Will Hobbs

Will Hobbs
University of Tasmania · Australian Antarctic Program Partnership

PhD, MSc, MEng

About

53
Publications
14,834
Reads
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1,515
Citations
Additional affiliations
June 2019 - December 2019
University of Tasmania
Position
  • Physical Oceanographer
March 2015 - May 2019
University of Tasmania
Position
  • Physical Oceanographer
September 2012 - March 2015
University of Tasmania
Position
  • Climate scientist - detection and attribution
Education
January 2005 - June 2009
University of California, Los Angeles
Field of study
  • Geography (Southern Hemisphere atmospheric variability and its impact on sea ice)
October 2003 - September 2004
University of Reading
Field of study
  • Applied Meteorology
October 1991 - June 1995
The University of Sheffield
Field of study
  • Mechanical Engineering

Publications

Publications (53)
Article
Full-text available
Plain Language Summary Antarctic sea ice is a critical component of climate and a vital habitat for Southern Ocean ecosystems. Therefore, understanding the drivers and physical processes influencing Antarctic sea ice, and being able to predict Antarctic sea ice is of broad interest. We assess the predictability of sea ice and underlying upper ocean...
Article
Full-text available
The Earth system is accumulating energy due to human-induced activities. More than 90% of this energy has been stored in the ocean as heat since 1970, with ~64% of that in the upper 700 m. Differences in upper ocean heat content anomaly (OHCA) estimates, however, exist. Here, we use a dataset protocol for 1970–2008 – with six instrumental bias adju...
Article
Full-text available
Reanalysis products are an invaluable tool for representing variability and long-term trends in regions with limited in situ data, and especially the Antarctic. A comparison of eight different reanalysis products shows large differences in sea level pressure and surface air temperature trends over the high-latitude Southern Ocean, with implications...
Article
In this study, we compare observed Southern Ocean temperature and salinity changes with the historical simulations from 13 models the Coupled Model Intercomparison Project version 5 (CMIP5), using an optimal fingerprinting framework. We show that there is an unequivocal greenhouse gas-forced warming in the Southern Ocean. This warming is strongest...
Preprint
The Earth system is accumulating energy due to human-induced activities. More than 90 percent of this energy has been stored in the ocean as heat since 1970, with about 64 percent of that in the upper 700 m. Differences in upper ocean heat content anomaly (OHCA) estimates, however, exist. Here, we evaluate spread in upper OHCA estimates arising fro...
Preprint
Full-text available
Reanalysis products are an invaluable tool for representing variability and long-term trends in regions with limited in-situ data, and especially the Antarctic. A comparison of 8 different reanalysis products shows large differences sea level pressure and surface air temperature trends over the high latitude Southern Ocean, with implications for st...
Chapter
This chapter discusses recent changes in Antarctic climate. Changes in the atmospheric circulation modes that influence Antarctic climate, namely, the Southern Annular Mode (SAM), the Amundsen Sea Low (ASL), and the Pacific South American pattern (PSA) are highlighted. The transition of the SAM to its positive polarity, the deepening of the ASL, an...
Article
Full-text available
The progress of science is tied to the standardization of measurements, instruments, and data. This is especially true in the Big Data age, where analyzing large data volumes critically hinges on the data being standardized. Accordingly, the lack of community-sanctioned data standards in paleoclimatology has largely precluded the benefits of Big Da...
Article
Full-text available
Quantitative estimates of future Antarctic climate change are derived from numerical global climate models. Evaluation of the reliability of climate model projections involves many lines of evidence on past performance combined with knowledge of the processes that need to be represented. Routine model evaluation is mainly based on the modern observ...
Article
Full-text available
Previous studies have shown that sea ice extent in the Southern Ocean is influenced by the intensity and location of the Amundsen Sea Low (ASL), through their effect on the meridional winds. However, the inhomogeneous nature of the influence of the ASL on sea ice as well as its influence during critical periods of the sea ice annual cycle is not cl...
Article
Antarctic sea ice trends have to date been linked to surface winds, through sea ice motion and atmospheric thermal advection. This paper analyzes sea ice volume in 10 Coupled Model Intercomparison Project Phase 5 (CMIP5) model configurations under pre-industrial and historical climate forcings, to compare the relative importance of ice motion and t...
Article
Full-text available
In 2017, the dominant greenhouse gases released into Earth's atmosphere-carbon dioxide, methane, and nitrous oxide-reached new record highs. The annual global average carbon dioxide concentration at Earth's surface for 2017 was 405.0 ± 0.1 ppm, 2.2 ppm greater than for 2016 and the highest in the modern atmospheric measurement record and in ice cor...
