More extreme El Niño events reduce ocean carbon uptake in the future

2021 ◽  
Author(s):  
Enhui Liao ◽  
Laure Resplandy ◽  
Junjie Liu ◽  
Kevin Bowman
Keyword(s):  
Biogeochemical Model ◽  
Historical Period ◽  
Terrestrial Biosphere ◽  
The Future ◽  
Thermally Driven ◽  
High Emission ◽  
Ocean Carbon ◽  
High Emission Scenario ◽  
Flux Response ◽  
The Impact

<p>El Niño events weaken the strong natural oceanic source of CO<sub>2</sub> in the Tropical Pacific Ocean, partly offsetting the simultaneous release of CO<sub>2</sub> from the terrestrial biosphere during these events. Yet, uncertainties in the magnitude of this ocean response and how it will respond to the projected increase in extreme El Niño in the future (Cai et al., 2014) limit our understanding of the global carbon cycle and its sensitivity to climate. Here, we examine the mechanisms controlling the air-sea CO<sub>2</sub> flux response to El Niño events and how it will evolve in the future, using multidecadal ocean pCO<sub>2</sub> observations in conjunction with CMIP6 Earth system models (ESMs) and a state‐of‐the‐art ocean biogeochemical model. We show that the magnitude, spatial extent, and duration of the anomalous ocean CO<sub>2</sub> drawdown increased with El Niño intensity in the historical period. However, this relationship reverses in the CMIP6 projections under the high emission scenario. ESMs project more intense El Niño events, but weaker CO<sub>2</sub> flux anomalies in the future. This unexpected response is controlled by two factors: a stronger compensation between thermally-driven outgassing and non-thermal drawdown (56% of the signal); and less pronounced wind anomalies limiting the impact of El Niño on air-sea CO<sub>2</sub> exchanges (26% of the signal). El Niños should no longer reinforce the net global oceanic sink in the future, but have a near-neutral effect or even release CO<sub>2</sub> to the atmosphere, reinforcing the concurrent release of CO<sub>2</sub> from the terrestrial biosphere.</p>

scholarly journals Estimation of future changes in photovoltaic potential in Australia due to climate change

2021 ◽  
Vol 16 (11) ◽  
pp. 114034
Author(s):  
Shukla Poddar ◽  
Jason P Evans ◽  
Merlinde Kay ◽  
Abhnil Prasad ◽  
Stephen Bremner
Keyword(s):  
Power Generation ◽  
Wind Speed ◽  
Emission Scenario ◽  
Radiation Temperature ◽  
Pv Systems ◽  
The Future ◽  
High Emission ◽  
High Emission Scenario ◽  
Far Future

Abstract Solar photovoltaic (PV) energy is one of the fastest growing renewable energy sources globally. However, the dependency of PV generation on climatological factors such as the intensity of radiation, temperature, wind speed, cloud cover, etc can impact future power generation capacity. Considering the future large-scale deployment of PV systems, accurate climate information is essential for PV site selection, stable grid regulation, planning and energy output projections. In this study, the long-term changes in the future PV potential are estimated over Australia using regional climate projections for the near-future (2020–2039) and far-future (2060–2079) periods under a high emission scenario that projects 3.4 °C warming by 2100. The effects of projected changes in shortwave downwelling radiation, temperature and wind speed on the future performance of PV systems over Australia is also examined. Results indicate decline in the future PV potential over most of the continent due to reduced insolation and increased temperature. Northern coastal Australia experiences negligible increase in PV potential during the far future period due to increase in radiation and wind speed in that region. On further investigation, we find that the cell temperatures are projected to increase in the future under a high emission scenario (2.5 °C by 2079), resulting in increased degradation and risks of failure. The elevated cell temperatures significantly contribute to cell efficiency losses, that are expected to increase in the future (6–13 d yr−1 for multi-crystalline silicon cells) mostly around Western and central Australia indicating further reductions in PV power generation. Therefore, long-term PV power projections can help understand the variations in future power generation and identify regions where PV systems will be highly susceptible to losses in Australia.

scholarly journals Abruptly attenuated carbon sequestration with Weddell Sea dense waters towards the end of the 21st century

2021 ◽  
Author(s):  
Cara Nissen ◽  
Ralph Timmermann ◽  
Mario Hoppema ◽  
Judith Hauck
Keyword(s):  
Carbon Sequestration ◽  
Deep Ocean ◽  
Weddell Sea ◽  
Carbon Accumulation ◽  
Ice Shelf ◽  
Warm Deep Water ◽  
High Emission ◽  
Ocean Carbon ◽  
High Emission Scenario ◽  
Model Setup

