Weather can change from hour to hour or day to day. It can change month to month or even from year to year. Climate is different. Climate is the pattern of weather in a certain area over a long period of time. Climate is usually the weather pattern over 30 years or more. A desert might have a rainy week. Still, it usually gets very little rain. It has a dry climate.  Living things change so that they can survive in different climates. Polar bears have ways to keep warm in the cold. Cactus plants in the desert can hold in water. There are many different climates in the world. That is one reason there are so many different animals. Climates change very slowly. It takes hundreds or even thousands of years. As climates change, plants and animals that live in the area must change, too. If they do not, they might die out. Earth's Changing Climate Earth's climate has changed many times. At some points, it has been much warmer than it is now. It has also had periods where it is very cold. These are called ice ages. Glaciers are big sheets of ice. They grow much bigger during ice ages. The last ice age began about 2 million years ago. It ended about 18,000 years ago.  Warmer temperatures have caused the glaciers on Earth to get smaller. The glaciers have not disappeared completely, though. They still exist in Antarctica and Greenland. Hundreds of years from now, the glaciers may grow again.  Scientists who study climate look for proof of past climate change. They can find proof in many different places. Glaciers leave many clues behind them. They scratch and rub rocks as they move. They leave little bits of rocks behind. This sometimes forms mounds or ridges. They also form long, oval-shaped hills. Finding certain rocks can also show that a glacier was there. Scientists also look at fossils. Fossils show the kinds of animals and plants that were around at different times. This tells scientists how big the glaciers were. Tree rings also tell us about the climate. The size of each tree ring shows how much a tree has grown each year. Trees do not grow as much when it is very cold or dry. When this happens, the rings are closer together.  Climate changes happen over shorter periods, too. There was a "Little Ice Age" that lasted only a few hundred years. It happened mostly during the 1500s and 1600s. During this time, the world was about 2-3 degrees Fahrenheit cooler than it is today. This may not seem like much. Still, it was enough to cause some pretty major changes.  Some climate changes are almost predictable. El Niño is a good example of this. It is a weather pattern that happens every few years. First, very warm waters move around in the Pacific Ocean. They head toward South America. Then, the air there becomes warmer and strong storms and winds happen. A year or two later it goes back to normal. Then the cycle repeats. Natural Causes Of Climate Change Climate changes happen for many reasons. Sometimes wind and oceans change naturally. This can change the climate.  Earth's relationship to the sun also affects climate. How the sun's rays hit Earth can change how hot it is. How far away the Earth is from the sun also makes a difference. These things change slowly over time.  Sometimes, large rocks from space fall onto Earth. These are called meteorites. They can also cause a change in the climate. If a meteorite hit Earth, it would send huge amounts of dirt and dust into the air. This would block some of the sun's rays. The Earth would become cold and dark. Many scientists believe that this is how dinosaurs died out. Dinosaurs could not survive in a cool, dark climate. The continents on Earth have moved over millions of years. The movements of oceans have also changed. Both of these changes had effects on climate.  Another cause of climate change is called the greenhouse effect. Earth is surrounded by a cloud of gases. This is called the atmosphere. You can think of it as a blanket of air. It holds in heat, keeping the planet warm. The greenhouse effect happens when gases trap the sun's heat in the atmosphere. Gases that do this are called greenhouse gases. Adding too many of these gases to the atmosphere slowly makes the Earth warmer.   Human Causes Of Climate Change Humans do many things that create greenhouse gases. People burn coal, oil and gas. They do this to power their cars and homes. This creates greenhouse gases.  Trees soak up carbon dioxide. Carbon dioxide is a greenhouse gas. This means that cutting down forests also adds to the greenhouse effect.  Landfills release greenhouse gases, like methane. This happens when garbage rots.  Many scientists worry about the changes in Earth's climate. The Earth has been getting warmer and warmer. It is getting warmer faster than it would naturally. This is called "global warming."  Global Warming Scientists worry that the Earth will get so warm that ice caps will begin seriously melting. This could happen in the next 20 years. This would cause the sea level to rise. Major floods would happen. Climate change could also cause more hurricanes, storms and tornadoes. Some places would get much more rain and snow. Other places would get much less. Places where crops now grow could become deserts.  Animals may not be able to survive if the climate changes. Humans will have a hard time, too. Certain crops are very important to some countries. The same crops may not grow if the climate gets warmer. Some diseases could spread further, too.  The Earth will continue to get warmer unless steps are taken to stop it. Most scientists say that we must put less greenhouse gases into the atmosphere. There are many ways to do this. Some are listed below.
  • Drive less. Use trains and buses, carpool, walk, or ride a bicycle. 
  • Fly less. Airplanes release huge amounts of greenhouse gas. 
  • Reduce, reuse and recycle. 
  • Plant a tree. Trees soak up carbon dioxide, keeping it out of the atmosphere. 
  • Use less electricity. 
  • Eat less meat. Cows are one of the biggest methane producers. 
  • Use types of power that do not burn coal, oil or gas. Instead, use power from the wind or the sun.
The climate has changed many times during Earth's history. These changes happened slowly, over thousands of years. Humans started changing the climate about 200 years ago. Scientists are still trying to understand what the consequences might be.
 

