scholarly journals Impact of climate change on volcanic processes: current understanding and future challenges

2021 ◽  
Author(s):  
Thomas Aubry ◽  
Jamie Farquharson ◽  
Colin Rowell ◽  
Sebastian Watt ◽  
Virginie Pinel ◽  
...  
Keyword(s):  
Climate Change ◽  
Radiative Forcing ◽  
Climate Changes ◽  
Numerical Models ◽  
Anthropogenic Activities ◽  
Volcanic Eruptions ◽  
Climate Impacts ◽  
Volcanic Plume ◽  
Atmospheric Conditions ◽  
Climate Conditions

The impacts of volcanic eruptions on climate are increasingly well understood, but the mirror question of how climate changes affect volcanic systems and processes, which we term “climate-volcano impacts”, remains understudied. Accelerating research on this topic is critical in view of rapid climate change driven by anthropogenic activities. Over the last two decades, we have improved our understanding of how mass distribution on the Earth’s surface, in particular changes in ice and water distribution linked to glacial cycles, affects mantle melting, crustal magmatic processing and eruption rates. New hypotheses on the impacts of climate change on eruption processes have also emerged, including how eruption style and volcanic plume rise are affected by changing surface and atmospheric conditions, and how volcanic sulfate aerosol lifecycle, radiative forcing and climate impacts are modulated by background climate conditions. Future improvements in past climate reconstructions and current climate observations, volcanic eruption records and volcano monitoring, and numerical models will contribute to boost research on climate-volcano impacts. Important mechanisms remain to be explored, such as how changes in atmospheric circulation and precipitation will affect the volcanic ash lifecycle. Fostering a holistic and interdisciplinary approach to climate-volcano impacts is critical to gain a full picture of how ongoing climate changes may affect the environmental and societal impacts of volcanic activity.

scholarly journals Radiative and climate impacts of a large volcanic eruption during stratospheric sulfur geoengineering

2016 ◽  
Vol 16 (1) ◽  
pp. 305-323 ◽  
Author(s):  
A. Laakso ◽  
H. Kokkola ◽  
A.-I. Partanen ◽  
U. Niemeier ◽  
C. Timmreck ◽  
...  
Keyword(s):  
Volcanic Eruption ◽  
Radiative Forcing ◽  
Climate Changes ◽  
Climate Model ◽  
Volcanic Eruptions ◽  
Climate Impacts ◽  
Solar Radiation Management ◽  
Atmospheric Conditions ◽  
Maximum Increase ◽  
Global Mean

Abstract. Both explosive volcanic eruptions, which emit sulfur dioxide into the stratosphere, and stratospheric geoengineering via sulfur injections can potentially cool the climate by increasing the amount of scattering particles in the atmosphere. Here we employ a global aerosol-climate model and an Earth system model to study the radiative and climate changes occurring after an erupting volcano during solar radiation management (SRM). According to our simulations the radiative impacts of the eruption and SRM are not additive and the radiative effects and climate changes occurring after the eruption depend strongly on whether SRM is continued or suspended after the eruption. In the former case, the peak burden of the additional stratospheric sulfate as well as changes in global mean precipitation are fairly similar regardless of whether the eruption takes place in a SRM or non-SRM world. However, the maximum increase in the global mean radiative forcing caused by the eruption is approximately 21 % lower compared to a case when the eruption occurs in an unperturbed atmosphere. In addition, the recovery of the stratospheric sulfur burden and radiative forcing is significantly faster after the eruption, because the eruption during the SRM leads to a smaller number and larger sulfate particles compared to the eruption in a non-SRM world. On the other hand, if SRM is suspended immediately after the eruption, the peak increase in global forcing caused by the eruption is about 32 % lower compared to a corresponding eruption into a clean background atmosphere. In this simulation, only about one-third of the global ensemble-mean cooling occurs after the eruption, compared to that occurring after an eruption under unperturbed atmospheric conditions. Furthermore, the global cooling signal is seen only for the 12 months after the eruption in the former scenario compared to over 40 months in the latter. In terms of global precipitation rate, we obtain a 36 % smaller decrease in the first year after the eruption and again a clearly faster recovery in the concurrent eruption and SRM scenario, which is suspended after the eruption. We also found that an explosive eruption could lead to significantly different regional climate responses depending on whether it takes place during geoengineering or into an unperturbed background atmosphere. Our results imply that observations from previous large eruptions, such as Mount Pinatubo in 1991, are not directly applicable when estimating the potential consequences of a volcanic eruption during stratospheric geoengineering.

