ROM/A&S News Staff

Utah's Great Salt Lake a significant source of greenhouse gas emissions, study finds

Christopher.Sorensen — Tue, 13 Aug 2024 17:35:47 +0000

Utah's Great Salt Lake a significant source of greenhouse gas emissions, study finds

Christopher.Sorensen Tue, 08/13/2024 - 13:35

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(Photo courtesy of Soren Brothers)

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Researchers say drying lake beds are a potentially significant, but overlooked, source of greenhouse gases that may increase due to climate change

Researchers at the Royal Ontario Museum and University of Toronto estimate that 4.1 million tonnes of carbon dioxide and other greenhouse gases were released in 2020 by the drying lake bed of Great Salt Lake in Utah.

The finding, published in the journal One Earth, suggest that drying lake beds are an overlooked, but potentially significant, source of greenhouse gases, which may further increase due to climate change.

Soren Brothers’ research examines the effects of climate change on lakes, and how changes in aquatic systems influence their greenhouse gas emissions into the atmosphere (photo courtesy of Soren Brothers)

“Human-caused desiccation of Great Salt Lake is exposing huge areas of lake bed and releasing massive quantities of greenhouse gases into the atmosphere,” says lead author Soren Brothers, who is an assistant professor in the department of ecology and evolutionary biology in the Faculty of Arts & Science and Allan and Helaine Shiff Curator of Climate Change at the Royal Ontario Museum.

“The significance of lake desiccation as a driver of climate change needs to be addressed in greater detail and considered in climate change mitigation and watershed planning.”

The Great Salt Lake’s water level varies depending on the volume of meltwater that flows into the lake from the surrounding mountains – from record highs in the 1980s to a record low in 2022. However, growing freshwater consumption by agriculture, industry and municipalities has depleted the lake over time.

Similar trends are observed worldwide as competing uses for water have a significant impact on lake levels. As iconic saline lakes such as the Aral Sea, Lake Urmia, the Caspian Sea and Great Salt Lake dry up, they not only destroy critical habitat for biodiversity and create air quality conditions that deteriorate human health, but they accelerate climate change as newly exposed sediments emit carbon dioxide and methane.

Melissa Cobo, of Utah State University, conducts gas sampling in the field (photo courtesy of Soren Brothers)

The research team measured carbon dioxide and methane emissions from the exposed sediments of Great Salt Lake from April to November 2020 and compared them with aquatic emissions estimates to determine the anthropogenic greenhouse gas emissions associated with desiccation. Calculations based on this sampling indicate the lake bed emitted 4.1 million tonnes of greenhouse gases to the atmosphere – primarily carbon dioxide (94 per cent), constituting an approximately seven per cent increase to Utah’s human-caused greenhouse gas emissions.

Fieldwork was conducted while Brothers was assistant professor of limnology at Utah State University (USU). Lead author Melissa Cobo, meanwhile, was a master’s student at USU and co-author Tobias Goldhammer is a collaborating researcher at the Leibniz Institute for Freshwater Research (IGB Institute) in Berlin, Germany.

Measurements of carbon dioxide and methane gases were made every two weeks from the dried-up lake bed using a portable greenhouse gas analyzer attached to a closed chamber. Seven sites at one location at the south end of the lake were visited repeatedly over the course of the year, and another three locations were sampled during an intensive three-day campaign to determine spatial variability across the 4,400-square-kilometre lake, which is the largest saline lake in the western hemisphere. As methane is 28 times more powerful a greenhouse gas than carbon dioxide, the global warming impact of these emissions was calculated as “carbon dioxide equivalents.”

Ultimately, the research indicated that greenhouse gas emissions from the dried lake bed were strongly and positively related to warm temperatures – even at sites exposed for more than two decades. To determine whether the lake would have historically been a significant source of greenhouse gases, the team carried out measurements of near-shore greenhouse gas emissions, as well as analyzing water chemistry collected by the team and government data sets. Together, these analyses showed that the original lake was not likely a significant source of greenhouse gases to the atmosphere, making the dried-up lake bed a novel driver of atmospheric warming.

As climate change exacerbates drought in arid regions, researchers say desiccation of rivers and lakes may be contributing to climate change feedback loops and should be considered in assessments of global greenhouse gas output as well as reduction policies and efforts.

