scholarly journals Forced Decadal Changes in Summer Precipitation Characteristics over China: The Roles of Greenhouse Gases and Anthropogenic Aerosols

2020 ◽  
Vol 34 (6) ◽  
pp. 1226-1241
Author(s):  
Bo Zhang ◽  
Buwen Dong ◽  
Ronghua Jin
Keyword(s):  
Greenhouse Gases ◽  
Summer Precipitation ◽  
Anthropogenic Aerosols ◽  
Precipitation Characteristics

scholarly journals Detectable Anthropogenic Shift toward Heavy Precipitation over Eastern China

2017 ◽  
Vol 30 (4) ◽  
pp. 1381-1396 ◽  
Author(s):  
Shuangmei Ma ◽  
Tianjun Zhou ◽  
Dáithí A. Stone ◽  
Debbie Polson ◽  
Aiguo Dai ◽  
...  
Keyword(s):  
Greenhouse Gases ◽  
Climate Models ◽  
Eastern China ◽  
Heavy Precipitation ◽  
Water Vapor Transport ◽  
Significant Shift ◽  
Anthropogenic Aerosols ◽  
Precipitation Characteristics ◽  
Thermodynamic Mechanism ◽  
Precipitation Records

Abstract Changes in precipitation characteristics directly affect society through their impacts on drought and floods, hydro-dams, and urban drainage systems. Global warming increases the water holding capacity of the atmosphere and thus the risk of heavy precipitation. Here, daily precipitation records from over 700 Chinese stations from 1956 to 2005 are analyzed. The results show a significant shift from light to heavy precipitation over eastern China. An optimal fingerprinting analysis of simulations from 11 climate models driven by different combinations of historical anthropogenic (greenhouse gases, aerosols, land use, and ozone) and natural (volcanic and solar) forcings indicates that anthropogenic forcing on climate, including increases in greenhouse gases (GHGs), has had a detectable contribution to the observed shift toward heavy precipitation. Some evidence is found that anthropogenic aerosols (AAs) partially offset the effect of the GHG forcing, resulting in a weaker shift toward heavy precipitation in simulations that include the AA forcing than in simulations with only the GHG forcing. In addition to the thermodynamic mechanism, strengthened water vapor transport from the adjacent oceans and by midlatitude westerlies, resulting mainly from GHG-induced warming, also favors heavy precipitation over eastern China. Further GHG-induced warming is predicted to lead to an increasing shift toward heavy precipitation, leading to increased urban flooding and posing a significant challenge for mega-cities in China in the coming decades. Future reductions in AA emissions resulting from air pollution controls could exacerbate this tendency toward heavier precipitation.

scholarly journals Numerical simulations of the impact of climate variability and change on semiarid watershed response in central New Mexico

2009 ◽  
Vol 6 (1) ◽  
pp. 319-371
Author(s):  
E. R. Vivoni ◽  
C. A. Aragón ◽  
L. Malczynski ◽  
V. C. Tidwell
Keyword(s):  
Climate Change ◽  
New Mexico ◽  
Summer Precipitation ◽  
Climate Change Scenarios ◽  
Hydrologic Response ◽  
Watershed Model ◽  
Precipitation Regime ◽  
Hydrologic Processes ◽  
Precipitation Characteristics ◽  
The Impact

Abstract. Hydrologic processes in the semiarid regions of the southwest United States are considered to be highly susceptible to variations in temperature and precipitation characteristics due to the effects of climate change. Relatively little is known on the potential impacts of climate change on the basin hydrologic response, namely streamflow, evapotranspiration and recharge, in the region. In this study, we present the development and application of a continuous, semi-distributed watershed model for climate change studies in semiarid basins of the southwest US. Our objective is to capture hydrologic processes in large watersheds, while accounting for the spatial and temporal variations of climate forcing and basin properties in a simple fashion. We apply the model to the Río Salado basin in central New Mexico since it exhibits both a winter and summer precipitation regime and has a historical streamflow record for model testing purposes. Subsequently, we utilize a sequence of climate change scenarios that capture observed trends for winter and summer precipitation, as well as their interaction with higher temperatures, to perform long-term ensemble simulations of the basin hydrologic response. Results of the modeling exercise indicate that precipitation uncertainty is amplified in the hydrologic response, in particular for processes that depend on a soil saturation threshold. We obtained substantially different hydrologic sensitivities for winter and summer precipitation ensembles, indicating a greater sensitivity to more intense summer storms as compared to more frequent winter events. In addition, the impact of changes in precipitation characteristics overwhelmed the effects of increased temperature in the study basin. Nevertheless, combined trends in precipitation and temperature yield a more sensitive hydrologic response throughout the year.

