The web of life

4_1_image01.jpgAll the living things belong to the biosphere — this includes all humans, plants and animals, and even microorganisms that we don’t see. The many life forms in the biosphere play an important role in Earth’s ecosystems, and even influence how our planet has changed over time. Each living thing plays a crucial role in one or more ecosystems. If one thing is changed in an ecosystem, it can have big effects on everything else. Climate change is affecting many organisms, big and small, and their ecosystems. It’s important to recognize the kinds of changes that are already occurring, and what we can do to help all of Earth’s unique biodiversity.

There are about 1.7 million species on our planet that have been cataloged, or given a scientific name. That may sound like a lot, but researchers estimate that there are about 18.7 million species on Earth, including some that haven’t even been discovered yet.

You probably know that biodiversity isn’t the same everywhere on the planet — in some places there are many more plants and animals than in others. Think of a tropical rainforest with lots of monkeys, birds, amphibians and insects. An area that has a lot of endemic, or native, species in a relatively small or concentrated area is called a “hotspot of biodiversity.” Such hotspots include the Amazon, coral reefs, and the Hawaiian Islands. These places are important to study to see how climate change is affecting them, because if they get out of balance, then a great number of plants and animals are in danger. This affects not only wildlife and nature but people too. We depend on plants and animals for all kinds of reasons – from the air we breathe, to the food we eat, to the places we like to visit, and the birds, animals, landscapes and seascapes that we all like to see and enjoy. In recognizing that wildlife has a value for humans too, we use the term ecosystem services to describe the many positive benefits that wildlife or ecosystems also provide to people. 


Adaptation is key to any living organism's survival. Adaptation includes any special skill, behavior, or trait that an organism develops in order to survive. This can include physical traits that influence the genes of an organism that have developed over generations, to changes in daily life patterns or actions. Adaptation is not just for plants and animals, it can be applied to humans and societies too. For example, in terms of climate change, people may adapt to changes by taking new measures to protect their homes or adjust their food sources. We'll learn more about how people are adapting to climate change in the next chapter, but here we will consider the kinds of challenges that other organisms are facing and what they are doing about it. 

Plants and animals around the globe are already responding to climate change. Some are moving into new areas, increasing in numbers, interacting with new species, or searching for new habitats. Unfortunately, many are struggling to survive. Some are even threatened with extinction, either by losing their habitat or because they can’t adapt to the rapid changes occurring. So far, the International Union for Conservation of Nature (IUCN) has documented 19 species to have gone extinct due to climate change, including snails, toads, frogs, fishes, and birds. Many more are threatened.

All organisms have an optimum set of conditions in which they can survive and reproduce. So when those conditions change, the organisms have to adapt or move, or else they may die. Many of the environmental conditions that have been suitable for thousands of years are now changing, and making it more difficult for plants and animals to live as they used to. We will see in this chapter some of these current challenges in our biosphere, and how nature on Earth is responding.



Plants on Earth are a vital part of our global ecosystem that keeps our air clean and breathable. We learned that the atmosphere is composed of about 21% oxygen. Well, where did all that oxygen come from? Over billions of years, plants have released oxygen in the air through respiration. This makes life possible for many more organisms, including us humans! Some of the smallest plants on Earth – phytoplankton – play an important role in keeping our air clean.


Phytoplankton are microscopic plants that live in the upper layer of the ocean. They need sunlight for photosynthesis, carbon dioxide from the air and water, and vital nutrients to live. When all the environmental conditions are just right, there can be a big growth spurt, which is called a phytoplankton bloom. Blooms are made of billions of phytoplankton and cover very large areas in the ocean, sometimes lasting for several weeks. When they multiply really quickly, they are even visible from space, as you can see in the satellite image here.

Phytoplankton generate about half of the oxygen in our air. They are also a key part of the carbon cycle. Through photosynthesis, phytoplankton are responsible for most of the transfer of CO2 from the air to the ocean. They take in CO2, make energy, and release oxygen. When they die, some of that carbon is transferred to other animals that eat them. Other carbon falls deep into the ocean when the dead phytoplankton sinks to the bottom.


