Massive iceberg discharges during the last ice age had no impact on
nearby Greenland, raising new questions about climate dynamics

Date:
April 24, 2023
Source:
Oregon State University
Summary:
New findings suggest that Heinrich Events had no discernible impact
on temperatures in Greenland, which could have repercussions for
scientists' understanding of past climate dynamics.


Facebook Twitter Pinterest LinkedIN Email

==========================================================================
FULL STORY ========================================================================== During the last ice age, massive icebergs periodically broke off from
an ice sheet covering a large swath of North America and discharged
rapidly melting ice into the North Atlantic Ocean around Greenland,
triggering abrupt climate change impacts across the globe.

These sudden episodes, called Heinrich Events, occurred between 16,000
and 60,000 years ago. They altered the circulation of the world's oceans, spurring cooling in the North Atlantic and impacting monsoon rainfall
around the world.

But little was known about the events' effect on nearby Greenland, which
is thought to be very sensitive to events in the North Atlantic. A new
study from Oregon State University researchers, just published in the
journal Nature, provides a definitive answer.

"It turns out, nothing happened in Greenland. The temperature just stayed
the same," said the study's lead author, Kaden Martin, a fourth-year
doctoral candidate in OSU's College of Earth, Ocean, and Atmospheric
Sciences. "They had front-row seats to this action but didn't see
the show." Instead, the researchers found that these Heinrich events
caused rapid warming in Antarctica, at the other end of the globe.

The researchers anticipated Greenland, in close proximity to the ice
sheet, would have experienced some kind of cooling. To find that these
Heinrich Events had no discernible impact on temperatures in Greenland is surprising and could have repercussions for scientists' understanding of
past climate dynamics, said study co-author Christo Buizert, an assistant professor in the College of Earth, Ocean, and Atmospheric Sciences.

"If anything, our findings raise more questions than answers," said
Buizert, a climate change specialist who uses ice cores from Greenland
and Antarctica to reconstruct and understand the Earth's climate
history. "This really changes how we look at these massive events in
the North Atlantic. It's puzzling that far-flung Antarctica responds
more strongly than nearby Greenland." Scientists drill and preserve
ice cores to study past climate history through analysis of the dust
and tiny air bubbles that have been trapped in the ice over time. Ice
cores from Greenland and Antarctica provide important records of Earth's atmospheric changes over hundreds of thousands of years.

Records from ice cores from those regions have served as pillars for scientists' understanding of past climate events, with ice collected
from both locations often telling similar stories, Martin said.

The impact of Heinrich Events on Greenland and Antarctica was not well understood, spurring Martin and Buizert to try to find out more about
what was happening in those parts of the world.

The core used for the latest study was collected in 1992 from the highest
point of Greenland, where the ice sheet is around 2 miles thick. Since
then, the core has been in storage in the National Science Foundation
Ice Core Facility in Denver.

Advancement in scientific tools and measurements over the last few decades
gave Martin, Buizert and their colleagues the opportunity to re-examine
the core using new methods.

The analysis shows that no changes in temperatures occurred in Greenland
during Heinrich Events. But it also provides a very clear connection
between Heinrich Events and the Antarctic response.

"When these big iceberg discharges happen in the Arctic, we now know
that Antarctica responds right away," Buizert said. "What happens in
one part of the world has an effect on the rest of the world. This inter-hemispheric connection is likely caused by change in global wind patterns." The finding challenges the current understanding of global
climate dynamics during these massive events and raises new questions
for researchers, Buizert said. The researchers' next step is to take the
new information and run it through climate models to see if the models
can replicate what occurred.

"There has to be a story that fits all of the evidence, something that
connects all the dots," he said. "Our discovery adds two new dots; it's
not the full story, and it may not be the main story. It is possible that
the Pacific Ocean plays an important role that we haven't figured out
yet." The ultimate goal is to better understand how the climate system
is connected and how the components all interact, the researchers said.

"While Heinrich Events are not going to happen in the future, abrupt
changes in the globally interconnected climate system will happen again," Martin said.

"Understanding the global dynamics of the climate system can help us
better project future impacts and inform how we respond and adapt."
Additional co-authors are Ed Brook, Jon Edwards, Michael Kalk and Ben
Riddell- Young of OSU; Ross Beaudette and Jeffrey Severinghaus of the
Scripps Institution of Oceanography; and Todd Sowers of Pennsylvania
State University.

The research was supported by the National Science Foundation, the
Global Climate Change Foundation and the Gary Comer Science and Education Foundation.

* RELATED_TOPICS
o Earth_&_Climate
# Climate # Global_Warming # Ice_Ages #
Environmental_Awareness
o Fossils_&_Ruins
# Early_Climate # Ancient_DNA # Evolution # Fossils
* RELATED_TERMS
o Temperature_record_of_the_past_1000_years o
Attribution_of_recent_climate_change o Greenland_ice_sheet
o Ice_sheet o Annual_sedimentary_layer o Global_warming o
Chicxulub_Crater o Climate_model

========================================================================== Story Source: Materials provided by Oregon_State_University. Original
written by Michelle Klampe. Note: Content may be edited for style
and length.


========================================================================== Journal Reference:
1. Kaden C. Martin, Christo Buizert, Jon S. Edwards, Michael L. Kalk,
Ben
Riddell-Young, Edward J. Brook, Ross Beaudette, Jeffrey
P. Severinghaus, Todd A. Sowers. Bipolar impact and phasing
of Heinrich-type climate variability. Nature, 2023; DOI:
10.1038/s41586-023-05875-2 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2023/04/230424133551.htm

--- up 1 year, 8 weeks, 10 hours, 50 minutes
* Origin: -=> Castle Rock BBS <=- Now Husky HPT Powered! (1:317/3)