Potential state shifts in terrestrial ecosystems related to changes in El Niño-Southern Oscillation dynamics

2020 ◽  
Author(s):  
Mateo Duque-Villegas ◽  
Juan Fernando Salazar ◽  
Angela Maria Rendón
Keyword(s):  
Large Scale ◽  
Climate Model ◽  
Extreme Values ◽  
Southern Oscillation ◽  
Climatic Variability ◽  
Terrestrial Ecosystems ◽  
Eastern Africa ◽  
State Transitions ◽  
Climate Change Scenarios ◽  
Earth’S Climate

<p>The El Niño-Southern Oscillation (ENSO) phenomenon is regarded as a policy-relevant tipping element of the Earth's climate system. It has a prominent planetary-scale influence on climatic variability and it is susceptible to anthropogenic forcing, which could alter irreversibly its dynamics. Changes in frequency and/or amplitude of ENSO would have major implications for terrestrial hydrology and ecosystems. The amount of extreme events such as droughts and floods could vary regionally, as well as their intensities. Here, we use an intermediate complexity climate model, namely the Planet Simulator (PlaSim), to study the potential impact on Earth's climate and its terrestrial ecosystems of changing ENSO dynamics in a couple of experiments. Initially we investigate the global effects of a permanent El Niño, and then we analyse changes in the amplitude of the fluctuation. We found that PlaSim model yields a sensible representation of current large-scale climatological patterns, including ENSO-related variability, as well as realistic estimates of global energy and water budgets. For the permanent El Niño state, there were significant differences in the global distribution of water and energy fluxes that led to asymmetrical effects on vegetation production, which increased in the tropics and decreased in temperate regions. In terrestrial ecosystems of regions such as western North America, the Amazon rainforest, south-eastern Africa and Australia, we found that these El Niño-induced changes could be associated with biome state transitions. Particularly for Australia, we found country-wide aridification as a result of sustained El Niño conditions, which is a potential state in which recent wildfires would be even more dramatic. When the amplitude of the ENSO fluctuation changes, we found that although mean climatological values do not change significantly, extreme values of variables such as temperature and precipitation become more extreme. Our approach aims at recognizing potential threats for terrestrial ecosystems in climate change scenarios in which there are more frequent El Niño phenomena or the intensities of the ENSO phases change. Although it is not enough to prove such effects will be observed, we show a consistent picture and it should raise awareness about conservation of global ecosystems.</p>

scholarly journals Tipping the ENSO into a permanent El Niño can trigger state transitions in global terrestrial ecosystems

2019 ◽  
Vol 10 (4) ◽  
pp. 631-650 ◽  
Author(s):  
Mateo Duque-Villegas ◽  
Juan Fernando Salazar ◽  
Angela Maria Rendón
Keyword(s):  
El Niño ◽  
Large Scale ◽  
El Nino ◽  
Southern Oscillation ◽  
Global Climate ◽  
Terrestrial Ecosystems ◽  
Global Scale ◽  
Eastern Africa ◽  
State Transitions ◽  
Social Phenomena

Abstract. Some large-scale components of the Earth's climate system have been identified as policy-relevant “tipping elements”, meaning that anthropogenic forcing and perturbations may push them across a tipping point threshold, with potential global scale impact on ecosystems and concomitant environmental and social phenomena. A pronounced change in the amplitude and/or frequency of the El Niño–Southern Oscillation (ENSO) is among such tipping elements. Here, we use the Planet Simulator (PlaSim), an Earth system model of intermediate complexity, to investigate the potential impact on global climate and terrestrial ecosystems of shifting the current dynamics of the ENSO into a permanent El Niño. When forced with sea surface temperature (SST) derived from observations, the PlaSim model yields a realistic representation of large-scale climatological patterns, including realistic estimates of the global energy and water balances, and gross primary productivity (GPP). In a permanent El Niño state, we found significant differences in the global distribution of water and energy fluxes, and associated impacts on GPP, indicating that vegetation production decreases in the tropics, whereas it increases in temperate regions. We identify regions in which these El Niño-induced changes are consistent with potential state transitions in global terrestrial ecosystems, including potential greening of western North America, dieback of the Amazon rainforest, and further aridification of south-eastern Africa and Australia.