Abstract Antarctic Bottom Water formation, such as in the Weddell Sea, is an efficient vector for carbon sequestration on time scales of centuries. Possible changes in carbon sequestration under changing environmental conditions are unquantified to date, mainly due to difficulties in simulating the relevant processes on high-latitude continental shelves. Using a model setup including both ice-shelf cavities and oceanic carbon cycling, we demonstrate that by 2100, deep-ocean carbon accumulation in the southern Weddell Sea is abruptly attenuated to only 40% of the rate in the 1990s in a high-emission scenario, while still being 4-fold higher in the 2080s. Assessing deep-ocean carbon budgets and water mass transformations, we attribute this decline to an increased presence of Warm Deep Water on the southern Weddell Sea continental shelf, a 16% reduction in sea-ice formation, and a 79% increase in ice-shelf basal melt. Altogether, these changes lower the density and volume of newly formed bottom waters and reduce the associated carbon transport to the abyss.

scholarly journals Future projections of temperature and precipitation for Antarctica

2021 ◽  
Author(s):  
Kamal Tewari ◽  
Saroj Kanta Mishra ◽  
Popat Salunke ◽  
Anupam Dewan
Keyword(s):  
Climate Models ◽  
Historical Period ◽  
Sea Levels ◽  
Surface Warming ◽  
Temperature Bias ◽  
Temperature And Precipitation ◽  
The Future ◽  
High Emission ◽  
Precipitation Increase ◽  
Better Than

Abstract Antarctica directly impacts the lives of more than half of the world’s population living in the coastal regions. Therefore it is highly desirable to project its climate for the future. But it is a region where the climate models have large inter-modal variability and hence it raises questions about the robustness of the projections available. Therefore, we have examined 87 global models from three modeling consortia (CMIP5, CMIP6, and NEX-GDDP), characterized their fidelity, selected a set of 10 models (MM10) performing satisfactorily, and used them to make the future projection of precipitation and temperature, and assessed the contribution of precipitation towards sea-levels. For the historical period, the multi-model mean (MMM) of CMIP5 performed slightly better than CMIP6 and was worse for NEX-GDDP, with negligible surface temperature bias of approximately 0.5°C and a 17.5% and 19% biases in the mean precipitation noted in both CMIP consortia. These biases considerably reduced in MM10, with 21st century projections showing surface warming of approximately 5.1 - 5.3°C and precipitation increase approximately 44 - 50% against ERA-5 under high-emission scenarios in both CMIP consortia. This projected precipitation increase is much less than that projected using MMM in previous studies with almost the same level of warming, implying approximately 40.0 mm/year contribution of precipitation towards sea-level mitigation against approximately 65.0 mm/year.

scholarly journals Kilometer-scale modeling projects a tripling of Alaskan convective storms in future climate

2020 ◽  
Vol 55 (11-12) ◽  
pp. 3543-3564
Author(s):  
Basile Poujol ◽  
Andreas F. Prein ◽  
Andrew J. Newman
Keyword(s):  
Rain Gauge ◽  
Future Climate ◽  
The Arctic ◽  
Climate Simulation ◽  
Climate Conditions ◽  
Convective Storms ◽  
Convective Systems ◽  
High Emission ◽  
High Emission Scenario ◽  
The Impact

Abstract Convective storms produce heavier downpours and become more intense with climate change. Such changes could be even amplified in high-latitudes since the Arctic is warming faster than any other region in the world and subsequently moistening. However, little attention has been paid to the impact of global warming on intense thunderstorms in high latitude continental regions, where they can produce flash flooding or ignite wildfires. We use a model with kilometer-scale grid spacing to simulate Alaska’s climate under present and end of the century high emission scenario conditions. The current climate simulation is able to capture the frequency and intensity of hourly precipitation compared to rain gauge data. We apply a precipitation tracking algorithm to identify intense, organized convective systems, which are projected to triple in frequency and extend to the northernmost regions of Alaska under future climate conditions. Peak rainfall rates in the core of the storms will intensify by 37% in line with atmospheric moisture increases. These results could have severe impacts on Alaska’s economy and ecology since floods are already the costliest natural disaster in central Alaska and an increasing number of thunderstorms could result in more wildfires ignitions.

scholarly journals Reductions in Labor Capacity from Intensified Heat Stress in China under Future Climate Change

2020 ◽  
Vol 17 (4) ◽  
pp. 1278
Author(s):  
Xingcai Liu
Keyword(s):  
Heat Stress ◽  
Occupational Health ◽  
Labor Force ◽  
Socioeconomic Development ◽  
Large Population ◽  
Future Climate Change ◽  
The Future ◽  
High Emission ◽  
Globe Temperature ◽  
The Impact

