Northern Hemisphere drought risk in a warming climate

AbstractDrought frequency and severity are projected to increase in the future, but the changes are expected to be unevenly distributed across the globe. Based on multi-model simulations under three different future emissions and shared socioeconomic pathways, we show that a significant drought intensification is expected in dry regions, whereby the severity depends on greenhouse gas emissions and development pathways. The drought hotspots are located in the sub-tropical regions where a moderate to extreme summer drought in today’s climate is expected to become a new normal by the end of the 21st century under the warmest scenario. On average, under the warmest future scenario, the drought occurrence rate is projected to be 100% higher than that of the low emission scenario. Further, for the regions which are currently less affected by long-lasting droughts, such as the European continent, climate models indicate a significant increase in drought occurrence probability under the warmest future scenario.

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Increased Drought Risk in South Asia under Warming Climate: Implications of Uncertainty in Potential Evapotranspiration Estimates

Journal of Hydrometeorology ◽

10.1175/jhm-d-19-0224.1 ◽

2020 ◽

Vol 21 (12) ◽

pp. 2979-2996 ◽

Cited By ~ 5

Author(s):

Saran Aadhar ◽

Vimal Mishra

Keyword(s):

Soil Moisture ◽

South Asia ◽

Climate Models ◽

Potential Evapotranspiration ◽

Global Climate ◽

Global Climate Models ◽

Drought Risk ◽

Severe Drought ◽

Considerable Uncertainty ◽

Warming Climate

AbstractObserved and projected changes in potential evapotranspiration (PET) and drought are not well constrained in South Asia. Using five PET estimates [Thornthwaite (PET-TH), Hargreaves–Samani (PET-HS), Penman–Monteith (PET-PM), modified Penman–Monteith (PET-MPM), and energy (PET-EN)] for the observed (1979–2018, from ERA5) and future warming climate, we show that significant warming has occurred in South Asia during 1979–2018. PET changes show considerable uncertainty depending on the method used. For instance, PET-TH has increased significantly while all the other four methods show a decline in PET in the majority of South Asia during the observed period of 1979–2018. The increase in PET-TH is substantially higher than PET-HS, PET-PM, and PET-MPM due to a higher (3–4 times) sensitivity of PET-TH to warming during the observed period. Under the 1.5°, 2.0°, and 2.5°C warming worlds, global climate models from phase 5 of the Coupled Model Intercomparison Project (CMIP5 GCMs) project increases in PET and drought frequency over the majority of the regions. Drought estimates based on PET-EN and PET-MPM are consistent with soil moisture–based drought estimates and project a substantial increase in the frequency of severe droughts under warming climate in South Asia. In addition, the projected frequency of severe drought based on PET-TH, which is an outlier, is about 5 times higher than PET-EN and PET-MPM. Methods to estimate PET contribute the most in the overall uncertainty of PET and drought projections in South Asia, primarily due to PET-TH. Drought estimates based on PET-TH are not reliable for the observed and projected future climate. Therefore, future drought projections should be either based on PET-EN/PET-MPM or soil moisture.

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Future Australian Severe Thunderstorm Environments. Part II: The Influence of a Strongly Warming Climate on Convective Environments

Journal of Climate ◽

10.1175/jcli-d-13-00426.1 ◽

2014 ◽

Vol 27 (10) ◽

pp. 3848-3868 ◽

Cited By ~ 30

Author(s):

John T. Allen ◽

David J. Karoly ◽

Kevin J. Walsh

Keyword(s):

