scholarly journals Megadroughts and pluvials in southwest Australia: 1350–2017 CE

2021 ◽  
Author(s):  
Alison J. O’Donnell ◽  
W. Lachlan McCaw ◽  
Edward R. Cook ◽  
Pauline F. Grierson
Keyword(s):  
Rainfall Variability ◽  
Climate Change Scenarios ◽  
Winter Rainfall ◽  
Prolonged Drought ◽  
Instrumental Record ◽  
Southwest Australia ◽  
Tree Ring Reconstruction ◽  
Hydroclimatic Variability ◽  
Eighteenth And Nineteenth Centuries

AbstractDeclining winter rainfall coupled with recent prolonged drought poses significant risks to water resources and agriculture across southern Australia. While rainfall declines over recent decades are largely consistent with modelled climate change scenarios, particularly for southwest Australia, the significance of these declines is yet to be assessed within the context of long-term hydroclimatic variability. Here, we present a new 668-year (1350–2017 CE) tree-ring reconstruction of autumn–winter rainfall over inland southwest Australia. This record reveals that a recent decline in rainfall over inland southwest Australia (since 2000 CE) is not unusual in terms of either magnitude or duration relative to rainfall variability over the last seven centuries. Drought periods of greater magnitude and duration than those in the instrumental record occurred prior to 1900 CE, including two ‘megadroughts’ of > 30 years duration in the eighteenth and nineteenth centuries. By contrast, the wettest > decadal periods of the last seven centuries occurred after 1900 CE, making the twentieth century the wettest of the last seven centuries. We conclude that the instrumental rainfall record (since ~ 1900 CE) does not capture the full scale of natural hydroclimatic variability for inland southwest Australia and that the risk of prolonged droughts in the region is likely much higher than currently estimated.

scholarly journals Associations between the Global Energy Cycle and Regional Rainfall in South Africa and Southwest Australia

2005 ◽  
Vol 18 (15) ◽  
pp. 3032-3047 ◽  
Author(s):  
Warren J. Tennant ◽  
Chris J. C. Reason
Keyword(s):  
South Africa ◽  
Large Scale ◽  
Rainfall Variability ◽  
Summer Rainfall ◽  
Winter Rainfall ◽  
Self Organizing Maps ◽  
Energy Cycle ◽  
Southwest Australia ◽  
Physical Reasons ◽  
Regional Rainfall

Abstract Large-scale atmospheric processes in the Southern Hemisphere are examined on both seasonal and daily time scales in order to seek associations between these and regional rainfall variability in the summer rainfall areas of South Africa and the winter rainfall regions of South Africa and Western Australia. The basis of the analysis is atmospheric energetics of the vertical mean and shear flow. Self-organizing maps (SOMs) are then used to find archetypical states of the daily flow and to assess how the frequency characteristics of these states change between wet and dry years. The results show clear associations between the frequency of circulation archetypes on a hemispheric scale and regional rainfall for both summer and winter rainfall areas. Substantial changes in archetype frequencies between wet and dry years are found with as much as a doubling or halving of the number of days in which certain archetypes occur within a season. The physical reasons for observed teleconnections are shown by way of the atmospheric energy cycle, providing a deeper understanding of climate variability that may benefit extended-range prediction.

scholarly journals Broadening the Spatial Applicability of Paleoclimate Information—A Case Study for the Murray–Darling Basin, Australia

2014 ◽  
Vol 27 (7) ◽  
pp. 2477-2495 ◽  
Author(s):  
Michelle Ho ◽  
Danielle C. Verdon-Kidd ◽  
Anthony S. Kiem ◽  
Russell N. Drysdale
Keyword(s):  
Large Scale ◽  
Rainfall Variability ◽  
Principal Component ◽  
Optimal Interpolation ◽  
Proxy Records ◽  
Murray Darling Basin ◽  
Paleoclimate Records ◽  
Hydroclimatic Variability ◽  
Paleoclimate Data

