Accelerated warming in the northern midlatitude summer since the 1990s

2021 ◽  
Author(s):  
Haiyan Teng ◽  
Ruby Leung ◽  
Grant Branstator ◽  
Jian Lu ◽  
Qinghua Ding
Keyword(s):  
Climate Models ◽  
Wave Train ◽  
Coupled Model ◽  
Wave Model ◽  
Warming Trend ◽  
Forced Response ◽  
Regional Warming ◽  
Arctic Regions ◽  
Rossby Wave Train ◽  
A Chain

<p>The northern midlatitude summer has experienced rapid warming since the 1990s, especially in Europe, Central Siberia-Mongolia, the West Coast of North America as well as several continental Arctic regions. These “hot spots” are connected by a chain of high-pressure ridges from an anomalous wavenumber-5 Rossby wave train in the upper troposphere.  Here by cross-examining reanalysis datasets and a suite of Coupled Model Intercomparison Project Phase 6 (CMIP6) baseline experiments, we demonstrate that the anthropogenically forced response may be intertwined with internal multidecadal variability, making it difficult to partition the 1979-2020 trend with state-of-the-art climate models. Instead, we take a “storyline” approach with a planetary wave model and sensitivity experiments with an Earth system model to explore key underlying driving factors. Our results highlight the importance of multiscale interaction with synoptic eddy via atmosphere-ocean and atmosphere-land coupling in shaping the multidecadal regional warming trend which has enormous socioeconomic implications. </p>

scholarly journals Anthropogenic influence in observed regional warming trends and the implied social time of emergence

2021 ◽  
Vol 2 (1) ◽  
Author(s):  
Francisco Estrada ◽  
Dukpa Kim ◽  
Pierre Perron
Keyword(s):  
Climate Change ◽  
Radiative Forcing ◽  
Climate Models ◽  
Extreme Values ◽  
Statistical Tests ◽  
Warming Trend ◽  
Past Century ◽  
Anthropogenic Influence ◽  
Regional Warming ◽  
Social Time

AbstractThe attribution of climate change allows for the evaluation of the contribution of human drivers to observed warming. At the global and hemispheric scales, many physical and observation-based methods have shown a dominant anthropogenic signal, in contrast, regional attribution of climate change relies on physically based numerical climate models. Here we show, using state-of-the-art statistical tests, the existence of a common nonlinear trend in observed regional air surface temperatures largely imparted by anthropogenic forcing. All regions, continents and countries considered have experienced warming during the past century due to increasing anthropogenic radiative forcing. The results show that we now experience mean temperatures that would have been considered extreme values during the mid-20th century. The adaptation window has been getting shorter and is projected to markedly decrease in the next few decades. Our findings provide independent empirical evidence about the anthropogenic influence on the observed warming trend in different regions of the world.

scholarly journals Projected Characteristic Changes of a Typical Tropical Cyclone under Climate Change in the South West Indian Ocean

Atmosphere ◽  
2021 ◽  
Vol 12 (2) ◽  
pp. 232
Author(s):  
Callum Thompson ◽  
Christelle Barthe ◽  
Soline Bielli ◽  
Pierre Tulet ◽  
Joris Pianezze
Keyword(s):  
Indian Ocean ◽  
Climate Models ◽  
Surface Wind ◽  
Coupled Model ◽  
Wave Model ◽  
La Réunion ◽  
Intergovernmental Panel ◽  
Surface Warming ◽  
Wind Speeds ◽  
South West Indian Ocean

During 2 January 2014, Cyclone Bejisa passed near La Réunion in the southwestern Indian Ocean, bringing wind speeds of 41 m s−1, an ocean swell of 7 m, and rainfall accumulations of 1025 mm over 48 h. As a typical cyclone to impact La Réunion, we investigate how the characteristics of this cyclone could change in response to future warming via high-resolution, atmosphere–ocean coupled simulations of Bejisa-like cyclones in historical and future environments. Future environments are constructed using the pseudo global warming method whereby perturbations are added to historical analyses from six Coupled Model Intercomparison Project 5 (CMIP5) climate models. These models follow the Intergovernmental Panel for Climate Change’s (IPCC) Representative Concentration Pathways (RCP) RCP8.5 emissions scenario and project ocean surface warming of 1.1–4.2 °C by 2100. Under these conditions, we find that future Bejisa-like cyclones are 6.5% more intense on average and reach their lifetime maximum intensity 2 degrees further poleward. Additionally, future cyclones produce heavier rainfall, with a 33.8% average increase in the median rainrate, and are 9.2% smaller, as measured by the radius of 17.5 m s−1 winds. Furthermore, when surface wind output is used to run an ocean wave model in post, we find a 4.6% increase in the significant wave height.

