The Humans and Planet Earth, The Wondrous Workings of Planet Earth

In many ways, human beings are the most remarkable animals on the planet. Humans have gone from living in caves and scavenging for food to being able to order a pizza and get it delivered without leaving the couch! Human beings have walked on the moon, broken the sound barrier, and created artificial intelligence to help us solve extremely complicated problems. We have developed technologies that allow us to travel all over the world relatively quickly, and communicate with anyone with just the click of a button. Together humankind has transformed Earth’s landscape, striving to create shelter and provide food for our ever-growing population. Our caveman ancestors could never have dreamed of the safety, comforts, or technology that many people in the world have today!

But for all that we have built, there are still things that only nature can provide us. All around us, ecosystems create fuel in the form of wind, hydro, and solar energy. Thousands of years of decomposition have turned carbon into coal or fossil fuel that we can use to drive cars and heat homes. Ecosystems are the global cleanup crew, breaking down garbage and dead things into soil that can grow new plants and crops. Plants in certain ecosystems can prevent floods and coastal erosion. Intact, biodiverse ecosystems can even bounce back from natural disasters and “heal” themselves. Economists have valued the natural ecosystems of our world at over $142.7 trillion a year. But who could put a price on breathable air, fresh water, nutrient-rich soil, and a livable home planet? As people continue to build wondrous cities and large farms, we also need to preserve the natural world, so it can continue to work hard for us.

Human civilization all comes down to food. Long ago, before recorded history, the only way to eat was to find the food yourself. Our ancestors were nomadic, constantly on the move seeking new plants and animals to eat. But sometime after the Ice Age, nomadic tribes across the world started to plant seeds and cultivate crops. Farming created a surplus of food, and more food meant people could spend more time doing other kinds of work. People began to settle in fixed places around these new farms, and also took on new jobs, like inventing and building new tools. This created a boom in technology. New methods of farming were developed to yield even more crops. People began to transform the land around them, tilling the soil, irrigating to bring water to the crops, and selectively breeding the plants and animals that were most beneficial to their community. Large-scale civilizations and cities began to emerge.

Now, with new technology, we can feed humanity’s fast-growing population. Machines dig the soil, plant, and harvest; crops can be genetically selected to withstand drought or keep pests away; and chemical fertilizers boost soil productivity. Our food is grown all over the globe and transported worldwide. We can eat a slice of pizza that is made with tomatoes from Italy, wheat from Europe, and cheese from America. But with all of our progress, it is critical to remember that it is our limited natural resources that make farming possible at all.

Farming sustainably means feeding our growing population while keeping the environment healthy for the future. The main challenges to overcome when feeding a large population are depleting the soil of nutrients, overusing water, and using fossil fuels both to fertilize and to run farming machinery.

Biodiversity is as important on a farm as it is in the wild. Although planting a large field of one type of plant has its benefits and is easier to manage for a farmer, it also depletes the soil and forces farms to rely heavily on chemical fertilizers. An overuse of fertilizers can pollute the groundwater, which in turn pollutes our oceans. When farms grow only one type of plant, the entire crop becomes more prone to disease and pests, requires more pesticides, and is less able to withstand changes in the weather.

When there is a diversity of plants and animals on a farm, the natural benefits of an intact ecosystem abound. Different plants take different compounds from the soil and put back different nutrients. By rotating crops, farmers can naturally enrich the soil instead of overtaxing it to produce a single crop. Planting cover crops and using compost and animal manure can also lessen the need for chemical fertilizers. Certain plants can even repel insect pests. Biodiversity can also help us conserve water: by planting drought-resistant plants and using methods to reduce water volume irrigation, we can make water reserves go farther and last longer during dry seasons. Every place is different, and plants native to an area often have unique properties that can help keep the soil rich and moist! Introducing native grasses and trees often helps make farms more sustainable.

We use fossil fuels to run the machines that help to grow our food and ship it all over the world, so even a single carrot grown commercially has a carbon footprint. Eventually our oil reserves will run out, but our need for food will not. More and more people live in cities, and getting food to where people can eat it is just as important as growing the food in the first place. The high price of oil leads to a higher price for fresh, healthy food, creating “food deserts” in poorer parts of cities that often lack large grocery stores. Food deserts can be found in the United States and all over the world, wherever people do not have access to fresh fruits or vegetables. Advancements in technology, like electric-run engines, and alternative energy sources are necessary to feed the world.

