scholarly journals Different facets of dry–wet patterns in south-western China over the past 27 000 years

2021 ◽  
Vol 17 (5) ◽  
pp. 2291-2303
Author(s):  
Mengna Liao ◽  
Kai Li ◽  
Weiwei Sun ◽  
Jian Ni
Keyword(s):  
Soil Moisture ◽  
Current Knowledge ◽  
Global Climate ◽  
Water Shortage ◽  
Western China ◽  
Stress Index ◽  
Sw China ◽  
Hydrological Balance ◽  
Yunnan Region

Abstract. Frequently occurring mega-droughts under current global climate change have attracted broad social attention. A paleoclimatic perspective is needed to increase our understanding of the causes and effects of droughts. South-western (SW) China has been threatened by severe seasonal droughts. Our current knowledge of millennial-scale dry and wet phases in this region is primarily based on the variability of the Indian summer monsoon. However, water availability over land does not always follow patterns of monsoonal precipitation but also depends on water loss from evaporation and transpiration. Here, we reconstructed precipitation intensity, lake hydrological balance and the soil water stress index (SWSI) for the last 27 000 years. Grain size, geochemical and pollen records from Yilong Lake reveal the long-term relationships and inconsistencies of dry–wet patterns in meteorological, hydrological and soil systems in the central Yunnan region, SW China. Our results show that the long-term trends among precipitation, hydrological balance and soil moisture varied through time. The hydrological balance and soil moisture were primarily controlled by temperature-induced evaporation change during periods of low precipitation such as the Last Glacial Maximum and Younger Dryas. During periods of high precipitation (the early to late Holocene), intensified evaporation from the lake surface offset the effects of increased precipitation on the hydrological balance. However, abundant rainfall and the dense vegetation canopy circumvented a soil moisture deficit that might have resulted from rising temperature. In conclusion, the hydrological balance in the central Yunnan region was more sensitive to temperature change while soil moisture could be further regulated by vegetation changes over millennial timescales. Therefore, under future climate warming, the surface water shortage in the central Yunnan region may become even more serious. Our study suggests that reforestation efforts may provide some relief to soil moisture deficits in this region.

scholarly journals Different facets of dryness/wetness pattern in southwestern China over the past 27,000 years

2021 ◽  
Author(s):  
Mengna Liao ◽  
Kai Li ◽  
Weiwei Sun ◽  
Jian Ni
Keyword(s):  
Soil Moisture ◽  
Southwestern China ◽  
Stress Index ◽  
Soil Moisture Deficit ◽  
Hydrological Balance ◽  
Yunnan Region ◽  
Soil Systems ◽  
Moisture Deficit ◽  
Millennial Scale

Abstract. Frequently happened meta-droughts have arisen broad social attention under current global climate change. A paleoclimatic perspective is expected to gain our understanding on the causes and manifestation more comprehensively. Southwestern China has been threatened by severe seasonal droughts. Our current knowledge of millennial-scale drying/wetting processes in this region is primarily based on the variability of the Indian Summer Monsoon. However, water availability over land does not always follow the monsoonal precipitation but also depends on water loss from evaporation and transpiration. Here, we reconstructed precipitation intensity, lake hydrological balance and soil water stress index (SWSI) covering the last 27,000 yr, based on grain size, geochemical and pollen records from Yilong Lake, to discuss the long-term nexus and discrepancies of dryness/wetness patterns in meteorological, hydrological and soil systems in central Yunnan region, SW China. Our results show that the long-term change trajectories among precipitation, hydrological balance and soil moisture were not completely consistent. During periods of low precipitation, hydrological balance and soil moisture were primarily controlled by temperature-induced evaporation change. This caused opposite status of precipitation with hydrological balance and soil moisture during the Last Glacial Maximum and Younger Dryas. During periods of high precipitation – the early to late Holocene, intensified evaporation from the lake surface offset the effects of increased precipitation on hydrological balance. But meanwhile, abundant rainfall and dense vegetation canopy avoided soil moisture deficit that might result from rising temperature. To sum up, hydrological balance in central Yunnan region was more vulnerable to temperature change while soil moisture could be further regulated by vegetation changes on millennial scale. As such, under future climate warming, surface water shortage in central Yunnan region can be even more serious. But for soil systems, efforts to reforestation may bring some relief to soil moisture deficit in this region.

