A Long Winter’s Nap No More

hibernating bear

Many bears hibernate during the long, cold, and dark winter months. (Photo credit: Ralph A. Clevenger/Corbis)

When temperatures get colder and the days get shorter, many mammals settle into a period of hibernation. But what effect will climate change — and the associated changes in weather patterns — have on this annual behavior? [Read more…]

A Prehistoric Climate — Warmed by Dinosaurs Passing Gas?

dinosaur

Scientists think dinosaur flatulence could have had an affect on the climate. (Art credit: Linda Bucklin/iStockPhoto.com)

A common sight 150 million years ago, sauropod dinosaurs were some of the largest animals ever to have lived on Earth. These vegetarian dinosaurs produced a lot of methane gas — could these gaseous emissions have affected their prehistoric climate? [Read more…]

Warmer Climate, Shrinking Species?

Research indicates rising global temperatures may result in smaller plant and animal species. (Photo credit: Evgeny Dubinchuk/Fotolia)

Plants and animals are already beginning to change their behavior due to a warmer climate. Animals are beginning to migrate earlier, plants have changed their flowering periods, and many plants and animals have shifted their distribution away from the equator and closer to the cooler north and south poles. Recent research indicates that these modified behaviors are not the only change that species will undergo if the climate continues to warm as expected. These studies show that plant and animals may actually shrink in size as the climate continues to change.

Jennifer Sheridan, a professor of conservation biology at the University of Alabama, and David Bickford, a professor of environmental science at the National University of Singapore collaborated together on an article published in the journal Nature Climate Change. In the article, the scientists evaluated data from the fossil record, as well as modern-day studies to hypothesize what might happen if plant and animal sizes shrink due to a warming climate.

Their studies of the fossil record indicate that animals such as beetles, spiders, and pocket gophers significantly shrank in size during the Paleocene-Eocene Thermal Maximum, which occurred around 55.8 million years ago. Modern-day observations indicate that over the last 100 years, a variety of plant and animal species have decreased in size as average global temperatures have increased.

In addition to synthesizing data from the fossil record and current literature, the scientists also conducted two experiments. In one experiment, the scientists exposed ocean-dwelling creatures such as scallops, oysters, and scallops to conditions mimicking ocean water with increasing levels of acidity. As the acidity of the water increased, the marine animals ability to form their shells decreased, leading to an overall decrease in size. In a second experiment in which plants were grown under controlled climate conditions, the scientists found that for every 2 degrees that the temperature was increased, fruit size decreased by 3 to 17 percent. Similarly, when a variety of animals, including fish, beetles, marine invertebrates, and salamanders were exposed to increasing temperatures, they decreased in size, too. Fish, in particular, decreased between 6 and 22 percent in size.

ome species of salamanders are decreasing in size due to increased temperatures. (Photo credit: Carsten Meyer/Fotolia)

Research published in the journal The American Naturalist corroborates this data. This study focused on ectotherms, also known as cold-blooded animals, and how increased temperatures affect their growth rate and development. Experiments conducted with copepods, which are tiny aquatic crustaceans, showed that when exposed to warmer temperatures, the copepods go through their life stages at a quicker pace, meaning they reach adulthood at a smaller size than normal. This observation held true for a range of copepod species.

Why are species shrinking? Scientists point to a few explanations. Smaller plant size is linked to warmer and drier conditions and scarce water supplies. In addition, drought conditions often lead to forest fires, which diminish the amount of nitrogen, a nutrient necessary for plant growth, in the soil. These smaller plants in turn provide less of a satisfying meal for the herbivores that eat them. If the herbivores are unable to eat enough of their plant food source, or cannot find a replacement plant to eat, they will likely be unable to grow to their full size. Smaller herbivores in turn require predators to find more prey to eat to maintain their body size, or they too, will shrink in size.

Though not much is yet known about how worldwide food webs will be affected by a potential decrease in size across species, scientists hypothesize that changes in one species could have a ripple-effect on other species within their food web. They also foresee some species not feeling any affects due to a changing climate, which could also lead to imbalances within a food web, as some species thrive while others decline. Though computer models can help to show how shrinking species size may affect ecosystems in the future, only time will tell the actual impact these changes. As described above, current research indicates that shrinking species size could have a significant impact, though more research is necessary.

