salmon and the considerable economic benefits that restored salmon runs could play in revitalizing the central Idaho economy, the proposal may serve as a beginning for Idaho’s elected officials and its public to focus on the advantages that restored Idaho salmon runs could play in revitalizing the central Idaho economy. Anything resembling the Simpson proposal should be welcomed as a considerable economic stimulus for the region.

INVESTIGATING THE CORROSION INITIATION PROCESS IN REINFORCED CONCRETE STRUCTURES UNDER THE IMPACT OF CLIMATE CHANGE

Introduction: Climate change (temperature rise and sea level rise) has a considerable influence on the behavior of concrete structures over time. All concrete degradation processes are connected to climate variables and the effects of climate change. The RCP8.5 (Representative Concentration Pathway) scenario, which is part of the report on climate change and level rise scenarios for Vietnam, predicts that the beginning of the 21st century will see an average annual increase in temperature between 0.8 and 1.1°C. In the mid-21st century, the temperature will likely increase by 1.8–2.3°C, with the temperature in the north likely increasing by 2.0–2.3°C and in the south by 1.8–1.9°C. In marine environments, the degradation of concrete structures can occur rapidly due to chloride-induced reinforcement corrosion. Furthermore, sea level rise is going to reduce the distance from the coastline to the structures and lead to increased surface chloride concentration. Methods: The evaluation of chloride penetration was based on the ASTM C1202 test (ASTM, 2012). The cylinder specimens (d = 100 mm, h = 200 mm) used for a rapid chloride penetration test (RCPT) were immersed in water for 28 days in a water-curing tank. Results: This study proposes a predictive model for analyzing the impact of climate change on the service life of concrete structures on Vietnam’s North Central Coast. The corrosion initiation time decreases by 16.5% when the effects of both temperature rise and sea level rise are taken into consideration. When only temperature rise is taken into consideration, the rate of reduction is approximately 9.0%. These results reaffirm that climate change has a significant effect on the corrosion initiation time of concrete structures located in a marine environment.

Towards a Catholic North America? Projections of Religion in Canada and the US Beyond the Mid-21st Century

Religion and religiosity are important identity markers, and changes in a country’s religious composition may affect its culture, value orientations and policies. In recent decades the Protestants in both the US and Canada have lost their absolute population majority. In the present study we investigate the future of the religious composition in both the US and Canada jointly until the 2060s taking into consideration changes due to demographic forces, the level and composition of migration, fertility differentials and intergenerational religious transmissions. The joint focus on both the US and Canada allows one to better understand the commonalities and differences between these two nations which are tightly knit in terms of geography, politics, economics and culture. The projections reveal that North America should not become Catholic by mid-century but close to, with an increasing importance of minorities in the religious landscape.

Cutting Edge Ecumenism: Cutting Edge Ecumenism: Toward Ecumenism in the Mid-21st Century—Trends, Challenges, and Opportunities

Cutting Edge Ecumenism: Cutting Edge Ecumenism: Toward Ecumenism in the Mid-21st Century—Trends, Challenges, and Opportunities

Africa’s Prospects for Enjoying a Demographic Dividend

We assess Africa’s prospects for enjoying a demographic dividend. While fertility rates and dependency ratios in Africa remain high, they have started to decline. According to United Nations projections, they will fall further in the coming decades such that by the mid-21st century the ratio of the working-age to dependent population will be greater than in Asia, Europe, and Northern America. This projection suggests Africa has considerable potential to enjoy a demographic dividend. Whether and when it actually materializes, and also its magnitude, hinges on policies and institutions in key realms that include macroeconomic management, human capital, trade, governance, and labour and capital markets. Given strong complementarities among these areas, coordinated policies will likely be most effective in generating the momentum needed to pull Africa’s economies out of a development trap.

International inequality in in-use metal stocks: What it portends for the future

In-use stocks of metals underpin essential services in the world's economy and drive long-term anthropogenic metal cycles. Given this fact, the global distribution patterns of metal stocks provide a fundamental basis for examining ways to satisfy the basic needs of an expanding global population within the Earth's carrying capacity. Here we show that the in-use stocks of six major metals (steel, aluminum, copper, zinc, lead and nickel) are distributed very unevenly across 231 countries and regions. According to our analysis, the highest 20% of the world's population (ordered in terms of metal stock per capita) accounts for approximately 60-75% of the world's total metal stock, while the lowest 20% accounts for only about 1%. International inequality in metal stocks has been decreasing over time due to the strong growth in developing countries, mainly those in Asia. However, our analysis shows that the continued reduction of metal stock inequality through this growth-led pathway will put heavy pressure on the environment, with a 2-3-fold increase in global metal demand by mid-21st century. These findings imply the need for alternative stock evolution patterns involving contraction and convergence, where global per capita metal stock growth stabilizes at a level below that current for developed countries.