Heat stress would be intensified under global warming and become a key issue of occupational health for labor force working outdoors. The changes in labor force would affect regional socioeconomic development. So far, changes in labor force due to heat stress are not well documented in China. In this study, heat stress based on wet-bulb globe temperature (WBGT), which combines the thermal effects on the human body of both temperature and humidity, is projected for the near future (2021–2050) and the end of the century (2071–2099). Changes in labor capacity are then estimated for heavy and light work based on the relationships between labor capacity and the WBGT. Low and high emission scenarios, namely Representative Concentration Pathway (RCP) 2.6 and RCP8.5, are considered for the future projections in the hottest two months (July and August) in China. Results suggest that the WBGT would increase by more than 3–5 °C by the end of the century. The labor capacity would decrease by more than 40% for both heavy and light work in considerable areas such as South and East China, where there is a large population and developed economy. This indicates that labor force would reduce significantly due to intensified heat stress. This study calls for special attention to the impact of heat stress on occupational health and the labor force in China in the future.

scholarly journals Statistical Modeling to Predict Climate Change Effects on Watershed Scale Evapotranspiration

Atmosphere ◽  
2021 ◽  
Vol 12 (12) ◽  
pp. 1565
Author(s):  
Rajendra Khanal ◽  
Sulochan Dhungel ◽  
Simon C. Brewer ◽  
Michael E. Barber
Keyword(s):  
Emission Scenario ◽  
Climatic Conditions ◽  
Watershed Scale ◽  
Climate Change Effects ◽  
Machine Learning Model ◽  
The Future ◽  
Sensing Model ◽  
High Emission ◽  
High Emission Scenario ◽  
Agricultural Areas

Estimation of satellite-based remotely sensed evapotranspiration (ET) as consumptive use has been an integral part of agricultural water management. However, less attention has been given to future predictions of ET at watershed-scales especially since with a changing climate, there are additional challenges to planning and management of water resources. In this paper, we used nine years of total seasonal ET derived using a satellite-based remote sensing model, Mapping Evapotranspiration at Internalized Calibration (METRIC), to develop a Random Forest machine learning model to predict watershed-scale ET into the future. This statistical model used topographic and climate variables in agricultural areas of Lower Yakima, Washington and had a prediction accuracy of 88% for the region. This model was then used to predict ET into the future with changed climatic conditions under RCP4.5 and RCP8.5 emission scenarios expected by 2050s. The model result shows increases in seasonal ET across some areas of the watershed while decreases in other areas. On average, growing seasonal ET across the watershed was estimated to increase by +5.69% under the low emission scenario (RCP4.5) and +6.95% under the high emission scenario (RCP8.5).

scholarly journals Disentangling residence time and temperature sensitivity of microbial decomposition in a global soil carbon model

2014 ◽  
Vol 11 (23) ◽  
pp. 6999-7008 ◽  
Author(s):  
J.-F. Exbrayat ◽  
A. J. Pitman ◽  
G. Abramowitz
Keyword(s):  
Soil Carbon ◽  
Residence Time ◽  
Carbon Balance ◽  
Carbon Stocks ◽  
Historical Period ◽  
Microbial Decomposition ◽  
Total Soil ◽  
Industrial Soil ◽  
The Future ◽  
The Impact

Abstract. Recent studies have identified the first-order representation of microbial decomposition as a major source of uncertainty in simulations and projections of the terrestrial carbon balance. Here, we use a reduced complexity model representative of current state-of-the-art models of soil organic carbon decomposition. We undertake a systematic sensitivity analysis to disentangle the effect of the time-invariant baseline residence time (k) and the sensitivity of microbial decomposition to temperature (Q10) on soil carbon dynamics at regional and global scales. Our simulations produce a range in total soil carbon at equilibrium of ~ 592 to 2745 Pg C, which is similar to the ~ 561 to 2938 Pg C range in pre-industrial soil carbon in models used in the fifth phase of the Coupled Model Intercomparison Project (CMIP5). This range depends primarily on the value of k, although the impact of Q10 is not trivial at regional scales. As climate changes through the historical period, and into the future, k is primarily responsible for the magnitude of the response in soil carbon, whereas Q10 determines whether the soil remains a sink, or becomes a source in the future mostly by its effect on mid-latitude carbon balance. If we restrict our simulations to those simulating total soil carbon stocks consistent with observations of current stocks, the projected range in total soil carbon change is reduced by 42% for the historical simulations and 45% for the future projections. However, while this observation-based selection dismisses outliers, it does not increase confidence in the future sign of the soil carbon feedback. We conclude that despite this result, future estimates of soil carbon and how soil carbon responds to climate change should be more constrained by available data sets of carbon stocks.

scholarly journals How will climate change affect the planktonic food web and the biogeochemistry of the Mediterranean Sea according to the RCP 8.5 scenario ?