Climate Models ◽

Global Climate ◽

Convective Available Potential Energy ◽

Vertical Wind Shear ◽

Atmospheric Model ◽

Global Climate Models ◽

Historical Period ◽

Severe Thunderstorm ◽

Warming Climate ◽

Eastern Australia

Abstract The influence of a warming climate on the occurrence of severe thunderstorm environments in Australia was explored using two global climate models: Commonwealth Scientific and Industrial Research Organisation Mark, version 3.6 (CSIRO Mk3.6), and the Cubic-Conformal Atmospheric Model (CCAM). These models have previously been evaluated and found to be capable of reproducing a useful climatology for the twentieth-century period (1980–2000). Analyzing the changes between the historical period and high warming climate scenarios for the period 2079–99 has allowed estimation of the potential convective future for the continent. Based on these simulations, significant increases to the frequency of severe thunderstorm environments will likely occur for northern and eastern Australia in a warmed climate. This change is a response to increasing convective available potential energy from higher continental moisture, particularly in proximity to warm sea surface temperatures. Despite decreases to the frequency of environments with high vertical wind shear, it appears unlikely that this will offset increases to thermodynamic energy. The change is most pronounced during the peak of the convective season, increasing its length and the frequency of severe thunderstorm environments therein, particularly over the eastern parts of the continent. The implications of this potential increase are significant, with the overall frequency of potential severe thunderstorm days per year likely to rise over the major population centers of the east coast by 14% for Brisbane, 22% for Melbourne, and 30% for Sydney. The limitations of this approach are then discussed in the context of ways to increase the confidence of predictions of future severe convection.

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Representation of Soil Moisture Feedbacks during Drought in NASA Unified WRF (NU-WRF)

Journal of Hydrometeorology ◽

10.1175/jhm-d-12-069.1 ◽

2013 ◽

Vol 14 (1) ◽

pp. 360-367 ◽

Cited By ~ 46

Author(s):

Benjamin F. Zaitchik ◽

Joseph A. Santanello ◽

Sujay V. Kumar ◽

Christa D. Peters-Lidard

Keyword(s):

Soil Moisture ◽

Great Plains ◽

Climate Models ◽

Regional Climate ◽

Regional Climate Models ◽

Summer Drought ◽

Dynamic Surface ◽

Seasonal Drought ◽

Weather Forecasts ◽

Local Soil

Abstract Positive soil moisture–precipitation feedbacks can intensify heat and prolong drought under conditions of precipitation deficit. Adequate representation of these processes in regional climate models is, therefore, important for extended weather forecasts, seasonal drought analysis, and downscaled climate change projections. This paper presents the first application of the NASA Unified Weather Research and Forecasting Model (NU-WRF) to simulation of seasonal drought. Simulations of the 2006 southern Great Plains drought performed with and without soil moisture memory indicate that local soil moisture feedbacks had the potential to concentrate precipitation in wet areas relative to dry areas in summer drought months. Introduction of a simple dynamic surface albedo scheme that models albedo as a function of soil moisture intensified the simulated feedback pattern at local scale—dry, brighter areas received even less precipitation while wet, whereas darker areas received more—but did not significantly change the total amount of precipitation simulated across the drought-affected region. This soil-moisture-mediated albedo land–atmosphere coupling pathway is structurally excluded from standard versions of WRF.

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Aviation Impacts on Fuel Efficiency of a Future More Viscous Atmosphere

Bulletin of the American Meteorological Society ◽

10.1175/bams-d-19-0239.1 ◽

2020 ◽

Vol 101 (10) ◽

pp. E1761-E1780

Author(s):

Diandong Ren ◽

Rong Fu ◽

Robert E. Dickinson ◽

Lance M. Leslie ◽

Xingbao Wang

Keyword(s):

Skin Friction ◽

Climate Models ◽

Climate Model ◽

Fuel Efficiency ◽

Aviation Fuel ◽

Vertical Shear ◽

Friction Drag ◽

Dominant Term ◽

Warming Climate ◽

Additional Fuel

AbstractAircraft cruising near the tropopause currently benefit from the highest thermal efficiency and the least viscous (sticky) air, within the lowest 50 km of Earth’s atmosphere. Both advantages wane in a warming climate, because atmospheric dynamic viscosity increases with temperature, in synergy with the simultaneous engine efficiency reduction. Here, skin friction drag, the dominant term for extra aviation fuel consumption in a future warming climate, is quantified by 34 climate models under a strong emissions scenario. Since 1950, the viscosity increase at cruising altitudes (∼200 hPa) reaches ∼1.5% century‒1, corresponding to a total drag increment of ∼0.22% century‒1 for commercial aircraft. Meridional gradients and regional disparities exist, with low to midlatitudes experiencing greater increases in skin friction drag. The North Atlantic corridor (NAC) is moderately affected, but its high traffic volume generates additional fuel cost of ∼3.8 × 107 gallons annually by 2100, compared to 2010. Globally, a normal year after 2100 would consume an extra ∼4 × 106 barrels per year. Intermodel spread is <5% of the ensemble mean, due to high inter–climate model consensus for warming trends at cruising altitudes in the tropics and subtropics. Because temperature is a well-simulated parameter in the IPCC archive, with only a moderate intermodel spread, the conclusions drawn here are statistically robust. Notably, additional fuel costs are likely from the increased vertical shear and related turbulence at NAC cruising altitudes. Increased flight log availability is required to confirm this apparent increasing turbulence trend.

