Accumulating evidence on the impact of climate change on droughts, highlights the necessity for developing effective adaptation and mitigation strategies. Changes in future drought risk and severity in Australia are quantified by analyzing nine Coupled Model Intercomparison Project Phase 6 climate models. Historic conditions (1981–2014) and projections for mid-century (2015–2050) and end-century (2051–2100) from four shared socioeconomic pathways (SSP1-2.6, SSP2-4.5, SSP3-7.0 and SSP5-8.5) are examined. Drought events are identified using both the standardized precipitation index and the standardized precipitation evapotranspiration index. The spatial-temporal evolution of droughts is addressed by quantifying the areal extent of regions under moderate, severe and extreme drought from historic to end-century periods. Drought characteristics derived from the models are used to develop severity–duration–frequency curves using an extreme value analysis method based on ordinary events. Under SSP5-8.5, a tenfold increase in the area subject to extreme droughts is projected by the end of the century, while a twofold increase is projected under SSP1-2.6. Increase in extreme droughts frequency is found to be more pronounced in the southern and western regions of Australia. For example, frequency analysis of 12 month duration droughts for the state of South Australia indicates that, under SSP5-8.5, drought severities currently expected to happen on average only once in 100 years could happen as often as once in 3 years by the end of the century, with a 33 times higher risk (from 1% to 33%), while under SSP1-2.6, the increase is fivefold (1%–5%). The significant difference in the increase of drought risk between the two extreme scenarios highlights the urge to reduce greenhouse gases emission in order to avoid extreme drought conditions to become the norm by the end of the century.
Atmospheric rivers (ARs) impacting western North America are analyzed under climate intervention applying stratospheric aerosol injections (SAI) using simulations produced by the Whole Atmosphere Community Climate Model. Sulfur dioxide injections are strategically placed to maintain present-day global, interhemispheric, and equator-to-pole surface temperatures between 2020 and 2100 using a high forcing climate scenario. Three science questions are addressed: (1) How will western North American ARs change by the end of the century with SAI applied, (2) How is this different from 2020 conditions, and (3) How will the results differ with no future climate intervention. Under SAI, ARs are projected to increase by the end of the 21st century for southern California and decrease in the Pacific Northwest and coastal British Columbia, following changes to the low-level wind. Compared to 2020 conditions, the increase in ARs is not significant. The character of AR precipitation changes under geoengineering results in fewer extreme rainfall events and more moderate ones.more » « less
- NSF-PAR ID:
- Publisher / Repository:
- Nature Publishing Group
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- Journal Name:
- npj Climate and Atmospheric Science
- Medium: X
- Sponsoring Org:
- National Science Foundation
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