When new technology and our knowledge of ecology come together, we can feed our growing populations while preserving our planet for the future.

Every living thing on Earth has its habitat and its home, and that includes us humans. Our ancient ancestors lived in caves, for protection from predators and harsh weather. As humans have evolved and progressed, so have our homes. Whether they be tents, huts, houses, or skyscrapers, human-built structures protect us from the elements and provide functions we’ve come to rely on. Now humanity has transformed large parts of our earth to create a habitat designed specifically for human comfort.

Cities come in many shapes and sizes and are defined by the people living there. Some look more like a village than a concrete jungle. Right now, over half of the human population lives in cities. To support all of these people, cities need complex infrastructures: lines to deliver power and communication, plumbing and waste systems. Networks of wires and cables are laid underground, in the sky, and under the sea for places to have electric energy and internet capability. In most major cities, roads have been paved and subways have been dug so people can travel and transport food easily. There are also cities in undeveloped areas where not everyone has access to clean water, plumbing, and electricity.

The way cities are built now allows few animals to coexist with people. Biodiversity may be low, but there is still wildlife among us. In some cities, it’s not uncommon to see a pigeon, rat, or raccoon enjoy a snack out of a garbage can. There are also unexpected animals in cities who take advantages of these unusual ecosystems in new ways. Peregrine falcons, who have evolved to nest on tall cliffs, can now be found perched and nesting on skyscrapers. The rhesus macaque monkey scavenges in the markets of Indian cities. And in Albi, France, catfish, which usually stay at the bottom of a pond, actually jump out of the water to eat nearby unsuspecting pigeons.

As our population grows, so do our cities. Streets, fences, and walls cut off natural animal movement and light pollution disrupts the natural habits of nocturnal animals. The more concrete we lay down to build, the more wildlife habitat we destroy. Each decade, an area of wilderness the size of Great Britain is destroyed for city expansion worldwide.

Yet there are ways to build our cities without having to completely sacrifice our natural ecosystems. Some cities are starting to integrate plants into their urban planning. In 2015, giant vertical hanging gardens were built in Singapore. These 164-foot-tall steel structures are called “super trees,” and although they are not actual trees, there are so many plants growing on their sides that they naturally cool the area. In parts of Africa, North America, and Europe, passageways for animal migration are being built underneath highways so wildlife can pass through uninterrupted by roads.

Cities are the world leaders in finding ways to use renewable energy. In 2013, Malmö, Sweden, became Europe’s first “carbon neutral neighborhood.” It was powered entirely by renewable energy, including wind and solar power and the burning of compost. Their cars and buses were run on electricity and biofuel made out of food waste instead of gasoline. In 2015, Burlington, Vermont, became the first U.S. city to use renewable energy for 100 percent of its electricity. Since then, over 40 cities (and the number keeps growing!) in America have also pledged to be powered by 100-percent clean renewable energy before the year 2050.

People are responsible for building our cities, and we choose how they impact nature. With proper planning, we can preserve or even create wildlife habitats and lessen harmful impacts on nature.

Development and progress are good things! But as we continue to grow and work to provide for all humankind, we also need to be mindful of the ways we affect the natural world. By understanding the main ways we impact the environment, we can build and farm more sustainably.

DEFORESTATION

Forests around the world have been clear-cut for timber logging and to make space for farms, ranches, buildings, and other development. This creates many problems, such as stormwater runoff and loss of habitat for animals. We also depend on large forests to absorb carbon from the air and to create oxygen; scientists estimate that 15 percent of unwanted greenhouse gases in the atmosphere come from rapid deforestation and a lack of trees to filter the air. When a large forest is cleared, it alters the area’s rain and weather patterns. Water that once was absorbed by the trees and plants flows freely into and over the ground, causing erosion and the pollution of nearby rivers.

INVASIVE SPECIES

Many of the crops and domesticated animals we rely on are from different parts of the world. However, the introduction of invasive species in the wild can harm an ecosystem.

Sometimes invasive species are brought to a new region on purpose with unintended impacts. For example, your neighbor might love his pet python, but if it escapes, it can wreak havoc on nearby animals. The kudzu plant was brought to the United States as a garden novelty. Now kudzu is a rampant weed in the Southern United States that smothers other plant life and sometimes entire vehicles and buildings! Sometimes invasive species are introduced by accident, like the Mediterranean fruit fly, which infests fruit with its larvae. When produce is transported all over the world, so is this pesky fly, which now threatens crops globally.