scholarly journals Varying soil moisture-atmosphere feedbacks explain divergent temperature extremes and precipitation projections in Central Europe

2018 ◽  
Author(s):  
Martha M. Vogel ◽  
Jakob Zscheischler ◽  
Sonia I. Seneviratne
Keyword(s):  
Climate Change ◽  
Soil Moisture ◽  
Central Europe ◽  
Climate Models ◽  
Global Climate ◽  
Summer Precipitation ◽  
Global Climate Models ◽  
Temperature Extremes ◽  
Extreme Temperatures

Abstract. The frequency and intensity of climate extremes is expected to increase in many regions due to anthropogenic climate change. In Central Europe extreme temperatures are projected to change more strongly than global mean temperatures and soil moisture-temperature feedbacks significantly contribute to this regional amplification. Because of their strong societal, ecological and economic impacts, robust projections of temperature extremes are needed. Unfortunately, in current model projections, temperature extremes in Central Europe are prone to large uncertainties. In order to understand and potentially reduce uncertainties of extreme temperatures projections in Europe, we analyze global climate models from the CMIP5 ensemble for the business-as-usual high-emission scenario (RCP8.5). We find a divergent behavior in long-term projections of summer precipitation until the end of the 21st century, resulting in a trimodal distribution of precipitation (wet, dry and very dry). All model groups show distinct characteristics for summer latent heat flux, top soil moisture, and temperatures on the hottest day of the year (TXx), whereas for net radiation and large-scale circulation no clear trimodal behavior is detectable. This suggests that different land-atmosphere coupling strengths may be able to explain the uncertainties in temperature extremes. Constraining the full model ensemble with observed present-day correlations between summer precipitation and TXx excludes most of the very dry and dry models. In particular, the very dry models tend to overestimate the negative coupling between precipitation and TXx, resulting in a too strong warming. This is particularly relevant for global warming levels above 2 °C. The analysis allows for the first time to substantially reduce uncertainties in the projected changes of TXx in global climate models. Our results suggest that long-term temperature changes in TXx in Central Europe are about 20 % lower than projected by the multi-model median of the full ensemble. In addition, mean summer precipitation is found to be more likely to stay close to present-day levels. These results are highly relevant for improving estimates of regional climate-change impacts including heat stress, water supply and crop failure for Central Europe.

scholarly journals Relationships between photosynthesis and formaldehyde as a probe of isoprene emission

2015 ◽  
Vol 15 (8) ◽  
pp. 11763-11797 ◽  
Author(s):  
Y. Zheng ◽  
N. Unger ◽  
M. P. Barkley ◽  
X. Yue
Keyword(s):  
Soil Moisture ◽  
Radiative Forcing ◽  
Global Climate ◽  
Global Scale ◽  
Emission Model ◽  
Earth System ◽  
Isoprene Emission ◽  
Moisture Dependence ◽  
Southeast Us

Abstract. Atmospheric oxidation of isoprene emission from land plants affects radiative forcing of global climate change. There is an urgent need to understand the factors that control isoprene emission variability on large spatiotemporal scales but such direct observations of isoprene emission do not exist. Two readily available global-scale long-term observations hold information about surface isoprene activity: gross primary productivity (GPP) and tropospheric formaldehyde column variability (HCHOv). We analyze multi-year seasonal linear correlations between observed GPP and HCHOv. The observed GPP-HCHOv correlation patterns are used to evaluate a global Earth system model that embeds three alternative leaf-level isoprene emission algorithms. GPP and HCHOv are decoupled in the summertime southeast US (r = −0.03). In the Amazon, GPP-HCHOv are weakly correlated in March-April-May (MAM), correlated in June-July-August (JJA) and weakly anti-correlated in September-October-November (SON). Isoprene emission algorithms that include soil moisture dependence demonstrate greater skill in reproducing the observed interannual seasonal GPP-HCHOv correlations in the southeast US and the Amazon. In isoprene emission models that include soil moisture dependence, isoprene emission is correlated with photosynthesis and anti-correlated with HCHOv. In an isoprene emission model without soil moisture dependence, isoprene emission is anti-correlated with photosynthesis and correlated with HCHOv. Long-term monitoring of isoprene emission, soil moisture and meteorology is required in water-limited ecosystems to improve understanding of the factors controlling isoprene emission and its representation in global Earth system models.