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Detecting sulphate aerosol geoengineering with different methods

Scientific Reports ◽

10.1038/srep39169 ◽

2016 ◽

Vol 6 (1) ◽

Cited By ~ 9

Author(s):

Y. T. Eunice Lo ◽

Andrew J. Charlton-Perez ◽

Fraser C. Lott ◽

Eleanor J. Highwood

Keyword(s):

Climate Models ◽

Surface Air Temperature ◽

High Sensitivity ◽

Internal Variability ◽

Detection Methods ◽

Sulphate Aerosol ◽

Near Surface ◽

Future Scenario ◽

External Forcings ◽

Global Mean

Abstract Sulphate aerosol injection has been widely discussed as a possible way to engineer future climate. Monitoring it would require detecting its effects amidst internal variability and in the presence of other external forcings. We investigate how the use of different detection methods and filtering techniques affects the detectability of sulphate aerosol geoengineering in annual-mean global-mean near-surface air temperature. This is done by assuming a future scenario that injects 5 Tg yr−1 of sulphur dioxide into the stratosphere and cross-comparing simulations from 5 climate models. 64% of the studied comparisons would require 25 years or more for detection when no filter and the multi-variate method that has been extensively used for attributing climate change are used, while 66% of the same comparisons would require fewer than 10 years for detection using a trend-based filter. This highlights the high sensitivity of sulphate aerosol geoengineering detectability to the choice of filter. With the same trend-based filter but a non-stationary method, 80% of the comparisons would require fewer than 10 years for detection. This does not imply sulphate aerosol geoengineering should be deployed, but suggests that both detection methods could be used for monitoring geoengineering in global, annual mean temperature should it be needed.

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Monitoring and predicting the outstanding 2017 drought in Spain

10.5194/egusphere-egu2020-15225 ◽

2020 ◽

Author(s):

Miguel Ángel Torres Vázquez ◽

Amar Halifa Marín ◽

Juan Pedro Montávez ◽

Marco Turco

Keyword(s):

Standardized Precipitation Index ◽

Warning System ◽

Empirical Method ◽

Environmental Research ◽

Drought Risk ◽

Summer Drought ◽

Drought Event ◽

Streamflow Prediction ◽

Drought Prediction ◽

Drought Conditions

The increase in societal exposure and vulnerability to drought, call to move from post-crisis to pre-impact drought risk management. Accurate and timely information of evolving drought conditions is crucial to take early actions to avoid devastating long-term impacts. A previous study indicated that a statistical empirical method, the ensemble streamflow prediction system (ESP; an ensemble based on reordering historical data), represents a computationally fast alternative to dynamical prediction applications for drought prediction (Turco et al. 2017). Extending this work, here we present an assessment of the ability of the ESP method in predicting the drought of 2017 in Spain considering also the uncertainties coming from the observations. For this, four different datasets are used: that cover a period of 36 years (1981-2017) and with a spatial resolution of 0.25 x 0.25&#186; based on observations of interpolated stations (E-OBS, AEMET), on reanalysis data (ERA5), and on combining stations and satellite data (CHIRPS). Meteorological droughts are defined using the Standardized Precipitation Index aggregated over the months April&#8211;September. All the datasets show a similar spatial pattern, with most of the domain suffering extreme drought conditions. In addition, the ESP system achieves reasonable skill in predicting this drought event 2 months in advance with, again, similar pattern among the different datasets. These results suggest the feasibility of the development of an operational early warning system, also considering that the data of CHIRPS and ERA5 are updated every month, i.e., that are available for near-real time applications.&#160;ReferencesTurco, M., et al. (2017). Summer drought predictability over Europe: empirical versus dynamical forecasts.&#160;Environmental Research Letters,&#160;12(8), 084006.&#160;AcknowledgmentsThe authors acknowledge the ACEX project (CGL2017-87921-R) of the Ministerio de Economi&#769;a y Competitividad of Spain.&#160;AHM thanks his predoctoral contract FPU18/00824 to the Ministerio de Ciencia, Innovacio&#769;n y Universidades of Spain. M.T. has received funding from the Spanish Ministry of Science, Innovation and Universities through the project PREDFIRE (RTI2018-099711-J-I00).