Interactive stratospheric aerosol model experiments suggest a strong impact of climate change on the aerosol evolution and radiative forcing from future eruptions.

2020 ◽  
Author(s):  
Thomas Aubry ◽  
Anja Schmidt ◽  
Jim Haywood
Keyword(s):  
Climate Change ◽  
High Intensity ◽  
Radiative Forcing ◽  
Climate Model ◽  
Stratospheric Aerosol ◽  
Moderate Intensity ◽  
Volcanic Plume ◽  
Strong Impact ◽  
Atmospheric Conditions ◽  
Volcanic Forcing

<p>Radiative forcing from stratospheric volcanic sulfate aerosols is a key driver of climate variability. However, climate change may also impact volcanic forcing which remains largely unexplored. Atmospheric processes indeed control virtually all mechanisms that govern volcanic forcing, such as the rise of the volcanic column, the chemical and microphysical evolution of volcanic aerosols and their transport in the atmosphere.</p><p>Accordingly, we present novel numerical experiments combining chemistry-climate and volcanic plume modelling to investigate how climate change will affect volcanic forcing. We compare the aerosol evolution and radiative forcing following two eruption cases in two different climates (historical 1990’s and SSP5 8.5 2090’s). We chose two tropical eruptions: i) a strong intensity (i.e., mass flux), Pinatubo-like eruption emitting 10 Tg of sulfur dioxide (SO<sub>2</sub>); and ii) a moderate intensity eruption emitting 1 Tg of SO<sub>2</sub>, similar to eruptions such as those of Merapi in 2010, Nabro in 2011 or Kelud in 2014, which have had major impacts on the stratospheric aerosol background and are thought to have contributed to the global temperature hiatus in the early 21<sup>st</sup> century. The chemistry-climate model that we use (UM_UKCA version 11.2) has the capacity to interactively simulate the chemical and microphysical evolution of stratospheric sulfate aerosol given an initial injection of SO<sub>2</sub>. Furthermore, we use a plume model to calculate SO<sub>2</sub> injection heights for a given eruption intensity and atmospheric conditions simulated by UM-UKCA.</p><p>In our experiments, the peak stratospheric aerosol optical depth (SAOD) of the high-intensity, Pinatubo-like eruption increases by 10% in the SSP5 8.5 2090 climate compared to the historical 1990 climate. Furthermore, the peak global-mean top-of-the-atmosphere radiative forcing of the same eruption increases by 30%. In contrast, the peak SAOD of the moderate intensity eruption decreases by a factor of 4 (with radiative forcing being small compared to simulated natural variability). Our results thus suggest that volcanic forcing will become more extreme and polarized in the future, with the forcing associated with moderate-intensity and relatively frequent eruptions being muted, but the forcing associated with high-intensity and relatively rare eruptions being amplified. We analyze which mechanisms are responsible for the simulated impacts of climate change on volcanic forcing, and discuss potential additional feedbacks expected in our future ocean-atmosphere coupled simulations.</p>

scholarly journals Securing Horticulture in a Changing Climate—A Mini Review

Horticulturae ◽  
2019 ◽  
Vol 5 (3) ◽  
pp. 56 ◽  
Author(s):  
Mehdi B. Bisbis ◽  
Nazim S. Gruda ◽  
Michael M. Blanke
Keyword(s):  
Climate Change ◽  
Industrial Revolution ◽  
Elevated Temperatures ◽  
Heat Waves ◽  
Anthropogenic Activities ◽  
Climate Impacts ◽  
Extreme Weather Events ◽  
Cold Temperatures ◽  
Climate Conditions