With files from the Royal Ontario Museum

Massive new animal species discovered in half-billion-year-old Burgess Shale

Christopher.Sorensen — Wed, 29 Sep 2021 19:22:51 +0000

Massive new animal species discovered in half-billion-year-old Burgess Shale

Christopher.Sorensen Wed, 09/29/2021 - 15:22

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Titanokorys gainesi was a giant compared to most animals that lived in the seas during the Cambrian period, most of which barely reached the size of a pinky finger (illustration by Lars Fields/Royal Ontario Museum)

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University of Toronto palaeontologists based at the Royal Ontario Museum (ROM) have uncovered the remains of a huge new fossil species belonging to an extinct animal group in half-a-billion-year-old Cambrian rocks from Kootenay National Park in the Canadian Rockies.

Named Titanokorys gainesi and described in a study published in Royal Society Open Science earlier this month, the new species is remarkable for its size. With an estimated total length of half a metre, Titanokorys was a giant compared to most animals that lived in the seas at that time – most of which barely reached the size of a pinky finger.

Jean-Bernard Caron sits above a fossil of Titanokorys gainesi at the quarry site located in Kootenay National Park (ohoto by Joe Moysiuk)

“The sheer size of this animal is absolutely mind-boggling – this is one of the biggest animals from the Cambrian period ever found,” says Jean-Bernard Caron, an associate professor in the departments of Earth sciences and ecology and evolutionary biology (EEB) in the Faculty of Arts & Science at U of T and the Richard M. Ivey Curator of Invertebrate Palaeontology at the ROM.

Evolutionarily speaking, Titanokorys belongs to a group of primitive arthropods called radiodonts. The most iconic representative of this group is the streamlined predator Anomalocaris, which may itself have approached a metre in length. Like all radiodonts, Titanokorys had multifaceted eyes, a pineapple slice-shaped, tooth-lined mouth, a pair of spiny claws below its head to capture prey and a body with a series of flaps for swimming. Within this group, some species also possessed large, conspicuous head carapaces, with Titanokorys being one of the largest ever known.

“Titanokorys is part of a subgroup of radiodonts, called hurdiids, characterized by an incredibly long head covered by a three-part carapace that took on myriad shapes. The head is so long relative to the body that these animals are really little more than swimming heads,” added Joe Moysiuk, co-author of the study, and a PhD student in EEB based at the ROM.

Jean-Bernard Caron and Joe Moysiuk in the ROM palaeontogy lab room examining Titanokorys gainesi and Cambroraster falcatus (photo by Andrew Gregg/© Red Trillium)

Why some radiodonts evolved such a bewildering array of head carapace shapes and sizes is still poorly understood and was likely driven by a variety of factors, but the broad flattened carapace form in Titanokorys suggests this species was adapted to life near the seafloor.

“These enigmatic animals certainly had a big impact on Cambrian seafloor ecosystems. Their limbs at the front looked like multiple stacked rakes and would have been very efficient at bringing anything they captured in their tiny spines towards the mouth. The huge dorsal carapace might have functioned like a plough,” added Caron, who is Moysiuk’s PhD adviser.

All fossils in the study were collected around Marble Canyon in northern Kootenay National Park by successive ROM expeditions. Discovered less than a decade ago, this area has yielded a great variety of Burgess Shale animals dating back to the Cambrian period, including a smaller, more abundant relative of Titanokorys named Cambroraster falcatus in reference to its Millennium Falcon-shaped head carapace. According to the authors, the two species might have competed for similar bottom-dwelling prey.

These and other Burgess Shale specimens will be showcased in a new gallery at the ROM, the Willner Madge Gallery, Dawn of Life, opening in December 2021.

The Burgess Shale fossil sites are located within Yoho National Park and Kootenay National Park and are managed by Parks Canada. Parks Canada works with leading scientific researchers to expand knowledge and understanding of this key period of earth history and to share these sites with the world through award-winning guided hikes. The Burgess Shale was designated a UNESCO World Heritage Site in 1980 due to its outstanding universal value and is now part of the larger Canadian Rocky Mountain Parks World Heritage Site.

Support for the research came from a Natural Sciences and Engineering Research Council of Canada Discovery Grant to Caron and a Vanier Canada Graduate Scholarship to Moysiuk. Additional support for the research and fieldwork came from the Polk Milstein Family, the ROM, the National Geographic Society, the Swedish Research Council, the National Science Foundation and Pomona College.