The Science of Global Climate Change. Facing the Issues. What are the Issues?

Editor’s Note: This Cape Town 2010 Advance Paper has been written by John Houghton as an overview of the topic to be discussed at the Multiplex session on “The Environmental Crisis, the Gospel and Christian Witness.” Responses to this paper through the Lausanne Global Conversation will be fed back to the author and others to help shape their final presentations at the Congress.

God and Science (1)

First let me write a few words about God and science. A few prominent scientists are telling us that God does not exist and science is the only story there is to tell. To argue like that, however, is to demonstrate a fundamental misunderstanding of what science is about. At the basis of all scientific work are the ‘laws’ of nature – for instance, the laws of gravity, thermodynamics and electromagnetism, and the puzzling concepts and mathematics of quantum mechanics. Where do these laws come from? Scientists don’t invent them; they are there to be discovered. With God as Creator, they are God’s laws and the science we do is God’s science.

The Earth is the Lord’s and everything in it (Psalm 24), and Jesus is the agent and redeemer of all creation (John 1:2; Colossians 1:16-20; Ephesians 1:16). As we, made in God’s image, explore the structure of the universe that God has made with all its fascination, wonder and potential, we are engaging in a God given activity. Many of the founders of modern science three or four hundred years ago were Christians pursuing science for the glory of God. I and many other scientists today are privileged to follow in their footsteps.

A special responsibility that God has given to humans, created in His image, is to look after and care for creation (Genesis 2:15). Today the impacts of unsustainable use of resources, rapidly increasing human population and the threat of climate change almost certainly add up to the largest and most urgent challenge the world has ever had to face – all of us are involved in the challenge, whether as scientists, policy makers, Christians or whoever we are.

The science and impacts of Climate Change(2)

Let me start with the basic science underlying climate change, called the greenhouse effect, known for two hundred years and not in dispute. It describes how greenhouse gases in the atmosphere, such as water vapour, carbon dioxide and methane, by absorbing infra-red or thermal radiation emitted from the earth’s surface, act as blankets over the surface, keeping it warmer than it would otherwise be – hence providing our current climate to which ecosystems and we humans have adapted.

Over the last 200 years, the industrial revolution has developed through the availability of cheap power from the burning of fossil fuels, coal, oil and gas that has led to emissions of large amounts of carbon dioxide – one of the greenhouse gases. Its amount in the atmosphere is therefore increasing and will reach two or three times its pre-industrial level by the end of the 21st century if no action is taken to curb its growth. As the carbon dioxide ‘blanket’ becomes thicker, surface temperature averaged over the globe rises with a strong impact on climate.

We are all familiar with the great variability we experience in weather. Climate, which is weather averaged over long periods, also varies and, in addition to the effects of greenhouse gases, is influenced by many factors, for instance the occurrence of volcanoes or the small variations that occur in the output of energy from the sun.

However, although there are uncertainties about much of the detail, especially concerning regional change, the main messages uncovered by scientists(3) about the world’s climate over the next decades and centuries are clear and unequivocal. First, there is compelling evidence that the world is warming and the climate changing – largely because of humans burning coal, oil and gas. Second, because ocean water expands as it warms and because of increased melting of ice from glaciers and the polar ice caps, the sea level is rising at a rate of at least half a metre per century(4).

Third, increased global temperatures lead to more climate extremes. For instance, more intense heat waves of unprecedented intensity have already occurred, such as that in central Europe in 2003 (with the premature deaths of over 20,000 people) and in Russia this year 2010. Further, increased temperatures means more energy entering the atmosphere’s circulation(5), which in turn brings more frequent and intense floods, droughts and storms. This year 2010 has seen devastating floods in Pakistan (the worst disaster in UN history!), the worst floods in more than a decade in China and floods following a long drought in West Africa.

Because of the variability of climate it is rarely possible to argue that any one extreme event is caused directly by the increase of greenhouse gases in the atmosphere. It is the risk of such events that increases. As they become more frequent, matching the rising trend expected from our scientific understanding, it becomes valid to link their increased frequency to humanly induced climate change.