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Assessing the Risk of Persistent Drought Using Climate Model Simulations and Paleoclimate Data

Journal of Climate ◽

10.1175/jcli-d-12-00282.1 ◽

2014 ◽

Vol 27 (20) ◽

pp. 7529-7549 ◽

Cited By ~ 134

Author(s):

Toby R. Ault ◽

Julia E. Cole ◽

Jonathan T. Overpeck ◽

Gregory T. Pederson ◽

David M. Meko

Keyword(s):

Climate Models ◽

Climate Model ◽

State Of The Art ◽

Global Climate ◽

Global Climate Models ◽

Mitigation Strategies ◽

Drought Risk ◽

Climate Model Simulations ◽

Projected Changes ◽

Paleoclimate Data

Abstract Projected changes in global rainfall patterns will likely alter water supplies and ecosystems in semiarid regions during the coming century. Instrumental and paleoclimate data indicate that natural hydroclimate fluctuations tend to be more energetic at low (multidecadal to multicentury) than at high (interannual) frequencies. State-of-the-art global climate models do not capture this characteristic of hydroclimate variability, suggesting that the models underestimate the risk of future persistent droughts. Methods are developed here for assessing the risk of such events in the coming century using climate model projections as well as observational (paleoclimate) information. Where instrumental and paleoclimate data are reliable, these methods may provide a more complete view of prolonged drought risk. In the U.S. Southwest, for instance, state-of-the-art climate model projections suggest the risk of a decade-scale megadrought in the coming century is less than 50%; the analysis herein suggests that the risk is at least 80%, and may be higher than 90% in certain areas. The likelihood of longer-lived events (>35 yr) is between 20% and 50%, and the risk of an unprecedented 50-yr megadrought is nonnegligible under the most severe warming scenario (5%–10%). These findings are important to consider as adaptation and mitigation strategies are developed to cope with regional impacts of climate change, where population growth is high and multidecadal megadrought—worse than anything seen during the last 2000 years—would pose unprecedented challenges to water resources in the region.

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Ocean acidification limits temperature-induced poleward expansion of coral habitats around Japan

Biogeosciences Discussions ◽

10.5194/bgd-9-7165-2012 ◽

2012 ◽

Vol 9 (6) ◽

pp. 7165-7196 ◽

Cited By ~ 4

Author(s):

Y. Yara ◽

M. Vogt ◽

M. Fujii ◽

H. Yamano ◽

C. Hauri ◽

...

Keyword(s):

Ocean Acidification ◽

Climate Models ◽

Tropical Regions ◽

Temperate Coral ◽

Future Global Warming ◽

Coral Communities ◽

Potential Habitats ◽

Suitable Habitats ◽

Business As Usual

Abstract. Using results from four coupled global carbon cycle-climate models combined with in situ observations, we estimate the combined effects of future global warming and ocean acidification on potential habitats for tropical/subtropical and temperate coral communities in the seas around Japan. The suitability of the coral habitats are identified primarily on the basis of the currently observed ranges for temperature and saturation states Ω with regard to aragonite (Ωarag). We find that under the "business as usual" SRES A2 scenario, coral habitats will expand northward by several hundred kilometers by the end of this century. At the same time, coral habitats are projected to become sandwiched between the tropical regions, where the frequency of coral bleaching will increase, and the temperate-to-subpolar latitudes, where Ωarag will become too low to support sufficiently high calcification rates. As a result, the area of coral habitats around Japan that is suitable to tropical-subtropical communities will be reduced by half by the 2020s to 2030s, and is projected to disappear by the 2030s to 2040s. The suitable habitats for the temperate coral communities are also becoming smaller, although at a less pronounced rate due to their higher tolerance for low Ωarag.