2020 ◽  
Author(s):  
Melika Baklouti ◽  
Rémi Pagès ◽  
Mohamed Ayache ◽  
Nicolas Barrier ◽  
Florence Sevault ◽  
...  
Keyword(s):  
Climate Change ◽  
Food Web ◽  
Global Scale ◽  
Biogeochemical Model ◽  
Historical Period ◽  
Planktonic Food ◽  
Rcp 8.5 ◽  
The Mediterranean ◽  
The Impact ◽  
Recorded Temperature

<p>In recent studies, the Mediterranean region is once again identified as a region particularily sensitive to climate change, with recorded temperature and sea level rises during the last decades exceeding the mean variations recorded at global scale. Moreover, according to climate scenarios, there seems to be some consensus regarding the impact on climate change on some hydrodynamical features, as for example on stratification which should become stronger and more persistant. However, nothing or very few is known about the expected changes nor in the structure and the functionning of the planktonic food web, neither in the main biogeochemical cycles. This study is intended to progress on this issue, using a coupled (one way) physical-biogeochemical model: CNRM-RCSM4/NEMO-MED12/Eco3M-Med. A 110-year simulation over the period 1990-2100 has been run and from 2006, the simulation is forced by a RCP 8.5 regional scenario of the Med Sea (a control simulation has also been run simultaneously). After having verified the model's ability to describe the main characteristics of the marine planktonic food web and biogeochemistry through several comparisons with available data during the historical period, the model outputs have been analyzed. Preliminary results indicate a significant decrease in the annual primary production and the export of organic carbon at 200 and 1000 m in both the eastern and the western basins, associated with changes in the structure of the planktonic community.</p>

The impact of thermokarst lakes on streamflow generation in Central Yakutia (Russia): data assessment and modelling

2020 ◽  
Author(s):  
Olga Makarieva ◽  
Nataliia Nesterova ◽  
Alexander Fedorov ◽  
Andrey Shikhov
Keyword(s):  
River Basin ◽  
Hydrological Modeling ◽  
Hydrological Regime ◽  
Historical Period ◽  
Annual Streamflow ◽  
Landsat Images ◽  
Thermokarst Lakes ◽  
Central Yakutia ◽  
The Future ◽  
The Impact

<p>Central Yakutian Plain (Russia) is situated in Eastern Siberia in the Lena River basin and is characterized by severe continental climate, continuous permafrost and flat relief. The combination of semi-arid climate, gentle topography and ice-rich permafrost provides favorable conditions for the development of thermokarst lakes. Poorly developed river drainage system and the distribution of thermokarst lakes within the river basins form the areas with internal drainage which contribute runoff to river network only in wet conditions. The results of such environment are the special hydrological regime of the region which is characterized by extreme seasonal and annual variability of streamflow.</p><p>In this project we study the hydrological processes in four rivers of Central Yakutia with the basin area from 1270 to 8290 km<sup>2</sup> and available long-term streamflow data. Thermokarst lakes take up to 5-10 % of the area of those basins. Annual precipitation of this area is about 240 mm, while average annual streamflow varies from 1 to 15 mm depending on the river basin. Due to climate warming the number and area of thermokarst lakes in Central Yakutia is increasing (Kravsova, Tarasenko, 2011). The aim of the project is to investigate the impact of thermokarst lakes on hydrological regime and provide some reasonable projections of its changes in the future. Previous study (Lebedeva, 2018) has shown that the results of streamflow simulations in this region based on standard hydrological modeling approach were not satisfactory.</p><p>We used remote sensing data (Landsat images) to assess the seasonal and annual variation of thermokarst lakes area and their contributing area and combined that data with hydrological modelling of runoff formation processes. The hydrological model Hydrograph (Vinogradov et al., 2011) was applied in this study. The model contains the algorithms of heat and moisture dynamics in the upper part of soil profile which allow its use in the permafrost conditions. New part of the model algorithm was developed which considers the variations of thermokarst area depending on meteorological conditions, evaporation from open water areas and the dynamic of surface runoff retention depth. These model improvements allowed for the satisfactory results in streamflow simulations for historical period and future projections. In general, with the future development of thermokarst lakes in Central Yakutia one may expect the decrease of annual streamflow and its higher variation from one year to another.</p><p>Th results of the study will be presented. The study was funded by RFBR, project number 19-35-50030.</p>

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