Phytoplankton are at the very beginning of the marine food chain for most of the planet. Many small fish eat phytoplankton, which in turn are eaten by larger fish, seabirds, and penguins. These are then eaten by larger mammals, like seals. And of course, people eat the big fish too. Included in this marine food chain are a wide range of sea organisms that feast on these tiny creatures including whales, shrimp, snails, and jellyfish. Fishermen sometimes study color images of the ocean to see where the phytoplankton are, in order to find good feeding spots and catch larger fish. Since phytoplankton are plants, they have a green color from the plant pigments that are high concentrations of chlorophyll. Scientists use satellite imagery to monitor their populations every year, because these small plants are vitally important to the ocean and the whole planet.



But phytoplankton, like many other organisms, are very sensitive to changes in their environment. Researchers are finding out that the warming sea temperatures are disrupting the delicate phytoplankton ecosystem. Just as we learned about glaciers, phytoplankton are excellent environmental indicators of the changes occurring on our planet.


The name phytoplankton comes from the combination of two Greek words: phyto which means ‘plant', and plankton which means ‘wanderer' or ‘drifter'. This is indeed a proper name for all the tiny plants found in marine environments. Phytoplankton include many different species that come in many different sizes and forms. Sometimes they are called microalgae. Phytoplankton have also been nicknamed the "lungs of the Earth" because they use a lot of carbon and return so much oxygen to the air. They are also nicknamed the "grass of the oceans” because they are the base of the marine food chain that provides food for so many animals. 


 Nature on the move


Many plants and animals on Earth are specialized, which means that they have adapted to a certain range of environmental conditions, whether it be very cold or hot temperatures, or very wet or dry places. Even in some places where you wouldn’t think to look for life, some kind of organism has usually adapted, whether it’s high in the mountains, deep in the ocean, or in a dark cave.

With global temperature rise, both habitats and species around the world are affected. Scientists have discovered that some plants and animals are moving in response to climate change, including big changes in their habitat and shifts in environmental conditions, including precipitation and temperature. Climate change is causing shifts in a species range — this means the plant or animal is moving to new areas where they haven’t been documented before. Climate change is also causing biome shifts — this means that entire vegetation and ecosystem zones, like deserts or forests, are also expanding into new areas or reducing their size.

4_2_image02.jpgPlaces that are typically cold year-round are most affected by the warming temperature trend. This includes areas of high elevations in the mountains, or high latitudes such as at the poles. Animals that are adapted to cold temperatures in the mountains are moving up higher and higher to keep cool. For example, the mountain pika of North America has been moving to higher elevations every decade. Places that used to be too cold to inhabit for some plant animals are now becoming warmer, and new species are moving in. As the glaciers are melting in South America, new lakes are being formed, and amphibians are moving up to record elevations above 5,200 meters (more than 17,000 feet). Some plants and animals can move more easily than others, while others are limited by either their own physiological (or biological) constraints, or because there is simply no place to move to. The alpine plants that grow high in the mountains generally have thick and slow growing root systems. This helps them survive the colder temperatures. But with warming temperatures at higher elevations, new, faster growing grasses are moving in and taking over the newly exposed areas. These new plant communities influence local ecosystems. Also, the alpine plants are already at the top of the mountain, so that can’t move up any higher either, and if temperatures warm up too much, they may be forced into extinction. Some of these mountainous areas are called "sky islands", where the high alpine ecosystems are islands of life up in the sky, and are completely different from everything below. These sky islands are especially vulnerable to warming temperatures.



4_2_globe_argentina.pngClimate change is having a big impact on penguins. The world’s biggest colony of penguins is in Argentina, some of them reaching as many as 400,000 birds. The Magellanic penguins typically can endure both hot and cold temperatures as an adult, but extreme weather events such as big rainstorms and heat waves are making it very hard for the chicks to survive. Parents take turns caring for the chicks, babysitting and hunting for food offshore. The chicks can’t swim to cool off if the days get too hot, and they don’t have weatherproof feathers to get through downpours. When food is scant and extreme events occur, the chicks are especially vulnerable.

