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which grows greater with each passing day. The extinction of humans from earth is inevitable in the short term. Please read the following: Climate change and population Continuous population growth, fuelled by expected population growth of 2.5 billion by 2050, is multiplying the impacts of climate change and will be ecologically unsustainable. In a world of weather extremes, where land is being lost to desertification caused by rising temperatures, rising sea levels and extreme weather events, the world will not be able to feed, water and sustain even its current 6.6 billion population. As people are forced off their land by climate change, mass migration movements may will be joined by up to 200m environmental refugees. The poorest peoples will be most affected. Although northern temperate climates may benefit in the short term, they too will be affected adversely by climate change. Under these circumstances, Europe and the UK will suffer climate change impacts, and will be in no position to accept greater migration flows. Stabilisation and decrease of populations, globally and nationally, is an essential component of policies to mitigate and adapt to climate change, and urgent action is needed. CLIMATE CHANGE AND POPULATION SIZE: EARTH 1. GREENHOUSE GASES AND CLIMATE CHANGE Earth's atmosphere is the skin of air nearly 600 kilometres thick that envelopes the planet and allows life to survive on it. The lowest band, in which most weather patterns develop, is known as the troposphere, which extends for 8-14 kilometres upwards from the Earth's surface. Above this is a slightly narrower tropopause which also comprises part of the lower atmosphere, topped by the ozone layer in the lower stratosphere. The ozone layer forms a protective boundary between the troposphere and the stratosphere, a layer of upper atmosphere that fills the band about 10+km to 50km above Earth. Above this come the mesosphere, mesopause, thermosphere and exosphere. See NASA: Earth's Atmosphere. The 'greenhouse effect' is a natural process by which naturally occurring greenhouse gases in the Earth's atmosphere, mainly water vapour, ozone, carbon dioxide, methane and nitrous dioxide, trap some of the sun's radiation as it bounces off the Earth's surface. This warming has enabled life to develop on Earth and, without it, the planet would be frozen. However, mainstream climate scientists believe that since the Industrial Revolution an increase in human-induced (anthropogenic) emissions of greenhouse gases is increasing the warming artificially, causing temperatures to rise. Click here for a diagram showing the Greenhouse Effect. The main offender in volume terms is carbon dioxide (CO2), which is released mainly by burning fossil fuels such as coal, oil and natural gas. Carbon dioxide from fossil fuels accounts for 59 per cent of the potential global warming effect of man-made greenhouse gas emissions, and carbon dioxide released by changes in land use, together with other greenhouse gas releases, contribute more than 40 per cent <2000 figures, Pew Center on Climate Change, December 2004>. Carbon dioxide has an atmospheric lifetime of between 5 and 200 years . This means that carbon dioxide emitted into the atmosphere today could cause global warming for two centuries to come. Because carbon dioxide emissions remain in the atmosphere for 5-200 years, levels of greenhouse gas concentration will continue to rise for a long time after annual emissions levels are stabilised and reduced. Not only does carbon dioxide damage the atmosphere - it is also now known to be causing rises in temperature and acidity in the oceans. This is already endangering our food chain by destabilising the marine ecosystem on which it depends. Humans have already used up about one-third of the ocean's potential to absorb the greenhouse gas carbon dioxide - for more information see the report The Ocean in a High-CO2 World .
Some scientists have concluded that a sustainable climate change target means limiting global temperature increase to no more than 2.0 degrees above pre-industrial levels in the 21st century, and add that this threshold is likely to be exceeded by 2050 unless policy measures are taken to prevent it. Greenhouse gases already pumped into the atmosphere already commit us to a global average temperature rise of up to 1.3 degrees. See Climate Action Network: Preventing dangerous climate change and 'Fewer fossil fuel burners' below.
For the official Climate Change Information Kit published by the United Nations Environment Programme and the Climate Change Secretariat for the UN Climate Convention in Milan in December 2003, see UNFCCC Climate Change Information Kit . This report states: "Future greenhouse gas emissions will depend on global population, economic, technological and social trends. The link to population is clearest: the more people there are, the higher emissions are likely to be."
