There’s been a shift in how we think about climate change
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New Study Makes First-Ever Direct Link Between Greenhouse Gases And Polar Bear Deaths—Here’s Why It Could Change U.S. Climate Rules
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Story by William Skipworth, Forbes Staff •1h
Topline
Anew scientific study offers the first-ever estimates of how many polar bear cubs die because of greenhouse gas emissions—something experts hope will allow the federal government to use the Endangered Species Act to regulate individual projects for their greenhouse gas emissions.
A polar bear (Ursus maritimus) is looking for food at the edge of the pack ice north of Svalbard, Norway in 2015. (Photo by Wolfgang Kaehler/LightRocket via Getty Images) LightRocket via Getty Images© Provided by Forbes
Key Facts
The study by researchers with Polar Bears International, published Thursday in the academic journal Science, explains that polar bears’ survival is heavily dependent on sea ice concentration, because when that sea ice melts, polar bears are forced onto land where food is less abundant and they are forced to fast for long periods of time.
Polar bears are normally able to fast for long periods of time and survive, but the study says sea ice melting is forcing them to fast for even longer than typical.
The longer they fast, the more weight they lose—nearly a kilogram of body mass each day—and this makes mother bears less able to care for and provide milk for their cubs, which makes cubs less likely to survive into adulthood.
As less cubs survive into adulthood, the species grows closer to extinction.
This study, researchers say, was able to quantify just how much each individual greenhouse-gas emitting project contributes to that sea ice melting and thus contributes to the extinction of polar bears—though the rate at which greenhouse gas emissions contribute to polar bear extinction varies by what region those polar bears live as there are 12 distinct subpopulations of polar bears each living in a different ecoregion.
For example, the study found that 24.1 gigatons of carbon dioxide (a greenhouse gas) emissions will decrease the amount of polar bears that survive into adulthood by 2.7% in the Chukchi Sea subpopulation and by 0.6% in the West Hudson Bay subpopulation.
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Key Background
In 2008, after projections showed that two-thirds of the world’s polar bears could die by the middle of the 21st century, polar bears became the first animal to be listed as a protected species under the Endangered Species Act as a result of human-caused climate change. Section Seven of the Endangered Species Act establishes a process with which the Department of the Interior must ensure projects they fund or authorize do not further jeopardize the survival of listed endangered species like polar bears. However, in October 2008, then-Solicitor of the Department of Interior David Bernhardt issued a legal opinion declaring Section Seven considerations wouldn’t be required unless one can differentiate the effects of greenhouse gas emissions of specific projects from the total greenhouse gas emissions created by humans since the start of the industrial revolution. This made it impossible for the Department of the Interior to evaluate projects based on how their greenhouse gas emissions would contribute to the death of endangered species, because the department previously had no way to establish one specific project’s impact separate from all the other greenhouse gas-emitting projects in the world. However, the researchers at nonprofit Polar Bears International believe this study has finally discovered how to do that. This study, the researchers argue, provides the scientific basis to rescind Bernhardt’s memo and begin including consideration of greenhouse gas emissions in reviews of all new projects.
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Tangent
The researchers behind this paper said that they focused on polar bears because Bernhardt’s memo was created in response to polar bears being listed under the Endangered Species Act. However, they said their findings can be extended to other endangered species. For example, they believe with more research, scientists would be able to establish a similar direct link between individual greenhouse-gas-emitting projects and the survival of marine turtles.
Further Reading
Unlock the Endangered Species Act to address GHG emissions (Nature)
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Is Reversing Evolution Possible? Exploring The Implications Of Dollo’s Law
Dollo’s law says nay, but some organisms say yay.
DR. BECCY CORKILL
- https://www.iflscience.com/is-reversing-evolution-possible-exploring-the-implications-of-dollos-law-70463
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Back in 1893, Belgian paleontologist Louis Dollo developed the principle that, once a structure is lost in evolution, then it is lost forever. It basically treats evolution like a one-way street and that evolution is not reversible. This simple concept became known as Dollo’s law. However, the law may not be as simple as you might think.
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Harvard Team Claims They Have Recovered Pieces OfAn Interstellar Object
Some scientists have broken down Dollo’s law even further into two parts.
- Lost complex characters are not regained.
- For an organism to lose the complex characteristics, the genetic and/ or developmental features have to accumulate so many mutations that they are unlikely to be reversed.
The first point seems simple enough. What gets more complicated is the second point, as with the development of new genetic methodologies, the thought that random genetic mutations cause some genes to be lost forever is becoming more doubtful. This means that old genetic pathways could be reactivated to reacquire characters or genes that are switched off can be switched on again.
For the second part of Dollo’s law to occur, it is presumed that this accumulation of mutations takes time, and during this time features could be re-expressed and could lead to the short-term reacquisition of some features.
Scientists have found wonderous natural examples that seem to go against at least the first point of the law, and this breakage may be more common than people think.
The lizards who began to re-lay eggs
One case is of the lizards who re-evolved to lay eggs, after previously evolving to give birth to live young. The Liolaemus lizard is a species that lives in colder climates, and to keep their offspring warm, they evolved internal gestation. Scientists found that when some Liolaemus species moved down to colonize the lowlands, where it was warmer, they seemed to start laying eggs again – seemingly, breaking Dollo’s law while they are at it.
This was not just unique to this type of lizard. The common lizard Zootoca vivipara also seemed to go from birthing live young to producing eggs.
The “missing” bone in birds
There was one study that found that the ancestral wrist bone seemed to make a comeback in the lineage leading to birds.
There were some dinosaurs that liked to walk on all fours. This meant that they needed strong wrists to support their weight, and one bone was called the pisiform. When dinosaurs began to walk on two legs, the bones in the wrist changed and the pisiform seemed to disappear, or there was no trace left in the fossil record.
As one group of dinosaurs evolved into birds, the wrist changed again and went from being straight to bent and hyperflexible, which allowed the birds to hold wings against their body. The birds developed a different type of wrist bone called the ulnare.
Investigating both the fossil record and modern bird embryos, researchers saw that the ulnare bone was present early in the development, but not in grown birds. However, there was a certain bone present in the adult form, which turned out to be the missing pisiform, that seemed to have emerged again.
Dust mites
Parasites are entirely dependent on the host, and once they become a parasite there is often no going back. Unless they are a dust mite, that is.
Dust mites are teeny tiny arachnids that are often living beside us in cushions and carpets. They are also organisms that have a free-living lifestyle. So, it was a surprise when scientists discovered that the house dust mite evolved from permanent parasites of warm-blooded vertebrates.
Despite Dollo’s attempt to simplify the world around him. There are plenty of examples found in nature that go against it.
All “explainer” articles are confirmed by fact checkers to be correct at time of publishing. Text, images, and links may be edited, removed, or added to at a later date to keep information current.