The animals and plants in a local ecosystem have evolved to compete only with each other, and when a new species is introduced, it can become invasive, dominating the landscape and out-competing the local species for resources, which can destroy the ecosystem. Right now, we can see this happening in the American Great Lakes, where invasive species like zebra mussels threaten entire ecosystems.

OVERHARVESTING

Overfishing, overhunting and overgrazing are major strains on our ecosystems. Overharvesting occurs when we use our natural resources at a faster rate than they can be replenished. Some animals, like the passenger pigeon, have been overhunted to extinction. We are depleting the ocean of marine life by indiscriminately fishing in massive amounts, killing off marine species before they have had a chance to breed. Often, large-scale industrial fishing nets catch and kill animals people don’t even eat, which is called bycatch. We are overusing the land for livestock, and overgrazing grasslands. Without enough grass roots to stabilize it, the soil erodes quickly. Large monocrop farms tax the soil and deplete it of nutrients. All of this makes plants harder to grow, and can even lead to soil death. Farming, fishing, and herding on a large scale are necessary to support our population. But we need to use our resources in sustainable ways so that they do not become depleted.

DESERTIFICATION

A drought or rise in temperature—combined with human activity like deforestation, overgrazing, or the overexploitation of soil—can lead to desertification. Dust storms become frequent, and nothing can grow in the dry, nutrient-depleted land. Even the most fertile land can be turned into a desert. The United States experienced its own desertification problems when the Dust Bowl of the 1930s was created by bad farming practices and overgrazing. Land can bounce back with the correct intervention, like growing and rotating an appropriate succession of crops or, with luck, by a rainy season. But desert can also spread. For example, the Gobi Desert in China is getting larger every year by 1,300 square miles because of overgrazing and deforestation in the surrounding areas. Global warming continues to speed the process of desertification worldwide.

POLLUTION

We have all seen someone throw trash out of their car window or drop litter on the sidewalk. Although this is annoying, the most harmful type of pollution comes from chemicals that are overabundant or in the wrong place. When chemical compounds, both naturally occurring and synthetic, are overused or disposed of in the wrong way, they can wreak havoc on our ecosystems.

There can be too much of a good thing. For example, phosphorus and nitrogen are necessary for plants to grow, and we depend on chemical fertilizers that include these nutrients for large-scale farming. But our overuse of these fertilizers has caused agricultural runoff, which has polluted the groundwater in the Mississippi basin. All of that water flows into the Gulf of Mexico, where the excess chemicals cause an extreme algae bloom, which uses up most of the oxygen in the water. Low-oxygen water can’t support life, and every year, this pollution creates a “dead zone” the size of New Jersey where no marine life can survive.

It’s also harmful when toxic chemicals enter the ecosystem. For example, mining operations and the burning of coal release tons of mercury into the atmosphere every year. Too much mercury can cause nerve and kidney damage in humans. And certain chemicals in plastics and medications act as endocrine blockers (affecting hormones); when they are thrown away or flushed down the toilet, their harmful chemicals contaminate our water and harm fish and other water creatures.

Light and sound pollution also have a negative effect on wildlife. To see how this works, we can look at a new problem for baby sea turtles. For thousands of years, baby sea turtles have hatched on beaches at night and relied on moonlight to guide them toward the ocean. But bright lights from beachfront towns confuse many turtle hatchlings, making them follow electric lights away from the ocean. Many towns turn off their lights during turtle hatching seasons, but in the places that don’t, entire generations of turtles have been lost. Sound pollution also confuses animals and cuts off their communication with each other during important mating seasons. There have even been extreme cases of submarine sonar causing hearing loss in whales, destroying their ability to navigate the ocean.

Climate Change

The earth’s climate has changed a lot over 4.5 billion years. Before human beings even existed, the earth experienced at least five Ice Ages and warmings due to small changes in its orbit. Since the last Ice Age, Earth has had a climate ideal for supporting human life. But now, a new type of climate change threatens our existence, and it’s not due to the shifting of Earth’s position in relation to the sun—it is because of humanity’s own actions. The excessive burning of fossil fuels is causing the climate to warm, and the effects will devastate the planet we call home.

