that we breathe, and the increase in surface temperatures felt throughout the world.
What percentage of animal species have become extinct over the last 40 years?
According to a 2014 report issued by experts at the World Wildlife Fund, 52% of all animal species on our planet have become extinct in the past 40 years, due to the degradation of our environment.
What is the cryosphere?
The cryosphere is the area of the Earth where water has solidified and includes ice, floating ice, glaciers, permafrost, and snow.
How much of the Earth’s surface is frozen?
About one-fifth of the planet is permafrost, or frozen for all or most of the year.
What do deserts and polar regions have in common?
Deserts and polar regions both have average rainfall of less than four inches (10 cm) per year. Both regions contain some of the driest places on Earth.
What is a jungle?
A jungle is a forest that is composed of very dense vegetation. The term tropical rain forest can often be used interchangeably with jungle. Jungles occur most often in tropical areas such as the Amazon and Congo river basins.
What is a rain forest?
A rain forest is any densely vegetated area that receives over 40 inches (100 centimeters) of rain a year.
What is a tropical rain forest?
A tropical rain forest is a rain forest that lies between the Tropic of Cancer in the north (northernmost latitude around the Earth, where the sun appears directly overhead during the Northern Solstice) and the Tropic of Capricorn in the south (the southernmost latitude around the Earth, where the sun appears directly overhead during the Southern Solstice) or within the “tropics.” Tropical rain forests are known for their very diverse species of plant and animal life. Tropical rain forests exist throughout Central America, northern Brazil, the Congo River Basin, and Indonesia.
Where is the northernmost rain forest?
Juneau, the capital of Alaska, is in the middle of one of the largest and most northerly rain forests in the world, which is located within the Chugach National Forest and Chugach State Park. Other rain forests extend to the northern regions of Japan and Siberia, Russia.
What is a desert?
A desert is an area of light rainfall. Deserts usually have little plant or animal life due to the dry conditions. Contrary to the popular image, deserts are not just warm, sand-swept areas like the Sahara Desert; they can also be frigid areas like Antarctica, one of the driest places on Earth.
How can an area be lower than sea level?
Land in the midst of a continent can be lower than sea level because the land is not close enough to the sea to be flooded with water. Movement of the tectonic plates pushes areas like the Dead Sea in Israel and Death Valley in California to elevations lower than sea level.
What was the highest temperature ever recorded?
World temperature records have been sources of controversy for many years, with many temperature records decertified by such groups as the World Meteorological Organization. For example, the world’s highest temperature, thought to have been recorded in error in the desert in Libya in 1922 as 136 degrees Fahrenheit (57.78 degrees Celsius) was decertified in 2012. California’s Death Valley, in the United States, holds the record set in 1913 for the highest temperature in the world of 134 degrees Fahrenheit (56.7 degrees Celsius).
Do oases really exist?
Oases do exist and they are quite prevalent throughout the eastern Sahara Desert in Africa. An oasis has a source of water, often an underground spring, that allows vegetation to grow. Small towns are located at some larger oases in the desert. Oases have been traditional stopping places for nomads traveling across deserts.
How do sand dunes move?
Sand dunes are created and transported by wind. Wind blows sand from the windward side of the dune to the opposite side, slowly transporting it across the landscape.
What causes erosion?
Wind, ice, and water are the most common agents of erosion. They wear down and carry away pieces of rock and soil. The process is accelerated when trees that help hold the soil in place have been destroyed by fire or have been chopped down. With fewer trees, the soil is easily eroded and washed away, leaving a barren surface where plants can no longer grow.
What does a glacier leave behind?
When a glacier moves across the land, it acts like a giant bulldozer, pushing and collecting rock, dirt, and debris. A moraine is a deposit of rock and dirt carried by a glacier and left behind once the glacier melts and recedes.
What is a tree line?
A tree line is the point of elevation at which trees can no longer grow. The tree line is caused by low temperatures and frozen ground (permafrost).
Glaciers retreating as the last ice age ended left behind the spectacular valley and mountains of Yosemite National Park.
How high is a tree line?
Tree lines vary, depending on where they are in the world and how close they are to a geographic pole. Trees stop growing in mountain regions from around 2,600 feet (800 meters) in places such as Sweden to over 17,000 feet (5,200 meters) in the Andes Mountains in Bolivia.
How do forest fires help forests?
An occasional fire is often necessary for a forest. Forest fires clear undergrowth, giving more room for trees to grow, thus rejuvenating the forest. Since forest fires are usually extinguished by firefighters as rapidly as possible, the amount of undergrowth in forests has increased. This extra undergrowth can become extremely flammable, making fires even more dangerous to people. It is thought by many experts that a policy of allowing the forest to burn naturally, while protecting human structures, produces a more natural environment.
What is tundra?
A tundra is a dry, barren plain that has significant areas of frozen soil or permafrost. Tundra is common in the northernmost parts of North America, Greenland, Europe, and Asia. Although rather inhospitable, there is plant life on the tundra. This life consists of low, dense plants such as shrubs, herbs, and grasses. There are even some species of insects and birds that can survive the harsh conditions of tundra.
ASTEROIDS AND NEAR EARTH OBJECTS
Did an asteroid cause a mass extinction of the dinosaurs?
Known as the Cretaceous-Paleogene extinction event approximately 66 million years ago, a six-mile wide (about 10 km) asteroid struck the Earth. Most scientists believe that this impact might have started a chain of events that led to the extinction of between 71% and 81% of the Earth’s species of animals and plants, including nonavian dinosaurs. Today’s birds, having evolved from surviving dinosaurs over millions of years of evolution, continue living, even after such
