January 11, 2012
A new study in PLoS ONE has found that harp seal pups are dying en masse due to a decline in winter sea ice.
"The kind of mortality we're seeing in eastern Canada is dramatic. Entire year-classes may be disappearing from the population in low ice years—essentially all of the pups die," explains David W. Johnston with the Duke University Marine Lab in a press release. "It calls into question the resilience of the population."
Harp seal. Photo by: Matthieu Godbout.
"As a species, they're well suited to deal with natural short-term shifts in climate, but our research suggests they may not be well adapted to absorb the effects of short-term variability combined with longer-term climate change and other human influences such as hunting and by-catch," Johnston said.
The study found that harp seal populations in eastern Canada fluctuated with sea ice cover in the region. Little ice cover and a weak North Atlantic Oscillation (NAO), which also impacts seasonal ice, were found to correspond to a high level of dead pups.
"Regardless of NAO conditions, our models show that sea ice cover in all harp seal breeding regions in the North Atlantic have been declining by as much as 6 percent a decade over the study period," Johnston said, adding that "the losses in bad years outweigh the gains in good years." The study's findings correspond to observations: seal hunters and conservationists have reported seeing seal pups drown during low ice years.
Despite the perils of climate change to their ecosystem, harp seals are currently listed as Least Concern by the IUCN Red List due to a large population of around 8 million animals. They are the most heavily hunted of the world's seal species.
While some people may be happy to see Spring arrive a little earlier, it can wreak havoc on migrating species that depend on nature's seasonal rhythms. A recent study in Global Change Biology links climate change to the mystery of missing migrating ducks in Canada. Two types of migrating ducks, scaups and scoters, incorporating a number of species, have seen populations drop to around half in Canada since the 1970s, but researchers have had little luck explaining why. Now, however, they believe they know the cause: earlier Springs mean the ducks are missing out on prime feeding time.
"Because of climate change, the ducks don't have the food that they need when they need it," Stuart Slattery, a research scientist with Ducks Unlimited Canada, told CBC News.
Greater scaup (Aythya marila). Photo by: Calibas.
"As this mismatch gets worse, the ducklings are impacted the most," says Slattery. "The food just simply isn't there in the amounts that it was historically."
Slattery adds that not all ducks are arriving late: mallards appear to have adjusted to the changing rhythms, but there is no certainty that the scaups and scoters will eventually learn. It may be that the change is simply happening too quickly for them.
"We are experiencing climate change in a very real way," he concluded.
Some plant species are also finding it difficult to adapt. A recent study in Nature Climate Change, found that mountain vegetation across Europe, covering 867 sites over 60 different summits, has suffered from drastic climatic changes in just seven years: between 2001 and 2008.
"We expected to find a greater number of warm-loving plants at higher altitudes, but we did not expect to find such a significant change in such a short space of time," lead author Michael Gottfried from the Global Observation Research Initiative in Alpine Environments (GLORIA) program said in a press release.
This alpine species (Nevadensia purpurea) could disappear from some European mountains in the next few decades. Photo by: Harald Pauli.
"Many cold-loving species are literally running out of mountain. In some of the lower mountains in Europe, we could see alpine meadows disappearing and dwarf shrubs taking over within the next few decades," Gottfried warned.
What's the solution? Given that cold-loving plants will not adapt to a warmer climate, there's only one answer according to Gottfried: "we must concentrate on mitigating climate change in order to preserve our biogenetic treasure."
Climate change is also having an indirect impact on species. Ecosystems are by their nature complex, and one change, such as warmer temperatures, is likely to drive unexpected shifts. Scientists in the U.S. were particularly surprised to see mountain plants and birds in the U.S. hurt not only by higher temperatures directly, but by the elk that took advantage of them.
Elk are considered "apex consumers," in other words they have an inordinately large impact on their ecosystems. The presence of elk can change plant communities, which in turn impact species all down the line.
In the case of climate change, researchers writing in Nature Climate Change found that higher temperatures and precipitation changes have resulted in reduced snowfall in some U.S. mountain ranges. This decline in snow cover has meant that elk herds have stayed longer in mountain ecosystems browsing to their heart's content. But this overbrowsing by elk decreased deciduous tree survival and degraded prime habitat for songbirds. Researchers mimicked the impact of longer elk-browsing versus elk-absence in controlled fenced areas to measure how songbirds and trees fared.
