scholarly journals Global precipitation response to changing forcings since 1870

2011 ◽  
Vol 11 (18) ◽  
pp. 9961-9970 ◽  
Author(s):  
A. Bichet ◽  
M. Wild ◽  
D. Folini ◽  
C. Schär
Keyword(s):  
Greenhouse Gas ◽  
Climate Model ◽  
Hydrological Cycle ◽  
Global Climate ◽  
Global Climate Model ◽  
Internal Variability ◽  
Temperature And Precipitation ◽  
Global Land ◽  
Climate Forcings ◽  
Aerosol Emissions

Abstract. Predicting and adapting to changes in the hydrological cycle is one of the major challenges for the 21st century. To better estimate how it will respond to future changes in climate forcings, it is crucial to understand how the hydrological cycle has evolved in the past and why. In our study, we use an atmospheric global climate model with prescribed sea surface temperatures (SSTs) to investigate how, in the period 1870–2005, changing climate forcings have affected the global land temperature and precipitation. We show that between 1870 and 2005, prescribed SSTs (encapsulating other forcings and internal variability) determine the decadal and interannual variabilities of the global land temperature and precipitation, mostly via their influence in the tropics (25° S–25° N). In addition, using simulations with prescribed SSTs and considering the atmospheric response alone, we find that between 1930 and 2005 increasing aerosol emissions have reduced the global land temperature and precipitation by up to 0.4 °C and 30 mm yr−1, respectively, and that between about 1950 and 2005 increasing greenhouse gas concentrations have increased them by up to 0.25 °C and 10 mm yr−1, respectively. Finally, we suggest that between about 1950 and 1970, increasing aerosol emissions had a larger impact on the hydrological cycle than increasing greenhouse gas concentrations.

scholarly journals Global precipitation response to changing external forcings since 1870

2011 ◽  
Vol 11 (3) ◽  
pp. 9375-9405
Author(s):  
A. Bichet ◽  
M. Wild ◽  
D. Folini ◽  
C. Schär
Keyword(s):  
Climate Model ◽  
Decadal Variability ◽  
Hydrological Cycle ◽  
Global Climate ◽  
Global Climate Model ◽  
Temperature And Precipitation ◽  
Global Land ◽  
Climate Forcings ◽  
Aerosol Emissions ◽  
Global Precipitation

Abstract. Predicting and adapting to changes in the hydrological cycle is one of the major challenges for the twenty-first century. To better estimate how it will respond to future changes in climate forcings, it is crucial to understand how it has evolved in the past and why. In our study, we use an atmospheric global climate model with prescribed sea surface temperatures (SSTs) to investigate how changing external climate forcings have affected global land temperature and precipitation in the period 1870–2005. We show that prescribed SSTs (encapsulating other forcings) are the dominant forcing driving the decadal variability of land temperature and precipitation since 1870. On top of this SSTs forcing, we also find that the atmosphere-only response to increasing aerosol emissions is a reduction in global land temperature and precipitation by up to 0.4 °C and 30 mm year−1, respectively, between about 1930 and 2000. Similarly, the atmosphere-only response to increasing greenhouse gas concentrations is an increase in global land temperature and precipitation by up to 0.25 °C and 10 mm year−1, respectively, between about 1950 and 2000. Finally, our results also suggest that between about 1950 and 1970, increasing aerosol emissions had a larger impact on the hydrological cycle than increasing greenhouse gases concentrations.

scholarly journals Global change in flood and drought intensities under climate change in the 21<sup>st</sup> century

2017 ◽  
Author(s):  
Behzad Asadieh ◽  
Nir Y. Krakauer
Keyword(s):  
21St Century ◽  
Climate Model ◽  
Hydrological Cycle ◽  
Global Climate ◽  
Global Climate Model ◽  
The Arctic ◽  
Simultaneous Increase ◽  
Drought Intensity ◽  
Global Land ◽  
Streamflow Extremes

