8.2 3.1.3 environment  (Page 3/8)

Many people associate the greenhouse effect with global warming. In fact, there is so much confusion, that these terms are sometimes used interchangeably. Thegreenhouse effect is naturally occurring on most planets, and it is necessary on Earth to maintain life as we know it.

Without the greenhouse effect, the temperature of the Earth might be as much as 30˚C cooler! That would alter the surface of the Earth significantly,covering much of it with ice. We need the greenhouse effect to survive on Earth.

However, there can be too much of a good thing. Human beings have begun adding a large amount of greenhouse gases, primarily carbon dioxide, into ouratmosphere. This came mostly with the industrial revolution when we began to burn coal and gasoline, and now many other fossil fuels (such as propane,natural gases), and even wood, in great quantities. With this increase in carbon dioxide in our atmosphere, there is more gas to absorb energy. With moreenergy being absorbed, the temperature of the atmosphere is beginning to increase, causing changes within our weather patterns, and other influences onthe ecosystems of the Earth. This is called climate change.

In the past few decades the population of the Earth has doubled to over six billion people. These six billion people foster a large increase in automobiletransportation; the major source of the increase in greenhouse gases. The greater population has also required more resources such as land. Large amountsof forest have been cut down. Trees are one of the most important organisms that actually remove carbon dioxide from the atmosphere during photosynthesis.So not only are humans adding more carbon dioxide to the atmosphere, but they are also destroying trees that would otherwise be helping to absorb excesscarbon dioxide from the atmosphere.

We will not know the full impact of global warming until perhaps the middle of this century. This is because it takes so long for the full impact to be felt.You may remember that water vapour and carbon dioxide are a very small part of the makeup of our original atmosphere (see Module 5, Tutorial 1). So as we addcarbon dioxide from burning fossil fuels there is only a very small change in the makeup of our atmosphere. In fact it takes a long time for the atmosphereto mix in the added greenhouse gases fully. Scientists say that even if we halted the release of greenhouse gases today, the climate would continue towarm until about the year 2050 as the atmosphere reaches a new stable state.

The effect of humans on biodiversity

This section will summarize some of the impacts that human’s have had on the natural environment, focussing on our impact on the biotic (living)environment.

Summary

Destruction of biodiversity - hunting, pollution, destruction of the natural environment and introduction of alien species can result in the extinction of native species.

Introduction of alien invasive species: These are plants and animals that are NOT indigenous to a particular country. The plants and animals grow rapidly as they are alien and have no naturalpredators to feed on them.