A new timeline for glacial retreat in Western Canada

November 09, 2017

Much of western Canada was ice-free as early as 14,000 years ago, a new study reports. The results suggest that the Cordilleran Ice Sheet (CIS) retreated more than a millennium sooner than previous estimates and hold important implications for understanding climate patterns and human migration. Previous estimates suggested that the CIS covered large portions of westernmost Canada as late as 12,500 years ago. Here, Brian Menounos and colleagues collected 76 samples from moraines, parallel ridges of debris deposited along the sides of a glacier, that formed after the CIS retreated. Using beryllium isotopes to date the samples, the authors found that the CIS may have in fact been largely melted by 14,000 years ago, while newer, smaller alpine glaciers appear to have sprung up in pockets after the mountain peaks were initially bared. Next, the authors used simulations to show how warm temperatures likely drove the retreat of the CIS, which alone contributed 2.5 to 3.0 meters of sea level rise between 14,500 and 14,000 years ago. The CIS response to abrupt climate change during the latest Pleistocene provides an analog for the behavior of the Greenland Ice Sheet, which is comparable in size, Menounos et al. say. They also suggest that the melting of the CIS had a substantial cooling effect in the Northern Hemisphere. Lastly, in terms of the peopling of the Americas, the authors suggest that their data does not support the migration of people down the west coast because much of the lower elevations across the area remained covered in ice until about 11,000 years ago. These results are highlighted in a Perspective by Shaun A. Marcott and Jeremy D. Shakun.
-end-


American Association for the Advancement of Science

Related Sea Level Rise Articles from Brightsurf:

Sea-level rise will have complex consequences
Rising sea levels will affect coasts and human societies in complex and unpredictable ways, according to a new study that examined 12,000 years in which a large island became a cluster of smaller ones.

UM researcher proposes sea-level rise global observing system
University of Miami (UM) Rosenstiel School of Marine and Atmospheric Science researcher Shane Elipot proposes a new approach to monitoring global sea-level rise.

Sea-level rise projections can improve with state-of-the-art model
Projections of potentially dramatic sea-level rise from ice-sheet melting in Antarctica have been wide-ranging, but a Rutgers-led team has created a model that enables improved projections and could help better address climate change threats.

How much will polar ice sheets add to sea level rise?
Over 99% of terrestrial ice is bound up in the ice sheets covering Antarctic and Greenland.

Sea-level rise could make rivers more likely to jump course
A new study shows that sea level rise will cause rivers to change course more frequently.

Sea level could rise by more than 1 meter by 2100 if emission targets are not met
An international study led by Nanyang Technological University, Singapore (NTU Singapore) scientists found that the global mean sea-level rise could exceed 1 meter by 2100 and 5 meters by 2300 if global targets on emissions are not achieved.

UCF study: Sea level rise impacts to Canaveral sea turtle nests will be substantial
The study examined loggerhead and green sea turtle nests to predict beach habitat loss at four national seashores by the year 2100.

Wetlands will keep up with sea level rise to offset climate change
Sediment accrual rates in coastal wetlands will outpace sea level rise, enabling wetlands to increase their capacity to sequester carbon, a study from the Marine Biological Laboratory, Woods Hole, shows.

Scientists discover evidence for past high-level sea rise
An international team of scientists, studying evidence preserved in speleothems in a coastal cave, illustrate that more than three million years ago -- a time in which the Earth was two to three degrees Celsius warmer than the pre-industrial era -- sea level was as much as 16 meters higher than the present day.

Corals in Singapore likely to survive sea-level rise: NUS study
Marine scientists from the National University of Singapore found that coral species in Singapore's sedimented and turbid waters are unlikely to be impacted by accelerating sea-level rise

Read More: Sea Level Rise News and Sea Level Rise Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.