(1) Background: Climate change is on the rise due to continuous greenhouse gas emissions from anthropogenic activities ever since the industrial revolution. Changing weather conditions are likely to have consequences for horticulture. (2) Objective and Methods: A short literature review was conducted, gathering findings on climate change and the impacts on the yield and product quality of special crops. (3) Results: Global warming will result in elevated temperatures and CO2 concentrations in all seasons. Extreme weather events such as heat waves are also on the increase. In vegetables, physiological processes such as vernalization and winter chilling strongly rely on temperature. Therefore, heat stress may cause irregularities in yield production and planning the harvest. For fruit crops, frost poses a risk that is enhanced through climate change, as does a lack of chilling, as cold temperatures in the winter are required for flowering in the spring. Abiotic disorders in horticulture are also related to changing temperatures and humidity. The nutritional quality of special crops may be threatened by increasing rates of plant development and premature ripening at high temperatures. Quality traits such as sugars, acids, or antioxidant capacity may also shift as well. (4) Conclusions: Adapting to these new climate conditions means developing new climate-resilient varieties to maintain high production levels with superior quality. In this mini review, cultivation measures to mitigate adverse climate impacts are also discussed. Current developments and recent findings are presented, pointing out further steps toward adaptation and sustainable production.

scholarly journals Key drivers of ozone change and its radiative forcing over the 21st century

2018 ◽  
Vol 18 (9) ◽  
pp. 6121-6139 ◽  
Author(s):  
Fernando Iglesias-Suarez ◽  
Douglas E. Kinnison ◽  
Alexandru Rap ◽  
Amanda C. Maycock ◽  
Oliver Wild ◽  
...  
Keyword(s):  
Climate Change ◽  
21St Century ◽  
Radiative Forcing ◽  
Climate Model ◽  
Stratospheric Ozone ◽  
Atmospheric Composition ◽  
Climate Conditions ◽  
Radiative Balance ◽  
Radiative Forcings ◽  
Year 2000

Abstract. Over the 21st century changes in both tropospheric and stratospheric ozone are likely to have important consequences for the Earth's radiative balance. In this study, we investigate the radiative forcing from future ozone changes using the Community Earth System Model (CESM1), with the Whole Atmosphere Community Climate Model (WACCM), and including fully coupled radiation and chemistry schemes. Using year 2100 conditions from the Representative Concentration Pathway 8.5 (RCP8.5) scenario, we quantify the individual contributions to ozone radiative forcing of (1) climate change, (2) reduced concentrations of ozone depleting substances (ODSs), and (3) methane increases. We calculate future ozone radiative forcings and their standard error (SE; associated with inter-annual variability of ozone) relative to year 2000 of (1) 33 ± 104 m Wm−2, (2) 163 ± 109 m Wm−2, and (3) 238 ± 113 m Wm−2 due to climate change, ODSs, and methane, respectively. Our best estimate of net ozone forcing in this set of simulations is 430 ± 130 m Wm−2 relative to year 2000 and 760 ± 230 m Wm−2 relative to year 1750, with the 95 % confidence interval given by ±30 %. We find that the overall long-term tropospheric ozone forcing from methane chemistry–climate feedbacks related to OH and methane lifetime is relatively small (46 m Wm−2). Ozone radiative forcing associated with climate change and stratospheric ozone recovery are robust with regard to background climate conditions, even though the ozone response is sensitive to both changes in atmospheric composition and climate. Changes in stratospheric-produced ozone account for ∼ 50 % of the overall radiative forcing for the 2000–2100 period in this set of simulations, highlighting the key role of the stratosphere in determining future ozone radiative forcing.