Abstract Recent advances in the collection and analysis of paleoclimate data have provided significant insights into preinstrumental environmental events and processes, enabling a greater understanding of long-term environmental change and associated hydroclimatic risks. Unfortunately, it is often the case that there is a dearth of readily available paleoclimate data from regions where such insights and long-term data are most needed. The Murray–Darling basin (MDB), known as Australia’s “food bowl,” is an example of such a region where currently there are very limited in situ paleoclimate data available. While previous studies have utilized paleoclimate proxy records of large-scale climate mechanisms to infer preinstrumental MDB hydroclimatic variability, there is a lack of studies that utilize Australian terrestrial proxy records to garner similar information. Given the immediate need for improved understanding of MDB hydroclimatic variability, this paper identifies key locations in Australia where existing and as yet unrealized paleoclimate records will be most useful in reconstructing such information. To identify these key locations, rainfall relationships between MDB and non-MDB locations were explored through correlations and principal component analysis. An objective analysis using optimal interpolation was then used to pinpoint the most strategic locations to further develop proxy records and gain insights into the benefits of obtaining this additional information. The findings reveal that there is potential for the future assembly of high-resolution paleoclimate records in Australia capable of informing MDB rainfall variability, in particular southeast Australia and central-northern Australia. This study highlights the need for further investment in the development of these potential proxy sources to subsequently enable improved assessments of long-term hydroclimatic risks.

scholarly journals Assessing the long-term effectiveness of Nature-Based Solutions under different climate change scenarios

2021 ◽  
pp. 148515
Author(s):  
Eulalia Gómez Martín ◽  
María Máñez Costa ◽  
Sabine Egerer ◽  
Uwe Schneider
Keyword(s):  
Climate Change ◽  
Climate Change Scenarios

scholarly journals Extreme rainfall deficits were not the cause of recurring colonial era famines of southern Indian semi-arid regions

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Ranjini Ray ◽  
Atreyee Bhattacharya ◽  
Gaurav Arora ◽  
Kushank Bajaj ◽  
Keyle Horton ◽  
...  
Keyword(s):  
Arid Regions ◽  
Human Impacts ◽  
Rainfall Variability ◽  
Extreme Rainfall ◽  
Southern India ◽  
Colonial Era ◽  
Regional Rainfall ◽  
Semi Arid ◽  
Rainfall Deficits

AbstractUsing information contained in the eighteenth to twentieth century British administrative documents, preserved in the National Archives of India (NAI), we present a 218-year (1729–1947 AD) record of socioeconomic disruptions and human impacts (famines) associated with ‘rain failures’ that affected the semi-arid regions (SARs) of southern India. By mapping the southern Indian famine record onto long-term spatiotemporal measures of regional rainfall variability, we demonstrate that the SARs of southern India repeatedly experienced famines when annual rainfall reduced by ~ one standard deviation (1 SD), or more, from long-term averages. In other words, ‘rain failures’ listed in the colonial documents as causes of extreme socioeconomic disruptions, food shortages and human distress (famines) in the southern Indian SARs were fluctuations in precipitation well within the normal range of regional rainfall variability and not extreme rainfall deficits (≥ 3 SD). Our study demonstrates that extreme climate events were not necessary conditions for extreme socioeconomic disruptions and human impacts rendered by the colonial era famines in peninsular India. Based on our findings, we suggest that climate change risk assessement should consider the potential impacts of more frequent low-level anomalies (e.g. 1 SD) in drought prone semi-arid regions.

scholarly journals Climate Change Influences Basidiome Emergence of Leaf-Cutting Ant Cultivars

2021 ◽  
Vol 7 (11) ◽  
pp. 912
Author(s):  
Rodolfo Bizarria ◽  
Pepijn W. Kooij ◽  
Andre Rodrigues
Keyword(s):  
Climate Change ◽  
Climate Change Scenarios ◽  
Nest Architecture ◽  
Historical Records ◽  
Climate Data ◽  
Temperature And Precipitation ◽  
Data Analyses ◽  
Symbiotic Mutualism ◽  
Leaf Cutting

Maintaining symbiosis homeostasis is essential for mutualistic partners. Leaf-cutting ants evolved a long-term symbiotic mutualism with fungal cultivars for nourishment while using vertical asexual transmission across generations. Despite the ants’ efforts to suppress fungal sexual reproduction, scattered occurrences of cultivar basidiomes have been reported. Here, we review the literature for basidiome occurrences and associated climate data. We hypothesized that more basidiome events could be expected in scenarios with an increase in temperature and precipitation. Our field observations and climate data analyses indeed suggest that Acromyrmex coronatus colonies are prone to basidiome occurrences in warmer and wetter seasons. Even though our study partly depended on historical records, occurrences have increased, correlating with climate change. A nest architecture with low (or even the lack of) insulation might be the cause of this phenomenon. The nature of basidiome occurrences in the A. coronatus–fungus mutualism can be useful to elucidate how resilient mutualistic symbioses are in light of climate change scenarios.

scholarly journals Synthesizing greenhouse gas fluxes across nine European peatlands and shrublands – responses to climatic and environmental changes

