Entry for:The Peer Prize for Women in Science 2017
1. Please give a brief summary of your work.
Are coasts already being impacted by anthropogenic climate change? How have coastlines evolved during higher sea-levels in the past? What is the frequency of erosive ‘super’ storms?
This research addresses these and other questions using an innovative methodology combining state-of-the-art geophysics, luminescence, and remote sensing techniques on sandy barriers that have built seaward (as opposed to the more commonly studied eroded barrier islands). This approach enables me to go back through time and compare shoreline behaviour since the onset of anthropogenic global warming to that in the preceding millennia, including periods when sea level was known to be higher than present in the mid-Holocene (~7, 000 to 2,000 years ago) and part of the Pleistocene (~124,000 – 119,000 years ago).
Deciphering past shoreline behavior can help forecast future responses in the Anthropocene, which is crucial for preparing coastal communities and mitigating impacts in this new era of human-induced climate change.
2. Describe your approach and broader findings.
Sea-level rise threatens a billion people living in coastal zones worldwide and has the potential to cost trillions of dollars in damages from impacts to infrastructure and the global economy. During the last century, carbon dioxide, temperatures, and sea level all exceeded measurements over the previous 12,000 years (a geologic period known as the Holocene). This contributed to a seven year study recently concluding that the Earth has entered a new ‘human’ Epoch, referred to as the Anthropocene.
Climate change models predict a two meter rise in sea-level by 2100 coupled with increased storm intensity. Determining how vulnerable sandy coasts will respond to global warming in the future, requires past records of sea-level and storm impacts to be deciphered. Extracting a record of coastal evolution prior to and since seas began to rise 200 years ago offers the opportunity to detect any difference indicating if/how shorelines have responded. Extending this record back over millennia to understand how shorelines evolved when seas were at least 4 m higher than today in the Pleistocene and possibly two meters higher in the mid-Holocene, can offer insight on the impact to coasts as sea-level returns to this 2 meter height by the end of the century.
For almost twenty years I’ve been developing a methodology that combines state-of-the-art geophysics, luminescence, and remote sensing techniques on prograded barriers to extract comprehensive chronostratigraphic records. Ground Penetrating Radar (GPR) data is used to document beach and dune stratigraphic structure at decimetre resolution. Optically Stimulated Luminescence (OSL) is utilized to directly date the formation of paleo-beachfaces and dunes. Light Detection and Ranging (LiDAR) images allow the lateral extent of relict shorelines to be studied. The resulting records of paleo-beach profiles spanning from the present-day beach through Holocene and Pleistocene barriers, enables an in-depth understanding of the factors controlling coastal evolution: storms, sea level, and sediment supply versus accommodation space.
Exploiting the fundamental link between the geometry of beach profiles and wave energy, I was one of the first people to demonstrate that strong geophysical signatures within coastal barrier stratigraphy were actually a record of storm eroded beach profiles. The potential of this research propelled me from the complicated barrier islands in the northeast of America to the pristine prograded barriers Down Under, which provided me a unique natural laboratory. Replicating this research in New Zealand yielded recurrence intervals of erosional surfaces with differing coastal impacts, which captured storm intensity increases as frequency decreased. I then mapped the elevation of paleo-beaches, intrinsically linked to sea level, to construct the first new sea-level curve for New Zealand in 20 years. Extending this research to Australia, I now have data from 13 sites that captures Pleistocene and mid-Holocene sea-level highstands as well as the nature of their subsequent fall. Additionally, I have quantified the volume of sand in these barriers to provide insight on sediment supply and accommodation space. The results indicate that the amount of sand has increased in the last few centuries forming large foredunes anomalous to previous millennia.
3. What is the wider contribution, or impact, to your scientific field(s)?
Deciphering how and exactly when these anomalously large foredunes formed within the past few centuries, and determining if sea-level rise or increased storm intensity contributed, will help define if global warming is already affecting coastlines and how they will likely evolve over the next century. This will fill a knowledge gap that exists with respect to coastal change over centennial time-scales. Currently the computer models that bridge this gap are limited by regional records of shoreline behaviour measured over decades and restricted by inferred large-scale landscape evolution. My combined methodology can fill this gap with high-resolution empirical data spanning form the present-day over 100,000 years.
Sea level has been documented over thousands of years and this data informs the predictions of a ~2 meter rise by the end of the century. However, debate exists with respect to timing and elevation of sea-level highstands during interglacial periods. Completing this research and providing a detailed sea-level curve, can contribute to this debate. Additionally, since these are tectonically quiet sites, they have implications for global ice-ocean mass flux modelling, possibly helping to refine forecasts of future sea-level rise.
Long-term storm records, similar to those of sea level, do not exist. Quantifying erosional events preserved along the coast can determine if storm frequency and intensity has increased since the onset of global warming and help predict when the next large event might occur.
Hurricane Sandy and Typhoon Haiyan alone cost over 6.5 thousand lives and US$80 billion; in the future this devastation from super storms will be exacerbated by sea-level rise associated with global warming. The results of this research has the potential to yield significant outcomes beyond theoretical debates in related fields of climate change research, by directly addressing practical issues of forecasting and managing impacts of global warming on vulnerable coastal communities.
4. Are there any potential ideas you would like to explore to take this research further?
Over ~20 years I have amassed data spanning three countries and two hemispheres. Aside from a University of Auckland International Doctoral Scholarship in New Zealand and a post-doc position at the University of Wollongong in Australia, this research has been self-funded with small grants and prizes awarded totalling less than AU$20,000. In 2013, I gave up my pick of prestigious post-doc positions in the US to return to this work in Australia. After several career interruptions I have finally immigrated and started a consulting firm to support myself and this research.
This Peer Prize would provide me with the time and resources to synthesize all of my data and establish this method such that it can be utilized like, and compared with, ice core and tree ring data. It would also enable me to focus on some rare opportunities that arose for my presentation at the 2017 European Geoscience Union Meeting. I was selected to talk at an inaugural coastal dynamics session, sponsored by the Commission on Coastal Systems, entitled “Coastal Morphodynamics: Nearshore, Beaches and Dunes”. This garnered the attention of a Review Papers Coordinator for Elsevier’s Earth Science journals, who asked me to author an invited research paper for Marine Geology and a manuscript for Earth-Science Reviews on this research. I was also contacted by the Senior Commissioning Editor from the Institute of Physics Publishing to write a text for their award winning ebooks digital series.
This Peer Prize could also facilitate the next phase of research focusing on a multidisciplinary approach that builds on existing collaborations with climate scientists, computer modellers, engineers, and government bodies. Ultimately, the aim is to acquire a better understanding of the human influence on climate change and determine how best to mitigate the impacts of global warming on coastal communities in the Anthropocene.
5. Please share a link for researchers to access a relevant publication, data-set, or thesis.
I have been an Honorary Research Fellow at the University of Wollongong since completing a post-doc with Colin Woodroffe in 2012. Prior to this I held a permanent position as a Research Scientist a...