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SimCloud version 1.0: a simple diagnostic cloud scheme for idealized climate models

Geoscientific Model Development ◽

10.5194/gmd-14-2801-2021 ◽

2021 ◽

Vol 14 (5) ◽

pp. 2801-2826

Author(s):

Qun Liu ◽

Matthew Collins ◽

Penelope Maher ◽

Stephen I. Thomson ◽

Geoffrey K. Vallis

Keyword(s):

General Circulation ◽

Large Scale ◽

Climate Models ◽

General Circulation Models ◽

Cloud Fraction ◽

Specific Humidity ◽

Polar Regions ◽

Modeling Framework ◽

Tropical Regions ◽

Subtropical Oceans

Abstract. A simple diagnostic cloud scheme (SimCloud) for general circulation models (GCMs), which has a modest level of complexity and is transparent in describing its dependence on tunable parameters, is proposed in this study. The large-scale clouds, which form the core of the scheme, are diagnosed from relative humidity. In addition, the marine low stratus clouds, typically found off the west coast of continents over subtropical oceans, are determined largely as a function of inversion strength. A “freeze-dry” adjustment based on a simple function of specific humidity is also available to reduce an excessive cloud bias in polar regions. Other cloud properties, such as the effective radius of cloud droplet and cloud liquid water content, are specified as simple functions of temperature. All of these features are user-configurable. The cloud scheme is implemented in Isca, a modeling framework designed to enable the construction of GCMs at varying levels of complexity, but could readily be adapted to other GCMs. Simulations using the scheme with realistic continents generally capture the observed structure of cloud fraction and cloud radiative effect (CRE), as well as its seasonal variation. Specifically, the explicit low-cloud scheme improves the simulation of shortwave CREs over the eastern subtropical oceans by increasing the cloud fraction and cloud water path. The freeze-dry adjustment alleviates the longwave CRE biases in polar regions, especially in winter. However, the longwave CRE in tropical regions and shortwave CRE over the extratropics are both still too strong compared to observations. Nevertheless, this simple cloud scheme provides a suitable basis for examining the impacts of clouds on climate in idealized modeling frameworks.

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Assessing the Robustness of Future Extreme Precipitation Intensification in the CMIP5 Ensemble

Journal of Climate ◽

10.1175/jcli-d-17-0683.1 ◽

2018 ◽

Vol 31 (16) ◽

pp. 6505-6525 ◽

Cited By ~ 13

Author(s):

Margot Bador ◽

Markus G. Donat ◽

Olivier Geoffroy ◽

Lisa V. Alexander

Keyword(s):

Extreme Precipitation ◽

Climate Models ◽

Internal Variability ◽

Global Scale ◽

Grid Cells ◽

Wet Season ◽

Tropical Regions ◽

Projected Changes ◽

Background Climate ◽

Climate Noise

Abstract A warming climate is expected to intensify extreme precipitation, and climate models project a general intensification of annual extreme precipitation in most regions of the globe throughout the twenty-first century. We investigate the robustness of this future intensification over land across different models, regions, and seasons and evaluate the role of model interdependencies in the CMIP5 ensemble. Strong similarities in extreme precipitation changes are found between models that share atmospheric physics, turning an ensemble of 27 models into around 14 projections. We find that future annual extreme precipitation intensity increases in the majority of models and in the majority of land grid cells, from the driest to the wettest regions, as defined by each model’s precipitation climatology. The intermodel spread is generally larger over wet than over dry regions, smaller in the dry season compared to the wet season and at the annual scale, and largely reduced in extratropical compared to tropical regions and at the global scale. For each model, the future increase in annual and seasonal maximum daily precipitation amounts exceeds the range of simulated internal variability in the majority of land grid cells. At both annual and seasonal scales, however, there are a few regions where the change is still within the background climate noise, but their size and location differ between models. In extratropical regions, the signal-to-noise ratio of projected changes in extreme precipitation is particularly robust across models because of a similar change and background climate noise, whereas projected changes are less robust in the tropics.

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