Underestimation of temperature variability in weather generators and implications for the representation of extreme temperatures in downscaled climate change scenarios

2020 ◽  
Author(s):  
Pierluigi Calanca
Keyword(s):  
Climate Change ◽  
Large Scale ◽  
Extreme Values ◽  
Climatic Variability ◽  
Model Performance ◽  
Maximum Temperature ◽  
Climate Change Scenarios ◽  
Modes Of Variability ◽  
Weather Generators ◽  
Total Variability

<p>Stochastic weather generators are still widely used for downscaling climate change scenarios, in particular in the context of agricultural and hydrological impact assessments. Their performance is in many respects satisfactory, except perhaps for the fact that they fail to represent climatic variability in an adequate way. This has implications for the representation of extreme values and their statistics. Concerning precipitation, different approaches for amending this situation have proposed in the past, including using more sophisticated models to better simulate the persistence of wet and dry spells, conditioning rainfall-generating parameters on indices of the large-scale atmospheric circulation, or employing autoregressive models to represent year-to-year variations in annual precipitation amounts. With regard to (minimum and maximum) temperature, efforts to address the question of why weather generators underestimate total variability have been less systematic. Based on results obtained with a well-known weather generator (LARS-WG), this contribution aims to discuss which modes of variability are missing and why, elaborate on the implications of underrepresenting temperature variance for the simulation of temperature extremes in downscaled climate change scenarios, and suggest options to tackle the problem and improve the model performance.</p>

scholarly journals Tipping the ENSO into a permanent El Niño can trigger state transitions in global terrestrial ecosystems

2019 ◽  
Author(s):  
Mateo Duque-Villegas ◽  
Juan F. Salazar ◽  
Angela M. Rendón
Keyword(s):  
Primary Production ◽  
El Niño ◽  
Large Scale ◽  
El Nino ◽  
Southern Oscillation ◽  
Global Climate ◽  
Gross Primary Production ◽  
Terrestrial Ecosystems ◽  
Global Scale ◽  
State Transitions

Abstract. Some large-scale components of the Earth's climate system have been identified as policy-relevant tipping elements, meaning that anthropogenic forcing and perturbations may push them across a tipping point threshold, with potential global scale impact on ecosystems and concomitant environmental and social phenomena. A pronounced change in the amplitude and/or frequency of the El Niño-Southern Oscillation (ENSO) is among such tipping elements. Here we use the Planet Simulator (PlaSim), an Earth system model of intermediate complexity, to investigate the potential impact on global climate and terrestrial ecosystems of shifting the current dynamics of the ENSO into a permanent El Niño. When forced with sea surface temperature (SST) derived from observations, the PlaSim model yields a realistic representation of large-scale climatological patterns, including realistic estimates of the global energy and water balances, and gross primary production. In a permanent El Niño state, we found significant differences in the global distribution of water and energy fluxes, and associated impacts on gross primary production, indicating that vegetation productivity decreases in the tropics whereas it increases in temperate and boreal regions. We identify regions in which these El Niño-induced changes are consistent with potential state transitions in global terrestrial ecosystems, including potential dieback of the Amazon rainforest, southward expansion of the Sahel, and further aridification of Australia.

scholarly journals The advective Brewer-Dobson circulation in the ERA5 reanalysis: variability and trends

2020 ◽  
Author(s):  
Mohamadou Diallo ◽  
Manfred Ern ◽  
Felix Ploeger
Keyword(s):  
Gravity Wave ◽  
Large Scale ◽  
Climate Model ◽  
Southern Oscillation ◽  
Natural Variability ◽  
Radiation Budget ◽  
Residual Circulation ◽  
Quasi Biennial Oscillation ◽  
Acceleration Rate ◽  
Good Agreement