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CO2 Emissions Also a Concern in the Oceans

Though carbon dioxide (CO2) emissions are well-known as a contributor to global warming, it is not as well known that CO2 emissions also cause ocean acidification. Ocean acidity has risen 30 percent since the arrival of the Industrial Age. Research indicates that if CO2 continues to be emitted at today’s rates, it is expected that ocean acidity will increase by an additional 100 percent by the year 2100. Researchers based in Europe are currently conducting an experiment to determine how an increase in oceanic CO2 concentrations will affect oceanic organisms such as plankton.

This research project, funded by the European Union, is a multi-disciplinary affair. Among the researchers involved in this experiment are cell biologists, molecular biologists, marine ecologists, biogeochemists, and oceanic and atmospheric chemists. The scientists’ experiment is taking place off the coast of Svalbard, an island archipelago in the Arctic Sea. This oceanic experiment is the first of its kind to test the effect of increased CO2 concentrations in the Arctic Ocean. Ocean acidification is particularly worrisome in polar seas because carbon dioxide is absorbed more readily in cold water. This absorption of CO2 leads to unnaturally low carbonate saturation states in the water. This situation is particularly problematic because these sub-saturated waters could be corrosive to organisms made of calcium, such as shellfish, sea urchins, and calcareous plankton.

Many of these organisms play a key role in the oceanic food web. For example, plankton are eaten by organisms including fish, sea birds, and whales. The loss of plankton, or any other organism in the polar oceans, could have a disastrous effect on the rest of the food web.

In their six-week long experiment, the scientists have enclosed ocean plankton into nine 17-meter long “test tubes,” which each hold a volume of 50 cubic meters of seawater. Inside each “test tube,” the confined plankton are exposed to a range of CO2 concentrations that are expected to occur between now and the middle of the next century. The scientists are monitoring how these different CO2 concentrations affect the plankton, and their results should provide important information as to how increased CO2 concentrations in the ocean will affect oceanic organisms in the future.

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Increased Global Temperatures Impact Seed Dispersal in Northern Forests

Research conducted by scientists in Finland indicates that an increase in global temperatures may lead to a greater dispersal of seed and pollen in northern boreal forests. One impact of global warming is the formation of stronger wind currents; it is these wind currents that help spread seeds and pollen over a greater distance.

The research was led by Dr. Anna Kuparinen, a scientist with the ecological genetics research unit in the department of biological and environmental services at the University of Helsinki. Kuparinen and her colleagues analyzed micrometeorological data gathered over a 10-year period by researchers at the Hyytiala Forestry Field Station, located 210 kilometers northwest of Helsinki. Using statistical analysis techniques, the scientists determined that an increase in global temperatures had a positive correlation with increased dispersal of plant seeds and pollen. The scientists also discovered that a temperature change of three degrees Celsius increased the speed at which seeds and pollen were dispersed as well as increased the rate at which plant populations grew.

Research indicates that the long-distance dispersal of seeds and pollen is a key factor in the spatial dynamics of plant genotypes, populations, and communities. As global temperatures increase and seeds and pollen are able to disperse farther, plants may be able to colonize areas where they previously did not exist, helping to ensure their survival in a warming climate.

The results of the scientists’ research was published online in the June 10, 2009 edition of the journal Proceedings of the Royal Society B and is found in the September 7, 2009 print edition of the same journal. Other scientists who contributed to the research included Gabriel Katul, Ran Nathan, and Frank M. Schurr.

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Tree Mortality in West Caused by Warming Climate

Research published today in the journal Science indicates that the major contributing factors to tree mortality in the West is regional warming and drought stress. There has been a rapid increase in the number of dead trees found in old-growth forests over the past 50 years. Forests in the Pacific Northwest (Oregon, Washington in the US; British Columbia in Canada) have been particularly negatively-affected by regional warming.

The results from the study indicate that a continued increase in mortality rate could eventually lead to a 50 percent decrease in the average age of trees, a potential decrease in average tree size, and an increased susceptibility to a sudden die-back of trees throughout western forests.

Another concern is the development of a “feedback loop” within the forest system. As regional warming causes trees to die, forests become smaller. The smaller forests absorb less carbon dioxide from the air than the once-larger forests. This means that more carbon dioxide remains in the atmosphere, which in turn fuels an even higher level of atmospheric warming.