scholarly journals Past warming trend constrains future warming in CMIP6 models

2020 ◽  
Author(s):  
Martin Stolpe ◽  
Katarzyna Tokarska ◽  
Sebastian Sippel ◽  
Erich Fischer ◽  
Christopher Smith ◽  
...  
Keyword(s):  
Climate Models ◽  
Coupled Model ◽  
Warming Trend ◽  
Paris Agreement ◽  
Cmip5 Models ◽  
Model Intercomparison ◽  
Mitigation Scenario ◽  
Future Global Warming ◽  
Intercomparison Project ◽  
Future Warming

<div>Future global warming estimates have been similar across past assessments, but several climate models of the latest Sixth Coupled Model Intercomparison Project (CMIP6) simulate much stronger warming, apparently inconsistent with past assessments. Here we show that projected future warming is correlated with the simulated warming trend during recent decades across CMIP5 and CMIP6 models, enabling us to constrain future warming based on consistency with the observed warming. These findings carry important policy-relevant implications: the observationally-constrained CMIP6 median warming in high emissions and ambitious mitigation scenarios is over 16% and 14% lower by 2050 compared to the raw CMIP6 median, respectively, and over 14% and 8% lower by 2090, relative to 1995-2014. Observationally-constrained CMIP6 warming is consistent with previous assessments based on CMIP5 models, and in an ambitious mitigation scenario, the likely range is consistent with reaching the Paris Agreement target.</div><div> </div><div>Reference: </div><div>Tokarska, K.B.<sup>†</sup>, Stolpe, M.B.<sup>†</sup>, Sippel, S., Fischer, E.M., Smith, C.J., Lehner, F., and Knutti, R. (2020). Past warming trend constrains future warming in CMIP6 models. <em>Science Advances</em>  (accepted).</div><div><sup>†</sup>equal first authors</div>

scholarly journals The Making of an Extreme Event: Putting the Pieces Together

2014 ◽  
Vol 95 (3) ◽  
pp. 427-440 ◽  
Author(s):  
Randall Dole ◽  
Martin Hoerling ◽  
Arun Kumar ◽  
Jon Eischeid ◽  
Judith Perlwitz ◽  
...  
Keyword(s):  
United States ◽  
Extreme Event ◽  
Coupled Model ◽  
Warming Trend ◽  
Physical Factors ◽  
Eastern United States ◽  
Regional Warming ◽  
Temperature Anomalies ◽  
Order Of Magnitude

We examine how physical factors spanning climate and weather contributed to record warmth over the central and eastern United States in March 2012, when daily temperature anomalies at many locations exceeded 20°C. Over this region, approximately 1°C warming in March temperatures has occurred since 1901. This long-term regional warming is an order of magnitude smaller than temperature anomalies observed during the event, indicating that most of the extreme warmth must be explained by other factors. Several lines of evidence strongly implicate natural variations as the primary cause for the extreme event. The 2012 temperature anomalies had a close analog in an exceptionally warm U.S. March occurring over 100 years earlier, providing observational evidence that an extreme event similar to March 2012 could be produced through natural variability alone. Coupled model forecasts and simulations forced by observed sea surface temperatures (SSTs) show that forcing from anomalous SSTs increased the probability of extreme warm temperatures in March 2012 above that anticipated from the long-term warming trend. In addition, forcing associated with a strong Madden–Julian oscillation further increased the probability for extreme U.S. warmth and provided important additional predictive information on the timing and spatial pattern of temperature anomalies. The results indicate that the superposition of a strong natural variation similar to March 1910 on longterm warming of the magnitude observed would be sufficient to account for the record warm March 2012 U.S. temperatures. We conclude that the extreme warmth over the central and eastern United States in March 2012 resulted primarily from natural climate and weather variability— a substantial fraction of which was predictable.

scholarly journals Potential impact of climate change to the future streamflow of Yellow River Basin based on CMIP5 data