scholarly journals Coupled Wave-2D Hydrodynamics Modeling at the Reno River Mouth (Italy) under Climate Change Scenarios

Water ◽  
2018 ◽  
Vol 10 (10) ◽  
pp. 1380 ◽  
Author(s):  
Maria Gabriella Gaeta ◽  
Davide Bonaldo ◽  
Achilleas G. Samaras ◽  
Sandro Carniel ◽  
Renata Archetti
Keyword(s):  
Climate Change ◽  
Open Source ◽  
Climate Changes ◽  
Adriatic Sea ◽  
Numerical Study ◽  
Numerical Models ◽  
Joint Probability ◽  
River Mouth ◽  
Climate Change Scenarios ◽  
Coupled Wave

This work presents the results of the numerical study implemented for the natural area of Lido di Spina, a touristic site along the Italian coast of the North Adriatic Sea, close to the mouth of River Reno. High-resolution simulations of nearshore dynamics are carried out under climate change conditions estimated for the site. The adopted modeling chain is based on the implementation of multiple-nested, open-source numerical models. More specifically, the coupled wave-2D hydrodynamics runs, using the open-source TELEMAC suite, are forced at the offshore boundary by waves resulting from the wave model (SWAN) simulations for the Adriatic Sea, and sea levels computed following a joint probability analysis approach. The system simulates present-day scenarios, as well as conditions reflecting the high IPCC greenhouse concentration trajectory named RCP8.5 under predicted climate changes. Selection of sea storms directed from SE (Sirocco events) and E–NE (Bora events) is performed together with Gumbel analysis, in order to define ordinary and extreme sea conditions. The numerical results are here presented in terms of local parameters such as wave breaking position, alongshore currents intensity and direction and flooded area, aiming to provide insights on how climate changes may impact hydrodynamics at a site scale. Although the wave energy intensity predicted for Sirocco events is expected to increase only slightly, modifications of the wave dynamics, current patterns, and inland flooding induced by climate changes are expected to be significant for extreme conditions, especially during Sirocco winds, with an increase in the maximum alongshore currents and in the inundated area compared to past conditions.

scholarly journals AirClim: an efficient tool for climate evaluation of aircraft technology

2008 ◽  
Vol 8 (16) ◽  
pp. 4621-4639 ◽  
Author(s):  
V. Grewe ◽  
A. Stenke
Keyword(s):  
Climate Change ◽  
Water Vapour ◽  
Radiative Forcing ◽  
Climate Impacts ◽  
Assessment Tools ◽  
Surface Temperature Change ◽  
Near Surface ◽  
Temperature Changes ◽  
Wide Range ◽  
Concentration Changes

Abstract. Climate change is a challenge to society and to cope with requires assessment tools which are suitable to evaluate new technology options with respect to their impact on global climate. Here we present AirClim, a model which comprises a linearisation of atmospheric processes from the emission to radiative forcing, resulting in an estimate in near surface temperature change, which is presumed to be a reasonable indicator for climate change. The model is designed to be applicable to aircraft technology, i.e. the climate agents CO2, H2O, CH4 and O3 (latter two resulting from NOx-emissions) and contrails are taken into account. AirClim combines a number of precalculated atmospheric data with aircraft emission data to obtain the temporal evolution of atmospheric concentration changes, radiative forcing and temperature changes. These precalculated data are derived from 25 steady-state simulations for the year 2050 with the climate-chemistry model E39/C, prescribing normalised emissions of nitrogen oxides and water vapour at various atmospheric regions. The results show that strongest climate impacts (year 2100) from ozone changes occur for emissions in the tropical upper troposphere (60 mW/m2; 80 mK for 1 TgN/year emitted) and from methane changes from emissions in the middle tropical troposphere (−2.7% change in methane lifetime; –30 mK per TgN/year). For short-lived species (e.g. ozone, water vapour, methane) individual perturbation lifetimes are derived depending on the region of emission. A comparison of this linearisation approach with results from a comprehensive climate-chemistry model shows reasonable agreement with respect to concentration changes, radiative forcing, and temperature changes. For example, the total impact of a supersonic fleet on radiative forcing (mainly water vapour) is reproduced within 10%. A wide range of application is demonstrated.