China y el arte de la guerra (tecnológica)

China se encamina a convertirse en una potencia tecnológica a mediados del siglo XXI. Este proceso se funda sobre cuatro pilares: sostenido incremento del presupuesto asignado al desarrollo científico-tecnológico, su directa vinculación con estrategias de innovación a fin de aumentar la productividad y sostener competitividad exportadora, creación e internacionalización de firmas tecnológicas, y expectativas gubernamentales por cerrar las brechas de conocimiento aún existentes que separan a China de competidores asiáticos y occidentales. A lo largo de cuatro décadas, las reformas pro mercado confirman esta senda de transformación y generación de capacidades en sectores tecnológicos de punta. La competencia estratégica con Estados Unidos acelera esta carrera y confirma objetivos sobre posicionamiento de firmas tecnológicas chinas como líderes en inteligencia artificial (IA), telecomunicaciones y redes 5G.

Projected Impact of Mid-21st Century Climate Change on Wildfire Hazard in a Major Urban Watershed outside Portland, Oregon USA

Characterizing wildfire regimes where wildfires are uncommon is challenged by a lack of empirical information. Moreover, climate change is projected to lead to increasingly frequent wildfires and additional annual area burned in forests historically characterized by long fire return intervals. Western Oregon and Washington, USA (westside) have experienced few large wildfires (fires greater than 100 hectares) the past century and are characterized to infrequent large fires with return intervals greater than 500 years. We evaluated impacts of climate change on wildfire hazard in a major urban watershed outside Portland, OR, USA. We simulated wildfire occurrence and fire regime characteristics under contemporary conditions (1992–2015) and four mid-century (2040–2069) scenarios using Representative Concentration Pathway (RCP) 8.5. Simulated mid-century fire seasons expanded in most scenarios, in some cases by nearly two months. In all scenarios, average fire size and frequency projections increased significantly. Fire regime characteristics under the hottest and driest mid-century scenarios illustrate novel disturbance regimes which could result in permanent changes to forest structure and composition and the provision of ecosystem services. Managers and planners can use the range of modeled outputs and simulation results to inform robust strategies for climate adaptation and risk mitigation.

Climate change reduces frost exposure for high-value California orchard crops

Frost exposure is a particular challenge for cultivating perennial crops, whose adaptive capacity to weather and climate impacts is limited. Irrigation is a common means of mitigating damage, but draws on limited water resources, is costly, and energy intensive. Here we examined the projected impact of climate change on the incidence of frost temperatures during the coldest winters, defined by the 98th percentile of cool season (November–April) frost hours, under both early- and mid-21st century time periods, as compared to contemporary conditions, across a range of threshold temperatures. We focused on three high-value perennial orchard crops – almonds, avocados, and oranges – to assess the effects of climate change on the incidence of temperatures below crop-specific threshold temperatures and for crop-specific critical development phases, and what these temporal changes in frost exposure may mean for the water and energy requirements for mitigating damages. Across time periods and temperature thresholds, frost exposure declines in California's agricultural regions, with an average of reduction in frost exposure of 63% by the mid-21st century. The majority of almond and orange acreage saw 50–75% reductions in frost exposure by mid-century, while avocado acreage experienced >75% fewer frost hours. This yielded attendant reductions in water use and energy costs, and growers in the highest acreage counties may save more than 50,000 acre feet of water and $4.2 million in electricity costs for water pumping per year, collectively. Although climate change is projected to increase growing season crop water demands, pest pressures, and have an overall net-negative impact on agriculture, the potential reduction in frost exposure and the accompanying water and energy costs to mitigate frost damages may allow growers to reprioritize some of their long-term decisions around farm management.