 

Earth's Changing Climate
The most recent phase of climate change has resulted in warmer, drier weather.
adapt
Verb

to adjust to new surroundings or a new situation.

aerosol can
Noun

container of liquid material under high pressure. When released through a small opening, the liquid becomes a spray or foam.

agricultural development
Noun

modern farming methods that include mechanical, chemical, engineering and technological methods. Also called industrial agriculture.

agricultural technology
Noun

the art and science of complex machines used to perform tasks associated with farming and ranching.

animal
Noun

organisms that have a well-defined shape and limited growth, can move voluntarily, acquire food and digest it internally, and can respond rapidly to stimuli.

annual
Adjective

yearly.

Noun

layers of gases surrounding a planet or other celestial body.

Noun

an invisible line around which an object spins.

breadfruit
Noun

large fruit native to trees found on islands in the south Pacific Ocean.

carbon dioxide
Noun

greenhouse gas produced by animals during respiration and used by plants during photosynthesis. Carbon dioxide is also the byproduct of burning fossil fuels.

carpool
Noun

system of transportation where one car transports several riders.

century
Noun

100 years.

chlorofluorocarbon (CFC)
Noun

chemical compound mostly used in refrigerants and flame-retardants. Some CFCs have destructive effects on the ozone layer.

Noun

all weather conditions for a given location over a period of time.

Noun

gradual changes in all the interconnected weather elements on our planet.

climatologist
Noun

person who studies long-term patterns in weather.

coal
Noun

dark, solid fossil fuel mined from the earth.

coincide
Verb

to occur at the same time.

consequence
Noun

result or outcome of an action or situation.

continental plate
Noun

tectonic plate found beneath continents.

Noun

agricultural produce.

Noun

steady, predictable flow of fluid within a larger body of that fluid.

debris
Noun

remains of something broken or destroyed; waste, or garbage.

decade
Noun

10 years.

decompose
Verb

to decay or break down.

decrease
Verb

to lower.

deposit
Verb

to place or deliver an item in a different area than it originated.

Noun

area of land that receives no more than 25 centimeters (10 inches) of precipitation a year.

development
Noun

construction or preparation of land for housing, industry, or agriculture.

dinosaur
Noun

very large, extinct reptile chiefly from the Mesozoic Era, 251 million to 65 million years ago.

dramatic
Adjective

very expressive or emotional.

Noun

period of greatly reduced precipitation.

drumlin
Noun

earthen mound shaped by glaciers.

dry climate
Noun

climate group that experiences low precipitation.

electricity
Noun

set of physical phenomena associated with the presence and flow of electric charge.

Noun

irregular, recurring weather system that features a warm, eastern-flowing ocean current in the eastern Pacific Ocean.

emission
Noun

discharge or release.

emit
Verb

to give off or send out.

engulf
Verb

to surround or submerge.

enormous
Adjective

very large.

environment
Noun

conditions that surround and influence an organism or community.

Noun

imaginary line around the Earth, another planet, or star running east-west, 0 degrees latitude.

expansion
Noun

process of enlarging.

extinct
Adjective

no longer existing.

factory
Noun

one or more buildings used for the manufacture of a product.

Noun

material, usually of plant or animal origin, that living organisms use to obtain nutrients.

forest
Noun

ecosystem filled with trees and underbrush.

Noun

remnant, impression, or trace of an ancient organism.

fossil fuel
Noun

coal, oil, or natural gas. Fossil fuels formed from the remains of ancient plants and animals.

fossilize
Verb

to become a solid mineral.

Noun

mass of ice that moves slowly over land.

Noun

increase in the average temperature of the Earth's air and oceans.

Noun

phenomenon where gases allow sunlight to enter Earth's atmosphere but make it difficult for heat to escape.

greenhouse gas
Noun

gas in the atmosphere, such as carbon dioxide, methane, water vapor, and ozone, that absorbs solar heat reflected by the surface of the Earth, warming the atmosphere.

Noun

environment where an organism lives throughout the year or for shorter periods of time.

hurricane
Noun

tropical storm with wind speeds of at least 119 kilometers (74 miles) per hour. Hurricanes are the same thing as typhoons, but usually located in the Atlantic Ocean region.

hydrochlorofluorocarbon
Noun

greenhouse gas often used as an industrial cooling material.

hydrofluorocarbon
Noun

greenhouse gas often used as an industrial cooling material.

ice age
Noun

long period of cold climate where glaciers cover large parts of the Earth. The last ice age peaked about 20,000 years ago. Also called glacial age.