"This study demonstrates that the indirect effects of climate on plant communities may be just as important as the effects of climate-change-induced mismatches between migrating birds and food abundance because plants, including trees, provide the habitat birds need to survive," explained U.S. Geological Survey (USGS) director Marcia McNutt in a press release.
Climate change and extinction
Climate change is caused by burning fossil fuels, such as oil, gas, and coal, and other activities that emit carbon like deforestation. Global temperatures are currently 0.8 degrees Celsius (1.44 degrees Fahrenheit) higher since the Industrial Revolution. The 13 warmest years on record have all occurred in the last 15 years with the 2000s being the warmest decade to date. Scientists have argued for decades that the only way to mitigate climate change is to cut greenhouse gas emissions.
Past studies have projected that a warmer planet will likely hurt everything from lizards to African apes, and clown fish to koalas. While it is not surprising that a warmer world will cause drastic changes to the Earth's ecosystems, scientists have been continually alarmed at how quickly these changes are occurring. In an age when many species already struggle against the onslaught of human societies on nature—including habitat loss, deforestation, pollution, overexploitation for food or medicine, and invasive species—many biologist fear climate change could be the last straw, leading to a mass extinction.
"Ordinary people are not powerless to stop these tragic losses," Simon Stuart, Chair of IUCN’s Species Survival Commission, said in 2009 related to the threat of climate change to the world's biodiversity. "They can cut down on their own CO2 emissions and voice their support for strong action by their governments to change the dire climate prognosis we are currently facing."
Four different global temperature records show the Earth is warming. Graph courtesy of the IPCC. Click to enlarge.
Drever, M.C., R.G. Clark, C. Derksen, S.M. Slattery, P. Toose, and T.D. Nudds. 2011. Population vulnerability to climate change linked to timing of breeding in boreal ducks. Global Change Biology AIP.
Michael Gottfried, Harald Pauli, Andreas Futschik, Maia Akhalkatsi, Peter Barancok, José Luis Benito Alonso, Gheorghe Coldea, Jan Dick, Brigitta Erschbamer, María Rosa Fernández Calzado, George Kazakis, Ján Krajci, Per Larsson, Martin Mallaun, Ottar Michelsen, Dmitry Moiseev, Pavel Moiseev, Ulf Molau, Abderrahmane Merzouki, Laszlo Nagy, George Nakhutsrishvili, Bård Pedersen, Giovanni Pelino, Mihai Puscas, Graziano Rossi, Angela Stanisci, Jean-Paul Theurillat, Marcello Tomaselli, Luis Villar, Pascal Vittoz, Ioannis Vogiatzakis & Georg Grabherr (2012). Continent-wide response of mountain vegetation to climate change. Nature Climate Change. DOI:10.1038/nclimate1329.
Johnston DW, Bowers MT, Friedlaender AS, Lavigne DM (2012) The Effects of Climate Change on Harp Seals (Pagophilus groenlandicus). PLoS ONE 7(1): e29158. doi:10.1371/journal.pone.0029158
Thomas E. Martin, John L. Maron. Climate impacts on bird and plant communities from altered animal–plant interactions. Nature Climate Change, 2012; DOI: 10.1038/nclimate1348.
Photos: ten beloved species threatened by global warming
(12/14/2009) The International Union for the Conservation of Nature (IUCN) has released a list of ten species that are likely to be among the hardest hit by climate change, including beloved species such as the leatherback sea turtle, the koala, the emperor penguin, the clownfish, and the beluga whale. The timing of the list coincides with the negotiations by world leaders at the UN Climate Change Conference to come up with an international agreement to combat climate change.
Ocean prognosis: mass extinction
(06/20/2011) Multiple and converging human impacts on the world's oceans are putting marine species at risk of a mass extinction not seen for millions of years, according to a panel of oceanic experts. The bleak assessment finds that the world's oceans are in a significantly worse state than has been widely recognized, although past reports of this nature have hardly been uplifting. The panel, organized by the International Program on the State of the Ocean (IPSO), found that overfishing, pollution, and climate change are synergistically pummeling oceanic ecosystems in ways not seen during human history. Still, the scientists believe that there is time to turn things around if society recognizes the need to change.
