What is global warming?
The global warming resulting from the build-up of pollutants such as carbon dioxide, the halocarbons (such as CFCs), methane, nitrous oxide and other greenhouse gases presents humanity with an unprecedented challenge.
The composition of the atmosphere is undergoing a radical change as we consume more and more energy, demand new products from industry and intensify agriculture to feed an ever-increasing population.
Greenhouse gases shroud the Earth, allowing heat and light from the Sun to pass down through the air unhindered but trapping heat emitted from the planet's surface before it can escape to space. This is the greenhouse effect.
According to current estimates, the greenhouse effect will warm the planet by up to 3 degrees Celsius by the year 2050. This is a change in climate on the scale that brought the planet out of the most recent Ice Age — all within decades, rather than the thousands of years it took the ice sheets to retreat.
Climate zones will move towards the poles as global warming progresses. The coniferous forests of northern latitudes could be all but lost, replaced by deciduous woodland. The grasslands of the continental interiors will spread towards the poles. Some species and ecosystems will become extinct as the rate of change exceeds their ability to adapt.
Warming of the world's ice masses and of the oceans will result in a rise in sea level — perhaps by as much as one metre by the end of the 21st century. Even a rise of tens of centimetres would have major consequences. three billion people live in low-lying coastal zones.
The northern continental interiors may dry out, resulting in frequent drought — the "dust bowl" conditions experienced in the United States during the 1930s. This would have major implications for crop yields, with global repercussions as North American production accounts for a substantial proportion of the world's grain reserves.
With world reserves depleted and food aid diminishing, harvest failure in the Third World will lead to ever more tragic levels of starvation and famine. It is feared that the dry regions of the tropics will become drier, while the monsoon regions may receive more rainfall, leading to catastrophic flooding.
Predicting the ultimate impact of global warming is a difficult matter. It is, nevertheless, possible to forecast with absolute precision the people who will experience the greatest impacts — it will be the poor, the vulnerable, those living on the margins of survival due to social injustice, economic deprivation or environmental degradation.
At the root of this crisis is the waste, the overconsumption, the lack of justice and the misplaced priorities that characterise the model of development — of economic growth — that we have adopted. And it is in combating these failings in our civilisation that we can find solutions to the problem.