Chapter 49: People and the Biosphere

Section 1: Human Population

Human Population

When humans formed ______, they began a long history of profoundly affecting the environment

They to the environment that were not

Because people did not really understand how the natural environments on Earth functioned, they could not assess the effects of their activities on the environment

For a long time, the human population was ______that it was harming the world around it

Over time, the human population has – as has our of the Earth’s fragile environments

Today we are more aware of how our actions affect our world

But at the same time, we are also more capable of permanently damaging not just particular places on Earth but the ______itself

Population Growth

Many environmental problems seem large and urgent today because of the rapid increase in ______

The huge numbers of humans on Earth are making enormous demands on the planet

A population grows when the is greater then the

oBoth of these must be taken into consideration when trying to understand the growth of the human population

Birthrate

Vary dramatically from ______

In the US and much of Europe, the birthrate decreased during the ______

In the ______, American birthrates rose slightly

If current birthrates are maintained, our population will double in less than ______

In some European countries, the growth rate is so low that populations are actually ______

The situation is quite different in other countries

More than ______of the world’s population live in the tropical countries of ______

In some of these countries, the population continues to grow at an annual rate of about ______

Although this rate of growth appears to be low, it will ______the present population in only ______

Deathrate

The deathrate has ______worldwide

Over the past few hundred years, changes in agriculture have made more and better foods available throughout the world

Improvements in the quality and availability of ______have wiped out many deadly diseases and contributed to an increase in the ______of the average person

Effects of Human Population Growth

A high birthrate, a low deathrate, and a longer lifespan all contribute to population growth

As human populations grow, their effects on the environment also grow

Countries with a rapidly growing population are often unable to produce enough ______to satisfy the demand

Today, scientists worry about the destruction of ______

Such devastation seems to be a high price to pay for farmland that is productive for only a few short years

In addition, many of these tropical forests are often cleared by ______

The burning produces large amounts of ______, which is added to our ______

Effects of Lifestyles

It is not population growth alone that causes environmental problems

After all, the rate of population growth in many industrial countries has actually slowed

The ______also contributes to the extraordinary environmental demands made on the Earth

Chapter 49: People and the Biosphere