Homo sapiens rise. While homo habilis, homo neanderthalensis and homo erectus die out, leaving us the sole surviving human species. Our capacity for abstract thought, the ability to plan ahead and the ability to record information were necessary to our survival, but also allowed us to mould the world to our will and benefit. As homo sapiens spread many species such as the mammoths and giant ground sloths were hunted to extinction. Humans gradually abandoned the hunter-gatherer life, settling in agricultural communities. This change allowed much larger groups of humans to coexist, and so our settlements grew. Land was cleared for growing crops and animal husbandry and yet more species of plants and animals became extinct. The industrial revolution saw another surge in population as cities grew. In addition to manufacturing, agriculture became industrialized so yet more land was taken for intensives farming as well as for mines and factories. New materials were used and exploited, and harmful chemicals were spread over the land, oceans and atmosphere with no consideration to the environment. Yet more plant and animal species were wiped out; some, like the Dodo and the giant Galapagos Tortoise within a
few years of their discovery. Of course, humans are not the only cause of change to the climate and environment. There are natural cycles in climate, both astronomical and as a result of natural disasters. At one time the British Isles were tropical and the
land covered in jungle. There have also been five ice ages where most of the area of the world was covered in ice, the most recent of which ended about 10,000 years ago. A mini ice age between 1645 and 1715 saw the Thames regularly freeze. As temperatures change so does sea level. When temperatures rise water tied up as ice melts and the seas rise, when temperatures fall more of that water freezes up and the seas fall. Up to about 8,000 years ago the
land which is now under the North Sea was above water and Britain was connected by land to mainland Europe; the English Channel an estuary of the rhine. Volcanoes, earthquakes and asteroid impacts can all throw up vast amounts of dust, blotting out the Sun and causing an immediate and major change in the climate. We are currently in a period of dramatic change to our climate and environment. There are some who claim that this is the result of
natural cycles, however these people are wrong. Virtually all scientists working in the fields
of ecology and climate say that this is not so. In addition to natural effects it is industrial activity by human beings that is the major cause of the changes we are witnessing. Global average temperatures are rising, the weather is becoming more erratic, species are dying out at a rate of an extinction level event, and the sea level is rising as the ice caps at the North and South poles melt. There are two main approaches to these problems, other than denying that they exist and allowing the world to burn. Act now to stop the pollution, or rely on
technological advantages to save us later down the line, so called geoengineering, and hope that the side effects of such technology are not just as devastating as the alternative. In later parts of this series we will look
in detail at some of the effects of global warming, what they mean for us and the way we live, and what is is possible to do about it.