Since the Industrial Revolution, humans have made wonderful advances in technology, but we have also increased our use of energy. Right now, humanity’s main sources of fuel are coal, gas and other fossil fuels that are burned to release energy. When they are burned, they rapidly release carbon dioxide and other greenhouse gases that pollute the atmosphere. The cycling of carbon is a natural process in our ecosystems, and carbon has many natural reservoirs, like forests and underground rocks. But we are releasing too much carbon at a faster rate than our carbon reservoirs can absorb. That means that these greenhouse gases linger and build up in our atmosphere and oceans. These greenhouse gases over-insulate our planet, trapping the sun’s heat much longer than is normal before it escapes back into space. This trapped heat raises global temperatures.

Scientists measure global climate of the past by looking at ice cores, fossils, sedimentary rocks, and tree core samples. Satellites orbiting the planet and a network of sophisticated scientific instruments on earth are used to measure recent climate change. Our planet’s temperature has raised approximately two degrees Fahrenheit over the past 100 years, and most of that change has happened in the past few decades. Two degrees may seem small, but measuring climate over a long period of time is different than measuring the daily temperature. The difference between the climate of the last Ice Age—when the United States was covered in 3,000 feet of ice—and today is less than nine degrees Fahrenheit in total. By measuring the climate in recent years, scientists have seen a pattern of longer and hotter summers. Extremely cold winter days are less frequent and the number of extremely hot days per year is increasing. For the past decade, we have had some of the hottest years for the global temperature in human history.

The overwhelming majority of scientists agree that global warming is caused by human activity and the burning of fossil fuels. As the global climate continues to rise at this rapid rate, scientists predict that in the next century there will be more frequent natural disasters and many inhabited parts of the earth may become too extreme for human life. But there is hope! If humanity works together to reduce the amount of greenhouse gases in the atmosphere, we can slow down and maybe even stop the negative effects of global warming. By changing how we use our resources, we can give people and the planet more time to adapt to our changing climate.

Global Warming Causes

A RISE IN SEA LEVELS

As glaciers and sea ice melt, more water is released into the ocean. For the past twenty years, sea levels have been rising at a rate of about three millimeters per year. That may seem small, but the ocean is enormous, so it takes a lot of water to make the entire ocean rise three millimeters! The rise in sea levels has already caused erosion, storm surges, and flooding in coastal cities. If this continues, it could lead to even larger problems, and possibly the total flooding of low-lying coastal cities.

THE ACIDIFICATION OF THE OCEAN

Excess carbon dioxide has nowhere to go but the surface of the ocean and into the air, causing the ocean’s acidity to increase. In the past 200 years, the ocean’s acidity level has risen by 30 percent, the fastest rate seen in the past 50 million years. Many marine animals, including coral reefs, cannot survive this change.

EXTREME WEATHER

A warmer climate means that more water evaporates from the ocean, creating more intense rainstorms. Warmer oceans also mean that hurricanes can grow much larger and travel much farther than they previously could. Meanwhile, the warmer climates cause dry parts of the world to become drier, which means more frequent and extreme droughts and larger forest fires.

MELTING OF THE POLAR ICE CAPS

One of the clearest indicators of global warming is the melting of the polar ice caps and surrounding permafrost. We depend on those ice caps to reflect the sun’s heat back into space and ultimately cool the entire planet. Melting sea ice is the largest contributor to higher sea levels.

THE EXTINCTION OF CERTAIN SPECIES

As extreme changes in the environment continue, not all plant and animal species will be able to adapt quickly enough to survive. Right now, cold weather animals continue to migrate in search of their shrinking natural habitats. Some animals, like polar bears, who live on sea ice, may eventually lose their habitat completely. Deserts are getting hotter and harsher, and with an increase in dust storms and evaporation, animals are being pushed farther to the deserts’ edges. All over the world, animals are migrating to escape the effects of global warming.

Protecting Our Planet

Truly seeing and understanding our world is the first step to protecting it. In this book, you have learned about ecosystems all over the world, why they are important, and how they are at risk of being destroyed. You have seen how mountains are connected to rivers and oceans, why forests are important to the atmosphere, and how the faraway ice caps keep our whole planet cool. The natural world and its wildlife provide us with irreplaceable benefits. With a new understanding of our earth, we can begin to protect it. As the great conservationist Jane Goodall said, “Only if we understand, will we care. Only if we care, will we help. Only if we help shall all be saved.” There are many things we can do to preserve the natural world. Never forget that you have the power to protect our planet!