population and climate change
Climate change has been described as the biggest global health threat of the 21st century. World population is projected to reach 9.1 billion by 2050, with most of this growth in developing countries. While the principal cause of climate change is high consumption in the developed countries, its impact will be greatest on people in the developing world. Climate change and population can be linked through adaptation (reducing vulnerability to the adverse effects of climate change) and, more controversially, through mitigation (reducing the greenhouse gases that cause climate change).
The contribution of low-income, high-fertility countries to global carbon emissions has been negligible to date, but is increasing with the economic development that they need to reduce poverty. Rapid population growth endangers human development, provision of basic services and poverty eradication and weakens the capacity of poor communities to adapt to climate change. Significant mass migration is likely to occur in response to climate change and should be regarded as a legitimate response to the effects of climate change. Linking population dynamics with climate change is a sensitive issue, but family planning programmes that respect and protect human rights can bring a remarkable range of benefits. Population dynamics have not been integrated systematically into climate change science. The contribution of population growth, migration, urbanization, ageing and household composition to mitigation and adaptation programmes needs urgent investigation.
There is general agreement that human industrial activity has released vast quantities of greenhouse gases, about 900 billion tonnes of carbon dioxide, 450 of which have stayed in the atmosphere. About 80% of carbon dioxide emission is caused by industrialization and the remaining by land use such as deforestation. There is strong evidence that the burning of fossil fuels since the beginning of the industrial revolution has already caused a 0.758C rise in global temperatures and 22 cm rise in sea level during the twentieth century. During the twenty-first century, the earth’s average surface temperature rises are likely to exceed the realistic target threshold of 28C above preindustrial average temperature. The Intergovernmental Panel on Climate Change (IPCC, the leading body on climate change, comprising over 2500 international scientists) estimates that by 2100, global temperatures could rise by 1.1 – 6.48C and sea level by 28–79 cm. In addition, weather patterns will become less predictable and extreme climate events, such as storms, floods, heat waves and droughts, will occur with increasing frequency and severity.
It is important to recognize two distinct ways in which population issues can be linked to climate change: mitigation (reducing the greenhouse gases that cause climate change) and adaptation (reducing vulnerability to the adverse effects of climate change). Few experts doubt the importance of population in relation to climate change adaptation, but the link between population and climate change mitigation is more controversial. The statement that ‘people cause climate change’ is often made to emphasize that climate change, as it currently unfolds, is a human-induced, rather than a natural, phenomenon. However, the principle cause of climate change is high consumption by people in developed countries where population growth has been low or negative. At national the level, therefore, there is a lack of association between growth of greenhouse gas emissions and growth of populations during the last century. It is more accurate to say that consumers, rather than people, cause climate change; there is enormous variation in greenhouse gas emissions between individuals with high consumption levels in developed nations with low fertility rates, and individuals with low or negligible consumption in poor nations with high fertility rates. In other words, climate change is driven more by consumer behaviour than simply by population number.
Rapid population growth has a negative impact on human development, provision of basic services and poverty eradication; these effects are magnified and become more urgent in the context of climate change. Reducing the rate of population growth has long been a development goal because of the detrimental effect of rapid population growth on economic development. No country, barring a few oil-rich states has risen from poverty while still maintaining high average fertility. In developing countries, where birth rates have successfully declined ( particularly Asia and Latin America) by 25–40%, the resulting economic growth can be directly attributed to fertility decline.
1. Rapid population growth acts in tandem with climate change to deplete key natural resources, such as water, fuel and soil fertility;
2. Rapid population growth can cause a significant increase in demand and often mismanagement of natural resources that are compromised and in decline due to environmental variability and climate change;
3. Population growth heightens human vulnerability to climate change in numerous ways and may force people to migrate to areas that are either environmentally marginal or more at risk to the negative impacts of climate change. For example, population growth in Ethiopia is resulting in soil degradation, dwindling land holdings and low agricultural productivity, which increases pressure on poor people to move either to environmentally marginal or urban areas. This leaves them more vulnerable and more likely to exploit new resources in an unsustainable way, leading to a vicious cycle of poverty and degradation