Warmer temperatures may be exterminating pika populations one-by-one
(04/21/2011) The last decade has not been a good one for the American pika (Ochotona princeps) according to a new study in Global Change Biology. Over the past ten years extinction rates have increased by nearly five times for pika populations in the Great Basin region of the US. Examining extinctions of pike populations in the region over the past 110 years, researchers found that nearly half of the extinction events occurred since 1999.
Not enough data on world's tropical plants to predict impact of warming world
(02/14/2011) How many tropical plant species are threatened by climate change? Which plants have big enough ranges to survive a warming world, not to mention deforestation? How likely is it that the tropics are undergoing a current mass extinction? These questions may appear straight forward, but a new study in Global Change Biology finds that researchers lack the hard data necessary to come to any confident conclusions. According to the study, nine out of ten tropical plants from Africa, Asia, and South America lack the minimum number of collections needed (at least 20) to determine the species' range, and therefore predict the impact of climate change.
Photos: Scientists race to protect world's most endangered corals
(01/11/2011) As corals around the world disappear at alarming rates, scientists are racing to protect the ones they can. At a workshop led by the Zoological Society of London (ZSL), the world's foremost coral experts met in response to a decade of unprecedented reef destruction to identify and develop conservation plans for the ten most critically endangered coral species.
Disappearance of arctic ice could create 'grolar bears', narlugas; trigger biodiversity loss
(12/22/2010) The melting of the Artic Ocean may result in a loss of marine mammal biodiversity, reports a new study published in the journal BNature and conducted jointly by the National Oceanic and Atmospheric Association (NOAA), the University of Alaska, and the University of Massachusetts. The study is the first to project what might happen if species pushed into new habitats because of ice loss hybridize with one another, resulting in such crossbreeds as "narlugas" and "grolar bears".
African apes threatened by rising temperatures
(11/10/2010) Most people wish each day had more than 24 hours. But as the planet heats up, that limited number of hours might push endangered African apes even closer to extinction by making their current habitats unsuitable for their lifestyle, according to a controversial study published on 23 July in the Journal of Biogeography.
Carbon emissions hurting coral recruitment
(11/08/2010) While research has shown that ocean acidification from rising CO2 levels in the ocean imperils the growth and survival mature coral reefs, a new study has found that it may also negatively impact burgeoning corals, by significantly lowering the success of coral recruitment. A study in the Proceedings of the National Academy of Sciences (PNAS) has found that coral recruitment could fall by 73% over the next century due to increasing acidification.
Coral reefs doomed by climate change
(07/22/2010) The world's coral reefs are in great danger from dual threats of rising temperatures and ocean acidification, Charlie Veron, Former Chief Scientist of the Australian Institute of Marine Science, told scientists attending the Association for Tropical Biology and Conservation meeting in Sanur, Bali. Tracing the geological history of coral reefs over hundreds of millions of years, Veron said reefs lead a boom-and-bust existence, which appears to be correlated with atmospheric carbon dioxide levels. With CO2 emissions rising sharply from human activities, reefs—which are home to perhaps a quarter of marine species and provide critical protection for coastlines—are poised for a 'bust' on a scale unlike anything seen in tens of millions of years.
Study points to global snake decline
(06/09/2010) A number of reports over the last decade have shown amphibians, lizards, fish, and birds facing steep population declines across species and continents, providing further evidence that the planet is undergoing a mass extinction. Now a new study in Biology Letters adds another group of animals to that list: snakes.
Already on the edge, lemurs could become victims of climate change
(06/08/2010) Expanding beyond well-known victims such as polar bears and coral reefs, the list is growing of species likely to be hard hit by climate change: from lizards to birds to amphibians. Now a new study has uncovered another group of species vulnerable to a warmer world: lemurs.
Climate change devastating lizards worldwide: 20 percent estimated to face extinction
(05/13/2010) Lizards have evolved a variety of methods to escape predators: some will drop their tail if caught, many have coloring and patterning that blends in with their environment, a few have the ability to change their colors as their background changes, while a lot of them depend on bursts of speed to skitter away, but how does a lizard escape climate change? According to a new study in Science they don't. The study finds that lizards are suffering local extinctions worldwide due exclusively to warmer temperatures. The researchers conclude that climate change could push 20 percent of the world's li