Projections and simulation of water balance in the Southern Ice Field, Patagonia, Chile

2020 ◽  
Author(s):  
Catalina Jerez Toledo ◽  
Ximena Vargas Mesa
Keyword(s):  
Climate Change ◽  
Water Balance ◽  
Climatic Change ◽  
Radiative Forcing ◽  
General Circulation ◽  
Numerical Models ◽  
Natural State ◽  
Historical Period ◽  
Argentine Patagonia ◽  
Ice Field

<p>The Southern Ice Field (CHS) corresponds to one of the largest continental ice plains, representing a water source for the entire globe. It extends from 40°20' S to 51°30' S, covering an area of approximately 16.800 km<sup>2</sup> and consisting of 49 glaciers distributed in the southern territory of Chile and part of the Argentine Patagonia. Due to climatic change, the CHS has been affected, like all the ecosystems that compose the planet, generating disturbances in their natural state, consequently, the systems that constitute the CHS tend to look for a new balance. However, the new state(s) of equilibrium can present a great deal of variability, which is why the Intergovernmental Panel on Climate Change (IPCC) has drawn up the Representative Concentration Pathways (RCP), which aim to account for the effects of climate change by representing the total radiative forcing calculated for the year 2100 and including the net effect of Greenhouse Gases (GHG), in addition to other anthropogenic forcing. Based on this, the main objective of the present study is to give an account of a projection and simulation of the water balance in the CHS, informing about the physical processes occurred in the historical period (1970 - 2005), the current period considering a near past and future (2006 - 2050) and a projection to the distant future (2051 - 2100). The simulation of the water balance considers two General Circulation Models (GCMs: MPI-ESM and CSIRO-Mk3-6-0), which are numerical models frequently implemented to simulate the effects of climate change. These models are evaluated under two RCP scenarios 4.5 and 8.5, giving the most unfavorable results under the latter scenario when evaluating the CSIRO-Mk3-6-0 model, since temperature increases of up to 8°C and an oscillating precipitation regime are observed. On the other hand, the MPI-ESM model indicates increases of 1.5°C and 2.5°C accordingly to each scenario and decreases of ± 1/3 of the current observed precipitation. Both models, when evaluated in the previously mentioned scenarios, indicate that the basins that make up the CHS present an emptying to a greater or lesser degree according to the scenario, for which reason, the ice mass that makes up the CHS will follow the behavior it has experienced up to now and will continue to detach itself. To this last, we must add the effect of the decreases in precipitations that reach an average deficit of 30 mm by year 2050 and increases in temperature that exceed the values reported by the IPCC (2019), which they look for to control the effects of the climatic change in the present situation.</p>

Earth’s Energy Imbalance

2014 ◽  
Vol 27 (9) ◽  
pp. 3129-3144 ◽  
Author(s):  
Kevin E. Trenberth ◽  
John T. Fasullo ◽  
Magdalena A. Balmaseda
Keyword(s):  
Climate Change ◽  
Time Scales ◽  
Radiative Forcing ◽  
Heat Content ◽  
Volcanic Eruptions ◽  
Climate Change Signal ◽  
Ocean Reanalysis ◽  
Climate System Model ◽  
Energy Imbalance ◽  
Rates Of Change