Abstract. Global warming is expected to intensify the Earth’s hydrological cycle and increase flood and drought risks. Changes in global high and low streamflow extremes over the 21st century under two warming scenarios are analyzed as indicators of hydrologic flood and drought intensity, using an ensemble of bias-corrected global climate model (GCM) fields fed into different global hydrological models (GHMs). Based on multi-model mean, approximately 37 % and 43 % of global land areas are exposed to increases in flood and drought intensities, respectively, by the end of the 21st century under RCP8.5 scenario. The average rates of increase in flood and drought intensities in those areas are projected to be 24.5 % and 51.5 %, respectively. Nearly 10 % of the global land areas are under the potential risk of simultaneous increase in both flood and drought intensities, with average rates of 10.1 % and 19.8 %, respectively; further, these regions tend to be highly populated parts of the globe, currently holding around 30 % of the world’s population (over 2.1 billion people). In a world more than 4 degrees warmer by the end of the 21st century compared to the pre-industrial era (RCP8.5 scenario), increases in flood and drought intensities are projected to be nearly twice as large as in a 2 degree warmer world (RCP2.6 scenario). Results also show that GHMs contribute to more uncertainties in streamflow changes than the GCMs. Under both forcing scenarios, there is high model agreement for significant increases in streamflow of the regions near and above the Arctic Circle, and consequent increases in the freshwater inflow to the Arctic Ocean, while subtropical arid areas experience reduction in streamflow.

scholarly journals Future shift in winter streamflow modulated by internal variability of climate in southern Ontario

2019 ◽  
Author(s):  
Olivier Champagne ◽  
Altaf Arain ◽  
Martin Leduc ◽  
Paulin Coulibaly ◽  
Shawn McKenzie
Keyword(s):  
Climate Model ◽  
Global Climate ◽  
Global Climate Model ◽  
Regional Climate ◽  
Internal Variability ◽  
Early Spring ◽  
Large Ensemble ◽  
Fluvial Systems ◽  
Southern Ontario ◽  
Temperature And Precipitation

Abstract. Fluvial systems in southern Ontario are regularly affected by widespread early-spring flood events primarily caused by rain-on-snow events. Recent studies have shown an increase in winter floods in this region due to increasing winter temperature and precipitation. Streamflow simulations are associated with uncertainties tied to the internal variability of climate. These uncertainties can be assessed using hydrological models fed by downscaled Global Climate Model Large Ensemble (GCM-LE) data. The Canadian Regional Climate Model Large Ensemble (CRCM5-LE), a dynamically downscaled version of a GCM-LE, was developed to simulate climate variability over northeastern North America under different future climate scenarios. In this study, CRCM5-LE temperature and precipitation projections under RCP 8.5 scenario were used as input in the Precipitation Runoff Modelling System (PRMS) to simulate near future (2040s) streamflow for four watersheds in southern Ontario. Model simulations show that 14 % of the ensemble project a high (low) increase of streamflow volume in January-February. Streamflow increases may be driven by rain and snowmelt modulation caused by the development of high (low) pressure anomalies in North America’s East Coast. Additionally, the streamflow may be enhanced by high pressure circulation patterns directly over the Great Lakes creating warm conditions and increasing snowmelt and rainfall/snowfall ratio (16 %). These results are important to assess the internal variability of the hydrological projections and to inform society of increased winter streamflow.

scholarly journals Global change in streamflow extremes under climate change over the 21st century

2017 ◽  
Vol 21 (11) ◽  
pp. 5863-5874 ◽  
Author(s):  
Behzad Asadieh ◽  
Nir Y. Krakauer
Keyword(s):  
Climate Change ◽  
21St Century ◽  
Climate Model ◽  
Hydrological Cycle ◽  
Global Climate ◽  
Global Climate Model ◽  
The Arctic ◽  
Average Decrease ◽  
Global Land ◽  
Streamflow Extremes

Abstract. Global warming is expected to intensify the Earth's hydrological cycle and increase flood and drought risks. Changes over the 21st century under two warming scenarios in different percentiles of the probability distribution of streamflow, and particularly of high and low streamflow extremes (95th and 5th percentiles), are analyzed using an ensemble of bias-corrected global climate model (GCM) fields fed into different global hydrological models (GHMs) provided by the Inter-Sectoral Impact Model Intercomparison Project (ISI-MIP) to understand the changes in streamflow distribution and simultaneous vulnerability to different types of hydrological risk in different regions. In the multi-model mean under the Representative Concentration Pathway 8.5 (RCP8.5) scenario, 37 % of global land areas experience an increase in magnitude of extremely high streamflow (with an average increase of 24.5 %), potentially increasing the chance of flooding in those regions. On the other hand, 43 % of global land areas show a decrease in the magnitude of extremely low streamflow (average decrease of 51.5 %), potentially increasing the chance of drought in those regions. About 10 % of the global land area is projected to face simultaneously increasing high extreme streamflow and decreasing low extreme streamflow, reflecting the potentially worsening hazard of both flood and drought; further, these regions tend to be highly populated parts of the globe, currently holding around 30 % of the world's population (over 2.1 billion people). In a world more than 4° warmer by the end of the 21st century compared to the pre-industrial era (RCP8.5 scenario), changes in magnitude of streamflow extremes are projected to be about twice as large as in a 2° warmer world (RCP2.6 scenario). Results also show that inter-GHM uncertainty in streamflow changes, due to representation of terrestrial hydrology, is greater than the inter-GCM uncertainty due to simulation of climate change. Under both forcing scenarios, there is high model agreement for increases in streamflow of the regions near and above the Arctic Circle, and consequent increases in the freshwater inflow to the Arctic Ocean, while subtropical arid areas experience a reduction in streamflow.