4_2_globe_antarctica.pngOther penguins are finding it hard to find food, and some are even moving to new places as a result. On Ross Island in Antarctica, the Adélie penguins are dependent on ice. But the ice is changing with climate change, and so is the amount of food available. During the summer, Adélie penguins breed onshore in many colonies such as Palmer Station. When the chicks are born, the adult Adélies hunt offshore for food in a nearby area called Palmer Deep.

But all the signs of climate change, including decreasing ice, warmer winter air, and warmer sea temperatures around the peninsula, are impacting the penguins. The warm water means less sea ice and therefore fewer krill (krill are tiny crustaceans that serve as penguin food) beneath the sea ice. The parent penguins have to travel farther and farther for food, often leaving their chicks unprotected from predators such as the skua, a seabird. The Palmer Station population of Adélie penguins has decreased by 80% in the past 35 years, and unfortunately these penguins won’t be able to find a colder place than Antarctica to live. The Adélie penguins are definitely threatened by climate change.

Other penguins that are accustomed to warmer temperatures are moving into areas that used to be a lot colder. At Palmer Station, while the Adélie population is declining, chinstrap penguins are now moving in. This area on Antarctica used to be too cold for the chinstrap penguins, but now they seem to be taking over the place. Fur seals and leopard seals are moving in too.

Here is video taken by the Extreme Ice Survey of the King penguin colonies located on South Georgia Island in the southern Atlantic Ocean. Only a few years ago, much of the natural wildlife on South Georgia was endangered, including populations of seals, penguins, and whales. But recent conservation efforts have helped the dwindling wildlife to recover and flourish. 

Emperor penguins lay their eggs on sea ice around Antarctica and take care of newborn chicks there. Living on the sea ice makes it easier for them to hunt for food. But with warming temperatures, the sea ice sometimes forms later in the year, or isn’t strong enough to support the emperor colonies during breeding season. This has led to a big decline in their population in some areas. A few colonies are already starting to relocate their nesting areas to a higher ice shelf, but moving there has been really hard for these birds as they have to climb almost 100 feet. While the ice shelf may be more stable to live on, it will be harder for the penguins to travel back and forth for hunting.


 Early spring, late fall

4_3_image01.jpgPhenology is the study of the seasonal cycles of all living things, including when flowers bloom in the spring, when animals hibernate in the winter, and when trees shed their leaves in the fall. The phenological cycles are being studied closely because the seasons, which are influenced by things like precipitation and temperature, may be changing due to climate change. Spring, for example, is occurring a few days earlier each year than usual across the globe. And fall is coming a bit later every year.

Changes in the seasons over the past 30 years or so influence animal breeding, feeding, migration, and hibernation schedules. Take a look at this map of animals across the United Sates that are being impacted not only by a change in seasons, but also by warming temperatures and shifts in precipitation, all due to climate change.

One big problem with the change in seasons is that flowering plants, including many of our fruits and vegetables, depend on insects, like bees, for pollination. Bees move from flower to flower collecting nectar. In the process they get covered in pollen, which they then carry on to the next flower, making pollination possible. There is a symbiotic relationship between the flowering plants and the bees — meaning that they depend on each other and benefit from interacting with each other. They are an important part of a sustainable ecosystem, which provides a lot of ecosystem services. Humans are also linked to that ecosystem, because we smell the flowers, and most important, eat the food that comes from the bees’ work.

Scientists recognize that phenological changes are occurring for lots of plants and animals, but changes for one species may not sync up with changes occurring for another. For example, the spring is coming earlier each year, but not early enough for the bees, which are emerging even earlier than the flowering plants. This means that bees are ready to pollinate, but there are no flowering plants available. Every year, bees have the important job of pollinating crops that people all over the world depend on, such as apples, carrots, berries, cabbages, cucumbers, almonds and pears. All of these crops are worth billions of dollars each year, and the food goes straight to our markets and homes.

