Is Theory on Earth’s Climate in the Last 15 Million Years Wrong?
Rutgers-led study casts doubt on Himalayan rock weathering hypothesis
September 22, 2019
A key theory that attributes the climate evolution of the Earth to the breakdown of Himalayan rocks may not explain the cooling over the past 15 million years, according to a Rutgers-led study.
The study in the journal Nature Geoscience could shed more light on the causes of long-term climate change. It centers on the long-term cooling that occurred before the recent global warming tied to greenhouse gas emissions from humanity.
“The findings of our study, if substantiated, raise more questions than they answered,” said senior author Yair Rosenthal, a distinguished professor in the Department of Marine and Coastal Sciences in the School of Environmental and Biological Sciences at Rutgers University–New Brunswick. “If the cooling is not due to enhanced Himalayan rock weathering, then what processes have been overlooked?”
For decades, the leading hypothesis has been that the collision of the Indian and Asian continents and uplifting of the Himalayas brought fresh rocks to the Earth’s surface, making them more vulnerable to weathering that captured and stored carbon dioxide – a key greenhouse gas. But that hypothesis remains unconfirmed.
Lead author Weimin Si, a former Rutgers doctoral student now at Brown University, and Rosenthal challenge the hypothesis and examined deep-sea sediments rich with calcium carbonate.
Over millions of years, the weathering of rocks captured carbon dioxide and rivers carried it to the ocean as dissolved inorganic carbon, which is used by algae to build their calcium carbonate shells. When algae die, their skeletons fall on the seafloor and get buried, locking carbon from the atmosphere in deep-sea sediments.
If weathering increases, the accumulation of calcium carbonate in the deep sea should increase. But after studying dozens of deep-sea sediment cores through an international ocean drilling program, Si found that calcium carbonate in shells decreased significantly over 15 million years, which suggests that rock weathering may not be responsible for the long-term cooling.
Meanwhile, the scientists – surprisingly – also found that algae called coccolithophores adapted to the carbon dioxide decline over 15 million years by reducing their production of calcium carbonate. This reduction apparently was not taken into account in previous studies.
Many scientists believe that ocean acidification from high carbon dioxide levels will reduce the calcium carbonate in algae, especially in the near future. The data, however, suggest the opposite occurred over the 15 million years before the current global warming spell.
Rosenthal’s lab is now trying to answer these questions by studying the evolution of calcium and other elements in the ocean.
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Rutgers-led University Consortium Awarded Funding for Atlantic Seaboard Fisheries Research
Led by Rutgers University, a consortium of 14 shellfish geneticists from 12 East Coast universities and government agencies has won a five-year, $4.4 million grant from the Atlantic States Marine Fisheries Commission to develop new tools to accelerate selective breeding to support oyster aquaculture.
Ximing Guo, distinguished professor and renowned shellfish geneticist at Rutgers Haskin Shellfish Research Laboratory, is the lead principal investigator for the project, which will advance the pace of genetic improvement by identifying genes responsible for desirable traits, such as disease tolerance. Improved broodstock will then be made available to commercial hatcheries thereby sustaining the rapidly-expanding $90 million enterprise of farming eastern oysters, Crassostrea virginica, along the East Coast.
The East Coast breeding consortium was formed to support the industry so that hatcheries could provide domesticated lines with desirable traits. For example, over many generations, researchers from Rutgers and the Virginia Institute of Marine Science developed varieties of oysters that are now quite tolerant of MSX, the parasite that essentially wiped out much of the oyster harvest in the mid-Atlantic. Other traits, such as faster growth rate and meatier oysters, have also been substantially improved.
The improvement of traits for the eastern oyster, however, is a regional endeavor. With a native range from Atlantic Canada through the Gulf of Mexico, eastern oysters display clear physiological differences among regions.
“Oysters tend to be adapted to local environmental conditions,” explained Guo. “One goal of our project is to develop genetic strains that are adapted to different regions along the Atlantic Seaboard.”
Shellfish geneticist and distinguished professor Ximing Guo.
According to Guo, several years ago consortium scientists were able to sequence the oyster genome, providing new tools to make direct associations between the genetic code and important traits.
“The team will develop a tool called a “SNP chip” to detect variations across the genome, and through a process called genomic selection, these genetic markers will help identify the best performing oysters,” he added.
Once the markers associated with economically important traits are identified, breeders along the East Coast will be able to select those broodstock that carry the superior genes.
“While disease resistance is the most important trait for the eastern oyster, we hope to use the same technology to select for other desired traits, such as fast growth and hardiness.”
Other aspects of the project will evaluate the usefulness of genomic selection to address emerging issues, such as resistance to ocean acidification or tolerance to hypoxia, a condition in which oysters are deprived of adequate oxygen supply.
The Eastern Oyster Breeding Consortium comprises 14 research scientists from 12 institutions located along the East Coast from Maine to North Carolina. The team includes the top oyster genetics researchers from Rutgers, the Virginia Institute of Marine Science, the University of Rhode Island, the University of Maryland Center for Environmental Science, Northeastern University Marine Science Center, Stony Brook University, University of Maine, Cornell University, Morgan State University, University of North Carolina at Wilmington, NOAA’s Northeast Fisheries Science Center and the USDA’s Agricultural Research Service. The Consortium is strongly supported industry support from the East Coast Shellfish Growers Association.
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The NOAA Marine Debris Program Awards Funding to 4 New Projects to Research Marine Debris
After an intensive evaluation process, the NOAA Marine Debris Program is proud to announce the four recipients of our 2019 research awards, totaling $1.2 million of funding toward marine debris research efforts. Marine debris is a relatively new field of research, and there are many opportunities to advance understanding of how debris impacts the environment. The NOAA Marine Debris Program held a nationwide competitive funding opportunity to support original, hypothesis-driven research projects focused on the ecological risk assessment, exposure studies, and fate and transport of marine debris. These awards continue the Marine Debris Program’s commitment to improve our understanding of the ecological risks associated with marine debris including levels of exposure to debris, as well as the fate and transport of marine debris in nearshore, coastal environments.
Rutgers University (New Jersey, $320,000) will study the movement of microplastics from riverine to oceanic systems and the role this area may play as the entry point for microplastics into the food chain. Unique oceanographic characteristics exist where rivers and the ocean meet, and these characteristics may influence the movement of marine debris from one system to the other and the assimilation of microplastics in the marine food chain.
To read more about this project: https://www.noaa.gov/media-release/noaa-awards-27-million-in-grants-for-marine-debris-removal-and-research
Official NOAA Press Release: https://marinedebris.noaa.gov/noaa-marine-debris-program-awards-funding-4-new-projects-research-marine-debris