scholarly journals Disruptions in precipitation cycles: Attribution to anthropogenic forcing

2016 ◽  
Vol 121 (5) ◽  
pp. 2161-2177 ◽  
Author(s):  
Francisco J. Tapiador ◽  
Ali Behrangi ◽  
Ziad S. Haddad ◽  
Dimitris Katsanos ◽  
Manuel de Castro
Keyword(s):  
Anthropogenic Forcing ◽  
Precipitation Cycles

scholarly journals A Regime View of the North Atlantic Oscillation and Its Response to Anthropogenic Forcing

2010 ◽  
Vol 23 (6) ◽  
pp. 1291-1307 ◽  
Author(s):  
Tim Woollings ◽  
Abdel Hannachi ◽  
Brian Hoskins ◽  
Andrew Turner
Keyword(s):  
North Atlantic Oscillation ◽  
North Atlantic ◽  
Anthropogenic Forcing ◽  
The Third ◽  
The North ◽  
Nao Index ◽  
Future Behavior ◽  
Real Change ◽  
The North Atlantic Oscillation

Abstract The distribution of the daily wintertime North Atlantic Oscillation (NAO) index in the 40-yr ECMWF Re-Analysis (ERA-40) is significantly negatively skewed. Dynamical and statistical analyses both suggest that this skewness reflects the presence of two distinct regimes—referred to as “Greenland blocking” and “subpolar jet.” Changes in both the relative occurrence and in the structure of the regimes are shown to contribute to the long-term NAO trend over the ERA-40 period. This is contrasted with the simulation of the NAO in 100-yr control and doubled CO2 integrations of the third climate configuration of the Met Office Unified Model (HadCM3). The model has clear deficiencies in its simulation of the NAO in the control run, so its predictions of future behavior must be treated with caution. However, the subpolar jet regime does become more dominant under anthropogenic forcing and, while this change is small it is clearly statistically significant and does represent a real change in the nature of NAO variability in the model.

scholarly journals Role of synoptic eddy feedback on polar climate responses to the anthropogenic forcing

2010 ◽  
Vol 37 (14) ◽  
pp. n/a-n/a ◽  
Author(s):  
Jong-Seong Kug ◽  
Da-Hee Choi ◽  
Fei-Fei Jin ◽  
Won-Tae Kwon ◽  
Hong-Li Ren
Keyword(s):  
Anthropogenic Forcing ◽  
Polar Climate ◽  
Synoptic Eddy ◽  
Climate Responses

Anthropogenic forcing on the Hadley circulation in CMIP5 simulations

2015 ◽  
Vol 46 (9-10) ◽  
pp. 3337-3350 ◽  
Author(s):  
Lijun Tao ◽  
Yongyun Hu ◽  
Jiping Liu
Keyword(s):  
Hadley Circulation ◽  
Anthropogenic Forcing

scholarly journals Air Temperature and Anthropogenic Forcing: Insights from the Solid Earth

2011 ◽  
Vol 24 (2) ◽  
pp. 569-574 ◽  
Author(s):  
Jean O. Dickey ◽  
Steven L. Marcus ◽  
Olivier de Viron
Keyword(s):  
Air Temperature ◽  
Decadal Variability ◽  
Surface Air Temperature ◽  
Radiation Budget ◽  
Cloud Formation ◽  
Length Of Day ◽  
Anthropogenic Forcing ◽  
The Core ◽  
Earth’S Radiation Budget ◽  
Gas Effect

Abstract Earth’s rotation rate [i.e., length of day (LOD)], the angular momentum of the core (CAM), and surface air temperature (SAT) all have decadal variability. Previous investigators have found that the LOD fluctuations are largely attributed to core–mantle interactions and that the SAT is strongly anticorrelated with the decadal LOD. It is shown here that 1) the correlation among these three quantities exists until 1930, at which time anthropogenic forcing becomes highly significant; 2) correcting for anthropogenic effects, the correlation is present for the full span with a broadband variability centered at 78 yr; and 3) this result underscores the reality of anthropogenic temperature change, its size, and its temporal growth. The cause of this common variability needs to be further investigated and studied. Since temperature cannot affect the CAM or LOD to a sufficient extent, the results favor either a direct effect of Earth’s core-generated magnetic field (e.g., through the modulation of charged-particle fluxes, which may impact cloud formation) or a more indirect effect of some other core process on the climate—or yet another process that affects both. In all three cases, their signals would be much smaller than the anthropogenic greenhouse gas effect on Earth’s radiation budget during the coming century.