Large internal variability dominates over global warming signal in observed lower stratospheric QBO amplitude

2021 ◽  
pp. 1-43
Author(s):  
Aaron Match ◽  
Stephan Fueglistaler
Keyword(s):  
Global Warming ◽  
Climate Model ◽  
Global Climate ◽  
Global Climate Model ◽  
Internal Variability ◽  
Dynamical Process ◽  
Quasi Biennial Oscillation ◽  
Amplitude Profile ◽  
Biennial Oscillation ◽  
Middle Stratosphere

AbstractGlobal warming projections of dynamics are less robust than projections of thermodynamics. However, robust aspects of the thermodynamics can be used to constrain some dynamical aspects. This paper argues that tropospheric expansion under global warming (a thermodynamical process) explains changes in the amplitude of the Quasi-Biennial Oscillation (QBO) in the lower and middle stratosphere (a dynamical process). A theoretical scaling for tropospheric expansion of approximately 6 hPa K−1 is derived, which agrees well with global climate model (GCM) experiments. Using this theoretical scaling, the response of QBO amplitude to global warming is predicted by shifting the climatological QBO amplitude profile upwards by 6 hPa per Kelvin of global warming. In global warming simulations, QBO amplitude in the lower- to mid-stratosphere shifts upwards as predicted by tropospheric expansion. Applied to observations, the tropospheric expansion framework suggests a historical weakening of QBO amplitude at 70 hPa of 3% decade−1 from 1953-2020. This expected weakening trend is half of the 6% decade−1 from 1953-2012 detected and attributed to global warming in a recent study. The previously reported trend was reinforced by record low QBO amplitudes during the mid-2000s, from which the QBO has since recovered. Given the modest weakening expected on physical grounds, past decadal modulations of QBO amplitude are reinterpreted as a hitherto unrecognized source of internal variability. This large internal variability dominates over the global warming signal, such that despite 65 years of observations, there is not yet a statistically significant weakening trend.

scholarly journals Internal Variability of the Canadian RCM’s Hydrological Variables at the Basin Scale in Quebec and Labrador

2012 ◽  
Vol 13 (2) ◽  
pp. 443-462 ◽  
Author(s):  
Marco Braun ◽  
Daniel Caya ◽  
Anne Frigon ◽  
Michel Slivitzky
Keyword(s):  
Climate Model ◽  
Model Simulation ◽  
Global Climate ◽  
Global Climate Model ◽  
Regional Climate ◽  
Internal Variability ◽  
Spectral Nudging ◽  
Model Driven ◽  
Basin Scale ◽  
Hydrological Variables

Abstract The effect of a regional climate model’s (RCM’s) internal variability (IV) on climate statistics of annual series of hydrological variables is investigated at the scale of 21 eastern Canada watersheds in Quebec and Labrador. The analysis is carried out on 30-yr pairs of simulations (twins), performed with the Canadian Regional Climate Model (CRCM) for present (reanalysis and global climate model driven) and future (global climate model driven) climates. The twins differ only by the starting date of the regional simulation—a standard procedure used to trigger internal variability in RCMs. Two different domain sizes are considered: one comparable to domains used for RCM simulations over Europe and the other comparable to domains used for North America. Results for the larger North American domain indicate that mean relative differences between twin pairs of 30-yr climates reach ±5% when spectral nudging is used. Larger differences are found for extreme annual events, reaching about ±10% for 10% and 90% quantiles (Q10 and Q90). IV is smaller by about one order of magnitude in the smaller domain. Internal variability is unaffected by the period (past versus future climate) and by the type of driving data (reanalysis versus global climate model simulation) but shows a dependence on watershed size. When spectral nudging is deactivated in the large domain, the relative difference between pairs of 30-yr climate means almost doubles and approaches the magnitude of a global climate model’s internal variability. This IV at the level of the natural climate variability has a profound impact on the interpretation, analysis, and validation of RCM simulations over large domains.