Article
Full-text available
Strong heat loss and brine release during sea ice formation in coastal polynyas act to cool and salinify waters on the Antarctic continental shelf. Polynya activity thus both limits the ocean heat flux to the Antarctic Ice Sheet and promotes formation of Dense Shelf Water (DSW), the precursor to Antarctic Bottom Water. However, despite the presence...
Article
Full-text available
Ch 7. Regional Climates: f. Europe and the Middle East
Article
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The response of Antarctic sea ice to large-scale patterns of atmospheric variability varies according to sea ice sector and season. In this study, interannual atmosphere–sea ice interactions were explored using observations and reanalysis data, and compared with simulated interactions by models in the Coupled Model Intercomparison Project Phase 5 (...
Article
Full-text available
Contrasting regional changes in Southern Ocean sea ice have occurred over the last 30 years with distinct regional effects on ecosystem structure and function. Quantifying how Antarctic predators respond to such changes provides the context for predicting how climate variability/change will affect these assemblages into the future. Over an 11-year...
Article
Full-text available
The response of Antarctic sea ice to large-scale patterns of atmospheric variability varies according to sea ice sector and season. In this study, interannual atmosphere-sea ice interactions were explored using observation-based data and compared with simulated interactions by models in the Coupled Model Intercomparison Project Phase 5. Simulated r...
Article
Full-text available
Observations show that Southern Ocean sea ice extent has increased since 1979, whereas global coupled climate models simulate a decrease over the same period. It is uncertain whether the observed trends are anthropogenically forced or due to internal variability, and whether the discrepancy between models and observations is also due to internal va...
Article
Full-text available
Circumpolar upwelling circulation near the Antarctic has mainly been attributed to winds. An analysis of water-mass transformation shows that the dominant driver is instead the formation of sea ice near Antarctica and its melt offshore.
Article
Over the past 37 years, satellite records show an increase in Antarctic sea ice cover that is most pronounced in the period of sea ice growth. This trend is dominated by increased sea ice coverage in the western Ross Sea, and is mitigated by a strong decrease in the Bellingshausen and Amundsen seas. The trends in sea ice areal coverage are accompan...
Conference Paper
Full-text available
Understanding the long term trends in sea ice coverage is important, particularly in the context of recent reports of increases in Antarctic sea ice extent. Prior to the satellite era, ice core records have been used as a proxy for past sea ice extent in Antarctica, allowing investigations of the natural variability of Antarctic sea ice extent. The...
Article
Full-text available
Climate model simulations of changes to Earth's energy budget are fundamental to improve understanding of both historical and future climate change. However, coupled models are prone to "drift" (i.e., they contain spurious unforced trends in state variables) due to incomplete spinup or nonclosure of the energy budget. This work assesses the globall...
Article
The Amundsen Sea low (ASL) is a climatological low pressure center that exerts considerable influence on the climate of West Antarctica. Its potential to explain important recent changes in Antarctic climate, for example, in temperature and sea ice extent, means that it has become the focus of an increasing number of studies. Here, the authors summ...
Article
Full-text available
Using optimal fingerprinting techniques, a detection analysis is performed to determine whether observed trends in Southern Ocean sea ice extent since 1979 are outside the expected range of natural variability. Consistent with previous studies, it is found that for the seasons of maximum sea ice cover (i.e., winter and early spring), the observed t...
Article
Full-text available
Antarctic sea ice, a key component of the Southern Hemisphere climate system, is influenced by several large scale modes of the atmospheric circulation. Antarctic sea ice variability is spatially heterogeneous and links between the atmospheric circulation modes and sea ice variability are unclear. Using observed sea ice concentration data, this res...
Article
Full-text available
The meridional overturning circulation is related to the meridional heat transport (MHT) in the oceans, and the variability of MHT can impact heat storage, sea-level rise, and air-sea fluxes, and hence influence local climate on land. Time series of the oceanic heat transport are more rare than time series of the meridional overturning circulation...
Article
Full-text available
