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Threatened Wildlife

Global Warming Affects Ecosystem, Survival of Polar Bears, Gelada Monkeys

February 17, 2009

By Peter J. Fashing

A family of Gelada monkeys. Photo by Peter Fashing

The gelada monkey, which I study, is thought to be one of the nonhuman primate species most threatened by global warming.

Many of the hottest years on record have occurred during the past decade. And, the U.S.A. is the biggest global warming polluter per capita in the world. By the end of the 21st century, average temperatures are predicted by most climate models to rise by between 1 and 6 degrees Celsius.

Most scientific studies of global climate change have been focused at the ecosystem level. This focus on ecosystems and how they are affected by global warming makes sense – ecosystems contain many different species of plants and animals. However, sometimes it is helpful to use a single flagship species to motivate people to care about the threats facing a fragile or threatened ecosystem.

Climate change threatens the long-term survival of all creatures on Earth, from polar bears to sea turtles to migratory birds to humans.

For many people, polar bears are the first species that comes to mind when they think of the adverse effects of climate change on wild animals. Polar bears inhabit an arctic environment that is under severe threat from global warming. For many animals, the response to global warming has been to shift their ranges further toward the earth’s poles.

This pattern has been observed among butterflies and birds in Europe, where the ranges of many species occur further north today than they did just several decades ago. For example, the sooty copper butterfly, which occurred 50 years ago as far south as Catalonia, has exhibited a northward range expansion all the way into the green area that is southern Estonia in recent years. This northward expansion and southern range retraction with climate change allows these butterflies to survive for now.

However, this solution really doesn’t work for animals like polar bears who already live close to the poles.

Peter Fashing

Polar Bears Need Ice

For polar bears to survive, they need sea ice. Not to eat the ice itself, of course, but because the animal that represents their primary prey item, the ringed seal or netsik, requires sea ice as its primary habitat for resting, mating and giving birth. Polar bears hunt for ringed seals on this ice and are virtually incapable of successfully hunting seals in open water.

But with climate warming, less and less sea ice remains, and each year, more polar bears die of starvation, and in some cases, drowning, from having to swim long distances to reach more sea ice. Population density of polar bears in one intensively studied population in Hudson Bay, Canada, declined by 22 percent over the past decade alone. Even those at Hudson Bay that remain alive have suffered from inadequate nutrition – surviving bears were found to be 15 percent thinner on average than bears in this population were only a few decades ago. Furthermore, there have been several recent reports of polar bears resorting to cannibalism – not an unprecedented behavior – but the fear is that this cannibalistic behavior is on the rise.

All Arctic Species Threatened

The trouble with polar bears declining, aside from the loss of these spectacular bears themselves, is that many other species benefit from their presence in the arctic ecosystem. Several species, including the arctic fox and Thayer’s gull, rely on scavenging the remains of seals killed by polar bears as an important component of their diet. If polar bears become extinct, these species also may follow them into extinction. In fact, the loss of polar bears and the climate change that is behind this loss are, unfortunately, likely to ultimately result in the collapse of the entire arctic ecosystem as we know it today.

Another charismatic taxon that will be especially hard hit by global warming are sea turtles. With sea levels predicted to rise up to 1 meter this century, climate change is predicted to destroy many beach nesting sites for sea turtles. Nearly a third of the beaches used by turtles in the Caribbean would be lost with the sea level rise anticipated during this century, and many wading birds also face destruction of their coastal habitats in this region.

Even subtle changes in sea temperature can have dramatic impacts on sea turtles and other wildlife. For example, the sex of sea turtle hatchlings is determined by water temperature. All seven of the world’s sea turtle species are already classified as endangered, but warmer seas could lead to some turtle species becoming entirely female, dooming them to extinction.

Global warming is predicted to lead not only to rising sea levels, but to the conversion of once fertile areas into deserts. The spreading extent of the Sahara desert in Africa could threaten long-range migratory birds such as the swallow. Swallows normally spend the winter in Africa, then return to Europe in the spring when things have warmed up a bit. To make the long journey, swallows typically ‘fuel up’ on vegetation at the edge of the desert before they begin flying over it.

Sahara Expansion

However, with global warming, the Sahara is expanding southward, making the distance swallows have to travel longer and longer each year. Eventually with continued warming, the journey may become so long that the swallows will be unable to complete it and the species could eventually become extinct. In fact, there already is evidence that swallows are returning to their breeding areas in Europe following migration from southern Africa in poorer condition and also laying fewer eggs than in the past.