Floods and droughts are the most damaging disasters that occur. On average, they cause more deaths, misery and economic loss than any other natural disasters. Their increased frequency and intensity is very bad news, especially in the world’s poorest countries. Regarding droughts, careful studies of the incidence of droughts show that, at the present time, about 2% of the world’s useable land area is under extreme drought. Twenty years ago it was around 1%. By 2050 as greenhouse gases increase, it is likely to be more like 10%(6)– an increase by a factor of around five from today. That is the most disturbing climate statistic I know!

Within a few decades, impacts of climate extremes and sea level rise could severely affect billions of people, disproportionately those in poor countries in the developing world  – it is there that climate extremes will be most severe and where there is little capability to adapt to them. By the second half of this century, there could be hundreds of millions of environmental refugees(7) whose homes are no longer habitable either because of rising sea level, gross flooding or persistent drought. The impact on the world’s ecosystems will also be large. Many species are already threatened by the destruction of tropical forests; climate change is adding to this. Millions of species are likely to be lost in the coming decades.

Can we be sure of Climate Change?

I am frequently asked, ‘Just how sure are scientists about the reality of humanly induced climate change?’ A very good question, given increasingly confused messages in the media.

The scientific story I have presented is based largely on the very thorough work of the Intergovernmental Panel on Climate Change (IPCC)(8). I had the privilege of being chairman or co-chairman of the Panel’s scientific assessments from 1988 to 2002. The IPCC has produced four assessments – in 1990,1995, 2001 and 2007. The 2007 assessment comprised three volumes each of about 1000 pages including many thousands of references to the scientific literature. It confirms the main conclusions of previous reports, and in the light of six more years of climate observations and research is able to express them with greater certainty. Several thousand scientists were involved as contributors and reviewers in these assessments. Each report began with no preconceived agenda as to its conclusions. For each report, the IPCC’s summary conclusions went through tough scrutiny, sentence by sentence, at a meeting of government delegates to ensure their clarity, accuracy and balance. In addition to governments’ endorsement, the IPCC’s work has been endorsed by the Academies of Science of the world’s major countries. However, despite these endorsements, strong vested interests have spent many millions of dollars on spreading misinformation about the climate change issue, especially in the media, and have tried to discredit the work of the IPCC(9).  First they tried to deny the existence of any humanly induced climate change. More recently they have largely accepted that such change might be occurring but argue that its impact will be too small to require much attention or action. The scientific evidence cannot support such arguments.

Action by governments

At the Copenhagen conference last December, nearly all the world’s countries agreed that the increase in global average temperature from pre-industrial times should not be allowed to rise above two degrees Centigrade.  Even at that level of increase the damages are likely to be serious(10).  Above that target level, the damages will be increasingly more devastating in many parts of the world.

To have a good chance of achieving the two degree maximum, global carbon dioxide emissions must come to a peak well before 2020 and reduce as rapidly as possible thereafter – to close to zero emissions by mid century. Further, scientists have recently realised that if carbon concentrations rise such that the two degree target is exceeded, inertia in the system is such that reversing the process, if possible at all, would likely take centuries.

But can the two-degree target be achieved and can the world’s nations afford the cost? Many assume the cost would be large and unaffordable in this time of recession. A thorough study of the cost to the world’s energy industry of meeting the two-degree target has been carried out by the International Energy Agency (IEA), the world’s top energy body, in their volume, Energy Technology Perspectives published in June 2010. It concludes that, compared with ‘business-as-usual’ (i.e. no changes in energy provision to combat climate change) the additional investment needed, averaged over the next 40 years, would be about 1% of the world’s gross national product (GNP), an additional cost that would be more than balanced by savings in fuel cost over this period. They further point out that the changes made would bring co-benefits in terms of energy security and avoided pollution. You may well ask why, therefore, do many of the world’s governments seem hesitant to take the necessary action? A senior diplomat has commented, we know what to do but lack the will to do (11).

