Zealandia Switch may be the link needed in understanding the ice age climate

IMAGE

IMAGE: Moraines during retrograde rounds lifted one of the glaciers that expanded out of the Southern Alps in New Zealand in the last ice age. About 18,000 years ago, … a scene more

Credit: Image courtesy of Aaron Putnam

Orono, Maine – The origins of ice age climate change may lie in the Southern Hemisphere, where interactions between the western, South Pacific and tropical Pacific wind systems can cause rapid, global changes stimulated in atmospheric temperatures, according to an international research team. led by the University of Maine.

The equipment, known as Switch Zealandia, applies to the general location of the western Southern Hemisphere wind zone – the strongest wind system on Earth – and the southwestern continental platforms of the Pacific Ocean, and their control of ocean currents. Movements in the latitude of western winds affect the strength of subtropical oceanic gyres and, in turn, affect the release of energy from the waters of the tropical ocean, the “heat engine” of the planet. Tropical heat spreads rapidly through the atmosphere and ocean to the polar regions of the two hemispheres, acting as the planet’s thermostat.

The climate dynamics of the Southern Hemisphere may be the missing link in understanding long-term questions about ice ages, based on the findings of the research team from UMaine, the Lamont-Doherty World Observatory at Columbia University , University of Arizona, and GNS Science in New Zealand. into Quaternary Science Reviews.

For more than a quarter of a year, George Denton, Professor of Geological Sciences UMaine Libra, the first author in the journal article, has led research recreating the history of mountain glaciers in the Southern Hemisphere . In the late 1980s, he and Wallace Broecker, a geologist at Columbia University, noted that a key question about ice ages remained unresolved – the link between the ice age climate and orbital cycles in length and the strength of the Earth season. Evidence showed that climate changes from the ice age were parallel in both polar hemispheres, with a rapid transition from glaciers to interspecific climatic conditions. They concluded that the existing theories could not adequately account for changes in seasonality, ice sheet size and regional climate.

Mountain glaciers are very climate-sensitive and well-suited for climate reconstruction, using special moraine deposits that mark the boundaries of the former glacier. In the 1990s, Denton led research teams in mapping and advancing moraine series in South America and, more recently, in the Southern Alps of New Zealand, with co-author David Barrell, geologist and geologist -morphologist with New Zealand government geoscience research institute, GNS Science.

With advances in isotopic separation of moraines in the mid-2000s, Denton teamed up with Joerg Schaefer at Columbia University, who heads the Cosclogenic Nuclide Laboratory at the Lamont-Doherty Global Observatory. Together with CU-LDEO colleague and co-author Michael Kaplan, Schaefer, Denton, and UMaine associate professor and co-author Aaron Putnam have guided the continuation of UMaine student and student laboratory projects (noting -in the work of Putnam) Ph.D.) who have developed a schedule of glacial changes caused by climate in the Southern Alps spanning tens of thousands of years. The most recent partner in the UMaine-CU partnership is UMaine Ph.D. student and co-author Peter Strand.

Together, the UMaine, CU-LDEO and GNS Science partners have been working to create and compile mountain glacier histories from New Zealand and South America, comprising a table- complete time of glacier rate during and since the last ice age. The team then compared the neck to paleoclimate data around the world to gain insights into the climate dynamics of ice ages and sudden climate events on a millennial scale. The findings highlight a general global concordance of mountain glacier progress and retreat during the last ice age.

In-depth insights into climate dynamics come from co-author Joellen Russell, a climate scientist at the University of Arizona and Thomas R. Brown, distinguished Chair of Integrative Science. Following her long-term efforts in shaping westerly wind climate change, she evaluated simulations carried out as part of the South Sea Model Intersection Project, part of the South Sea Carbon and Climate Observation and Modeling initiative. The modeling showed that the changes to the southern wind systems have a major impact on the global warming budget, as monitored by glacier systems.

The “version” takes its name from New Zealand, an underwater continental platform about a third the size of Australia, with the islands of New Zealand being the most prominent parts. Zealand is a physical barrier to the flow of ocean currents. When the western wind zone is further north, the southward flow of the warm waters of the Pacific Ocean is directed north on the New Zealand landslide (glacial mode). With the wind zone further south, the warm ocean water stretches south of New Zealand (interspecific mode). Computer modeling shows that the effects of global climate arise from the latitude at which the aftershocks orbit. A southwesterly movement to the south stimulates the circulation of water in the South Pacific and southern oceans, and warms surface ocean waters throughout much of the world.

The researchers assume that small changes in the Earth’s orbit affect the winds of the Western Hemisphere’s western winds, and that behavior is at the heart of the ice age circles of the Earth. This view is fundamentally different from the long-held view that the orbital influence on the level of the continental ice sheet of the Northern Hemisphere regulates the climate of ice age. Emphasizes the idea of ​​Switch Zealandia that the western Hemisphere regulates the exchange of carbon dioxide and heat between the ocean and the atmosphere, and, therefore, other influences on global climate.

“Combined with interstellar paleoclimate charts and the results of ocean atmosphere climate modeling, these results represent a vast, rapid and global end to the last ice age in which a southern warming program linked in half. global, ”according to the researchers, whose work was funded by the Comer Family Foundation, the Quesada Family Foundation, the National Science Foundation and the New Zealand government.

The last glacial end was the event of global warming that led to extreme seasonal (winter versus summer) weather in the northern latitudes by stimulating the flow of melting water and iceberg. into the Atlantic Ocean from adjacent ice sheets. The warming of the summer caused the influx of freshwater, resulting in widespread sea ice in the Atlantic which caused very cold winters in the north and contributed to the annual movement south of the Commonwealth Zone. Interregional movement and the monsoonal water belts. Although this has created an idea of ​​different temperature responses between the polar hemispheres, the so-called “bipolar sawaw,” the researchers suggest that this is due to inter- regional between global warming or cooling. It is suggested that events of cold, short-lived winters in the last ice age continued with temporary movements of the Switch Zealandia engine.

They were shifted south along the western side of the Southern Hemisphere at the end of the last ice age with the gradual release of carbon dioxide from the South Sea, which may have helped lock in the climate system to interspecific warm mode.

The researchers recommend the introduction of fossil CO2 into the atmosphere it may be restoring the same dynamics that ended the last ice age, which may have forced the climate system to be in a new mode .

“The mapping and date of the mid-latitude South Hemisphere glacier moraines gives us the impression of the latitude and strength of the western hemisphere, and their impact on the tropical / sub-oceanic ocean. -tropical, especially in the region that spans the Indo-Pacific Warm Pool and Tasman Sea through to the South Ocean, provides an explanation for driving orbital-level global movements between modes glacial and interspecific climate, through the Switch Zealandia device, ”wrote the research team. “Such behavior of the ocean air system could be active in today’s warming world, including a highly unusual mechanism to accelerate global warming due to CO atmospheric2 get up. ”

###

.Source