2012 ◽  
Vol 9 (3) ◽  
pp. 3693-3738 ◽  
Author(s):  
M. S. Carter ◽  
K. S. Larsen ◽  
B. Emmett ◽  
M. Estiarte ◽  
C. Field ◽  
...  
Keyword(s):  
Global Warming ◽  
Greenhouse Gas ◽  
Air Temperature ◽  
Environmental Changes ◽  
Negative Relationship ◽  
Co2 Efflux ◽  
Soil Co2 ◽  
Prolonged Drought ◽  
Mean Annual Air Temperature

Abstract. In this study, we compare annual fluxes of methane (CH4), nitrous oxide (N2O) and soil respiratory carbon dioxide (CO2) measured at nine European peatlands (n = 4) and shrublands (n = 5). The sites range from northern Sweden to Spain, covering a span in mean annual air temperature from 0 to 16 °C, and in annual precipitation from 300 to 1300 mm yr−1. The effects of climate change, including temperature increase and prolonged drought, were tested at five shrubland sites. At one peatland site, the long-term (>30 yr) effect of drainage was assessed, while increased nitrogen deposition was investigated at three peatland sites. The shrublands were generally sinks for atmospheric CH4 whereas the peatlands were CH4 sources, with fluxes ranging from −519 to +6890 mg CH4-C m−2 yr−1 across the studied ecosystems. At the peatland sites, annual CH4 emission increased with mean annual air temperature, while a negative relationship was found between net CH4 uptake and the soil carbon stock at the shrubland sites. Annual N2O fluxes were generally small ranging from –14 to 42 mg N2O-N m−2 yr−1. Highest N2O emission occurred at the sites that had highest concentration of nitrate (NO3−) in soil water. Furthermore, experimentally increased NO3− deposition led to increased N2O efflux, whereas prolonged drought and long-term drainage reduced the N2O efflux. Soil CO2 emissions in control plots ranged from 310 to 732 g CO2-C m−2 yr−1. Drought and long-term drainage generally reduced the soil CO2 efflux, except at a~hydric shrubland where drought tended to increase soil respiration. When comparing the fractional importance of each greenhouse gas to the total numerical global warming response, the change in CO2 efflux dominated the response in all treatments (ranging 71–96%), except for NO3− addition where 89% was due to change in CH4 emissions. Thus, in European peatlands and shrublands the feedback to global warming induced by the investigated anthropogenic disturbances will be dominated by variations in soil CO2 fluxes.

scholarly journals Salvage felling in the Slovak forests in the period 2004–2013

2015 ◽  
Vol 61 (3) ◽  
pp. 188-195 ◽  
Author(s):  
Andrej Kunca ◽  
Milan Zúbrik ◽  
Juraj Galko ◽  
Jozef Vakula ◽  
Roman Leontovyč ◽  
...  
Keyword(s):  
Norway Spruce ◽  
Forest Health ◽  
Control Measures ◽  
Climate Change Scenarios ◽  
The European Union ◽  
Spruce Bark ◽  
Important Pest ◽  
Health Quality ◽  
And Control

Abstract Salvage felling is one of the indicators of the forest health quality and stability. Most of the European Union countries monitor forest harmful agents, which account for salvage felling, in order to see trends or functionality between factors and to be able to predict their development. The systematic evidence of forest harmful agents and volume of salvage felling in Slovakia started at the Forest Research Institute in Zvolen in 1960. The paper focuses on the occurrence of the most relevant harmful agents and volume of salvage felling in the Slovak forests over the last decade. Within the 10 years period (2004–2013) salvage felling in Slovakia reached 42.31 mil. m3 of wood, which was 53.2% of the total felling. Wind and European spruce bark beetle Ips typographus damaged 78.4% of salvage wood, i.e. they were the most important pest agents. Norway spruce (Picea abies) was the most frequently damaged tree species that represented the amount of 35.6 mil. m3 of wood (81.2% of total volume of salvage felling). As Norway spruce grows mostly in mountains, these regions of Central and Northern Slovakia were most affected. At the damaged localities new forests were prevailingly established with regard to suitable ecological conditions for trees, climate change scenarios and if possible, natural regeneration has been preferred. These approaches in forest stand regeneration together with silvicultural and control measures are assumed to gradually decrease the amount of salvage felling over long term perspective.

scholarly journals Soil salinization under different climate change scenarios: A global scale analysis