scholarly journals Varying soil moisture–atmosphere feedbacks explain divergent temperature extremes and precipitation projections in central Europe

2018 ◽  
Vol 9 (3) ◽  
pp. 1107-1125 ◽  
Author(s):  
Martha M. Vogel ◽  
Jakob Zscheischler ◽  
Sonia I. Seneviratne
Keyword(s):  
Climate Change ◽  
Soil Moisture ◽  
Central Europe ◽  
Climate Models ◽  
Global Climate ◽  
Substantial Reduction ◽  
Summer Precipitation ◽  
Global Climate Models ◽  
Temperature Extremes

Abstract. The frequency and intensity of climate extremes is expected to increase in many regions due to anthropogenic climate change. In central Europe extreme temperatures are projected to change more strongly than global mean temperatures, and soil moisture–temperature feedbacks significantly contribute to this regional amplification. Because of their strong societal, ecological and economic impacts, robust projections of temperature extremes are needed. Unfortunately, in current model projections, temperature extremes in central Europe are prone to large uncertainties. In order to understand and potentially reduce the uncertainties of extreme temperature projections in Europe, we analyze global climate models from the CMIP5 (Coupled Model Intercomparison Project Phase 5) ensemble for the business-as-usual high-emission scenario (RCP8.5). We find a divergent behavior in long-term projections of summer precipitation until the end of the 21st century, resulting in a trimodal distribution of precipitation (wet, dry and very dry). All model groups show distinct characteristics for the summer latent heat flux, top soil moisture and temperatures on the hottest day of the year (TXx), whereas for net radiation and large-scale circulation no clear trimodal behavior is detectable. This suggests that different land–atmosphere coupling strengths may be able to explain the uncertainties in temperature extremes. Constraining the full model ensemble with observed present-day correlations between summer precipitation and TXx excludes most of the very dry and dry models. In particular, the very dry models tend to overestimate the negative coupling between precipitation and TXx, resulting in a warming that is too strong. This is particularly relevant for global warming levels above 2 ∘C. For the first time, this analysis allows for the substantial reduction of uncertainties in the projected changes of TXx in global climate models. Our results suggest that long-term temperature changes in TXx in central Europe are about 20 % lower than those projected by the multi-model median of the full ensemble. In addition, mean summer precipitation is found to be more likely to stay close to present-day levels. These results are highly relevant for improving estimates of regional climate-change impacts including heat stress, water supply and crop failure for central Europe.

scholarly journals Long-Term Trends in Root-Zone Soil Moisture across CONUS Connected to ENSO

2020 ◽  
Vol 12 (12) ◽  
pp. 2037
Author(s):  
Kenneth J. Tobin ◽  
Roberto Torres ◽  
Marvin E. Bennett ◽  
Jianzhi Dong ◽  
Wade T. Crow
Keyword(s):  
Soil Moisture ◽  
El Niño ◽  
Root Zone ◽  
El Nino ◽  
Southern Oscillation ◽  
Global Climate ◽  
Kendall Test ◽  
La Niña ◽  
La Nina

