Section 16.1: Human Population Growth and Natural Resources Biology

Objectives How is the human population stretching the Earth’s carrying capacity? How is the growing human population exerting pressure on Earth’s natural resources? Explain how effective management of Earth’s resources will help meet the needs of the future.

Earth’s carrying capacity Thomas Malthus: 1700s First proposed that human population was growing faster than Earth’s resources could support His observations and predictions are still being used today Today’s human population is about 7 billion people, higher than earlier predictions of what the Earth could hold Do not know the exact number of people that can be supported, but it is not unlimited, and it changes depending on how we utilize resources

Technology and human population Human modifications has changed the carrying capacity of Earth Agriculture, transportation, medical advances, and sanitation Farming Farming equipment has allowed for vastly more food production than simple human and animals could have ever produced Medical Advances Contributed to population growth Decrease in infant mortality, death from infection prevented by antibiotics and antiseptic cleaners

Nonrenewable resources Nonrenewable resources are resources that are used faster than they form Oil and coal make up the majority of our energy use Made from dead organisms that have been concentrated over thousands of years 2006: 77 million barrels per day of oil This growth cannot continue indefinitely, new technologies need to be developed to use other forms of energy

Renewable Resources Renewable Resources: Resources that cannot be used up or can replenish themselves over time Wind and Solar Energy cannot be used up by humans Plant and animal resources are renewable because they could last indefinitely if allowed to regrow and reproduce over time Need to be replenished faster than they are used If renewable resources are not used carefully they can become nonrenewable

Drinking water Currently drinking water is a renewable resource Pollution (pesticides, industrial waste, and other contaminants) have been found in water sources This contaminates water sources for millions of people Groundwater is also being extracted from aquifers faster than it is being replaced This is one of the reason’s the drought in California has been going on for so long Both contamination and overuse can lead to a loss of this renewable resources

waste The United States uses more resources and produces more waste than any other country on Earth 230 million tons of garbage per year 4.2 pounds per day per person (1 ton per person per year) If we all generated that must trash (everyone on Earth) could our planet sustain our usage and out waste?

Easter island First landed in A.D. 400 and 700 Thick forest, rich soil, with many bird species Human population increased over 1000 years Forests were cut down for boats and houses Trees were not replenished and eventually there were no trees left No trees means no wood for shelter or boats, but also means no habitat for native bird species No boat = no fishing = no food Soil washes away

Easter Island Eventually human population crashed and people left Easter Island Islanders used their renewable resources in a nonrenewable way This had a long term negative effect on the island and on them

Ecological footprint Earth’s carrying capacity is dependent upon how much land is needed to support each person on Earth Ecological Footprint: amount of land necessary to produce and maintain enough food and water, shelter, energy, and waste Size of ecological footprint depends on number of factors Factors: Amount of resources Efficient use of resources Amount and toxicity of waste produced

Ecological Footprint Many decisions need to be made about the way humans live and use their resources Waste production and management Rules to regulate resource use and waste production How much resource use and waste production should individuals and populations be allowed? How much land is needed for agriculture, living space, other uses? How much water for crop irrigation and for humans drinking water? Humans need to move away from consumerism to sustainability

Output Use the Frayer model to define nonrenewable and renewable resources. The progressive increase in Earth’s human carrying capacity came from advances in technology. What density-independent and density- dependent limiting factors may prevent the human population from continued growth?