Abstract Climate change from increased greenhouse gases arises from a global energy imbalance at the top of the atmosphere (TOA). TOA measurements of radiation from space can track changes over time but lack absolute accuracy. An inventory of energy storage changes shows that over 90% of the imbalance is manifested as a rise in ocean heat content (OHC). Data from the Ocean Reanalysis System, version 4 (ORAS4), and other OHC-estimated rates of change are used to compare with model-based estimates of TOA energy imbalance [from the Community Climate System Model, version 4 (CCSM4)] and with TOA satellite measurements for the year 2000 onward. Most ocean-only OHC analyses extend to only 700-m depth, have large discrepancies among the rates of change of OHC, and do not resolve interannual variability adequately to capture ENSO and volcanic eruption effects, all aspects that are improved with assimilation of multivariate data. ORAS4 rates of change of OHC quantitatively agree with the radiative forcing estimates of impacts of the three major volcanic eruptions since 1960 (Mt. Agung, 1963; El Chichón, 1982; and Mt. Pinatubo, 1991). The natural variability of the energy imbalance is substantial from month to month, associated with cloud and weather variations, and interannually mainly associated with ENSO, while the sun affects 15% of the climate change signal on decadal time scales. All estimates (OHC and TOA) show that over the past decade the energy imbalance ranges between about 0.5 and 1 W m−2. By using the full-depth ocean, there is a better overall accounting for energy, but discrepancies remain at interannual time scales between OHC- and TOA-based estimates, notably in 2008/09.

The Bakerian Lecture, 1991 The predictability of weather and climate

1991 ◽  
Vol 337 (1648) ◽  
pp. 521-572 ◽  
Keyword(s):  
Climate Change ◽  
Greenhouse Gases ◽  
Human Activities ◽  
Radiative Forcing ◽  
El Nino ◽  
Numerical Models ◽  
Milankovitch Cycles ◽  
The Past ◽  
Weather And Climate ◽  
Sst Anomalies

There is large public and political interest in the predictability of weather and climate, in particular in the influence of human activities on the likely climate change during the next century. Numerical models are the main tools which enable the nonlinear processes involved in the dynamics and physics of the atmosphere and other components of the climate system to be integrated in an effective way. The performance of such models used for weather forecasting has continued to improve as more accurate data with better coverage has become available, as improved descriptions of the physics and dynamics have been incorporated and as computing capacity and speed have increased. Studies of the predictability with models suggest that with further improvements in data and models deterministic forecasting of detailed weather may ultimately have useful skill up to 2-3 weeks ahead. Beyond the limit of deterministic forecasting, some skill remains for the forecasting of general weather patterns which can be pursued by studying ensembles of model forecasts from slightly varying initial conditions. The largest difficulty with further improvements of numerical models lies in their inadequate treatment of the motions too small to be explicitly resolved. Interactions between the atmosphere and the ocean are responsible for substantial variations on seasonal, interannual and longer timescales. Forecasts are being provided of seasonal precipitation in the Sahel region of Africa based on a knowledge of global sea surface tem perature (SST) anomalies together with the assumption that such anomalies tend to persist from one season to the next. Attempts to forecast SST anomalies have centred on tropical regions in particular on the El Nino. Simple models show some skill in forecasting El Nino events 3-9 months in advance. Studies with more elaborate models which as yet only show partial success in simulating these events demonstrate the complex nature of the interactions involved. Turning to the likely changes in climate next century: if no changes occur in the atmosphere other than the increase in C0 2 and other greenhouse gases due to human activities, the increase in radiative forcing due to a doubling of atmospheric C0 2 concentration would lead to an increase of about 1.2 °C in global average temperature. Water vapour and ice-albedo feedbacks raise this to a figure of about 2.5 °C (with an uncertainty range of 1.5—4.5 °C) as estimated by the Intergovernmental Panel for Climate Change. Such a change would dominate over forcing likely to arise from other factors, and this estim ated rate of change next century is probably greater than any which has occurred on earth during the past 10000 years. The main uncertainties in climate change predictions arise from the inadequacies of the models in their descriptions of cloud-radiation and ocean circulation feedbacks. Until there is more confidence in the treatment of these feedbacks there are bound to be large uncertainties associated with any predictions of regional climate change. To reduce the uncertainties there need to be improvements in computer power, in model formulation and in our understanding of climate processes together with a large programme of observations of climate parameters to provide early detection of climate change and to provide validation of climate models and to provide data for initialization of model integrations. An important question is whether changes in climate due to changes in radiative forcing are predictable. It is pointed out that the response to climate over the past half million years to changes in forcing due to the variations in the Earth ’s orbit (Milankovitch cycles) is a regular one; some 60% of variations in the global temperature as established from the palaeontological record occur near frequencies of the Milankovitch cycles. We can, therefore, expect the changes in climate due to increasing greenhouse gases to be a largely predictable response. Large, but probably predictable, changes in the circulation of the deep ocean have modified climate change during past epochs and could have significant influence on future climate change.