High-resolution Ensemble Climate Projections of Water Deficit in Arid Regions by the Mid-21st Century

High-resolution Ensemble Climate Projections of Water Deficit in Arid Regions by the Mid-21st Century

Insight from CMIP6 SSP-RCP scenarios for future drought characteristics in China

In this paper, future drought characteristics (frequency, duration and intensity) over China are analysed by using four climate models from CMIP6 under the seven SSP-RCP (shared socioeconomic pathway-representative concentration pathway) scenarios (SSP119, SSP126, SSP434, SSP245, SSP460, SSP370, and SSP585) for three defined periods of 2021–2040 (near-term), 2041–2060 (mid-term) and 2081–2100 (long-term). The corresponding four climate models output from CMIP5 are also used to conduct a comparison analysis between CMIP5 and CMIP6 to address the improvements added to CMIP6 in terms of drought identification. The drought characteristics are identified by applying the standardized precipitation-evapotranspiration index (SPEI) at a 12-month timescale and run theory. The results show that CMIP6 has a robust capability to capture historical (1986–2005) drought characteristics. For the future period of 2021–2040, the decrease in precipitation and increase in potential evapotranspiration will lead to continuous dry conditions in the upper and middle Yangtze River basin and eastern Pearl River basin. Relative to the reference period, drought events will be more frequent and severe with longer durations in the Northwest River basins and middle Yangtze River basin. Furthermore, higher emissions signify a greater increase in drought frequency and intensity in the long-term period. Except for the SSP585 scenario, the lower emission scenario corresponds to the higher drought duration soon and in the mid-21st century (2021–2060). This finding is regarded as a “strange phenomenon”, which cannot be detected by the previous CMIP5-based emission scenarios (RCP2.6, RCP4.5 and the unlikely pathway RCP8.5). Therefore, additional “possible future”-based scenarios (SSP119, SSP126, SSP434, SSP245, SSP460, and SSP370) should be included in extreme climate studies, especially for the near future and mid-21st century. Notably, compared with CMIP5, the reduced biases in drought characteristics are more likely associated with improvements in the representation of physical processes in climate models from CMIP6. The results of this study could provide a basis for the development of drought adaptation measures over China.

Thawing permafrost and methane emission in Siberia: Synthesis of observations, reanalysis, and predictive modeling.

Permafrost has been warming in the last decade at rates up to 0.39°C 10year-1, raising public concerns about the local and global impacts, such as methane emission. We used satellite data on atmospheric methane concentrations to retrieve information about methane emission in permafrost and non-permafrost environments in Siberia with different biogeochemical conditions in river valleys, thermokarst lakes, wetlands, and lowlands. We evaluated the statistical links with air temperature, precipitation, depth of seasonal thawing, and freezing and developed a statistical model. We demonstrated that by the mid-21st century methane emission in Siberian permafrost regions will increase by less than 20 Tg year-1, which is at the lower end of other estimates. Such changes will lead to less than 0.02°C global temperature rise. These findings do not support the "methane bomb" concept. They demonstrate that the feedback between thawing Siberian wetlands and the global climate has been significantly overestimated.

The Convention on Biological Diversity (CBD)’s Post-2020 target on invasive alien species – what should it include and how should it be monitored?

The year 2020 and the next few years are critical for the development of the global biodiversity policy agenda until the mid-21st century, with countries agreeing to a Post-2020 Global Biodiversity Framework under the Convention on Biological Diversity (CBD). Reducing the substantial and still rising impacts of invasive alien species (IAS) on biodiversity will be essential if we are to meet the 2050 Vision where biodiversity is valued, conserved, and restored. A tentative target has been developed by the IUCN Invasive Species Specialist Group (ISSG), and formally submitted to the CBD for consideration in the discussion on the Post-2020 targets. Here, we present properties of this proposal that we regard as essential for an effective Post-2020 Framework. The target should explicitly consider the three main components of biological invasions, i.e. (i) pathways, (ii) species, and (iii) sites; the target should also be (iv) quantitative, (v) supplemented by a set of indicators that can be applied to track progress, and (vi) evaluated at medium- (2030) and long-term (2050) time horizons. We also present a proposed set of indicators to track progress. These properties and indicators are based on the increasing scientific understanding of biological invasions and effectiveness of responses. Achieving an ambitious action-oriented target so that the 2050 Vision can be achieved will require substantial effort and resources, and the cooperation of a wide range of stakeholders.