2021 ◽  
Author(s):  
Nima Shokri ◽  
Amirhossein Hassani ◽  
Adisa Azapagic
Keyword(s):  
Climate Change ◽  
Water Resources ◽  
Soil Salinity ◽  
Global Scale ◽  
Soil Salinization ◽  
Water Evaporation ◽  
Climate Change Scenarios ◽  
Spatio Temporal ◽  
Salt Affected Soils

<p>Population growth and climate change is projected to increase the pressure on land and water resources, especially in arid and semi-arid regions. This pressure is expected to affect all driving mechanisms of soil salinization comprising alteration in soil hydrological balance, sea salt intrusion, wet/dry deposition of wind-born saline aerosols — leading to an increase in soil salinity. Soil salinity influences soil stability, bio-diversity, ecosystem functioning and soil water evaporation (1). It can be a long-term threat to agricultural activities and food security. To devise sustainable action plan investments and policy interventions, it is crucial to know when and where salt-affected soils occur. However, current estimates on spatio-temporal variability of salt-affected soils are majorly localized and future projections in response to climate change are rare. Using Machine Learning (ML) algorithms, we related the available measured soil salinity values (represented by electrical conductivity of the saturated paste soil extract, EC<sub>e</sub>) to some environmental information (or predictors including outputs of Global Circulation Models, soil, crop, topographic, climatic, vegetative, and landscape properties of the sampling locations) to develop a set of data-driven predictive tools to enable the spatio-temporal predictions of soil salinity. The outputs of these tools helped us to estimate the extent and severity of the soil salinity under current and future climatic patterns at different geographical levels and identify the salinization hotspots by the end of the 21<sup>st</sup> century in response to climate change. Our analysis suggests that a soil area of 11.73 Mkm<sup>2</sup> located in non-frigid zones has been salt-affected in at least three-fourths of the 1980 - 2018 period (2). At the country level, Brazil, Peru, Sudan, Colombia, and Namibia were estimated to have the highest rates of annual increase in the total area of soils with an EC<sub>e</sub> ≥ 4 dS m<sup>-1</sup>. Additionally, the results indicate that by the end of the 21<sup>st</sup> century, drylands of South America, southern and Western Australia, Mexico, southwest United States, and South Africa will be the salinization hotspots (compared to the 1961 - 1990 period). The results of this study could inform decision-making and contribute to attaining the United Nation’s Sustainable Development Goals for land and water resources management.</p><p>1. Shokri-Kuehni, S.M.S., Raaijmakers, B., Kurz, T., Or, D., Helmig, R., Shokri, N. (2020). Water Table Depth and Soil Salinization: From Pore-Scale Processes to Field-Scale Responses. Water Resour. Res., 56, e2019WR026707. https://doi.org/ 10.1029/2019WR026707</p><p>2. Hassani, A., Azapagic, A., Shokri, N. (2020). Predicting Long-term Dynamics of Soil Salinity and Sodicity on a Global Scale, Proc. Nat. Acad. Sci., 117, 52, 33017–33027. https://doi.org/10.1073/pnas.2013771117</p>

scholarly journals A new scenario logic for the Paris Agreement long-term temperature goal

2020 ◽  
Author(s):  
Joeri Rogelj ◽  
Daniel Huppmann ◽  
Volker Krey ◽  
Keywan Riahi ◽  
Leon Clarke ◽  
...  
Keyword(s):  
Global Warming ◽  
Integrated Assessment ◽  
Transition Period ◽  
Paris Agreement ◽  
Climate Change Scenarios ◽  
Industrial System ◽  
Carbon Neutrality ◽  
Climate Action ◽  
Near Term

<p>To understand how global warming can be kept well-below 2°C and even 1.5°C, climate policy uses scenarios that describe how society could transform in order to reduce its greenhouse gas emissions. Such scenario are typically created with integrated assessment models that include a representation of the economy, and the energy, land-use, and industrial system. However, current climate change scenarios have a key weakness in that they typically focus on reaching specific climate goals in 2100 only. <br><br>This choice results in risky pathways that delay action and seemingly inevitably rely on large quantities of carbon-dioxide removal after mid-century. Here we propose a framework that more closely reflects the intentions of the UN Paris Agreement. It focusses on reaching a peak in global warming with either stabilisation or reversal thereafter. This approach provides a critical extension of the widely used Shared Socioecononomic Pathways (SSP) framework and reveals a more diverse picture: an inevitable transition period of aggressive near-term climate action to reach carbon neutrality can be followed by a variety of long-term states. It allows policymakers to explicitly consider near-term climate strategies in the context of intergenerational equity and long-term sustainability.</p>

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