Science Background Natural Events and Survival 3.10

Bad Stuff Happens… Here on earth, there are natural and man made events that cause a lot of trouble and destruction. In this unit we’ll take a look at these events and their effect on our world. Then we’ll see what we can do to help.

Natural Destruction – Sometimes Mother Nature Makes a Mess…

• Forest and Brush Fires – Sometimes they’re started by people, but lightning is often the culprit in these natural disasters. Fires destroy habitats, killing the animals that live in them or forcing them to move to space nearby. Fires have another, more positive side, however. They burn up old, dead forest material and clear the way for new, healthier growth. Some tree seeds are only able to grow if they are exposed to the very high heat that a fire provides. The bottom line – in some ways, forest fires are a part of a natural cycle that leads to healthy forest growth.

• Floods – Too much rain in a short period of time causes rivers and streams to overflow onto nearby land in an event called a flood. Floods are very destructive events for people and farm animals. They ruin property and kill animals and people. Plants can usually survive floods. Flash floods have rushing water that destroys everything in its path. These types of floods usually occur in areas of hills or mountains where the water has a chance to run downhill into streams and collect very quickly.

• Disease – Diseases don’t just affect people. Plants and animals can be attacked by germs or viruses and killed in huge numbers.

• Erosion – Erosion is the wearing away of soil or rock. It can be caused by wind or water. The problem with erosion is that it leaves areas of ground with no soil. When there’s no soil, most plants can’t grow and the food chain gets messed up. (The plant eaters – herbivores have nothing to eat so they die, and so do the animals that eat them and so on.) People can keep erosion form happening by planting plants in the earth. The plants protect the soil from the drying effects of the sun and plant roots hold soil in place in the wind and rain.

• Earthquakes – Earthquakes are caused when parts of the earth’s crust rub together. (The earth’s crust is like a puzzle. The cracks between the pieces are called faults – when the pieces move, they rub together and we have an earthquake.) In an earthquake:

o The ground shakes violently. o Sometimes large cracks open up in the earth. o Earthquakes near large bodies of water can cause tidal waves that bring extra destruction.

Earthquakes are mostly destructive to houses and buildings and the people and animals inside of them. Entire cities can be destroyed, but animal habitats are usually preserved.

Volcanic Eruption - The most destructive natural event is a volcanic eruption. When a volcano erupts it covers the surrounding land with a killing layer or ash. Nearly everything beneath the ash dies – all animals and plants are destroyed and the land remains a waste area for many years before plants can begin new growth. Sometimes lava (liquid rock) flows from a volcano. Lava burns up everything in its path and then hardens to a layer of stone. It’s the earth’s way of forming new land, but it takes many years for the land to support life.

Man-made Disasters Natural disasters are destructive, but people cause much more damage to animal habitats. Here’s how… • Pollution o Our factories, power plants and cars pollute the air with chemicals. These chemicals come down when it rains and kill plants and fish. o Oil tankers wreck and spill huge amounts of oil into the sea, killing animals that come in contact with the oil and destroying habitats by blocking sunlight to water plants and disrupting the food chain of the spill area. o Factories, farms and people dump pollutants into the water supply, damaging habitats of all living things – including us.

• Deforestation – Sometimes people harvest wood from large areas of land, destroying habitats.

• Bad Farming – Sometimes people grow crops in a way that leaves the soil unable to support new growth. The soil turns to dust and blows away (erosion) and all habitats in the area are destroyed.

• Over harvesting – As our population grows we need more and more food. Our ocean resources (fish, shellfish) have been caught in such huge amounts that they’re running out. How Can We Help? Conservation People are destructive to habitats, but people can help build healthy habitats and stop destruction through conservation. Conservation is doing things to help the environment. Here are some examples:

• Cleaning up and Reducing Pollution o Build factories that create less pollution. o Drive cars that need less gasoline to run. o Build wastewater treatment plants that clean our dirty water before it goes back to the river or the sea. o Insulate our houses so they use less fuel for heating and cooling. o Use less electricity by turning off things we’re not using (Lights, TV’s, etc.) Electricity is produced in power plants that burn coal or gas and cause large amounts of air pollution. o Recycling saves energy, protects our limited resources and helps us to produce less trash.

• Saving Animals and their Habitats o People can create environments that are great habitats for living things. Some examples: planting certain types of plants or building artificial reefs in the ocean to attract sea creatures. o People can help endangered species (animals that are in danger of becoming extinct) by protecting them from hunting, protecting their habitats from destruction and by protecting the animals’ young from predators.