Gelada Monkey

I particularly want to focus on a species that has become the subject of my own research in recent years – the gelada monkey. There are very few zoos that have them, they occur in the wild only in the highlands of one African country, Ethiopia, and they don’t get a whole lot of attention in the newspaper like polar bears.

Yet, the gelada is one of the world’s most fascinating animals and lives in one of the most picturesque places on earth. A place that is changing as the world’s climate heats up and the gelada loses more and more of its remaining habitat.

So, let me tell you the story of the gelada.

About 125,000 years ago, at the beginning of the later Pleistocene era, the gelada was one of the earth’s most successful and widespread primates. There were at least six species of geladas belonging to the genus Theropithecus.

Based on the fossil record, the six known species of Theropithecus extended throughout the open savannas of Africa and even to India on the Asian subcontinent.

One of these six gelada species, Theropithecus oswaldi, was enormous, weighing more than 200 pounds, or the size of a big female gorilla.

Sadly, by the end of the late Pleistocene about 10,000 years ago, all but one of these gelada species, including the giant gelada, had gone extinct.

What explains the extinction of Theropithecus over much of its former range during a period of only about 100,000 years?

No one knows the answer for sure, but most scientists believe that hunting by humans, changing climate and competition for resources with common baboons are likely factors behind why Theropithecus now is only a relict population surviving in the highlands of Ethiopia.

Today, the one remaining gelada species, Theropithecus gelada, only lives at altitudes between 2,000 to 4,000 meters above sea level on alpine grasslands in Ethiopia.

There is only so much we can learn about the extinct geladas from their fossils. So at this point, if we want to understand the last remaining species of geladas and prevent the few existing populations from following their cousins into extinction, we’ve got to study Theropithecus gelada and do it soon.

One researcher who has taken a keen interest in the fate of geladas as global warming continues is Robin Dunbar, a British biologist who conducted the first major study of wild geladas back in the early 1970s. Dunbar and his wife, Patsy, collected data on the basic behavior and ecology of geladas in the Simen Mountains of northern Ethiopia and intended to continue their work for many years.

The History

However, a violent revolution took place among the people of Ethiopia in the mid-1970s leading to the end of a 2,000-year-old monarchy and a sudden conversion to a communist state. A civil war ensued that continued for more than 25 years and put a sudden stop to all research on geladas and other animals inhabiting the Ethiopian highlands.

So, instead of being able to go back to Ethiopia and continue learning about geladas in the wild, Robin Dunbar had to become an armchair biologist. He wrote tons of papers and books about geladas and other primates, and became one of the most famous and influential primate biologists in the world.

Eleven years ago, Dunbar became one of the first scientists to consider the implications of global warming on a large bodied mammal like the gelada.

Along with polar bears and other creatures that live in the arctic, animals living in mountainous environments like geladas are believed to be among the most threatened by global warming. This is because animals living in the mountains or near the poles are well adapted to life in cold climates. As the earth becomes warmer, the habitat to which these animals are adapted changes – changes that happen too quickly for the animals to keep up.

At the site where I study geladas, a big alpine grassland called Guassa in the mountains of northern Ethiopia, the weather seems abysmal to me – nights below freezing, frequent hailstorms, heavy winds, months of nothing but thick fog. But, that is the sort of climate to which geladas are adapted – you can see from the males especially with their long hair that these animals are adapted to life in a frigid environment.

The idea that began to worry Dunbar 11 years ago was that as the climate warms up, geladas will have to keep moving higher up the mountains. Right now, most geladas live at least 3,000 meters above sea level. The ones I study at Guassa are at 3,500 meters above sea level. The highest mountains in Ethiopia reach 4,500 meters and that is only at one location. At most places, the mountains end at 3,700 - 4,000 meters. That means that most remaining geladas have between 200 and 1,000 meters in altitude left to climb as the climate warms before they are literally pushed off the mountain tops and into extinction.

Based on a systems model Dunbar created to predict the effects of global climate change on geladas, his computer simulations found that for every 2 degrees Celsius increase in temperature, the species’ lower altitudinal limit will rise by ~500 meters. If his predictions are correct, only a handful of gelada populations at best will remain by the end of this century.

Why does warmer weather bother geladas so much? Well, for one thing, the grasses and herbs they survive on for food are most nutritious, particularly in terms of protein content, in a specific climate. In particular, a climate where the days are 10-15 degrees Celsius most of the time and the nights are around freezing is thought to be ideal for geladas in terms of nutrient contents in their grasses. This climate occurs presently at 3,200-3,700 meters. As the climate warms, the grasses and herbs geladas eat in an area will become less nutritious and abundant. That means fewer geladas can be sustained.

