Extinctions linked to climate change

Extinctions linked to climate change
Oregon State University release
January 11, 2006

A new report that links global warming to the recent extinction of dozens of amphibian species in tropical America is more evidence of a large phenomena that may affect broad regions, many animal species and ultimately humans, according to researchers at Oregon State University.

A study being published Thursday in the journal Nature finds compelling evidence that global climate change created favorable conditions for a pathogenic fungus in Central and South America. That fungus, in turn, led to widespread extinctions of harlequin frogs at middle elevations of mountainous regions.

In a commentary article in that same publication, an OSU scientist who pioneered the study of global amphibian decline said this is another key example of unanticipated and complex impacts from climate change. The Central and South American crisis is “an amphibian alarm call,” he said, but also is a harbinger of much greater biological disruption. What had been seen as an enigma is now understood as a complex relationship between global warming and major extinction of species.

“This new study is a breakthrough, and the powerful synergy between pathogen transmission and climate change should give us cause for concern about human health in a warmer world,” said Andrew Blaustein, a professor of zoology at OSU, in the Nature article. “As global change is occurring at an unprecedented pace, we should expect many other host taxa, from ants to zebras, to be confronted with similar challenges.”

Related mongabay.com articles Extinction–an overview The greatest loss with the longest-lasting effects from the ongoing destruction of wilderness will be the mass extinction of species that provide Earth with biodiversity. Although great extinctions have occurred in the past, none has occurred as rapidly or has been so much the result of the actions of a single species. The extinction rate of today may be 1,000 to 10,000 times the biological normal, or background, extinction rate of 1-10 species extinctions per year. Global warming may have triggered worst mass extinction A dramatic rise in carbon dioxide 250 million years ago may have caused global temperatures to soar and result in Earth’s greatest mass extinction, according to a study published in the September issue of Geology. Global warming, which may have produced temperatures 10 to 30 degrees Celsius higher than today, would have had a significant impact both on oceans, where about 95% of lifeforms became extinct, and on land, where almost 75% of species died out. Massive climate change rocked ecosystems, animals 55 million years ago Continued increases in greenhouse gas concentrations in the atmosphere from the combustion of fossil fuels could trigger large-scale changes in global biodiversity and require thousands of years of recovery according to recent research on an extreme global warming episode 55 million years ago. Is Global Warming Killing Polar Bears? — WSJ Today The Wall Street Journal ran an article asking “Is Global Warming Killing the Polar Bears?” The article cited several recent studies that suggest polar bears are increasingly under threat from receding ice and warming temperatures. Invasive species may increase with global warming New research published in Molecular Ecology suggests that climate change could trigger the expansion of invasive species into wider ranges. The study looked at the genetic history of a goby species in the Eastern Atlantic which appears to have expanded its range dramatically when the world warmed about 150,000 years ago. Food demand greater threat to wildlife than global warming “Claims that global warming will destroy up to a million wildlife species — as recently featured on ABC’s Nightline — are willfully misleading,” warned Dennis Avery of Hudson Institute’s Center for Global Food Issues at the American Society of Animal Science’s annual meeting on July 24. 794 species on brink of extinction find study Protecting 595 sites around the world would help address an imminent global extinction crisis, according to a study published today in the Proceedings of the National Academy of Sciences. Conducted by scientists working with the 52 member organizations of the Alliance for Zero Extinction (AZE), the study identifies 794 species threatened with imminent extinction by virtual of existing at only a single remaining site on Earth. The study found that just one-third of the sites are known to have legal protection, and most are surrounded by human population densities that are approximately three times the global average. Safeguarding these sites is key to saving these species from extinction say the authors of the study.

Very few of the current studies on biodiversity consider how climate affects disease dynamics, said Blaustein. Until the potential impacts of pathogens, parasites and other types of disease transmission are factored in, it will be difficult to accurately gauge the full effects of climate change, and its true impact on biodiversity will often be underestimated, he said.

Five years ago, in a study also published in Nature, OSU scientists documented another of the complex impacts of global warming. In that case, they found that greenhouse warming and other climate changes were increasing the frequency and intensity of El Nino events, which affected precipitation in the Cascade Range of the Pacific Northwest. Ultimately, that resulted in lowered water depths in mountain lakes, higher levels of exposure of amphibian embryos to UV-B radiation in sunlight, and egg mortality in the western toad that approached 100 percent in some years, due to an opportunistic disease.

In the current Nature article, researchers pointed to more examples.

“The climate change in the Arctic and sub-Arctic has modified the life cycle of the nematode parasites of musk oxen,” the researchers said. “These worms can now complete their life cycle in one year, instead of two, and their rising numbers are having a significant impact on musk oxen survival.”

In a similar interaction, Blaustein said, the mountain pine beetle in parts of the western United States is completing its life cycle in one year, instead of two, leading to increasing problems with the fungus they carry. “When pathogens such as this can spread more rapidly, they can do more damage in much less time,” he said.

The problem does not stop with amphibians or other species. Dengue fever, a deadly disease of humans, is increasing its range out of the tropics and is now found in parts of the southern United States. And predicting how climate change will favor a certain pathogen or disease transmission is extremely difficult.

“We should expect the unexpected,” Blaustein and Andy Dobson of Princeton University wrote in their report. “Terms such as ‘enigmatic decline’ and ‘pathogen-climate paradox’ will probably dominate explanations of extinctions until we develop a better understanding of the relationships between global change, pathogens and their hosts.”

For years, zoologists and biologists have been warning that global amphibian declines, which are believed to be caused by climate change, environmental degradation, pollution and invasive species, are just the first examples of a broader biological crisis.

Thousands of amphibian species have declined, and hundreds are on the brink of extinction or have already vanished, a group of 14 researchers said in the new Nature report. They concluded that climate change is promoting infectious disease, eroding biodiversity, and that the urgency of reducing greenhouse gas concentrations is now undeniable.

This article is a modified new release from the Oregon State University.