 |
Hotting
up
 The  sun
is getting hotter. It is also incredibly old — about 4,500 million years
old! One day it will blow up but that won't be for another 4,000 million years or so. But the Earth's climate seems to be heating up much much faster than can be explained by the sun making more
heat. And the reason seems to be you people and your  machines
Scientists (called astronomers or cosmologists) who study the sun and stars know
this because they can look at millions of other 'suns' (the stars) and
find out what's happened to the different types over billions of years.
It's this heating up which scientists call 'global warming' or 'climate change
Almost all machines use oil, gas or coal. All of them produce pollution
— you know, the smelly stuff that comes out of car
exhaust pipes and factory chimneys, that sort of thing. Much of this
is a gas you can't see called carbon dioxide (CO2). It's this gas which seems
to be the main cause of the trouble.
  Opening
Pandora's carbon box
Pandora
was a woman who figured in one of the Greek myths. In the myth, the gods gave her a mysterious box. They'd
put something nasty in the box and told her never to open it. But
she was overcome by curiosity and opened the box. Out flew horrible
stuff like plagues, sorrow and misery. She tried in vain to shut
the lid but it was too late: the horrors were free.
A myth is a sort of fairy story. The ancient Greeks made up lots of them over 2000 years ago.
It's a little
like that with fossil
fuels. For millions of years, the planet has been tucking away
its  carbon dioxide in the form of coal, oil, limestone.
This natural sequestering of carbon and burying it deep in the Earth's crust has kept the
climate machine in balance. Too much carbon means global warming;
too little means cooling. Humans have opened the planetary Pandora's
carbon box and let out fossil fuels on a vast scale. Burning them
releases the carbon they contained back into the air as carbon dioxide, CO2.
Coral reefs and limestoneLimestone is a rock formed from carbon, oxygen and calcium: calcium carbonate. Most limestone forms when the skeletons of once-living animals like coral turn into rock. When they were alive, the coral polyp animals built their skeletons out of carbon dioxide and calcium. So, like coal-forming swampy forests, they usefully take carbon dioxide out of the air (though it has to dissolve in the seawater first, which it easily does). The ancestors of today's coral animals have been building vast coral reefs for hundreds of millions of years. These are now limestone rock. Today, as they always have, reefs make nurseries and homes for myriads of living things, so they teem with life. Many people depend on some of this life, like fish. Sadly, pollution and the warming climate are causing many of these giant reefs to die.
'Sequester' means to give up for safekeeping, to remove. So carbon is taken out of the ocean-land-atmosphere carbon cycle and sealed away safely.
|