The scientists also took a look at other factors that affect forest health, such as insect attack, fire suppression, forest overcrowding, forest fragmentation, and air pollution. However, even after taking these factors into consideration, they found that the most significant mechanism affecting forests was indeed atmospheric warming. Over the period of the study, average temperatures in the western United States have increased by less than 1 degree. Though this amount may seem insignificant, this increase in temperature is enough to cause a number of changes in the region’s water cycle. For example, less precipitation falls as snow, snowmelt occurs earlier in the year, and the summer drought occurs for a longer period than before.

The researchers studied 50 years of data gathered by a number of different scientists in forest stands containing trees 200 years old or more. The areas they studied included sites in Oregon, Washington, California, Arizona, Colorado, New Mexico, and southwestern British Columbia. The main method used in the study was fairly simple–counting trees.

The study was led by Phillip J. van Mantgem and Nathan L. Stephenson of the US Geological Survey (USGS) Western Ecological Research Center. They worked in collaboration with researchers from the University of British Columbia, University of Washington, Oregon State University, Northern Arizona University, University of Colorado, Pennsylvania State University, and US Forest Service. Funding for the study was provided by the National Science Foundation, US Department of Agriculture, and USGS.

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Charging to Pollute

Carbon dioxide is the primary gas that causes the greenhouse effect which traps heat in our atmosphere and is part of global warming. Carbon dioxide is a product of many chemical reactions, such as the combustion of gasoline, coal, and other carbon-based materials. Our homes, factories, and cars release a lot of carbon dioxide into the atmosphere. Carbon dioxide gases that are released into the atmosphere are called carbon emissions.

The United States government and many economists, or people who study money and markets, have been looking for ways to charge for carbon emissions. They hope that charging for carbon emissions will discourage individuals and businesses from releasing so much carbon dioxide into our air. By making carbon emissions expensive to those who release them, individuals and companies may turn to the use of less-polluting products, vehicles, and ways of life.

In many different articles published in the Oxford University Press Journal, economists have proposed some interesting strategies of charging for carbon emissions:

  • Carbon tax A carbon tax is a tax applied to fossil fuels, such as gasoline, which are carbon-containing materials that release carbon dioxide when they are burned. This tax would increase the price of gasoline and other fossil fuels. A carbon tax would cost most to the people and companies that use the most fossil fuels.
  • Cap-and-Trade The cap-and-trade strategy begins with government setting limits for emissions. Then, the government will sell permits for companies to release carbon emissions up to that limit. Going over the limit will mean extra fines and costs for the company. Companies can trade permits with other companies, if they so choose.
  • Cap-and-Trade Hybrid This strategy is similar to the cap-and-trade strategy described above, except that government would set a maximum price that companies could be charged.

Do you think the government should charge for emissions? How do you think they should do it?

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Climate Change May Threaten Australia’s Kangaroo Populations

The kangaroo, an Australian icon, may not fare well if average global temperatures increase. (Photo credit: www.free-stockphotos.com)

The kangaroo, an Australian icon, may not fare well if average global temperatures increase. (Photo credit: www.free-stockphotos.com)

“Kangaroos” and “Australia” go together like peanut butter and jelly. Recent research released this week indicates that kangaroos might not fare so well in the future due to climate change. Researchers at Australia’s James Cook University have determined that an average increase in global temperatures of just 2 degree Celsius could have a devastating impact on their country’s iconic population of kangaroos.

Elian G. Ritchie and Elizabeth E. Bolitko, the study authors, relied on computer modeling and three years of field studies to form their conclusions. According to their model, the kangaroos’ geographic range could shrink by 48 percent if average global temperatures increased by 2 degrees Celsius. If average global temperatures increase by 6 degrees Celsius, the kangaroos’ range could shrink by 96 percent. Current climate-change models predict that the average temperatures in Northern Australia will increase between 0.4 and 2 degrees Celsius by 2030. By 2070, temperatures are expected to increase between 2 and 6 degrees Celsius.

Kangaroos themselves aren’t as much as risk as their habitat is. Increased global temperatures could lead to a longer dry season and less-predictable rain events. This means that there could be less water available for the kangaroos. The scientists are most concerned about the future of antilopine wallaroos. This species of kangaroo lives in a wet, tropical climate. These kangaroos are most at risk because an increase in temperature of just 2 degrees Celsius could shrink their habitat range by 89 percent. An increase in temperature of 6 degrees Celsius could lead to the species’ extinction, unless they can adapt in time to the newly arid grassland climate that would arise from such an increase in temperature.

The paper, entitled “Predicting Extinction: Investigating the Interface of Physiology, Ecology, and Climate Change” appears in the December issue of the journal Physiological and Biochemical Zoology.