Root zone soil moisture (RZSM) is one of the least-monitored variables within the hydrologic cycle. Given the importance of RZSM to agriculture, more effort is needed to understand the potential impacts of the El Niño southern oscillation (ENSO), Pacific decadal oscillation (PDO), and Atlantic multidecadal oscillation (AMO) on this critical variable. This study focused on the CONtiguous United States (CONUS) RZSM (0 to 40 cm depth) over nearly three decades (1992 to 2018). Basic trend analysis with the Mann–Kendall test and wavelet transform coherence (WTC) was utilized. The RZSM product examined was Soil MERGE (SMERGE 2.0). More CONUS pixels exhibited drying (56 to 75%) versus wetting (25 to 44%) trends between 1992 and 2018. Seasonal wetting trends were observed particularly during winter in the Southwest and Northwest regions associated with El Nino and La Nina episodes, respectively. The noted long-term RZSM trends are more clearly attributable to oceanic-atmospheric teleconnections than global climate change. The most significant result was the strong drying trend in central CONUS reflected a shift to La Nina and cool PDO conditions during the 2000s, further amplified by a change to positive AMO corresponding with this period.

scholarly journals Relationships between photosynthesis and formaldehyde as a probe of isoprene emission

2015 ◽  
Vol 15 (15) ◽  
pp. 8559-8576 ◽  
Author(s):  
Y. Zheng ◽  
N. Unger ◽  
M. P. Barkley ◽  
X. Yue
Keyword(s):  
Soil Moisture ◽  
Radiative Forcing ◽  
Global Climate ◽  
Global Scale ◽  
Emission Model ◽  
Earth System ◽  
Isoprene Emission ◽  
Moisture Dependence ◽  
Southeast Us

Abstract. Atmospheric oxidation of isoprene emission from land plants affects radiative forcing of global climate change. There is an urgent need to understand the factors that control isoprene emission variability on large spatiotemporal scales but such direct observations of isoprene emission do not exist. Two readily available global-scale long-term observation-based data sets hold information about surface isoprene activity: gross primary productivity (GPP) and tropospheric formaldehyde column variability (HCHOv). We analyze multi-year seasonal linear correlations between observed GPP and HCHOv. The observed GPP–HCHOv correlation patterns are used to evaluate a global Earth system model that embeds three alternative leaf-level isoprene emission algorithms. GPP and HCHOv are decoupled in the summertime in the southeast US (r=−0.03). In the Amazon, GPP and HCHOv are weakly correlated in March-April-May (MAM), correlated in June-July-August (JJA) and weakly anticorrelated in September-October-November (SON). Isoprene emission algorithms that include soil moisture dependence demonstrate greater skill in reproducing the observed interannual seasonal GPP–HCHOv correlations in the southeast US and the Amazon. In isoprene emission models that include soil moisture dependence, isoprene emission is correlated with photosynthesis and anticorrelated with HCHOv. In an isoprene emission model without soil moisture dependence, isoprene emission is anticorrelated with photosynthesis and correlated with HCHOv. Long-term monitoring of isoprene emission, soil moisture and meteorology is required in water-limited ecosystems to improve understanding of the factors controlling isoprene emission and its representation in global Earth system models.

Future trends in global water vs. energy-controlled evaporative regimes

2021 ◽  
Author(s):  
Jasper Denissen ◽  
Adriaan Teuling ◽  
Wantong Li ◽  
Markus Reichstein ◽  
Andy Pitman ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Land Surface ◽  
Climate Model ◽  
Global Climate ◽  
Coupled Model ◽  
Energy Availability ◽  
Water Control ◽  
Near Surface ◽  
Global Patterns

<p>Water and energy availability govern the exchange of carbon, energy and water between the land surface and the atmosphere and therefore exert influence on near-surface weather. Roughly one can distinguish between two evaporative regimes: One limited by available energy (under wet conditions) and one limited by available soil moisture (under dry conditions). The transition between these evaporative regimes has been studied on local to global scales using observational and modelled datasets. This revealed the complexity of defining this transition, as it varies both in space and time and is sensitive to climate, soil and vegetation characteristics.</p><p>In this study, we characterized this transition by comparing the correlations of evaporation anomalies with (i) soil moisture anomalies (proxy for strength of water control) and (ii) temperature anomalies (proxy for strength of energy control). In the first step, we use observation-based data to derive global patterns of evaporative regimes and establish that the regime transition is sensitive to not only long-term average soil moisture, but also long-term average temperature. Analyzing historical and future climate model simulations from the Coupled Model Intercomparison Project (CMIP6), we found that the ensemble mean of the CMIP6 models produces similar global patterns and sensitivities to energy and water availability. However, there is ample disagreement between results of individual models, with the largest spread around the transition zones. Further, the disagreement between individual models on the total area of water-limited regions increases gradually in time from historical to future experiments. In the next step, we attribute trends in evaporative regimes to trends in water and energy availability, CO<sub>2</sub> and vapor pressure deficit. This research reveals how global climate change translates into regional-global scale trends in water- vs. energy-controlled evaporative regimes. Our observational results can constrain modelled global evaporative regimes and inform future model development to decrease the substantial spread across the present model ensemble.</p>

