News

Understanding El Niño-Southern Oscillation Complexity

El Niño events are characterized by tropical Pacific surface warming and weakening of trade winds occurring every few years. Such conditions are accompanied by changes in atmospheric and oceanic circulation, affecting global climate, marine and terrestrial ecosystems, fisheries and human activities. The alternation of warm El Niño and cold La Niña conditions, referred to as the El Niño-Southern Oscillation (ENSO), represents the strongest year-to-year fluctuation of the global climate system. A Nature review paper published recenlty (Timmermann et al. 2018) provides a synthesis of the current understanding of the spatio-temporal complexity (In terms of amplitude, timing, duration, predictability and global impacts) of this important climate mode and its influence on the earth system. The paper proposes a unifying framework to explain ENSO spatio-temporal complexity, by considering the two most dominant coupled modes of variability on about two-year and four-year time scales. Read the full article at the following link. The CSIRO blog highlighting six reasons you should care about El Niño is also recommended reading.

Choosing the future of Antarctica

In a recent Nature article, Rintoul et al. present two narratives on the future of Antarctica and the Southern Ocean, from the perspective of an observer looking back from 2070. Read the CSHOR post, which includes a link to the full article, at this link.

The global influence of localised dynamics in the Southern Ocean

This Nature review by Dr Steve Rintoul evaluates the published research on Southern Ocean change: including changes in circulation, stronger winds, and increased freshwater input. The Southern Ocean exerts a disproportionate and profound influence on global ocean currents, climate, biogeochemical cycles, and sea level rise. The paper shows that substantial progress has been made in recent years in understanding the dynamics and global influence of the Southern Ocean. It is becoming clear that local scale processes play a fundamental part in shaping large-scale circulation. This is drive by the local topography which, of course, doesn’t change to a significant degree. Read the full article at this link.

Global Ocean Summit 2018 (GOS2018)

The 2nd Global Ocean Summit (GOS2018) is taking place in Qingdao, China on 3-5 July 2018. The Summit is jointly hosted by QNLM and Science. It will follow the spirit of Building the Partnerships on Ocean Observation and Research which was widely recognized by the 1st Global Ocean Summit held in Qingdao, China, during 26-28 September 2016.

The 1st GOS gathered nearly 70 leaders and heads from marine research institutions, universities and international organisations. It released the Summit Declaration 2016 advocating jointly to commit to ‘Building Partnership for Ocean Observation and Research’ to address the challenges arising from socio-economic development and global climate change, and to create opportunities for collaboration in marine research, observation, prediction, to inform use and sustainability.

The 2nd GOS will uphold the Summit Declaration 2016 and continually delve deeper into ‘Building the Partnerships on Ocean Observation and Research’, focusing on: (1) ocean observation and prediction; (2) deep-sea research; (3) polar seas research; and (4) ocean sustainability. Visit the GOS2018 website at this link.

CSHOR Science Seminar and Committee Meeting at CSIRO Hobart

The CSHOR office recently hosted a CSHOR Science Seminar and a joint CSHOR Steering and International Advisory Committee Meeting at CSIRO, Hobart. Over 40 guests attended the seminar on Thursday 3 May, including the CSHOR Steering and Advisory Committees. Advisory Committee Members commented that, ‘CSHOR is an excellent team and the science seminar is a great display. The presentations addressed important key questions and highlighted collaboration with other institutions’. Read more at this link.

Global warming is melting Antarctic ice from below

The results from a study published in Science Advances, and reported in a recent Guardian article, suggest that increased glacial meltwater input in a warming climate will both reduce Antarctic Bottom Water formation and trigger increased mass loss from the Antarctic Ice Sheet, with consequences for the global overturning circulation and sea level rise. The latest CSHOR post provides more detail and links to the paper and The Guardian article.

A new wave of southern hemisphere ocean researchers joins CSHOR

After a flood of applications and hours spent trawling through CVs, the Centre for Southern Hemisphere Oceans Research (CSHOR) welcomes six new Postdoctoral Fellows aboard. Read more about the new recruits here.

Recent progress in climate change research

In a paper published in Nature Communication (Cai et al. 2018a) we show that the extreme pIOD frequency is projected to increase linearly with the GMT but approaches a maximum as the GMT stabilises, in stark contrast to a continuous increase in the extreme El Niño frequency long after the GMT stabilisation. Further detail can be found at this link.

CSHOR wins award in China

CSHOR wins an award at the 16th China’s International Talents Exchange Meeting in Shenzhen. Read more about the award at this link.

 

Changes in the Southern Ocean revealed by researchers aboard the RV Investigator

Southern Ocean researchers aboard the RV Investigator  find a shift in a decades-long trend towards fresher, less dense water off Antarctica. Read the SMH article by Peter Hannam at this link.

Understanding the ultimate risk of extreme El Niño associated with a 1.5˚C warming target

In a paper published in Nature Climate Change (Wang et al., 2017a) we demonstrate that extreme El Niño frequency increases linearly with the GMT towards a doubling at 1.5 °C warming. This increasing frequency of extreme El Niño events continues for up to a century after GMT has stabilized, underpinned by an oceanic thermocline deepening that sustains faster warming in the eastern equatorial Pacific than the off-equatorial region. Ultimately, this implies a higher risk of extreme El Niño to future generations after GMT rise has halted. On the other hand, whereas previous research suggests extreme La Niña events may double in frequency under the 4.5 °C warming scenario8, the results presented here indicate little to no change under 1.5 °C or 2 °C warming.

The Paris Agreement aims to constrain global mean temperature (GMT) increases to 2 °C above pre-industrial levels, with an aspirational target of 1.5 °C. However, the pathway to these targets1,2,3,4,5,6 and the impacts of a 1.5 °C and 2 °C warming on extreme El Niño and La Niña events—which severely influence weather patterns, agriculture, ecosystems, public health and economies7,8,9,10,11,12,13,14,15,16—is little known. Here, by analysing climate models participating in the Climate Model Intercomparison Project’s Phase 5 (CMIP5; ref. 17) under a most likely emission scenario1,2.

Explaining the large increase in ocean heat content in the southern hemisphere oceans

A study based on previous Argo float deployments, published in Nature Climate Change (Gao et al., 2017), shows that wind-driven changes in formation and subduction of Subantarctic Mode Water in the Southern Ocean can explain the large increase in ocean heat content in the southern hemisphere oceans.  Further details at: https://doi.org/10.1038/s41558-017-0022-8.

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