Climate change attribution with large ensembles

2021 ◽  
Author(s):  
Megan Kirchmeier-Young ◽  
Xuebin Zhang ◽  
Hui Wan
Keyword(s):  
Extreme Precipitation ◽  
Extreme Event ◽  
Extreme Temperature ◽  
Anthropogenic Forcing ◽  
Robust Detection ◽  
Continental Scale ◽  
Extreme Precipitation Events ◽  
Event Attribution ◽  
Large Ensembles ◽  
Precipitation Events

<p>The large sample sizes from single-model large ensembles are beneficial for a robust attribution of climate changes to anthropogenic forcing. This presentation will review examples using large ensembles in two types of attribution:  standard detection and attribution of spatio-temporal changes and extreme event attribution. First, increases in extreme precipitation have been attributed to anthropogenic forcing at large scales (global and hemispheric). We present results from a study that used three large ensembles, including two Earth System Models and one Regional Climate Model, to find a robust detection of a combined anthropogenic and natural forcing signal in the intensification of extreme precipitation at the continental scale and some regional scales in North America. Second, we use six large ensembles to assess the robustness of the attribution of extreme temperature and precipitation events. An event attribution framework is used and each large ensemble is treated as a perfect model. Robustness of the attribution is defined based on consistent agreement between the different models on a significant change in the probability of an event with the inclusion of anthropogenic forcing. We demonstrate that the attribution of extreme temperature events is robust. Meanwhile, the attribution of extreme precipitation events becomes robust in many regions under additional warming, but uncertainties pertaining to changes in atmospheric dynamics hinder attribution confidence in other regions. We also demonstrate that smaller ensembles bring larger uncertainty to event attribution.</p>

scholarly journals Human Contribution to the Increasing Summer Precipitation in Central Asia from 1961 to 2013

2018 ◽  
Vol 31 (19) ◽  
pp. 8005-8021 ◽  
Author(s):  
Dongdong Peng ◽  
Tianjun Zhou ◽  
Lixia Zhang ◽  
Bo Wu
Keyword(s):  
Central Asia ◽  
Vertical Motion ◽  
Summer Precipitation ◽  
Specific Humidity ◽  
Moisture Budget ◽  
Anthropogenic Forcing ◽  
Radiative Forcings ◽  
Budget Analysis ◽  
Community Atmosphere Model ◽  
Advection Term

The ecosystem and societal development over arid Central Asia, the core connecting region of the Silk Road Economic Belt, are highly sensitive to climate change. The results derived from multiobservational datasets show that summer precipitation over Central Asia has significantly increased by 20.78% from 1961 to 2013. It remains unclear whether anthropogenic forcing has contributed to the summer wetting trend or not. In this study, the corresponding physical processes and contributions of anthropogenic forcing are investigated by comparing reanalysis and experiments of the Community Atmosphere Model, version 5.1 (CAM5.1), from the CLIVAR Climate of the Twentieth Century Plus (C20C+) Project. The observed wetting trend is well reproduced in the simulation driven by all radiative forcings (CAM5-All), but poorly reproduced in the simulation with natural forcings only (CAM5-Nat), confirming the important role of human contribution in the observed wetting trend. Moisture budget analysis shows that the observed wetting trend is dominated by the increasing vertical moisture advection term and results from enhanced vertical motion over nearly all of Central Asia. The observed contributions of moisture budget components to the wetting trend are only captured by CAM5-All experiments. The dynamic contribution is determined by the warm advection anomalies in association with a human-induced meridional uneven warm pattern. Human-induced warming increases the specific humidity over all of Central Asia, increasing (decreasing) the precipitation over the climatological ascent (descent) region in eastern (western) Central Asia.

scholarly journals Comparing modelled fire dynamics with charcoal records for the Holocene

2014 ◽  
Vol 10 (2) ◽  
pp. 811-824 ◽  
Author(s):  
T. Brücher ◽  
V. Brovkin ◽  
S. Kloster ◽  
J. R. Marlon ◽  
M. J. Power
Keyword(s):  
Land Surface ◽  
Burned Area ◽  
Surface Model ◽  
Model Output ◽  
Z Score ◽  
Fire Dynamics ◽  
Anthropogenic Forcing ◽  
Natural Fire ◽  
Fire Activity ◽  
Z Scores

Abstract. An earth system model of intermediate complexity (CLIMate and BiosphERe – CLIMBER-2) and a land surface model (JSBACH), which dynamically represent vegetation, are used to simulate natural fire dynamics through the last 8000 yr. Output variables of the fire model (burned area and fire carbon emissions) are used to compare model results with sediment-based charcoal reconstructions. Several approaches for processing model output are also tested. Charcoal data are reported in Z-scores with a base period of 8000–200 BP in order to exclude the strong anthropogenic forcing of fire during the last two centuries. The model–data comparison reveals a robust correspondence in fire activity for most regions considered, while for a few regions, such as Europe, simulated and observed fire histories show different trends. The difference between modelled and observed fire activity may be due to the absence of anthropogenic forcing (e.g. human ignitions and suppression) in the model simulations, and also due to limitations inherent to modelling fire dynamics. The use of spatial averaging (or Z-score processing) of model output did not change the directions of the trends. However, Z-score-transformed model output resulted in higher rank correlations with the charcoal Z-scores in most regions. Therefore, while both metrics are useful, processing model output as Z-scores is preferable to areal averaging when comparing model results to transformed charcoal records.

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