2018 ◽  
Vol 376 ◽  
pp. 97-104 ◽  
Author(s):  
Xiaoli Yang ◽  
Weifei Zheng ◽  
Liliang Ren ◽  
Mengru Zhang ◽  
Yuqian Wang ◽  
...  
Keyword(s):  
Climate Change ◽  
River Basin ◽  
Climate Models ◽  
Yellow River ◽  
Coupled Model ◽  
Northern China ◽  
Yellow River Basin ◽  
Warming Trend ◽  
Infiltration Capacity ◽  
The Future

Abstract. The Yellow River Basin (YRB) is the largest river basin in northern China, which has suffering water scarcity and drought hazard for many years. Therefore, assessments the potential impacts of climate change on the future streamflow in this basin is very important for local policy and planning on food security. In this study, based on the observations of 101 meteorological stations in YRB, equidistant CDF matching (EDCDFm) statistical downscaling approach was applied to eight climate models under two emissions scenarios (RCP4.5 and RCP8.5) from phase five of the Coupled Model Intercomparison Project (CMIP5). Variable infiltration capacity (VIC) model with 0.25∘ × 0.25∘ spatial resolution was developed based on downscaled fields for simulating streamflow in the future period over YRB. The results show that with the global warming trend, the annual streamflow will reduced about 10 % during the period of 2021–2050, compared to the base period of 1961–1990 in YRB. There should be suitable water resources planning to meet the demands of growing populations and future climate changing in this region.

Comment on “Rethinking the Lower Bound on Aerosol Radiative Forcing”

2017 ◽  
Vol 30 (16) ◽  
pp. 6579-6584 ◽  
Author(s):  
Jan Kretzschmar ◽  
Marc Salzmann ◽  
Johannes Mülmenstädt ◽  
Olivier Boucher ◽  
Johannes Quaas
Keyword(s):  
Radiative Forcing ◽  
Climate Models ◽  
Coupled Model ◽  
Warming Trend ◽  
Anthropogenic Aerosols ◽  
Aerosol Radiative Forcing ◽  
Aerosol Forcing ◽  
Interesting Study ◽  
Log Linear ◽  
Negative Formula

In an influential and interesting study, Stevens (2015) suggested that the global and also Northern Hemispheric warming during the early industrial period implies that the effective radiative forcing [Formula: see text] by anthropogenic aerosols in the year 2000 compared to 1850 cannot be more negative than −1.0 W m−2. Here results from phase 5 of the Coupled Model Intercomparison Project are analyzed and it is shown that there is little relationship between [Formula: see text] and the warming trend in the early industrial period in comprehensive climate models. In particular, some models simulate a warming in the early industrial period despite a strong (very negative) [Formula: see text]. The reason for this difference in results is that the global-mean log-linear scaling of [Formula: see text] with anthropogenic sulfur dioxide emissions introduced and used by Stevens tends to produce a substantially larger aerosol forcing compared to climate models in the first half of the twentieth century, when SO2 emissions were concentrated over smaller regions. In turn, it shows smaller (less negative) [Formula: see text] in the recent period with comparatively more widespread SO2 emissions.

scholarly journals Past warming trend constrains future warming in CMIP6 models

2020 ◽  
Vol 6 (12) ◽  
pp. eaaz9549 ◽  
Author(s):  
Katarzyna B. Tokarska ◽  
Martin B. Stolpe ◽  
Sebastian Sippel ◽  
Erich M. Fischer ◽  
Christopher J. Smith ◽  
...  
Keyword(s):  
Climate Models ◽  
Coupled Model ◽  
Warming Trend ◽  
Paris Agreement ◽  
Cmip5 Models ◽  
Model Intercomparison ◽  
Mitigation Scenario ◽  
Future Global Warming ◽  
Intercomparison Project ◽  
Future Warming

Future global warming estimates have been similar across past assessments, but several climate models of the latest Sixth Coupled Model Intercomparison Project (CMIP6) simulate much stronger warming, apparently inconsistent with past assessments. Here, we show that projected future warming is correlated with the simulated warming trend during recent decades across CMIP5 and CMIP6 models, enabling us to constrain future warming based on consistency with the observed warming. These findings carry important policy-relevant implications: The observationally constrained CMIP6 median warming in high emissions and ambitious mitigation scenarios is over 16 and 14% lower by 2050 compared to the raw CMIP6 median, respectively, and over 14 and 8% lower by 2090, relative to 1995–2014. Observationally constrained CMIP6 warming is consistent with previous assessments based on CMIP5 models, and in an ambitious mitigation scenario, the likely range is consistent with reaching the Paris Agreement target.