scholarly journals Precipitation Variations under a Changing Climate from 1961–2015 in the Source Region of the Indus River

Water ◽  
2019 ◽  
Vol 11 (7) ◽  
pp. 1366
Author(s):  
Muhammad Rizwan ◽  
Xin Li ◽  
Kashif Jamal ◽  
Yingying Chen ◽  
Junaid Nawaz Chauhdary ◽  
...  
Keyword(s):  
Daily Precipitation ◽  
Source Region ◽  
Summer Precipitation ◽  
Heavy Precipitation ◽  
Winter Precipitation ◽  
Indus Basin ◽  
Indus River ◽  
Precipitation Characteristics ◽  
Daily Precipitation Data ◽  
Increasing Trends

The source region of the Indus River (SRIR), which is located in the Hindukush, Karakoram and Himalayan (HKH) mountainous range and on the Third Pole (TP), is very sensitive to climate change, especially precipitation changes, because of its multifarious orography and fragile ecosystem. Climate changes in the SRIR also have important impacts on social and economic development, as well as on the ecosystems of the downstream irrigation areas in Pakistan. This paper investigates the changes in precipitation characteristics by dividing the daily precipitation rate into different classes, such as light (0–10 mm), moderate (10.1–25 mm) and heavy precipitation (>25 mm). Daily precipitation data from gauging and non-gauging stations from 1961–2015 are used. The results of the analysis of the annual precipitation and rainy day trends show significant (p < 0.05) increases and decreases, respectively, while light and heavy precipitation show significant decreasing and increasing trends, respectively. The analysis of the precipitation characteristics shows that light precipitation has the highest number of rainy days compared to moderate or heavy precipitation. The analysis of the seasonal precipitation trends shows that only 18 stations have significant increasing trends in winter precipitation, while 27 stations have significant increasing trends in summer precipitation. Both short and long droughts exhibit increasing trends, which indicates that the Indus Basin will suffer from water shortages for agriculture. The results of this study could help policymakers cope with floods and droughts and sustain eco-environmental resources in the study area.

scholarly journals The Role of Forcings in the Twentieth-Century North Atlantic Multidecadal Variability: The 1940–75 North Atlantic Cooling Case Study

2017 ◽  
Vol 30 (18) ◽  
pp. 7317-7337 ◽  
Author(s):  
A. Bellucci ◽  
A. Mariotti ◽  
S. Gualdi
Keyword(s):  
Twentieth Century ◽  
Greenhouse Gases ◽  
Surface Temperature ◽  
Sea Surface Temperature ◽  
North Atlantic ◽  
Sea Surface ◽  
Atlantic Multidecadal Variability ◽  
Anthropogenic Aerosols ◽  
Multimodel Ensemble ◽  
Multidecadal Variability

Abstract Results from a study inspecting the origins of multidecadal variability in the North Atlantic sea surface temperature (NASST) are presented. The authors target in particular the 1940–75 “warm-to-cold” transition, an event that is generally framed in the context of the longer-term Atlantic multidecadal variability (AMV) cycle, in turn associated with the Atlantic meridional overturning circulation (AMOC) internal variability. Here the authors examine the ability of uninitialized, historical integrations from the phase 5 of the Coupled Model Intercomparison Project (CMIP5) archive to retrospectively reproduce this specific episode of twentieth-century climatic history, under a hierarchy of forcing conditions. For this purpose, both standard and so-called historical Misc CMIP5 simulations of the historical climate (combining selected natural and anthropogenic forcings) are exploited. Based on this multimodel analysis, evidence is found for a significant influence of anthropogenic agents on multidecadal sea surface temperature (SST) fluctuations across the Atlantic sector, suggesting that anthropogenic aerosols and greenhouse gases might have played a key role in the 1940–75 North Atlantic cooling. However, the diagnosed forced response in CMIP5 models appears to be affected by a large uncertainty, with only a limited subset of models displaying significant skill in reproducing the mid-twentieth-century NASST cooling. Such uncertainty originates from the existence of well-defined behavioral clusters within the analyzed CMIP5 ensembles, with the bulk of the models splitting into two main clusters. Such a strong polarization calls for some caution when using a multimodel ensemble mean in climate model analyses, as averaging across fairly distinct model populations may result, through mutual cancellation, in a rather artificial description of the actual multimodel ensemble behavior. A potentially important role for both anthropogenic aerosols and greenhouse gases with regard to the observed North Atlantic multidecadal variability has clear implications for decadal predictability and predictions. The uncertainty associated with alternative aerosol and greenhouse gas emission scenarios should be duly accounted for in designing a common protocol for coordinated decadal forecast experiments.

