Human's Impact on Environment

Human's Impact on Environment

Hank Green

(Source: http://open.163.com)

（Chinese and English subtitles:王月悦）

Today, people have spent at least 50 years studying man's impact on the environment.While it is difficult to quantify the impact of everyday life on the environment, there is no doubt that our food, housing and love of plastic are eating into entire ecosystems.This spontaneous human activity, seemingly without incident, has led to the extinction of nearly 1,000 species of plants and animals, most of them in the last century.

Even if you don't care about the lions in the barbary, the olive trees in st. Helena, the carrier pigeons, or any other living thing that's dying out, these are creatures that matter to us, and ecosystems are our 24-hour servants: filtering water, treating carbon dioxide in the air, producing food, etc.These ecosystem services are so important, and they are given to us by nature for free, so can we destroy without fear?It is not only for the sake of the creatures that inhabit it, but for our own sake, and we are far more dependent on the ecosystem than we are on each other.

Ecosystem services fall into four categories, all of which we can't solve with our hands or props.First, healthy ecosystems provide support services that create the planet's biological systems and continually replenish them, such as recycling the compounds needed for life, including the carbon cycle, the water cycle, the nitrogen cycle and the phosphorus cycle.It also includes the functions we talked about earlier, such as reconditioning the soil and producing oxygen.Some ecosystems provide more support services than others, but they must be healthy or not.Second, ecosystems also provide a supply of services, raw materials necessary for survival, such as fish from the ocean, while rivers, groundwater and other fresh water sources provide us with water, and plants and animals provide us with all kinds of fiber, which we use to make clothes and houses and fuel.Whether it's dead grass or wood, hydroelectric power or carbon trapped in ancient trees for millions of years, humans are using it, and we're reciprocating by releasing it back into the atmosphere.Third, ecosystems also provide extremely important regulatory services, all of which are designed to save the day.As we learned of their biology: fungi and other microbes decompose dead things and waste, at the same time, the plant can filter the water we drink, breathe the air, and also help flood water, they also absorb all we breathe out carbon dioxide and carbon dioxide, which in turn help regulate the climate.Fourth, cultural services of ecosystem.The ecosystem is amazing, surrounded by thriving plants and happy animals doing what they love to do, so we have a place to play, and Newton has a place to discover gravity.These are invisible and intangible, but important.

Interestingly, economists can calculate the economic value that ecosystems provide to humans.If we were to design the ecosystem we want, we would spend $46 trillion a year, and the global economy produces $6.6 billion a year, and we would be happy not to have to pay for it.The health and integrity of an ecosystem here means that there is enough biodiversity, because an ecosystem is just a bunch of living and inanimate things living together, and if even living things are dying, there will be no living creatures to make friends with human beings.

Biodiversity is so important because it makes ecosystems more resilient to endless change, as we've discussed before.Ecosystems with high biodiversity recover faster from disturbances than those with low biodiversity.In ecosystems with high biodiversity, if one species disappears, the entire ecosystem is unlikely to collapse.A hectare of the amazon rainforest, for example, contains more plant and animal species than all of Europe.So the extinction of an insect species is unlikely to have any serious consequences.In contrast, the sonoran desert is so devoid of life that the loss of one species can affect entire ecosystems.The best way to understand man's impact on the environment is to understand how he affects biodiversity.Unfortunately, it turns out that we've been seriously harming the biodiversity of ecosystems, and some ecosystems at a high level.In some cases, our impact on living things is direct, and in others, our impact on biodiversity is indirect.We've created one or two problems in the ecosystem that affect a whole bunch of organisms.

The amazon rainforest, even though it's one of the most resilient ecosystems in the world, we've had a serious impact on it.We cut down a lot of what makes a forest a forest: trees, by some estimates, we cut down about eight hectares a day to provide land for cattle and wood for coffee tables.When we cut down a hectare of rainforest, we suddenly turn an area inhabited by thousands of species of animals into a place inhabited by just a few: some grass and insects, maybe some mice.And when you do that, a whole bunch of things happen, and they get out of hand, not just to this ecosystem but to the surrounding ecosystem.For example, all those trees that have been cut down provide a service to regulate rainfall in the rain forest. Not only do they absorb a little of the water themselves, but they also slow down the flow, allowing it to seep into the soil or fill up into streams and rivers and eventually reach the sea.But when the trees disappear, the rain hits the ground directly, carrying the mud away, causing soil erosion, carrying all kinds of minerals and chemicals all the way to the sea, and it can affect the Marine ecosystem, and it can have a bad effect, and that's called a knock-on effect.The impact of tree cutting is the most visible and intuitive of human activities.

In addition to causing more flooding and changing water quality, large-scale deforestation can lead to another effect: desertification, or the spread of unproductive landscapes.But cutting down trees doesn't automatically turn forests into deserts. Desertification is caused by other factors, such as overgrazing and overirrigation. Overwatering also has an effect.Over time, the fertile land around the desert eventually became overwhelmed, and the desert began to spread, as has happened in China in recent years.The gobi desert is growing by 3,600 square kilometres a year because of overgrazing and the city's thirst for water.These two effects significantly limit the biodiversity of ecosystems, resulting in fewer trees and fewer people to release oxygen and absorb carbon dioxide.

Climate is one of the key factors.Carbon dioxide is a greenhouse gas, it's the earth's quilt, so the more carbon dioxide in the atmosphere the warmer the earth gets.The point is that forests are shrinking, and we're burning fossil fuels to emit greenhouse gases, which are driving global warming.As a result, the polar ice caps are melting, which means fewer polar bears, seals and seabirds, more temperate animals are moving toward the poles, and drier climates are causing more prairie and forest fires.It is true that climate has changed many times in history, but the process of change usually takes hundreds or even thousands of years, giving life time to adapt or move.These changes will take place in our lifetime, and they are important and complex.

Another important reason is the introduction of exotic species, whether intentional or not, from kudza in North America to cane toads in Australia, with the same far-off ability as popeye ate spinach to kill native species.Finally, our most immediate impact on biodiversity is the overhunting of certain species.We overfish to meet growing demand for things like tuna.We also protect our livestock by hunting, for example, wolves.The less diverse an ecosystem is, the more likely it is to be stirred up.

In fact, all four of these effects could have spawned many more, because human influence on the biosphere is so severe that it almost always stems from the fact that we put so much stuff in the wrong place at the wrong time.