And, that’s a big deal because where geladas occur, they live in HUGE groups – at Guassa, the group I study includes about 220 individuals. There’s another group to the north that includes nearly 400 individuals. And some days, these two groups merge for a day or two and I’ve counted as many as 622 geladas traveling around together eating grass and herbs – and I’ll tell you, that is an amazing sight.

Unfortunately, with temperature increases reducing the nutrient content and abundance of gelada foods, the size of the gelada population that can be sustained in an area will reduce and group sizes will become smaller as animals die off.

While the reduction in nutrient content of gelada foods will be a big problem caused by global warming, it pales in comparison to another problem. Right now, the climate for the crops Ethiopian people like to grow, especially a local grain called tef that is their staple food, allows them to farm up to about 3,000 meters. You might remember that number as the altitude above which most current gelada populations occur.

It is absolutely no coincidence that farming extends up to 3,000 meters and geladas start to occur these days at 3,000 meters. The human population density in Ethiopia is so high that everywhere where land is farmable, it has already been farmed. If you make the drive from the capital of Ethiopia, Addis Ababa, up to Guassa, the journey covers about 300 km and takes anywhere from eight to 12 hours – sometimes longer if you don’t have your own car and are reliant on other people for transport, which is the case for me.

Along the way you start at 2,500 meters above sea level in Addis Ababa and make your way to about 3,000 to 3,500 meters as you near Guassa. And for that entire 300 km, you see nothing but farms. The farms are scenic no doubt, but they are still farms and there are no open grasslands left for geladas to inhabit once the farms move in.

What will happen with global warming is that over time, even Guassa, at 3,500 meters where my camp is based, will become farmable. What is now pristine alpine grassland will simply become more farms.

Here’s what’s happened in recent years in the Simen Mountains where the Dunbars used to study geladas 30 years ago. The overwhelming need for more land to farm in Ethiopia as its population continues to increase is one of the reasons that a leading conservation organization, Conservation International based in D.C., calls Ethiopia one of the countries whose biodiversity is most urgently threatened.

Heading for Extinction

Dunbar’s sad and almost inescapable conclusion 11 years ago was that geladas WILL go extinct over the next few centuries along with their Afroalpine grassland ecosystems and the other unique wildlife that inhabits these grasslands. In fact, I would be remiss if, due to my bias towards geladas, I did not show you some of this other endemic wildlife – wildlife like the Abyssinian hare and more spectacularly the Ethiopian wolf, the world’s rarest canid with only 500 remaining (50 of which live at my study site of Guassa).

So, according to Dunbar, it is not a question of whether geladas and other wildlife on the alpine grasslands of the Ethiopian highlands will go extinct, but rather a question of exactly HOW SOON. However, there are signs of hope that Dunbar’s grim assessment of the gelada’s demise in the next few centuries may prove to be wrong. One good sign is that here in the western world, over the past few years, people are suddenly beginning to accept in big numbers what the scientists have been warning us for years – that life on our planet is imperiled by global warming.

One of the most unfair aspects of global warming is that it is being caused mostly by people in a few rich nations – U.S.A. first and foremost — not only because of our consumption levels of fossil fuels and other pollutants but also by virtue of our size and population.

European nations also are big polluters, as is Japan and, increasingly, China – basically, anywhere that is wealthy and has a lot of people. Scarily enough, as China and India become even more prosperous, they have the potential to dwarf our contributions to global warming considering that their populations are each many times the size of ours.

Living in the poorest country in the world, Ethiopians contribute almost nothing to global warming. Very few people have cars, they don’t have any heat for their tiny stone or mud homes even when they live at high altitudes. Yet our consumptive tendencies here in the U.S. are leading to warming in places like Ethiopia and other poor countries. In fact, nearly all of the 20 poorest countries in the world are on the continent of Africa. And cruelly enough, many scientists predict that Africa is among the continents that will be most adversely affected by global warming. So even though they barely contribute to global warming, Africans are the ones who will face some of its greatest effects.

Now, getting back to the animals.

Geladas and polar bears, cold weather creatures of the mountaintops and arctic, are some of the early warning signs of the potential damage global warming will do to the world’s wildlife. Because of the unique habitats they occupy and their restricted ranges, global warming threatens polar bears and geladas with extinction first, but humans are not immune from this process. It will be our turn somewhere down the line if we do not stem the tide of global warming.

Peter J. Fashing is a Cal State Fullerton assistant professor of anthropology.

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