Some pollinators migrate, like hummingbirds, and their important work is even more threatened by a change in seasons. Hummingbirds eat a lot of nectar, but they travel great distances to find it, and carefully time their migration to the expected nectar blooms each year. With spring coming earlier, some flowers are blooming earlier than the arrival of the hummingbirds. Hummingbirds are being found outside their normal range as well, likely searching for food in unknown places. We hope each year that the hummingbird can find its blooming flower.


 Too little, too many—extinctions
 and invasions

While some species are moving and habitats are shifting, others are just disappearing. As we learned in chapter 3, polar sea ice is declining each year with the increasing temperatures. This is having a major impact on polar bears. Polar bears are some of the most beautiful animals, and the biggest! They are the largest carnivores on land. Living up in the Arctic, they make long migrations across the polar region in pursuit of food. For hunting, polar bears rely on thick ice near the shore as a platform. They will also venture out onto sea ice, if it is abundant and thick enough.

But in recent years, the sea ice has been breaking apart into big chunks separated by ocean. Many times the polar bears have to swim for several days searching for food and refuge. This can be really hard for a polar bear and its family. Without sea ice, polar bears can’t reach their prey — they can get stranded and go hungry for long periods of time. Polar bears can smell a seal from 20 miles away, and they will easily travel and swim that far to reach its prey and feed their cubs. But with decreasing sea ice, there are fewer opportunities to rest, and sometimes they can’t make it to the food. Even though polar bears can swim for more than 40 miles, after several days of swimming with no food they become exhausted. It’s especially dangerous if they have little cubs either trying to swim with them or waiting for their mother’s return. Researchers have found that polar bear population numbers are decreasing and their average body size is also getting smaller. Each year, fewer and fewer cubs are surviving.

Polar bears are now listed on the endangered species list by the IUCN, and they may be extinct within the next century. But this doesn’t have to be the whole story for these courageous animals. There is much we can do to help change the story of climate change, as we will find out in chapter 6.



The biodiversity on Earth is unique, and not found anywhere else in our known universe. This means that when a plant or animal disappears, that it is lost forever. Each species, no matter how small has an important role in a larger ecosystem. As a society, we rely on plants and animals for medicine, food, clean air or water, and simple enjoyment. Many species have benefits that haven’t even been discovered yet. But both climate change and human impacts are a big threat to many plants and animals. According to the IUCN Red List 2013, there are 16,928 species threatened with extinction. Based on the recorded extinctions of known species over the past century, scientists estimate that current rates of species extinction are about 100 times higher than long-term average rates of fossil data. 


There are over 1.5 million species that have been identified. This includes both plants and animals. Almost 1 million species are insects alone! There are a lot more species that we haven¹t even discovered yet. Each year, about 10,000 new species of animals are identified. Scientists estimate that there are anywhere from 2 to 50 million species of animals and plants on Earth.



Sometimes too many of one thing isn’t good. In the Rocky Mountains, the native bark beetle populations have increased with the warmer temperatures. Recent outbreaks have resulted in millions of trees dying. We can say that the forests caught a bug, because they get pretty sick when the beetles move in and stay too long. These beetles get going especially when forests aren’t doing well, for example after long periods of drought, old age, overcrowding, disease or weather damage. Forests all the way from Alaska through Canada and the United States, down to Mexico, are affected by the bark beetle.

Bark beetles bore into trees and eat the nutrients that the trees need to survive. Some regular chomping on the bark doesn’t bother the tree, but if the beetle eats all the way around it, the food reservoir at the center of the tree will be cut off from its root system and the tree won’t be able to feed all its many branches.

In the Rocky Mountains, the pine beetle is just one species of bark beetle that has had a major impact on the forests. They have been killing all kinds of trees including ponderosa pine, lodgepole pine, limber pine, Engelmann spruce, subalpine fir, and Colorado blue spruce. That’s a lot of trees! Normally, cold temperatures over winter can kill the beetle eggs and larvae that are laid on the outside layer of a tree’s bark. But the warmer winters mean that the beetle eggs hatch and the population grows. In addition, if there is low precipitation, the trees are weakened and more vulnerable to infestation. Not only are dying trees bad for the forests and all the animals that live there, but they can be dangerous. Dead trees make great firewood, and fires are also on the rise due to unhealthy forests. In Colorado and Wyoming alone, the mountain pine beetle has impacted over 4 million acres of forests. Colorado, like many other states hit by drought and beetle infestation, has suffered many wildfires in the past few years, burning thousands of acres and hundreds of homes. We need to make sure our forests stay healthy, and climate change certainly isn’t helping.