scholarly journals A Mathematical Framework for Analysis of Water Tracers. Part II: Understanding Large-Scale Perturbations in the Hydrological Cycle due to CO2 Doubling

2016 ◽  
Vol 29 (18) ◽  
pp. 6765-6782 ◽  
Author(s):  
Hansi K. A. Singh ◽  
Cecilia M. Bitz ◽  
Aaron Donohoe ◽  
Jesse Nusbaumer ◽  
David C. Noone
Keyword(s):  
Moisture Transport ◽  
Large Scale ◽  
Climate Model ◽  
Hydrological Cycle ◽  
Global Climate ◽  
Global Climate Model ◽  
Mathematical Framework ◽  
Surface Evaporation ◽  
And Shifts

Abstract The aerial hydrological cycle response to CO2 doubling from a Lagrangian, rather than Eulerian, perspective is evaluated using information from numerical water tracers implemented in a global climate model. While increased surface evaporation (both local and remote) increases precipitation globally, changes in transport are necessary to create a spatial pattern where precipitation decreases in the subtropics and increases substantially at the equator. Overall, changes in the convergence of remotely evaporated moisture are more important to the overall precipitation change than changes in the amount of locally evaporated moisture that precipitates in situ. It is found that CO2 doubling increases the fraction of locally evaporated moisture that is exported, enhances moisture exchange between ocean basins, and shifts moisture convergence within a given basin toward greater distances between moisture source (evaporation) and sink (precipitation) regions. These changes can be understood in terms of the increased residence time of water in the atmosphere with CO2 doubling, which corresponds to an increase in the advective length scale of moisture transport. As a result, the distance between where moisture evaporates and where it precipitates increases. Analyses of several heuristic models further support this finding.

scholarly journals Glacier dynamics in the Western Italian Alps: a minimal model approach

2014 ◽  
Vol 8 (2) ◽  
pp. 1479-1516
Author(s):  
D. Peano ◽  
M. Chiarle ◽  
J. von Hardenberg
Keyword(s):  
Climate Model ◽  
Global Climate ◽  
Global Climate Model ◽  
Climate Variations ◽  
Italian Alps ◽  
Temperature And Precipitation ◽  
Rcp 8.5 ◽  
Glacier Length ◽  
Glacier Modeling ◽  
Model Approach

Abstract. We study the response of a set of glaciers in the Western Italian Alps to climate variations using the minimal glacier modeling approach, first introduced by Oerlemans. The mathematical models are forced over the period 1959–2009, using temperature and precipitation recorded by a dense network of meteorological stations and we find a good match between the observed and modeled glacier length dynamics. Forcing the model with future projections from a state-of-the-art global climate model in the RCP 4.5 and RCP 8.5 scenarios, we obtain a first estimate for the "expiration date" of these glaciers.

scholarly journals Climate Data to Undertake Hygrothermal and Whole Building Simulations Under Projected Climate Change Influences for 11 Canadian Cities

Data ◽  
2019 ◽  
Vol 4 (2) ◽  
pp. 72 ◽  
Author(s):  
Abhishek Gaur ◽  
Michael Lacasse ◽  
Marianne Armstrong
Keyword(s):  
Climate Change ◽  
Snow Cover ◽  
Climate Model ◽  
Global Climate ◽  
Global Climate Model ◽  
Internal Variability ◽  
Climatic Conditions ◽  
Climate Data ◽  
Wide Range ◽  
The Future

Buildings and homes in Canada will be exposed to unprecedented climatic conditions in the future as a consequence of global climate change. To improve the climate resiliency of existing and new buildings, it is important to evaluate their performance over current and projected future climates. Hygrothermal and whole building simulation models, which are important tools for assessing performance, require continuous climate records at high temporal frequencies of a wide range of climate variables for input into the kinds of models that relate to solar radiation, cloud-cover, wind, humidity, rainfall, temperature, and snow-cover. In this study, climate data that can be used to assess the performance of building envelopes under current and projected future climates, concurrent with 2 °C and 3.5 °C increases in global temperatures, are generated for 11 major Canadian cities. The datasets capture the internal variability of the climate as they are comprised of 15 realizations of the future climate generated by dynamically downscaling future projections from the CanESM2 global climate model and thereafter bias-corrected with reference to observations. An assessment of the bias-corrected projections suggests, as a consequence of global warming, future increases in the temperatures and precipitation, and decreases in the snow-cover and wind-speed for all cities.

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