Many things in our world renew themselves -- they come back after we use them up: trees, animals, even water cleans itself again when it evaporates and rains back down.  There are some things in our world that will run out if we use them too much.  The Earth started out with only a set amount of many of the things we use everyday.   What are these things?  Care to guess?  I'll give you a hint.  You're staring at some right now.  That's right: metals that make your computer and phone and car and every other metallic thing you can think of.  How could they possibly run out, you ask?  I'm so glad you asked. 


Three million years ago, this was not a big problem.  There were only around 10 million people on Earth, and they did not need much metal.  They only needed a few simple tools, and they could make these out of the metals they found on the surface of the Earth.  In the last few thousand years, the number of people has grown a lot.  Population is the number of people in one place.  In 1950, the world's population was around 2,500,000 billion.  Now it's around 7,400,000 billion.  Our population has grown a lot in the last 100 years.  As there are more and more of us, we need more and more metals.  


To make machines for all these people in the world to use, we need metals, and those come from one place.  A mineral is anything that is natural, solid, and not living.  Things like salt, diamond, and metals.  Most of them are made as crystals and cannot be made by man as well as the Earth makes them.  Our need for these has risen so much thanks to the rise of machines.  Metals for computers, phones, wires, cars, and almost everything else you can think of that uses things from the earth.  These minerals are made over millions of years and most are found under the ground. 


In the old days, we could find all the metal we needed pushed up to the surface of the Earth.  These days it takes much more work.  Mining means digging different kinds of holes into the ground to pull out minerals.  This changes the environment, because we have to clear away land that supports life.  More trucks drive through the places where mines are found to take the valuable stuff out to a place where it can be processed or sold.  Mines are also dangerous because some of them produce lots of waste that can spill into rivers and streams.  The water in the rivers and streams can carry waste hundreds of miles to be used by people, plants, and animals.  Still, we need these minerals to have all the tools we use today.  


We cannot use many of these minerals again.  Once we turn them into a computer or a car or a phone, they are used and thrown away.  (After the car or computer or phone is dead, of course.)  To consume means to use something up.  We consume food when we eat it and consume gas when we use it to drive.  Once these things are used, we cannot use them again.  There is only so much of each mineral in the ground.  Once it's all used up, it's gone.  Scientists help to watch how much we are using and share what they learn.  People and politicians need to make choices with what they learn to make sure we have everything we need in the future and the environment stays safe and healthy. 


We have a big responsibility on our hands.  As our population, the number of people on Earth, has grown, we have used more and more minerals -- anything that is natural, not living and solid -- from the Earth.  In order to get these, we have to mine, dig deep down into the earth.  The bad news is that once we consume these minerals, use them up, they are gone forever.  So we are hurting the Earth and using up a part of it that will never come back.  Scientists are doing their best to show the world how much people are using, but it does not seem to be working.  People will have to make a choice to use fewer minerals for this to change.  This needs to happen before we run out of important things or hurt even more parts of the Earth. 


References: 

Population Reference Bureau.  "Population Growth"  prb.org, 2010.  <http://www.prb.org/Publications/Lesson-Plans/HumanPopulation/PopulationGrowth.aspx>

OpenStax CNX.  "Mineral Resources: Formation, Mining, Environmental Impact"  cnx.org, 2013.  <https://cnx.org/contents/SF-mRhQa@5/Mineral-Resources-Formation-Mi#id6716868>