A moral and a Christian imperative

For developed countries, associated with necessary action lies a very strong moral imperative. In rich countries, for over 200 years the growth of wealth has largely come through cheap energy from the burning of fossil fuels. Its effect on the world’s climate had not been realized, nor that the damage falls disproportionately on the world’s poorest countries. Now we know. There is therefore an inescapable moral imperative for rich countries to avoid further damage by rapidly reducing their carbon emissions and to share their wealth and skills with developing countries to enable them to adapt to climate change and to build their economies sustainably.

For rich Christians this imperative comes over with particular potency. We live in times when we are raping the earth and exploiting the poor. The Bible, from its first chapters, through the prophets, the ministry of Jesus and to its last book, puts much emphasis on caring for the earth and caring for the poor. At the beginning of his ministry, Jesus announced at Nazareth his anointing ‘to preach good news to the poor’ (Luke 4:18). Chapter 12 of Luke’s gospel contains some particularly relevant teaching. In the parable of the rich fool, Jesus roundly condemns the sin of greed. A few verses later comes the injunction to ‘sell your possessions and give to the poor’ followed by a parable about stewardship that ends with the words ‘from everyone who has been given much, much will be demanded.’

Many Christian agencies are in the forefront of action addressing extreme poverty. But the need is enormous. The question therefore is often asked, ‘Should not the problem of climate change be given lower priority until more progress has been made with combating world poverty?’ However, action on climate change is even more urgent than most other problems. This is because changes in climate that we experience today largely result from the emissions of carbon dioxide and other gases that occurred ten, twenty or thirty years ago – all because the climate system especially the oceans take time to warm up. If we fail to act to reduce emissions now, the climate impacts a few decades from now will be much greater and the plight of the poor, especially those in the most vulnerable areas, will become very much worse. The report from an international meeting of Nobel Prize winners addressing climate change last year was entitled The Fierce Urgency of Now. World poverty and climate change need to be addressed together and with equal urgency.

The need to share

We in rich countries need to learn to share very much more (see for example, 2 Corinthians 8). At the individual or family level a lot of sharing often occurs. At the national level in many countries, through social and benefits programmes, sharing has been built into the fabric of society. But at the international level, sharing occurs much less. But what about the aid, you may ask, that flows through aid agencies and from governments from the rich world to poorer countries? That is of course good and is increasing. But add to that the effects of trade. If aid and trade are taken together, the net flow of wealth is overwhelmingly from poor countries to rich ones – a statistic that should make us all blush with shame. A welcome response to this inequity is the recent growth of the Fair Trade movement that needs much greater support. Loving our neighbour as ourselves – wherever our neighbour may be – demands that we show much more care for the world’s poor.

Interpreting this present time           

At the end of the 12th chapter of Luke’s gospel to which I referred earlier, Jesus talks to his hearers about weather forecasting. He tells them how skilled they are at interpreting the face of the sky, but goes on to chide them for not being able to ‘interpret this present time’ – by which he implied that they failed to apply the message Jesus brought to their own lives and behaviour.

How do we as Christians today ‘interpret this present time’? We are aware of the obligation to care for the earth and care for the poor and also aware of the likely consequences of humanly induced climate change. How can we respond to this challenge of Jesus? First of all, for our personal response, I suggest the following.

  1. Those of us in rich societies need to recognise the extent to which selfishness and greed dominate attitudes and lifestyles in our communities that are becoming increasingly unsustainable(12). Of this we need to repent.
  2. The fundamental commandments to love God and to love our neighbours demand that we share the world’s resources much more fairly – in particular, by assisting aid agencies in poverty relief and by supporting Fair Trade.
  3. Our responsibility to care for the earth and to love our neighbour is not only for our own generation but for future generations too. To mitigate future damage we all need to play our part by reducing our personal carbon footprint and to lobby governments, industry and business urgently to take the necessary action.