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Great Migrations: A Thing of the Past?

bison

The largest herd of American bison is found within the confines of Yellowstone National Park. (Credit: Colton Stiffler/istockphoto.com)

When Europeans first came to America, the bison population numbered an estimated 30 to 60 million. The explorers Meriwether Lewis and William Clark commented on the massive herds of bison they passed during their exploration of the Louisiana Territory. In 1839, Thomas Farnham, an author traveling the Santa Fe Trail with the showman Buffalo Bill Cody, noted a herd covering 3510 square kilometers. Unfortunately, mass slaughters of bison in the 1870s nearly led to the animals extinction. By 1889, the bison population only number 1,091 animals. Today, the bison population has rebounded to 500,000a far-cry from historical populations, but safely away from the brink of extinction.

Returning from the brink of extinction came with a cost, however. The majority of bison today are the offspring of bison cross-bred with cattle–many are raised on ranches as livestock. Two hundred years ago, bison roamed across the whole expanse of America. Now, the largest herd of free-roaming plains bison–numbering 4,000–is confined to Yellowstone National Park.

At one time, American bison undertook a great migration during their life cycle. While some bison still migrate, their migration is much shorter, hardly the great undertaking that it once was. Today, scientists wonder whether other migrating animals may face the same fate as the American bison, due to habitat loss, habitat fragmentation, overexploitation, and climate change.

Why do animals migrate?

Migration is an important part of the life cycle of many different types of animals. Blue whales, monarch butterflies, caribou, and elegant terns are just a few of the many animal species that migrate from one place to another during any given year. Survival is the main reason why most animals migrate. Migration patterns are most often associated with seasonal changes or breeding patterns. When climate conditions become too harsh at one portion of an animals territory, it moves to a different portion of its territory where conditions are more favorable. Migration also prevents a species from completely depleting the resources it needs from portions of its territory. Animals also migrate to access breeding grounds. The areas they migrate to are often rich in resources and more protected than the areas where they live during other portions of the year. Salmon, which spend most of their lives in the ocean, return to the same freshwater rivers in which they were born to breed. Young salmon are less vulnerable to predators in river environments than they would be in the ocean.

Because over 90 percent of the world’s elegant tern population breeds on just one island in the Gulf of California, the species is highly susceptible to threats to its breeding habitat. (Credit: Elliott Brooks/istockphoto.com)

How do animals known when to migrate?

Several different cues initiate migratory behavior in animals. These cues include external cues such as photoperiod (length of daylight) and temperature, or internal cues such as the amount of fat stored in the animals body. Animals such as the snow goose know to migrate south when the days become shorter as winter approaches.

Once an animal is cued that it is time to migrate, how does it know where to go? For the most part, animals are born with an innate knowledge of their species migration pathway. Animals use several different methods to navigate along the pathway from one portion of their territory to another. These navigation methods use the position of the Sun, Moon, or stars; major landmarks such as mountains or coastlines; or detection of Earths magnetic field.

What obstacles prevent animals from migrating?

In an article published in the open-access and peer-reviewed journal PloS Biology, authors David S. Wilcove and Martin Wikelski, both of Princeton University, question whether or not its too late to save the great migrations. Wilcove and Wikelski point to four main categories of threats to migratory animals. These categories are habitat destruction, the creation of obstacles and barriers (such as dams and fences), overexploitation (or overhunting), and climate change. While many migratory species are far from becoming extinct, they are noticeably less common than they once were. For example, according to Wilcove and Wikelski, birdwatchers can still see the migratory songbird species they are used to seeing in the spring, they just have to work harder to find the birds than they had to before.

What is the ecological importance of migration?

Both Wilcove and Wikelski believe that protecting migratory animals and their pathways is a significant ecological issue. According to the authors, Protecting the abundance of migrants is the key to protecting the ecological importance of migration. As the number of migrants declines, so too do many of the most important ecological properties and services associated with them.

Migratory animals provide a number of services, such as the addition of nutrients to the ecosystems in which they live. For example, when salmon return from the ocean to rivers to spawn, they transfer nutrients from the ocean to the river system. After spawning, the salmon die, and nutrients are returned to the river system upon their decomposition. These nutrients encourage the growth of phytoplankton and zooplankton, which serve as nutrient sources for other animals, continuing the cycle.

What needs to be done to protect migration pathways?

