Back to search

FRINATEK-Fri prosj.st. mat.,naturv.,tek

Ultra-High-Resolution Marine Records from the Subarctic Atlantic (ULTRAMAR)

Alternative title: Høyoppløselige proksy rekorder fra det subarktiske Atlanterhavet

Awarded: NOK 6.0 mill.

Studies of past climate can contribute to understanding the climate system and form the basis for improved predictions about climate change in the future. In the ULTRAMAR project, past changes in marine climate are studied based on new reconstructions of sea temperature and sea ice in the Nordic Seas and adjacent marine areas. The project has developed a 230-year-long reconstruction of sea temperature off southwest Iceland. This is an area under the strong influence of the Irminger Current, an offshoot from the North Atlantic Current. This new record is based on measurement of annual growth rings and chemical analysis of isotopes in the bivalve Arctica islandica, a species that is particularly well-suited for marine reconstructions because the growth rings have annual resolution. The project has also put together and integrated existing data from marine sediment cores. The samples from these sediment cores contain small fossils, debris and traces of chemicals that allow us to reconstruct important climate parameters such as sea temperature and sea ice back in time. The project uses various statistical methods to better constrain and understand interannual to multidecadal climate variability. This includes variations associated with natural fluctuations such as the North Atlantic Oscillation (NAO) and the Atlantic Multidecadal Oscillation (AMO). We have found decadal (20-30 year) and multidecadal (60-90 year) signals in reconstructions from Iceland, the Greenland Sea and the Barents Sea. We have also identified irregular, abrupt changes in Arctic sea ice export through Fram Strait between Greenland and Svalbard. We thereby find robust evidence for extreme outflow of sea ice commencing abruptly around 1300 AD and terminating in the late 1300s, a so-called "Great Sea Ice Anomaly". The "mega-stream" can be traced further to south Greenland and the Labrador Sea, where the amount of meltwater and polar waters remained high throughout the subsequent, coldest centuries of the Little Ice Age (ca. 1350-1850). Such a scenario is strikingly consistent with modeled spontaneous abrupt cooling, further enhanced by sea-ice feedbacks. Our results provide evidence that marked climate changes may not require an external trigger, and moreover underscore the important role of sea ice in the climate system.

The outcomes of the project have advanced the state-of-the-art on multiple aspects of scientific importance. Expertise of early career scientists in the the emerging field of sclerochronology has been developed. Cross-disciplinary paleo science has been enhanced through integrating proxy data from different archives, a framework that takes advantage of advances in sclerochronology and bridges the gap between the separated research communities of marine geology, marine biogeochemistry and paleoclimatology. The project has improved scientific understanding of coupled modes of ocean-atmosphere variability and abrupt changes, including the occurrence of major sea-ice export events and their effects on ocean stratification other downstream changes in the northern North Atlantic.

The ULTRAMAR research project is focused on reconstructing and understanding the long-term (century to millennial scale) development of key aspects of ocean-ice-atmosphere dynamics at annual to sub-annual resolution. In ULTRAMAR, we aim to quantitatively constrain and explain interannual to multidecadal marine climate variability in the North Atlantic / Nordic Seas gateways and the broader subarctic-arctic Atlantic. The methodological approach of ULTRAMAR is based on: (1) Developing new sclerochronological data records based on the long-lived bivalve Arctica islandica; (2) Developing a comprehensive, integrated and statistically-evaluated dataset of pertinent ultra-high-resolution marine (and selected terrestrial) proxy records, and (3) Applying advanced time-frequency-domain time-series analysis techniques (e.g., wavelet analysis and Fourier methods) to ultra-high-resolution paleoenvironmental records. In ULTRAMAR we will develop new baseline sclerochronology data records from SW Iceland, and quantitatively analyse this material and more than 25 other ultra-high-resolution records using a suite of advanced statistical techniques. Temporally, the data records span century+ to millennial time ranges. Spatially, these records span from northeastern North America, Greenland, Iceland and across the northern North Atlantic/Nordic Seas to Scandinavia including Svalbard. The disparate records include: marine sclerochronological records from bivalves, extratropical corals, marine sediment-based proxies for ocean temperature and sea ice, pertinent terrestrial records with annual to sub-annual resolution, as well as several baseline time series of multi-proxy statistical reconstructions of air and ocean temperature.

Publications from Cristin

No publications found

No publications found

Funding scheme:

FRINATEK-Fri prosj.st. mat.,naturv.,tek