Are the climate scientists wrong?
They might be - even though those who agree that greenhouse gas emissions are the cause of global warming form an overwhelming majority of scientific opinion. However, in spite of large amounts of funding for research into climate change over the last decade, no alternative theory has emerged which is well-evidenced and offers quick solutions. Solar activity alone cannot explain the rise in temperatures. There is also a parallel concept of global dimming' and brightening. This is the finding that the amount of sun reaching the Earth's surface (which warms the air above it) decreased by about five per cent between 1960 and the late 1980s, a trend which has since been reversed. One theory is that this dimming was caused by particle pollution - the adhesion of small water droplets to visible pollution particles in the atmosphere - causing cloud formations which reflect heat back to the sun, which may have reduced additional warming that would have otherwise occurred. This has led some climate scientists (such as Dr Peter Cox, Head of the Carbon Cycle Group, Hadley Centre for Climate Change) that forecasts of global warming may now have to be drastically revised upwards. A temperature rise of 10 degrees Celsius by 2100 could be on the cards. For information on global dimming see the documentary broadcast by BBC TV Horizon in 2005. In the increasingly unlikely event that the world's climate scientists are proved to be wrong, the case for reducing human population to a sustainable level still stands - on the basis of the many other forms of environmental damage being caused by humans to their environment, and because of the speed at which they are depleting finite resources.
The concentration of carbon dioxide in the atmosphere has risen by about a third since 1850 and is higher than it has been for 20 million years. Before the Industrial Revolution carbon dioxide concentrations remained fairly stable at 280ppm (parts per million). Each year since global measurements of CO2 began, the amount of carbon dioxide in the atmosphere has increased. The first readings taken at the Mauna Loa Observatory in Hawaii show that concentrations rose at 1ppm a year in 1958, when they stood at 315ppm. The rate of increase has since accelerated - to an average 1.8ppm annual rise in the 1990s. According to measurements taken from air samples collected from more than 60 sites in the US National Oceanic and Atmospheric Administration (NOAA) Global Cooperative Observing Network, the amount of CO2 in the atmosphere increased by nearly 5 parts per million (ppm) between 2001 and 2003. The increase in 2002 was 2.43 ppm and the increase in 2003 was 2.30ppm. Oil company BP has calculated that half the growth of world carbon emissions in 2003 was due to increased coal burning by China. However, according to the NOAA in Colorado, USA , the rate of carbon dioxide increase returned to a level of about 1.5ppm per year in 2004, indicating that the temporary fluctuation was probably due to changes in the natural processes that remove CO2 from the atmosphere.
Atmospheric carbon is increasing by about 3.5 billion tonnes a year, and the IPCC has projected that if concentrations are not checked, they could reach 650-970 parts per million. Until recently most climate scientists agree that it would be dangerous for concentrations to exceed 550ppm. The threshold that would trigger irreversible and therefore catastrophic global warming is now believed to be as low as 400ppm .
An overwhelming body of scientific evidence indicates a creeping crisis on a vast scale. Average global temperature rose 0.6 per cent in the 20th century. By the end of 2006 – the sixth warmest year on record globally and the warmest in Britain since records began in 1659 - global temperatures had risen by 0.7°C since 1900, with most of this rise in the period since 1976 when temperatures have risen 0.18°C per decade. The 1990s was the hottest decade since records began while the 10 hottest years on record were in the 12 years to 2006, according the UK Meteorological Office. The EU has indicated that a rise of 2 degrees in the 21st century (from pre-industrial levels) is the maximum safe level allowable, a level likely to be exceeded in 2050. The World Wildlife Fund has stated that to keep the increase in global temperature beneath that 2 degree ceiling, global emissions must be cut by half by 2050, with industrialised countries slashing their carbon dioxide emissions by 80 per cent. Yet the Kyoto Protocol currently asks industrialised countries to reduce greenhouse gas emissions by as little as 5 per cent from 1990 levels by 2012. Meanwhile average global surface temperature was forecast by the Intergovernmental Panel on Climate Change in 2001 to rise by up to 5.8o Celsius by 2100. More recently, however, scientists have been predicting higher increases : a large-scale computer projection by the UK’s Hadley Centre for Climate Change in 2005 suggested rises of as much as 11oC while studies by Southampton and Plymouth universities in late 2006 said heat stores in oceans could raise global atmospheric temperature by almost 9oC. Analysis by the Centre for Global Atmospheric Monitoring in Reading (UK) in April 2004 concluded that a rise of 2.7 degrees Celsius in global temperatures could be enough to cause irreversible melting of the 2km-thick Greenland ice sheet, leading to a global sea level rise of 7 metres during the next 1,000 years. .