The Response of the Indian Ocean Dipole Asymmetry to Anthropogenic Aerosols and Greenhouse Gases

2015 ◽  
Vol 28 (7) ◽  
pp. 2564-2583 ◽  
Author(s):  
Tim Cowan ◽  
Wenju Cai ◽  
Benjamin Ng ◽  
Matthew England
Keyword(s):  
Indian Ocean ◽  
Greenhouse Gases ◽  
Indian Ocean Dipole ◽  
Climate Models ◽  
Coupled Model ◽  
Tropical Indian Ocean ◽  
Cmip5 Models ◽  
Anthropogenic Aerosols ◽  
The West ◽  
The Indian Ocean

Abstract The tropical Indian Ocean has experienced a faster warming rate in the west than in the east over the twentieth century. The warming pattern resembles a positive Indian Ocean dipole (IOD) that is well captured by climate models from phase 5 of the Coupled Model Intercomparison Project (CMIP5), forced with the two main anthropogenic forcings, long-lived greenhouse gases (GHGs), and aerosols. However, much less is known about how GHGs and aerosols influence the IOD asymmetry, including the negative sea surface temperature (SST) skewness in the east IOD pole (IODE). Here, it is shown that the IODE SST negative skewness is more enhanced by aerosols than by GHGs using single-factor forcing experiments from 10 CMIP5 models. Aerosols induce a greater mean zonal thermocline gradient along the tropical Indian Ocean than that forced by GHGs, whereby the thermocline is deeper in the east relative to the west. This generates strong asymmetry in the SST response to thermocline anomalies between warm and cool IODE phases in the aerosol-only experiments, enhancing the negative IODE SST skewness. Other feedback processes involving zonal wind, precipitation, and evaporation cannot solely explain the enhanced SST skewness by aerosols. An interexperiment comparison in one model with strong skewness confirms that the mean zonal thermocline gradient across the Indian Ocean determines the magnitude of the SST–thermocline asymmetry, which in turn controls the SST skewness strength. The findings suggest that as aerosol emissions decline and GHGs increase, this will likely contribute to a future weakening of the IODE SST skewness.

scholarly journals Detecting the influence of fossil fuel and bio-fuel black carbon aerosols on near surface temperature changes

2011 ◽  
Vol 11 (2) ◽  
pp. 799-816 ◽  
Author(s):  
G. S. Jones ◽  
N. Christidis ◽  
P. A. Stott
Keyword(s):  
Greenhouse Gases ◽  
Greenhouse Gas ◽  
Black Carbon ◽  
20Th Century ◽  
Radiative Forcing ◽  
Fossil Fuel ◽  
Climate Model ◽  
Global Climate ◽  
Anthropogenic Aerosols ◽  
Near Surface

Abstract. Past research has shown that the dominant influence on recent global climate changes is from anthropogenic greenhouse gas increases with implications for future increases in global temperatures. One mitigation proposal is to reduce black carbon aerosol emissions. How much warming can be offset by controlling black carbon is unclear, especially as its influence on past climate has not been previously unambiguously detected. In this study observations of near-surface warming over the last century are compared with simulations using a climate model, HadGEM1. In the simulations black carbon, from fossil fuel and bio-fuel sources (fBC), produces a positive radiative forcing of about +0.25 Wm−2 over the 20th century, compared with +2.52 Wm−2 for well mixed greenhouse gases. A simulated warming of global mean near-surface temperatures over the twentieth century from fBC of 0.14 ± 0.1 K compares with 1.06 ± 0.07 K from greenhouse gases, −0.58 ± 0.10 K from anthropogenic aerosols, ozone and land use changes and 0.09 ± 0.09 K from natural influences. Using a detection and attribution methodology, the observed warming since 1900 has detectable influences from anthropogenic and natural factors. Fossil fuel and bio-fuel black carbon is found to have a detectable contribution to the warming over the last 50 yr of the 20th century, although the results are sensitive to the period being examined as fBC is not detected for the later fifty year period ending in 2006. The attributed warming of fBC was found to be consistent with the warming from fBC unscaled by the detection analysis. This study suggests that there is a possible significant influence from fBC on global temperatures, but its influence is small compared to that from greenhouse gas emissions.

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