Evaluation of Statistical Downscaling Methods for Simulating Daily Precipitation Distribution, Frequency, and Temporal Sequence

2021 ◽  
Vol 64 (3) ◽  
pp. 771-784
Author(s):  
Xunchang Zhang ◽  
Mingxi Shen ◽  
Jie Chen ◽  
Joel W. Homan ◽  
Phillip R. Busteed
Keyword(s):  
Climate Change ◽  
Statistical Downscaling ◽  
Climate Changes ◽  
Daily Precipitation ◽  
Weather Generator ◽  
Temporal Sequence ◽  
Precipitation Distribution ◽  
Climate Conditions ◽  
Weather Stations ◽  
Distribution Frequency

HighlightsNine statistical downscaling methods from three downscaling categories were evaluated.Weather generator-based methods had advantages in simulating non-stationary precipitation.Differences in downscaling performance were smaller within each category than between categories.The performance of each downscaling method varied with climate conditions.Abstract. Spatial discrepancy between global climate model (GCM) projections and the climate data input required by hydrological models is a major limitation for assessing the impact of climate change on soil erosion and crop production at local scales. Statistical downscaling techniques are widely used to correct biases of GCM projections. The objective of this study was to evaluate the ability of nine statistical downscaling methods from three available statistical downscaling categories to simulate daily precipitation distribution, frequency, and temporal sequence at four Oklahoma weather stations representing arid to humid climate regions. The three downscaling categories included perfect prognosis (PP), model output statistics (MOS), and stochastic weather generator (SWG). To minimize the effect of GCM projection error on downscaling quality, the National Centers for Environmental Prediction (NCEP) Reanalysis 1 data at a 2.5° grid spacing (treated as observed grid data) were downscaled to the four weather stations (representing arid, semi-arid, sub humid, and humid regions) using the nine downscaling methods. The station observations were divided into calibration and validation periods in a way that maximized the differences in annual precipitation means between the two periods for assessing the ability of each method in downscaling non-stationary climate changes. All methods were ranked with three metrics (Euclidean distance, sum of absolute relative error, and absolute error) for their ability in simulating precipitation amounts at daily, monthly, yearly, and annual maximum scales. After eliminating the poorest two performers in simulating precipitation mean, distribution, frequency, and temporal sequence, the top four remaining methods in ascending order were Distribution-based Bias Correction (DBC), Generator for Point Climate Change (GPCC), SYNthetic weather generaTOR (SYNTOR), and LOCal Intensity scaling (LOCI). DBC and LOCI are bias-correction methods, and GPCC and SYNTOR are generator-based methods. The differences in performances among the downscaling methods were smaller within each downscaling category than between the categories. The performance of each method varied with the climate conditions of each station. Overall results indicated that the SWG methods had certain advantages in simulating daily precipitation distribution, frequency, and temporal sequence for non-stationary climate changes. Keywords: Climate change, Climate downscaling, Downscaling method evaluation, Statistical downscaling.

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