Saving migratory species is not an easy endeavor. Unlike other threatened animals, migratory species must be protected as a large group to ensure that their migratory behaviors stay intact. According to Wilcove and Wikelski, it is important to understand a migratory species demographic connectivityhow events at any stage in a species migratory cycle affects other stages of the migration. For example, while scientists have studied migratory songbirds at their breeding grounds, wintering grounds, and stopover sites, they remain unsure exactly why migratory songbird populations are declining. Without more intensive studies, it is hard to figure out whether the bird populations are declining because of loss of breeding habitat, loss of winter habitat, increased mortality during migration, or some combination of the three.

Another important aspect that needs to be understood about migration is how animals decide when to migrate, where to migrate, how long to stay, and when to leave. Understanding the decision rules they use is made even more important by the potential impact of climate change on a migratory animals behavior.

One of the biggest challenges to the effort to protect migratory species is the need to protect them before they reach the brink of extinction. It is imperative that lawmakers choose to protect migratory species while they are still abundant–an idea that is counterintuitive to most people. Why protect a species when for all intents and purposes it appears to be far from extinction?

During the zebras’ great migration, the African mammals travel across the Serengeti plains of northern Tanzania before crossing the Kenyan border to reach the Masai Mara National Reserve. (Credit: Liz Leyden/istockphoto.com)

Migratory species are particularly difficult to protect given that their migratory pathways often cross a number of different political (and national) boundaries. Protecting a migratory species includes preserving its habitat at both ends of its migration–and all the areas in between. Doing so will require collaboration between local, national, and international governments, and the people who live within the animals territory as well.

As Wilcove and Wikelski conclude, The challenges–scientific, economic, and social–associated with protecting migratory species are enormous. But so too are the payoffs. We can preserve phenomena that have awed and sustained us since the dawn of humanity. We can protect ecological processes that are integral to many of the planets ecosystems. And we can solve scientific puzzles that have baffled natural historians for millenia. If we are successful, it will be because governments and individuals have learned to act proactively and cooperatively to address environmental problems, and because we have created an international network of protected areas that is capable of sustaining much of the planets natural diversity.

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Sometimes Even Algae Gets Sunburned

The pale color and white tips of this red algae is the result of too much ultraviolet radiation. (Photo Credit: Max Schwanitz, Alfred Wegener Institute)

The pale color and white tips of this red algae is the result of too much ultraviolet radiation. (Photo Credit: Max Schwanitz, Alfred Wegener Institute)

Plants and photosynthetic algae rely on the Sun as a source of energy to power photosynthesis. Without the Sun, these organisms would not be able to make the energy needed to perform the functions necessary for survive. However, there is such a thing as too much Sun. Similar to the sunburn you may get after sitting in the Sun too long, plants are also susceptible to overdoses of ultraviolet radiation.

When plants receive more light than they can use, light sensitive pigments used to absorb light for photosynthesis may become damaged. Overexposure to light may result in black spots, pale leaves, or rotten parts on the affected plant. Many plants and photosynthetic algae have developed strategies to deal with an excess of ultraviolet radiation.

For example, when a certain species of red algae receives too much ultraviolet radiation, the algae produces fewer red light-collecting proteins so that less radiation is absorbed. Outwardly, the algae turns a paler shade of red and forms white tips. In addition, the algae also produces mycosporin amino acids, a substance similar to melanin in humans. In humans, melanin absorbs ultraviolet radiation, protecting the skin from harm and forming a natural suntan.

However, due to the depletion of the ozone layer, more dangerous short-wavelength ultraviolet radiation is able to penetrate the Earth’s surface and seawater. The mechanisms that plants and photosynthetic algae have to protect themselves from ultraviolet radiation do not work well against these more harmful ultraviolet rays. In algae, the more dangerous ultraviolet radiation harms the organism’s ability to photosynthesize and negatively impacts the organism’s DNA. This damage leads to a much slower rate of growth and reduced reproductive success for the algae. Particularly sensitive are spores and algal gametes, for which even tiny doses of ultraviolet radiation are deleterious.

Researchers associated with the German French Research Base AWIPEV on Spitsbergen (a Norwegian island in the Arctic) have found that the distribution of certain species of algae are inhibited by ultraviolet radiation. They also found that as ultraviolet radiation increases, the algae are displaced into even deeper waters. According to the researchers, continued study of underwater algae is important as it illustrates how marine coastal ecosystems are being impacted by global climate change.

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