Noun

thick layer of glacial ice that covers a large area of land.

impact
Noun

meaning or effect.

interglacial period
Noun

time between ice ages, when global temperatures are warmer and sea levels rise.

Noun

body of land surrounded by water.

landfill
Noun

site where garbage is layered with dirt and other absorbing material to prevent contamination of the surrounding land or water.

Noun

distance north or south of the Equator, measured in degrees.

Little Ice Age
Noun

(~1600-~1850) period of cooling climate (~1° Celsius), documented largely in the Northern Hemisphere.

malaria
Noun

infectious disease caused by a parasite carried by mosquitoes.

massive
Adjective

very large or heavy.

merge
Verb

to combine.

Noun

rocky debris from space that enters Earth's atmosphere. Also called a shooting star or falling star.

methane
Noun

chemical compound that is the basic ingredient of natural gas.

Noun

material, such as earth, sand, and gravel, transported by a glacier.

Noun

type of fossil fuel made up mostly of the gas methane.

oil
Noun

fossil fuel formed from the remains of marine plants and animals. Also known as petroleum or crude oil.

orbit
Noun

path of one object around a more massive object.

organism
Noun

living or once-living thing.

paleontologist
Noun

person who studies fossils and life from early geologic periods.

Pangaea
Noun

supercontinent of all the Earth's landmass that existed about 250 million years ago.

phase out
Verb

to get rid of in stages, or stop using over time.

plant
Noun

organism that produces its own food through photosynthesis and whose cells have walls.

plate tectonics
Noun

movement and interaction of the Earth's plates.

polar climate
Noun

climate group found within the Arctic and Antarctic Circles.

pollutant
Noun

chemical or other substance that harms a natural resource.

predictable
Adjective

regular or able to be forecasted.

preventive
Adjective

slowing or stopping.

proportion
Noun

amount.

public transportation
Noun

methods of movement that are available to all community members for a fee, and which follow a fixed route and schedule: buses, subways, trains and ferries.

radiate
Verb

to move outward from a central spot.

rainfall
Noun

amount of precipitation that falls in a specific area during a specific time.

range
Noun

agricultural land where livestock graze.

recede
Verb

to retreat or withdraw.

refrigerant
Noun

substance used to keep materials cool.

relocate
Verb

to move a residence or business from one place to another.

retreat
Verb

to go back to a familiar or safe place.

rock
Noun

natural substance composed of solid mineral matter.

scour
Verb

to rub harshly, often to polish.

Noun

base level for measuring elevations. Sea level is determined by measurements taken over a 19-year cycle.

Noun

period of the year distinguished by special climatic conditions.

Noun

solid material transported and deposited by water, ice, and wind.

sedimentary rock
Noun

rock formed from fragments of other rocks or the remains of plants or animals.

severe
Adjective

harsh.

solar power
Noun

rate of producing, transferring, or using solar energy.

starvation
Noun

dying from lack of food.

storm
Noun

severe weather indicating a disturbed state of the atmosphere resulting from uplifted air.

sunspot
Noun

dark, cooler area on the surface of the sun that can move, change, and disappear over time.

technology
Noun

the science of using tools and complex machines to make human life easier or more profitable.

temperate
Adjective

moderate.

Noun

degree of hotness or coldness measured by a thermometer with a numerical scale.

till
Noun

rock, earth, and gravel left behind by a retreating or melting glacier.

timber
Noun

wood in an unfinished form, either trees or logs.

tornado
Noun

a violently rotating column of air that forms at the bottom of a cloud and touches the ground.

trade
Noun

buying, selling, or exchanging of goods and services.

trade wind
Noun

winds that blow toward the Equator, from northeast to southwest in the Northern Hemisphere and from southeast to northwest in the Southern Hemisphere.

transportation
Noun

movement of people or goods from one place to another.

tree ring
Noun

layered formation in the trunk of a tree that marks its growth at least once a year.

tropical
Adjective

existing in the tropics, the latitudes between the Tropic of Cancer in the north and the Tropic of Capricorn in the south.

tropical disease
Noun

sickness that usually occurs in a warm, humid climate.

typhoon
Noun

tropical storm with wind speeds of at least 74 miles (119 kilometers) per hour. Typhoons are the same thing as hurricanes, but usually located in the Pacific or Indian Ocean region.

vapor
Noun

visible liquid suspended in the air, such as fog.

Noun

an opening in the Earth's crust, through which lava, ash, and gases erupt, and also the cone built by eruptions.

Noun

state of the atmosphere, including temperature, atmospheric pressure, wind, humidity, precipitation, and cloudiness.

weather pattern
Noun

repeating or predictable changes in the Earth's atmosphere, such as winds, precipitation, and temperatures.

West Nile virus
Noun

infectious disease spread by mosquitoes, with symptoms ranging from mild flu to possible death.

Noun

kinetic energy produced by the movement of air, able to be converted to mechanical power.

yellow fever
Noun

infectious disease spread by mosquitoes, primarily affecting the liver.