AND CAUSES | |
What is climate?
Ever since the human race began to walk the earth, we have been dominated by the climate. Our tribal ancestors were constantly on the move, following large mammals on their migratory routes and trying to avoid the extremes of cold, rain, and heat. But in due course they settled, and learned to adapt to theclimatic surroundings that ruled them.
Today, whoever and wherever we are, the climate still dictates the way we live. The cities we build, the clothes we wear, the kind of homes we live in, the food we eat, even our temperament... all are based on the weather.
Climate is the long-term characteristic weather pattern of any region in the world. And if climate controls us, it in turn isregulated by a myriad of factors - not least the radiation and angle of the sun, the rotation of the earth, the composition of air masses, the proximity and size of the oceans, the height of the mountains, and the depth of the valleys.
What is climate change?
Climate change is a warming or a cooling of the weather. Over the 4.5 billion years that the earth has existed, we have swung between both. Iceages have come and gone, and have lasted for up to 100,000 years.
They have been followed by shorter, warmer periods, one of which we are in at the moment: the earth's average temperature is around 4ºC hotter than it was during the last ice age some 13,000 years ago.
But recently, things have accelerated so much that it is now also half a degree warmer than it was during the 1860s. That maynot seem a very big increase at all, but it is huge for a relatively short timespan of 130 years.
And there is one significant difference between previous periods of warmth and the current one. In the past, they have been due to natural phenomena and have taken thousands of years to evolve, so species have had time to adapt. But this time the cause is the 5.8 billion human beings in the world.Data from ice cores suggest that we are living in the warmest century for 600 years - and we certainly know that the final two decades of the 20th century are the hottest on record. We are turning up the planet's thermostat so fast that nature can no longer cope.
What are the causes?
Every time we turn on a light switch, use a computer, watch TV, or cook a meal, the chances are we are creatingcarbon dioxide (CO2), which is not only the world's most abundant naturally occurring gas with the potential to pollute, but also the principal contributor to global warming.
The electricity we use is generated by power stations, the vast majority of which burn "fossil fuels" - so called because they have been created over millions of years by the slow subterranean decay of vegetation andother living matter. The three fossil fuels we burn are coal, oil, and natural gas, each of which has hydrogen and carbon in its make-up. When they are burned, these components mix with oxygen in the atmosphere. The result is CO2.
We have been pumping CO2 into the air since the Industrial Revolution 200 years ago, and now we are paying the price. Carbon dioxide and other gases, including methane andnitrous oxide (generated by activities such as rubbish disposal, cattle farming, and the use of fertilizers), and highly damaging chlorofluorocarbons (CFCs), have now formed a blanket around the earth. As each year goes by, these gases trap more and more heat that would otherwise escape into space. The heat rebounds onto the earth's surface, and the planet's temperature rises - creating what iscommonly called the "greenhouse effect".
At the speed our climate is changing, the world will soon be warmer than at any time in the last 10,000 years.
Almost 5 billion tons of CO2 are produced each year by people in the prosperous developed world. And we add to the problem every time we drive a car, take a flight, or even burn wood.
Trees are great natural storehouses of CO2, some...