Abstract. The stratospheric Brewer-Dobson circulation (BDC) is an important element of climate as it determines the transport and distributions of key radiatively active atmospheric trace gases, which affect the Earth’s radiation budget and surface climate. Here, we evaluate the inter-annual variability and trends of the BDC in the ERA5 reanalysis and inter-compare with the ERA-Interim reanalysis for the 1979–2018 period. We also assess the modulation of the circulation by the Quasi-Biennial Oscillation (QBO) and the El Niño-Southern Oscillation (ENSO), and the forcings of the circulation by the planetary and gravity wave drag. A comparison of ERA5 and ERA-Interim reanalyses shows a very good agreement in the morphology of the BDC and in its structural modulations by the natural variability related to QBO and ENSO. Despite the good agreement in the spatial structure, there are substantial differences in the strength of the BDC and of the natural variability impacts on the BDC between the two reanalyses, particularly in the upper troposphere and lower stratosphere (UTLS), and in the upper stratosphere. Throughout most regions of the stratosphere, the variability and trends of the advective BDC are stronger in the ERA5 reanalysis due to stronger planetary and gravity wave forcings, except in the UTLS below 20 km where the tropical upwelling is about 40 % weaker due to a weaker gravity wave forcings at the equatorial flank of the subtropical jet. In the extra-tropics, the large-scale downwelling is stronger in ERA5 than in ERA-Interim linked to significant differences in planetary and gravity wave forcings. Analysis of the BDC trend shows a global acceleration of the annual mean residual circulation with an acceleration rate of about 1.5 % per decade at 70 hPa due to the long-term intensification in gravity and planetary wave breaking, consistent with observed and future climate model predicted BDC changes.

scholarly journals Space-based geoengineering: Challenges and requirements

2009 ◽  
Vol 224 (3) ◽  
pp. 571-580 ◽  
Author(s):  
C R McInnes
Keyword(s):  
Climate Change ◽  
Carbon Dioxide ◽  
Large Scale ◽  
Climate Model ◽  
Carbon Dioxide Concentration ◽  
Complex Solution ◽  
Lagrange Point ◽  
Simple Climate Model ◽  
Earth’S Climate

The prospect of engineering the Earth's climate (geoengineering) raises a multitude of issues associated with climatology, engineering on macroscopic scales, and indeed the ethics of such ventures. Depending on personal views, such large-scale engineering is either an obvious necessity for the deep future, or yet another example of human conceit. In this article a simple climate model will be used to estimate requirements for engineering the Earth's climate, principally using space-based geoengineering. Active cooling of the climate to mitigate anthropogenic climate change due to a doubling of the carbon dioxide concentration in the Earth's atmosphere is considered. This representative scenario will allow the scale of the engineering challenge to be determined. It will be argued that simple occulting discs at the interior Lagrange point may represent a less complex solution than concepts for highly engineered refracting discs proposed recently. While engineering on macroscopic scales can appear formidable, emerging capabilities may allow such ventures to be seriously considered in the long term. This article is not an exhaustive review of geoengineering, but aims to provide a foretaste of the future opportunities, challenges, and requirements for space-based geoengineering ventures.

scholarly journals Synchronous combined effects of fishing and climate within a demersal community

2012 ◽  
Vol 70 (2) ◽  
pp. 319-328 ◽  
Author(s):  
Antoni Quetglas ◽  
Francesc Ordines ◽  
Manuel Hidalgo ◽  
Sebastià Monserrat ◽  
Susana Ruiz ◽  
...  
Keyword(s):  
Climate Variability ◽  
Age Structure ◽  
Large Scale ◽  
Southern Oscillation ◽  
Climatic Variability ◽  
Early Period ◽  
Combined Effects ◽  
Population Fluctuations ◽  
Fishing Activity ◽  
The Mediterranean