Climate has always changed: in the UK the Thames has frozen over during the last two millennia, and vineyards have been cultivated at other times. Some analysts, however, believe that even a 60% reduction of emissions from 1990 levels will not be enough: it has been suggested that to stabilise atmospheric concentration of carbon dioxide in the atmosphere, emissions will have to be reduced to 5 - 10 per cent of 2003 levels.
Statisticians and experts on computer modelling rightly question some of the scenario assumptions of the IPCC - for example, that population will grow to the higher projections published by the UN. However, even if world population stabilises at a lower level than forecast, it is not likely to reduce significantly for another 200 years after stabilisation - for example, because falling birth rates are likely to be accompanied by rising life expectancy. World economic growth may also not be as rapid as forecast by the IPCC in its higher projections. Much depends, however, on the amount of fossil fuel remaining to be consumed, over what period it is consumed, and on the length of time that harmful emission levels remain in the atmosphere. Slower than forecast population and economic growth may delay climate change, but not prevent it from eventually taking place. Some environmental events, such as the irreversible melting of the Greenland ice cap, could also take place at lower levels of temperature increase than the maximum forecast.
World population limit 2.1 billion
The global population level needed in order to stabilise carbon dioxide may be as low as 2.1 billion, if other carbon dioxide-reducing measures are excluded. This allows for a relatively low per capita energy consumption of 2kW (17,250 kWh per annum) (US citizens currently about use about 9kW). Andrew Ferguson, OPT. For more information see Perceiving the Population Bomb , World Watch, Jul/Aug 2001.
In June 2003, the WMO (World Meteorological Organization) confirmed that record extremes in weather and climate events are already occurring round the world. A rise of up to 5.8 o Celsius in temperature implies a Mediterranean climate in the UK in the short term, becoming dryer and hotter in the long term. Earlier research indicating a 'big freeze' a century or more ahead, as the effect of freshwater entering the oceans from melting glaciers irreversibly disrupts ocean currents, including the Gulf Stream that warms the UK, and reduces UK temperatures to those of Newfoundland, Siberia or worse, has recently been qualified. Climate modelling carried out in 2005-6 suggests that a failing Gulf Stream might act as a brake on warming, but that UK temperatures will continue to rise. For countries that already have hot and dry climates, a rise of up to far less than 5.8 o implies increasing droughts that could turn whole countries into desert, with consequent famine and migration pressures. Africa, for example, is expected to bear the brunt of global warming: if current trends continue, temperatures in sub-Saharan Africa could rise by 2 degrees Celsius with rainfall declining by 10 per cent .
Such a collapse is now believed to have led to the extinction of almost all animal and plant species in earlier times. A global temperature rise higher than 6 o could be self-feeding. In scientific terms, it would result in 'positive feedback loops' which amplify the effects of climate change. For example, the die-back of the Amazon rainforest as the climate warms would release more carbon dioxide into the atmosphere. Likewise, a 3oC warming would release up to 85 per cent of the 5,000 billion tonnes of methane which is locked away in deep ocean sediments and in the permafrost on the land, after a few thousand years . As a potent greenhouse gas, this additional release of methane would raise the temperature still further and ultimately destroy all human life.