Trees do a lot for us. Healthy trees means that we have cleaner air, help regulate temperatures by providing summer shade and blocking winter winds, provide habitat for birds and animals, and help keep our urban and natural environments green. Healthy trees also means less risk of fire. The U.S. Forest Service finds that 100 trees remove 53 tons of carbon dioxide, remove 430 pounds of air pollutants per year, and catch about 139,000 gallons of rainwater each year.




4_5_conclusion_01.jpgAll around the world, plants and animals are responding to climate change. Some species are able to adapt to changes, either by moving or by changing their behavior. But some plants and animals are highly specialized and depend on resources or conditions in their environment that are no longer available — and so their lives are in danger. This means that many species are in danger of extinction because of climate change.

All of the life on Earth is what makes our planet very special. As we watch the challenges of wildlife unfold before our eyes, we recognize that climate change is affecting all of us. We are all interconnected. Nature is letting us know that now is the time to make changes in the course of our climate. Each of Earth’s natural creatures has an important role in sustaining a healthy planet, but many are threatened by climate change. In the next chapter, we find out that many people are and places are equally feeling the impacts of climate change. Together, we can do something to help find new solutions to our climate change challenges that help sustain Earth’s biodiversity and protect our wildlife.


 View of a Coral Reefscape

4_6_globe_bonaire.pngJames Balog traveled to the Caribbean island of Bonaire to photograph a coral reef for National Geographic. James wanted to test out a photography technique that he developed to take pictures of really big trees, like redwoods and sequoias. Like the tree landscapes he photographed, the coral reefs are much too large to fit into one picture with any great detail. James applied a mosaic photograph technique to capture the unique and complex components of the reef. He took a lot of close-up pictures and then stitched them together so you can see the entire reef.

But taking these pictures underwater so that they can be seen in colors true to their brilliance is a lot trickier than you may think. Underwater photography makes it really hard to capture something in its true color. Even in very clear water with the sun shining overhead, as you go below water everything starts to turn to shades of blue and green. At very deep depths, there is hardly any true color to be seen at all. James had to use strobe lights underwater to correct for the absorption (also known as attenuation) of sunlight as it goes through the water column. To correct for the darkening colors underwater, James took close-up photographs with very powerful strobe lights.

This coral reef is called Carl’s Hill. The top of the reef is about 6 meters (20 feet) below the water, and the bottom is about 20 meters (70 feet). What James captured with this special mosaic and lighting technique is a view of the reefscape seen in its entirety, showing all the vivid colors and unique biodiversity of a spectacular coral reef.

4_6_image_01.jpgSeascapes and reefscapes, like this one that James photographed, are certainly not immune to climate change, and in fact, they are indicators of just how much climate change is making a big impact. As you remember from chapter 3, high concentrations of carbon dioxide in the air are transferring to the ocean. The increase in CO2 in sewater is leading to ocean acidification. This acidification is eroding the minerals that marine life needs for their shells and skeletons, so many marine organisms are being affected by climate change.

Coral reefs are also declining and suffering from what is called coral bleaching. Coral bleaching occurs when corals are stressed by changes in their environmental conditions, such as warming temperatures or changes in the nutrients available to them. The corals kick out the symbiotic algae living in their tissues and turn white. Warm seawater causes coral bleaching, and while the corals don’t die, they certainly become weaker. There are many marine organisms that depend on healthy coral reefs for breeding grounds and as homes.

Take a look at this exciting video from our team to learn more about the recent changes in coral reefs due to climate change. We learn why coral reefs are important and find out about some exciting new ways to restore coral reefs.

4.6 Bleached coral.jpg