How analyzing ancient and modern polar bear samples reveals the full scope of global warming
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금요일, 9월 1, 2023
Association, Tissue, Mid-24th century BCE climate anomaly, Food, Zooplankton, Season, Eating, LIA, Phytoplankton, Arctic Report Card, Nitrogen oxide, Carbon, History, Garbage, Isotopes of nitrogen, Climate change, BP, Animal, Time, Rainier, Food chain, Climate, Ecosystem, Isotope, News, MWP, Agriculture, Aquaculture, Whaling, Anthropocene, Arctic, Lancaster Sound
These are objectively true statements that most people have come to accept.
Key Points:
- These are objectively true statements that most people have come to accept.
- But it is also true that Earth’s climate has never been stagnant and climate anomalies have been frequent throughout the past.
- Are the impacts of modern climate change comparable to those of the medieval warm period (MWP) or the little ice age (LIA)?
Ecosystem background
- Predators at the top of the food chain, like polar bears, reflect changes across the entire ecosystem, all the way down to microscopic algae.
- In the Arctic, the base of the food web is sourced from two categories: sea ice-associated algae and open-water phytoplankton, which are distinguishable through their carbon isotopes.
Results from our study
- In our study we examined stable carbon and nitrogen isotopes in polar bear bone collagen.
- The polar bears were all from the Lancaster Sound sub-population and spanned the last 4,000 years.
What it all means
- The results of the nitrogen isotopes showed that throughout time, 4,000 years BP to the present, the structure of the Lancaster Sound food web was relatively unchanged.
- Polar bears eat seals, seals eat cod, cod eat zooplankton, et cetera.
- There were no surprising shifts in the diets of polar bears despite past and present climate change.
Evidence of a warming climate
- For ringed seals, the primary prey of polar bears, it is a platform for denning and raising young.
- In this case, we have illustrated the magnitude of difference occurring in the modern Arctic, relative to past climate anomalies.
- We can, therefore, not dismiss calls to action on climate change on the basis that the climate has always fluctuated.