ENSO Modulates Summer and Autumn Sea Ice Variability Around Dronning Maud Land, Antarctica

Antarctica’s sea ice cover is an important component of the global climate system, yet the drivers of sea ice variability are not well understood. Here we investigated the effects of climate variability on sea ice concentration (SIC) around East Antarctica by correlating the 40-years (1979–2018) satellite sea ice record and ERA5 reanalysis data. We found that summer and autumn SIC around Dronning Maud Land (DML) between 10 and 70°E exhibited a statistically significant negative correlation with the Niño 3.4 index. Sea ice in DML was also correlated with sea surface temperature (SST) anomalies in the tropical Pacific, and to an atmospheric wave train pattern extending from the South Pacific to DML. We suggest that a southward-propagating atmospheric wave train triggered by SST anomalies in the tropical Pacific extends into DML and alters sea ice concentration by encouraging meridional airflow. Our results showed that shifts in meridional flow in DML affected sea ice thermodynamically, by altering local heat transport and in turn altering sea ice formation and melt.Isaacs, Renwick, Mackintosh & Dadic, 2021, ENSO Modulates Summer and Autumn Sea Ice Variability Around Dronning Maud Land, Antarctica, 'Journal of Geophysical Research: Atmospheres', 126, Citation number, 10.1029/2020jd033140. To view the published open abstract,go to http://dx.doi.org (http://dx.doi.org) and enter the DOI.</div

Devising urban ecosystem-based adaptation (EbA) projects with developing nations: A case study of Port Vila, Vanuatu

As the linked impacts of climate change and degradation of ecosystems continue to be felt, particularly in developing countries, it is vital that methods for development that concurrently address adaptation to climate change, rapid urbanisation, and ecosystem degradation be explored. Further development of approaches which are participatory and embedded in an understanding of the importance of symbiotic relationships between socio-cultural and ecological systems is particularly important. Ecosystem-based adaptation (EbA) is one such method that is gaining recognition and momentum in areas where developing nations face converging pressures and drivers of change. EbA methodologies to date, are often ill-defined in an urban context and lack consideration of future social and ecological scenarios however. In response, this paper describes a methodology for developing urban EbA projects in a small island developing nation context. The methodology was developed and applied by a multi-disciplinary team working under the auspices of the Secretariat of the Pacific Regional Environment Programme (SPREP). The application of this methodology in Port Vila, Vanuatu indicated: i) the needs of local people must be at the forefront of project planning, requiring a participatory design process; ii) EbA solutions development must be multidisciplinary and iterative; iii) appropriate quantitative and qualitative data is vital as a basis for EbA project development, requiring adequate time for data gathering; iv) urban and coastal EbA projects must be developed holistically, recognising socio-ecological systems that extend beyond the urban area itself; v) the complex overlapping landscape of governmental and international aid financed projects must inform the development of new EbA projects; vi) potential monetary and non-monetary benefits, costs and risks across multiple factors must be carefully assessed in EbA project development; and vii) project implementation requires ongoing engagement and a readiness to adapt to on-the-ground realities

The unprecedented coupled ocean-atmosphere summer heatwave in the New Zealand region 2017/18: Drivers, mechanisms and impacts

© 2019 The Author(s). Published by IOP Publishing Ltd. During austral summer (DJF) 2017/18, the New Zealand region experienced an unprecedented coupled ocean-atmosphere heatwave, covering an area of 4 million km2. Regional average air temperature anomalies over land were +2.2 °C, and sea surface temperature anomalies reached +3.7 °C in the eastern Tasman Sea. This paper discusses the event, including atmospheric and oceanic drivers, the role of anthropogenic warming, and terrestrial and marine impacts. The heatwave was associated with very low wind speeds, reducing upper ocean mixing and allowing heat fluxes from the atmosphere to the ocean to cause substantial warming of the stratified surface layers of the Tasman Sea. The event persisted for the entire austral summer resulting in a 3.8 ± 0.6 km3 loss of glacier ice in the Southern Alps (the largest annual loss in records back to 1962), very early Sauvignon Blanc wine-grape maturation in Marlborough, and major species disruption in marine ecosystems. The dominant driver was positive Southern Annular Mode (SAM) conditions, with a smaller contribution from La Niña. The long-term trend towards positive SAM conditions, a result of stratospheric ozone depletion and greenhouse gas increase, is thought to have contributed through association with more frequent anticyclonic 'blocking' conditions in the New Zealand region and a more poleward average latitude for the Southern Ocean storm track. The unprecedented heatwave provides a good analogue for possible mean conditions in the late 21st century. The best match suggests this extreme summer may be typical of average New Zealand summer climate for 2081-2100, under the RCP4.5 or RCP6.0 scenario