Abstract Quetglas, A., Ordines, F., Hidalgo, M., Monserrat, S., Ruiz, S., Amores, Á., Moranta, J., and Massutí, E. 2013. Synchronous combined effects of fishing and climate within a demersal community. – ICES Journal of Marine Science, 70: 319–328. Accumulating evidence shows that fishing exploitation and environmental variables can synergistically affect the population dynamics of exploited populations. Here, we document an interaction between fishing impact and climate variability that triggered a synchronic response in the population fluctuations of six exploited species in the Mediterranean from 1965–2008. Throughout this period, the fishing activity experienced a sharp increase in fishing effort, which caused all stocks to shift from an early period of underexploitation to a later period of overexploitation. This change altered the population resilience of the stocks and brought about an increase in the sensitivity of its dynamics to climate variability. Landings increased exponentially when underexploited but displayed an oscillatory behaviour once overexploited. Climatic indices, related to the Mediterranean mesoscale hydrography and large-scale north Atlantic climatic variability, seemed to affect the species with broader age structure and longer lifespan, while the global-scale El Niño Southern Oscillation index (ENSO) positively influenced the population abundances of species with a narrow age structure and short lifespan. The species affected by ENSO preferentially inhabit the continental shelf, suggesting that Mediterranean shelf ecosystems are sensitive to the hydroclimatic variability linked to global climate.

scholarly journals Black Carbon Increases Frequency of Extreme ENSO Events

2019 ◽  
Vol 32 (23) ◽  
pp. 8323-8333 ◽  
Author(s):  
Sijia Lou ◽  
Yang Yang ◽  
Hailong Wang ◽  
Jian Lu ◽  
Steven J. Smith ◽  
...  
Keyword(s):  
Black Carbon ◽  
Climate Models ◽  
Climate Model ◽  
Southern Oscillation ◽  
Global Climate ◽  
Global Climate Model ◽  
Co2 Concentration ◽  
Enso Events ◽  
Aerosol Forcing ◽  
Earth’S Climate

ABSTRACT El Niño–Southern Oscillation (ENSO) is the leading mode of Earth’s climate variability at interannual time scales with profound ecological and societal impacts, and it is projected to intensify in many climate models as the climate warms under the forcing of increasing CO2 concentration. Since the preindustrial era, black carbon (BC) emissions have substantially increased in the Northern Hemisphere. But how BC aerosol forcing may influence the occurrence of the extreme ENSO events has rarely been investigated. In this study, using simulations of a global climate model, we show that increases in BC emissions from both the midlatitudes and Arctic weaken latitudinal temperature gradients and northward heat transport, decrease tropical energy divergence, and increase sea surface temperature over the tropical oceans, with a surprising consequential increase in the frequency of extreme ENSO events. A corollary of this study is that reducing BC emissions might serve to mitigate the possible increasing frequency of extreme ENSO events under greenhouse warming, if the modeling result can be translated into the climate in reality.

Large-Scale Atmospheric Drivers of Snowfall on Thwaites Glacier

2020 ◽  
Author(s):  
Michelle Maclennan ◽  
Jan Lenaerts
Keyword(s):  
Temporal Variability ◽  
Large Scale ◽  
Climate Model ◽  
Southern Oscillation ◽  
Regional Climate ◽  
Southern Annular Mode ◽  
Spatial And Temporal Variability ◽  
Atmospheric Conditions ◽  
Amundsen Sea ◽  
Weather Patterns

<p>High snowfall events on Thwaites Glacier are a key influencer of its ice mass change. In this study, we diagnose the mechanisms for orographic precipitation on Thwaites Glacier by analyzing the atmospheric conditions that lead to high snowfall events. A high-resolution regional climate model, RACMO2, is used in conjunction with MERRA-2 and ERA5 reanalysis to map snowfall and associated atmospheric conditions over the Amundsen Sea Embayment. We examine these conditions during high snowfall events over Thwaites Glacier to characterize the drivers of the precipitation and their spatial and temporal variability. Then we examine the seasonal differences in the associated weather patterns and their correlations with El Nino Southern Oscillation and the Southern Annular Mode. Understanding the large-scale atmospheric drivers of snowfall events allows us to recognize how these atmospheric drivers and consequent snowfall climatology will change in the future, which will ultimately improve predictions of accumulation on Thwaites Glacier.</p>