scholarly journals Abrupt cooling over the North Atlantic in modern climate models

2017 ◽  
Vol 8 (1) ◽  
Author(s):  
Giovanni Sgubin ◽  
Didier Swingedouw ◽  
Sybren Drijfhout ◽  
Yannick Mary ◽  
Amine Bennabi
Keyword(s):  
North Atlantic ◽  
Climate Models ◽  
Coupled Model ◽  
Deep Ocean ◽  
Warming Trend ◽  
Necessary Condition ◽  
Adaptation Policy ◽  
The North ◽  
Intercomparison Project

Abstract Observations over the 20th century evidence no long-term warming in the subpolar North Atlantic (SPG). This region even experienced a rapid cooling around 1970, raising a debate over its potential reoccurrence. Here we assess the risk of future abrupt SPG cooling in 40 climate models from the fifth Coupled Model Intercomparison Project (CMIP5). Contrary to the long-term SPG warming trend evidenced by most of the models, 17.5% of the models (7/40) project a rapid SPG cooling, consistent with a collapse of the local deep-ocean convection. Uncertainty in projections is associated with the models’ varying capability in simulating the present-day SPG stratification, whose realistic reproduction appears a necessary condition for the onset of a convection collapse. This event occurs in 45.5% of the 11 models best able to simulate the observed SPG stratification. Thus, due to systematic model biases, the CMIP5 ensemble as a whole underestimates the chance of future abrupt SPG cooling, entailing crucial implications for observation and adaptation policy.

scholarly journals Relationship between Southern Hemispheric jet variability and forced response: the role of the stratosphere

2021 ◽  
Author(s):  
Philipp Breul ◽  
Paulo Ceppi ◽  
Theodore Gordon Shepherd
Keyword(s):  
Climate Models ◽  
Coupled Model ◽  
Austral Summer ◽  
Internal Variability ◽  
Analysis Data ◽  
Southern Annular Mode ◽  
Dominant Mode ◽  
Forced Response ◽  
Cmip5 Models ◽  
Wide Range

Abstract. Climate models show a wide range of Southern Hemispheric jet responses to greenhouse gas forcing. One approach to constrain future jet response is by utilising the fluctuation-dissipation theorem (FDT) that links forced response to internal variability timescales, with the Southern Annular Mode (SAM) the most dominant mode of variability of the Southern Hemispheric jet. We show that stratospheric variability approximately doubles the SAM timescale during austral summer in both re-analysis data and models from the Coupled Model Intercomparison Project, phase 5 (CMIP5). Using a simple barotropic model, we demonstrate how the enhanced SAM timescale subsequently leads to an overestimate of the forced jet response based on FDT, and introduce a method to correct for the stratospheric influence. Even after accounting for this influence, the SAM timescale cannot explain inter-model differences in the forced jet shift across CMIP5 models during austral summer, owing to other confounding factors.

scholarly journals Parameter Optimization for Real-World ENSO Forecast in an Intermediate Coupled Model

2019 ◽  
Vol 147 (5) ◽  
pp. 1429-1445 ◽  
Author(s):  
Yuchu Zhao ◽  
Zhengyu Liu ◽  
Fei Zheng ◽  
Yishuai Jin
Keyword(s):  
Data Assimilation ◽  
Parameter Optimization ◽  
Real World ◽  
Climate Models ◽  
Coupled Model ◽  
Prediction Skill ◽  
Model Parameters ◽  
Real World Data ◽  
The Real ◽  
Advection Term

Abstract We performed parameter estimation in the Zebiak–Cane model for the real-world scenario using the approach of ensemble Kalman filter (EnKF) data assimilation and the observational data of sea surface temperature and wind stress analyses. With real-world data assimilation in the coupled model, our study shows that model parameters converge toward stable values. Furthermore, the new parameters improve the real-world ENSO prediction skill, with the skill improved most by the parameter of the highest climate sensitivity (gam2), which controls the strength of anomalous upwelling advection term in the SST equation. The improved prediction skill is found to be contributed mainly by the improvement in the model dynamics, and second by the improvement in the initial field. Finally, geographic-dependent parameter optimization further improves the prediction skill across all the regions. Our study suggests that parameter optimization using ensemble data assimilation may provide an effective strategy to improve climate models and their real-world climate predictions in the future.

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