The World Health Organisation has estimated that climate change was responsible for approximately 2.4 % of worldwide diarrhoea and 6 per cent of malaria in some middle-income countries in the year 2000, and contributed to a total of 150,000 deaths worldwide (killing an estimated 35,000 people in Europe during the 2003 heatwave). It also contributes to the deaths of some 70 million a year from famine - higher numbers than ever before .
Fossil fuel emissions continue to rise
The International Energy Agency (IEA), a body established in 1974 in response to the oil crisis of 1973-4, with 26 member countries including most major economies, has warned that "there is an urgent need to consider ways to accelerate the decoupling of energy and CO2 emissions from economic growth". The statement <3 February 2004> accompanied the launch of its report 'Oil Crises and Climate Challenges: 30 Years of Energy Use in IEA Countries', which pointed out that IEA oil demand levels in 2001 were comparable to those of 1973, mainly because of the rise in vehicle use. Oil use for cars grew almost 50% between 1973 and 1998. On CO2 emissions, most IEA countries enjoyed significant reductions in CO2 emissions per unit of GDP between 1973 and 1990, but total emissions from IEA countries increased 13% between 1990 and 2001, a development that is in stark contrast to what is implied by the Kyoto targets. In late 2006 the Global Carbon Project, a consortium of international researchers, reported that global carbon dioxide emissions rose four times faster between 2000 and 2005, at 3.2 per cent a year, than in the years from 1990 to 1999, when annual growth was 0.8 per cent. Much of this is the result of rapid growth in economy, population and fossil-fuel use in countries such as China and India. See also Transport.
While technology and energy conservation can alleviate greenhouse gas emissions, growing populations as well as growing affluence are likely to negate these improvements. Some countries (for example, China and India) have population stabilisation policies, but few have explicit targets to reduce population numbers. In 2000 (excluding the smaller economies), the US produced most 20.6 per cent of global greenhouse gas emissions, with China catching up at 14.8 per cent, the European Union 14 per cent, Russia 5.7 per cent, India 5.5 per cent and Japan 4 per cent. Developed countries accounted for 52 per cent and the developing world for 48 per cent. "The strong correspondence among emission, population, and GDP rankings reflects the importance of population and economic growth as emissions drivers," according to the Pew Center on Climate Change .
In 1992 the IPCC suggested that in order to stabilise carbon dioxide concentrations in the atmosphere at the 1990 level of 353 parts per million, emissions needed to be cut by at least 60% from their 1990 level of 21.8 billion tonnes to 9 billion tonnes a year (carbon is usually expressed as CO2 divided by 3.664). UN agencies and the IPCC now hold that: "Stabilising concentrations at, for example, 450 ppm would require worldwide emissions to fall below 1990 levels within the next few decades."
Fewer fossil-fuel burners needed in Europe, not more
Although some parts of the world had cool summers, temperatures in the first two weeks of August 2003 in Europe were as much as 10 degrees Celsius higher than in the same period a year earlier, which along with prolonged drought caused falling yields, higher prices for crops such as wheat, US$13 billion of damage to European economies and nearly 35,000 deaths (see WHO 2004 World Disasters Report. The effects of even small rises in temperature can be severe, for example by increasing extreme weather events. Research by the United Nations University suggests that a combination of climate change and population growth might expose two billion people to catastrophic flood risk by 2050 worldwide. While technological and political action are essential to alleviate greenhouse gas emissions, they cannot, in our view, be achieved without parallel population stabilisation and reduction policies, including in Europe. From 1990 to 2100, the average temperature is projected to rise by 2 - 6.3 degrees Celsius in Europe, in the absence of policy measures to curb emissions. (See Impacts of Europe's Changing Climate, European Environment Agency, 2004.) Yet many EU policymakers continue to support further population growth - multiplying the number of Europeans who both cause and suffer from climate change. In the EU 27, where population is expected to stabilise and begin a gradual decline by 2050, many fail to see the environmental benefits that would come with fewer people.
Annual limits to CO2 emissions are discussed on this website: see CO2: the crucial limits.