Including climatic variability in stochastic rainfall for flood catastrophe modelling – The effect of ENSO and SOI in China

2020 ◽  
Author(s):  
Jose Luis Salinas ◽  
Rebecca Smith ◽  
Shuangcai Li ◽  
Ludovico Nicotina ◽  
Arno Hilberts
Keyword(s):  
Tropical Cyclone ◽  
Large Scale ◽  
Southern Oscillation ◽  
Rainfall Variability ◽  
Climatic Variability ◽  
Extreme Rainfall ◽  
Extreme Rainfall Events ◽  
Natural Catastrophes ◽  
Socio Economic Impact ◽  
Catastrophe Modelling

<p>Damages from flooding in China account on average for 60-70% of the total Annual Losses derived from natural catastrophes. The extreme rainfall events responsible for these inundations can be broadly categorised in two well differentiated mechanisms: Tropical Cyclone (TC) induced, and non Tropical Cyclone induced (nonTC) precipitation. Between 2001 and 2015, inland nonTC rainfall flood events occurred roughly with double the frequency as TC events. While TC events can be highly destructive for coastal locations, over the entire China territory nonTC flooding accounted for more than half of the total economic flood loss for events with significant socio-economic impact, highlighting the importance of the nonTC flooding mechanism on the regional and national scale.</p><p>Large-scale modes of climate variability modulate in different ways TC and nonTC induced precipitation, both in the frequency and the magnitude of the events. In a stochastic rainfall generation framework, it becomes therefore useful to model these two mechanisms separately and include their differentiated long-term climatic influences in order to fully reproduce the overall observed rainfall variability. This work presents results on the effect of ENSO and Southern Oscillation Index (SOI) values on seasonal rainfall in China, and how to include this climatic variability in stochastic rainfall for flood catastrophe modelling.</p>

Do Statistical Pattern Corrections Improve Seasonal Climate Predictions in the North American Multimodel Ensemble Models?

2017 ◽  
Vol 30 (20) ◽  
pp. 8335-8355 ◽  
Author(s):  
Anthony G. Barnston ◽  
Michael K. Tippett
Keyword(s):  
North American ◽  
Large Scale ◽  
Climate Model ◽  
Principal Component ◽  
Eastern Africa ◽  
Multimodel Ensemble ◽  
Anomaly Correlation ◽  
The North ◽  
The Individual ◽  
North American Multimodel Ensemble

Abstract Canonical correlation analysis (CCA)-based statistical corrections are applied to seasonal mean precipitation and temperature hindcasts of the individual models from the North American Multimodel Ensemble project to correct biases in the positions and amplitudes of the predicted large-scale anomaly patterns. Corrections are applied in 15 individual regions and then merged into globally corrected forecasts. The CCA correction dramatically improves the RMS error skill score, demonstrating that model predictions contain correctable systematic biases in mean and amplitude. However, the corrections do not materially improve the anomaly correlation skills of the individual models for most regions, seasons, and lead times, with the exception of October–December precipitation in Indonesia and eastern Africa. Models with lower uncorrected correlation skill tend to benefit more from the correction, suggesting that their lower skills may be due to correctable systematic errors. Unexpectedly, corrections for the globe as a single region tend to improve the anomaly correlation at least as much as the merged corrections to the individual regions for temperature, and more so for precipitation, perhaps due to better noise filtering. The lack of overall improvement in correlation may imply relatively mild errors in large-scale anomaly patterns. Alternatively, there may be such errors, but the period of record is too short to identify them effectively but long enough to find local biases in mean and amplitude. Therefore, statistical correction methods treating individual locations (e.g., multiple regression or principal component regression) may be recommended for today’s coupled climate model forecasts. The findings highlight that the performance of statistical postprocessing can be grossly overestimated without thorough cross validation or evaluation on independent data.

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