[1] Observations show that the upper 2 km of the subtropical North Atlantic Ocean cooled throughout 2010 and remained cold until at least December 2011. We show that these cold anomalies are partly driven by anomalous air-sea exchange during the cold winters of 2009/2010 and 2010/2011 and, more surprisingly, by extreme interannual variability in th...
Article
Full-text available
The traditional view of the open ocean is that surface waters should change faster and that the deep waters should be relatively stable. Now research shows that the depths of the Southern Ocean are also rapidly freshening and warming, and that these changes are spreading towards the Equator.
Article
Full-text available
For the first time in serveral years, the El Nino-Southern Oscillation did not dominate regional climate conditions around the globe. A weak La Ni a dissipated to ENSOneutral conditions by spring, and while El Nino appeared to be emerging during summer, this phase never fully developed as sea surface temperatures in the eastern conditions. Neverthe...
Article
Full-text available
work comparing historical hydrographic data with modern Argo observations shows a long-term change in the global ocean temperature. The magnitude of this change is greater than estimates of late 20th century warming, and implies a century-scale change in the global oceans. Using global coupled climate models from the Coupled Model Intercomparison P...
Article
Beginning in 2010 the subtropical Atlantic cooled from the surface to at least 2 km depth. The decrease in ocean heat content (OHC) associated with this cooling appears to be the most abrupt and vertically coherent change in the past 62 years. Here we diagnose the causes of this cooling by examining the changes in energy fluxes to the subtropical g...
Article
Full-text available
Using temperature, salinity, and displacement data from Argo floats combined with satellite sea surface height, a time series of the Atlantic meridional heat transport from January 2002 to August 2010 has been estimated for 41°N. The calculation method is validated against hydrographic climatologies and output from the ECCO2 ocean data assimilation...
Article
Full-text available
Much research concerning the Southern Hemisphere (SH) zonally asymmetric circulation has focused on the Pacific-South American mode (PSA) or the major zonal waves. However, these large-scale decompositions may mask important local variability. In this paper the month-to-month variability explained by the zonal waves 1 and 3 is examined, and an alte...
Article
Full-text available
At monthly and annual timescales, the zonally asymmetric circulation over the Southern Ocean is dominated by two quasi-stationary anticyclones: a western anticyclone approximately located south of New Zealand, and an eastern anticyclone located over the Drake Passage region. In this research their influence on late 20th century Antarctic sea ice is...
Article
Full-text available
Satellite data for the past three decades reveal a record-high sea surface temperature (SST) anomaly within a large mid-latitude region of the south-central Pacific (SCP) during the mature phase of the 2009–10 El Niño, with a peak magnitude that is 5 times the standard deviation of local SST anomaly and is warmer than the concurrent tropical-Pacifi...
Article
Full-text available
This study examines the influence of Antarctic sea ice distribution on the large scale circulation of the Southern Hemisphere using a fully coupled GCM where the sea ice submodel is replaced by a climatology of observed extremes in sea ice concentration. Three 150-year simulations were completed for maximum, minimum and average sea ice concentratio...
Article
Full-text available
The west Antarctic region has shown one of the strongest warming trends globally over the last half-century, whilst the remainder of the Antarctic region has shown either little change or a cooling trend. Despite this zonally heterogeneous change, many recent studies of high latitude Southern Hemisphere change focus on the role of the quasi zonally...
Article
Full-text available
Recent studies show that an ENSO component of west Antarctic climate variability is related to a persistent zonal pressure anomaly in the south Pacific, which in turn is related to the zonal wave 1 of the subpolar atmospheric circulation. In order to promote further investigation into its dynamics, a suite of time series are presented that describe...
Article
Full-text available
The west Antarctic region shows one of the strongest warming trends globally over the late 20th century, whilst much of the Antarctic continent shows little trend or even cooling. Additionally, sea ice reductions in the Antarctic Peninsula region have been balanced by sea ice increases in the Ross Sea region. Despite this heterogeneity, much recent...

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Projects

Projects (3)
Project
How is Antarctic sea ice affected by changes in the Southern Ocean? How does Antarctic sea ice impact the global climate? This (initially) 3-year project will address these important questions, using a mixture of models and observations
Project
There are observed changes in the southern Ocean - notably warming, freshening and changes in sea ice cover - that have global implications. Are these changes a response to anthropogenic forcings, or merely multidecadal natural variability?