2. BOTH EMISSIONS AND POPULATION LEVELS NEED TO BE REDUCED
In OPT's view, necessary emissions reductions cannot be achieved without rapid population stabilisation programmes. With a 2007 world population of 6.7 billion, projected to rise to 9.2 billion by 2050, according to the UN, , a worldwide desire to raise living standards may be impossible to achieve without catastrophic global warming. The UK, for example, is one of the world's better performers in emissions reduction, but by 2005 it had managed to reduce CO2 emissions by only 5.5 per cent from 1990 levels and in March 2006 said it was likely to reduce CO2 levels by only 10.6 per cent below 1990 levels by 2010. Measures to reduce emissions are under way (for example the EU emissions trading scheme), but are unlikely to be effective on their own.
Emissions reduction framework strategies need to be global, fair, and display no 'perverse incentives' that encourage population or consumption growth. One is the Global Commons Institute's Contraction and Convergence proposal, as described by the Global Commons Institute and in the Fresh Air report published by the New Economics Foundation in October 2002. This requires a defined target for atmospheric concentrations and an equitable allocation of greenhouse gas emissions quotas, and could be immediately put into action. The GCI approach favours emissions entitlements in proportion to national populations specified in a baseline year (probably 1990). Contraction to prescribed targets would lead to convergence at equal per capita emissions allocations.
Contraction and convergence
The Climate Change Convention, adopted in 1992, commits all countries to limit emissions and requires developed countries "to take measures aimed at returning their emissions to 1990 levels". The Kyoto Protocol, which came into effect in February 2005, requires developed countries to reduce collective emissions of six greenhouse gases by at least 5 per cent from 1990 levels during the period 2008-2012. The treaty expires in 2012. The RCEP (Royal Commission on Environmental Pollution), however, has said that a 60 per cent reduction from 1990 levels is needed, and this is the target that has been set by the government of the UK. However, in December 2004 the UK government admitted that its intermediate target to cut greenhouse gas emissions by 20% from 1990 levels by 2010 would not be met and has said more recently that only a 10.6% reduction in carbon dioxide emissions is likely by 2010 (see above).
Even if every country followed the lead set by the UK, the global emissions problem would not be solved. Taking population into account, the reality is very different. According to UN projections, world population may reach just over 9 billion by 2050. Since the world can safely emit only about 2.5 billion tonnes of carbon a year from burning fossil fuels, this would put a cap on emissions at 0.28 tonnes per person per year for 9 billion people. In 1996 the UK was emitting 2.6 tonnes per person per year, which would even then have implied an 89 per cent reduction in the UK's per capita emissions in order to achieve a 0.28 tonnes per capita per year target for atmospheric carbon stabilisation with a world population of 9 billion. An ultimate target of 11 per cent of 1996 emissions would have to be achieved. By the same logic, the USA would have to reduce its emissions to 5 per cent of their present levels.
A 'contraction and convergence' model of emissions reduction, therefore, needs to set fixed percentage reductions of fixed and specified total national emissions levels, not per capita targets that would allow emissions targets to be undermined or revised upwards to accommodate growth in population (rising numbers of greenhouse gas emitters).
Andrew Ferguson, OPT. For more information see Carbon dioxide: the crucial limits.
In the absence of population policies, population levels are likely to be so high by the time emissions 'convergence' is achieved that climate change will already have caused lasting damage to Earth. OPT calculates, on the basis of necessary carbon dioxide emissions limits alone, shared between individual countries at their 1990 population levels, as well as ecological footprinting calculations, that Earth cannot support more than 2.77 billion people at current levels of technology and consumption. See Sustainable numbers . Put simply, the IPCC limit for a stable atmosphere is about 9 billion tonnes of carbon emissions a year, giving a sustainable level of only 1.4 tonnes per capita for today's 6.6 billion people. This target will be impossible to meet without incorporating sustainable (lower) population levels. See Crucial limits . Improvements in technology and other factors will raise maximum sustainable populations from the levels suggested in this table, but perhaps not by much. At the post fossil-fuel stage, maximum sustainable population size is likely to be restricted by the land demands and low energy yields of green energy rather than by greenhouse gas emissions limits.
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