On Climate Change Risks of Long-Term Socio-Economic Development in Russia

2019 ◽  
pp. 79-95
Author(s):  
N.E. Terentiev
Keyword(s):  
Climate Change ◽  
Economic Development ◽  
Technological Innovation ◽  
Global Climate Change ◽  
Global Climate ◽  
Climate Risk ◽  
Climate Change Risks ◽  
Socio Economic Development ◽  
Management Policies

Based on the latest data, paper investigates the dynamics of global climate change and its impact on economic growth in the long-term. The notion of climate risk is considered. The main directions of climate risk management policies are analyzed aimed, first, at reducing anthropogenic greenhouse gas emissions through technological innovation and structural economic shifts; secondly, at adaptation of population, territories and economic complexes to the irreparable effects of climate change. The problem of taking into account the phenomenon of climate change in the state economic policy is put in the context of the most urgent tasks of intensification of long-term socio-economic development and parrying strategic challenges to the development of Russia.

scholarly journals Impact of mobile stroke units

2021 ◽  
pp. jnnp-2020-324005
Author(s):  
Klaus Fassbender ◽  
Fatma Merzou ◽  
Martin Lesmeister ◽  
Silke Walter ◽  
Iris Quasar Grunwald ◽  
...  
Keyword(s):  
Cost Efficiency ◽  
Current Knowledge ◽  
Vascular Imaging ◽  
Vessel Occlusion ◽  
Stroke Units ◽  
Stroke Treatment ◽  
Stroke Research ◽  
Mobile Stroke Unit ◽  
Novel Strategy

Since its first introduction in clinical practice in 2008, the concept of mobile stroke unit enabling prehospital stroke treatment has rapidly expanded worldwide. This review summarises current knowledge in this young field of stroke research, discussing topics such as benefits in reduction of delay before treatment, vascular imaging-based triage of patients with large-vessel occlusion in the field, differential blood pressure management or prehospital antagonisation of anticoagulants. However, before mobile stroke units can become routine, several questions remain to be answered. Current research, therefore, focuses on safety, long-term medical benefit, best setting and cost-efficiency as crucial determinants for the sustainability of this novel strategy of acute stroke management.

scholarly journals Cardiac Cell Therapy: Insights into the Mechanisms of Tissue Repair

2021 ◽  
Vol 22 (3) ◽  
pp. 1201
Author(s):  
Hsuan Peng ◽  
Kazuhiro Shindo ◽  
Renée R. Donahue ◽  
Ahmed Abdel-Latif
Keyword(s):  
Stem Cell ◽  
Immune Responses ◽  
Tissue Repair ◽  
Molecular Mechanisms ◽  
Clinical Evidence ◽  
Current Knowledge ◽  
Cell Delivery ◽  
Cardiac Cell Therapy ◽  
Stem Cell Treatment

Stem cell-based cardiac therapies have been extensively studied in recent years. However, the efficacy of cell delivery, engraftment, and differentiation post-transplant remain continuous challenges and represent opportunities to further refine our current strategies. Despite limited long-term cardiac retention, stem cell treatment leads to sustained cardiac benefit following myocardial infarction (MI). This review summarizes the current knowledge on stem cell based cardiac immunomodulation by highlighting the cellular and molecular mechanisms of different immune responses to mesenchymal stem cells (MSCs) and their secretory factors. This review also addresses the clinical evidence in the field.

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