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june 2008 Spaceship EarthSir John Houghton offers a report from the ship’s log
Imagine you are journeying on a spaceship to a distant planet. You have incoming energy from the sun but you’ll need to carry all other resources with you, and your waste. To survive you must live within the capacity of the spaceship. It is a concept known as sustainable living. Planet Earth is like an enormous spaceship with a crew of over six billion and rising, but the principle of sustainable living is just as applicable to Spaceship Earth as a smaller craft on an interplanetary journey.
The simplest definition of sustainable that I know is “not cheating on our children”. To that may be added, “not cheating on our neighbours” and “not cheating on the rest of creation”. However this is exactly what humanity is collectively doing through over-consumption of food, energy and water, destruction of nature’s richness and most seriously by global warming.
The atmosphere contains a mixture of gases, some of which act like the glass of a greenhouse, allowing the sun’s light rays to pass through but trapping the heat released when the sun strikes the earth. This natural phenomenon is essential for our climate and has allowed life as we know it to evolve. Amongst these so-called “greenhouse gases” is carbon dioxide (CO2).
Since the beginning of the industrial revolution the concentration of CO2 in the atmosphere has increased by over 35 per cent, largely through burning the fossil fuels coal, oil and gas. If no action is taken to curb these emissions, the CO2 concentration will rise during the 21st century to two or three times its pre-industrial level. This is compounded by the doubling of atmospheric methane, another greenhouse gas, over the last 200 years because of human activity. The effect is rather like double-glazing the earth and is known as global warming.
Looking back, the climate has naturally changed over millennia from factors such as solar variations. However, the rate of rise in global average temperature during the 20th century is well outside the range of known natural variability and there is scientific consensus that most of the warming over the last 50 years is due to the increase of greenhouse gases, especially CO2.
Looking forward, the global average temperature is projected to rise by between 2 and 6 ⁰C from its pre-industrial level in the 21st century. This represents a huge rise given that the difference between the middle of an ice age and the next warm period is only about 5 or 6 ⁰C.
The impact of global warming
Global warming is causing sea levels to rise through the expansion of the oceans as they warm and increasingly as ice-sheets melt. This could lead to an increase of around half a metre per century or more and will cause major problems for human communities living in low-lying regions, not least in low-lying Bangladesh where about 10 million live within the one metre contour.
Temperature itself is a problem. The extremely unusual high summer temperatures in central Europe during 2003 led to the deaths of over 20,000 people. Such summers are likely to be average by the middle of the 21st century and cool by the year 2100. Our warmer world is also disrupting climate patterns, leading to more intense rainfall events and also less rainfall in some semi-arid areas.
A five-fold increase in the most extreme floods and droughts is predicted in some places by 2050, with the consequent devastation that such events bring, not least in regions such as south-east Asia and sub-Saharan Africa, where such events already occur only too frequently. A careful estimate has suggested that climate change could create 150 million refugees by 2050. It is these sorts of events that provide some credence to the comparison of climate with weapons of mass destruction.
There are also longer-term changes about which there is less certainty, including ice cap melt and weakening of an ocean circulation system linked to the Gulf Stream, which if they occurred would be highly damaging and possibly irreversible. Whilst there are some positive impacts of global warming, for instance, high northern latitudes will have less severe winters and a longer growing season, the adverse impacts of climate change will far outweigh positive effects, especially as temperatures rise more than 1 or 2 ⁰C.
The evidence is largely based on assessments by the world scientific community, carried out through the work of the Intergovernmental Panel on Climate Change (IPCC). I had the privilege of being chairman or co-chairman of the Panel’s scientific assessment from its beginning in 1988 to 2002. Many hundreds of scientists from many countries were involved in honestly and objectively distinguishing what is reasonably well known and understood from those areas with large uncertainty. No assessments on any other scientific topic have been so thoroughly researched and reviewed.
Unfortunately, vested interests have spent millions of dollars spreading misinformation about climate change, denying scientific evidence and arguing that its impacts will not be great, that we can “wait and see” and “fix” the problem if necessary. Scientific evidence cannot support such arguments.
The greatest challenge nationally and internationally is to find ways to achieve the large emissions reductions required that are both realistic and equitable to ensure stabilisation of the climate. It requires significant and decisive action, and whilst one estimate of the cost is around one per cent of world GDP by 2050, the cost of failing to take action is estimated at between five and 20 times this amount. To this must be added the large cost in human terms, which will fall disproportionately on poorer nations who have benefited least from burning fossil fuel. The moral imperative for effective action by the rich countries is inescapable.
What action can be taken?
Positive actions can be taken, including improving energy efficiency in the building, transport and industrial sectors, developing more non-fossil fuel sources of energy such as solar power, hydro, wind, geothermal energy and nuclear, and developing carbon sequestration which involves removing carbon from the atmosphere. These present opportunities for industrial innovation, development and investment, and to promote equity and be effective they require technology transfer from developed to developing countries. We should also reduce our demand for carbon hungry activities and materials, travelling and consuming less.
Science and technology are widely seen as the solutions to many of our environmental problems, but to contribute effectively to environmental sustainability, they need to be more integrated with social and policy considerations.
Can the world take the necessary action? I am optimistic as a scientist because my personal experience of the world scientific community is of a group who work painstakingly and honestly to understand the problems and assess what needs to be done, and because the necessary technology is available. I am optimistic as a Christian because I believe we have a God-given calling to be good stewards of creation.
This demands sharing of wealth and of skills, particularly between the rich and the poor nations, as was advocated by the early church in Acts who drew on the teaching and example of Jesus. Whilst much sharing does happen at the individual level and aid sharing at the national level, internationally the average flow of wealth in the world is from the poor to the rich. It isn’t just climate change which challenges us!
Living sustainably on Spaceship Earth is a daunting challenge, but by reducing the size of our carbon footprint, embracing new technologies, changing our lifestyle choices and making greater demands on political leaders we can all make a contribution. It is a challenge to individual Christians and the Church to take on the God-given responsibility of caring for the environment. In doing so, we can demonstrate both love for God the world’s creator and redeemer and love for our neighbour, wherever they live in generations to come. Let us hope that the course we set ensures safe passage for all on Spaceship Earth.
This article is continued in the June 08 edition of Reform.
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