Through our shared commitment to Jesus Christ and his gospel, there is enormous potential for Christians worldwide to work in partnership on these issues. Taking on the God-given responsibilities for caring for creation and caring for the poor provides an unprecedented mission opportunity for Christians to demonstrate love for God, the world’s creator and redeemer, and love for our neighbours wherever they may be – so commending the gospel to those whom we serve and to those who look on. The task is extremely large and demanding, but we need not be overwhelmed by it because we are not just partnering with each other but with our Lord Himself (Ephesians 3:20-21 and John 15:5,14-16). Pastor Rick Warren’s PEACE plan at Saddleback Church, California is an example of such partnerships between the developed and the developing world. Let me suggest two possible areas for partnerships concerned with action on climate change.

  1. Even if the mitigation goal in (3) above is achieved, the rate of climate change will substantially increase, bringing a large requirement for adaptation. In particular, those in parts of the world most disadvantaged by the impacts of climate change will require much development help in adapting to changed climates.
  2. Over one billion people live in poor rural communities in the developing world. In the hope of a better life, an increasing number are moving to cities that are growing almost impossibly large. A great need is for rural communities to develop where they are – they all need clean water, sanitation, sustainable farming and sustainable energy. Providing these needs on the scale required is a great challenge but would, I believe, be well within the resources of the worldwide Christian community.

Some Christians point out that since God is in control, we should leave God to take care of the future and we should not be concerned. Where we have no knowledge or possibilities for action, we are bound to do that. But when human actions are causing the problem, obedience in our role as God’s stewards (Luke 12) requires that we take every possible action, knowing that God himself will be working with us (Eph 3:20-21).

A Climate Crisis 4000 years ago

Finally, let me refer to one of the best-known stories in the Old Testament that takes up 12 chapters of the book of Genesis. Around 4000 years ago, Pharaoh king of Egypt had a dream. Joseph with God’s help interpreted the dream in terms of a climate crisis. Seven years of plenty were to be followed by seven years of famine. Pharaoh believed the message from God and placed Joseph in charge of management of the grain storage over the years of plenty for use in the subsequent years of famine. Joseph’s brothers came to buy corn. Joseph made himself known to them and said, ‘Do not be angry with yourselves for selling me here, because it was to save lives that God sent me ahead of you’ (Genesis 45:5). God used Pharaoh and Joseph as his agents in ameliorating the famine that came from the climate crisis.

Today, we face a climate crisis of enormous magnitude and proportions, not local but global, not of seven years duration but lasting indefinitely. Information about it has come not through dreams but through science – a God-given activity. The world scientific community have described as honestly and accurately as possible the likely impacts of changing climate and indicated the actions to be taken. As with Egypt in Joseph’s time, the next seven years are likely to be crucial. May I urge the world Christian community to rise to the challenge.

© The Lausanne Movement 2010

  1. See John Ray Initiative Briefing Paper, Big Science, Big God, available from, also John Houghton, The Search for God, Can Science Help?
  2. See John Ray Initiative Briefing Paper, Global Warming, Climate Change and Sustainability, Challenge to Scientists, Policymakers and Christians, available from also my textbook John Houghton Global Warming: the Complete Briefing, 4th edition, CUP 2009.
  3. Based largely on the work of the Intergovernmental Panel on Climate Change (IPCC)
  4. The rate of ice melt in polar regions is very uncertain. Recent conservative studies suggest sea level rise of up to metre by 2100.
  5. As the Earth warms, there is more evaporation from the ocean surface, more water-vapour in the atmosphere and more average rainfall. Increased water vapour condensing to form clouds releases increased latent heat (the largest single source of energy for the atmosphere’s circulation) leading to a more intense hydrological cycle with more likelihood of floods and droughts.
  6. E.J.Burke et al, J Hydrometeorology, 7, pp 1113-1125.
  7. See, e.g. Myers, N., Kent, J.  1995, Environmental Exodus: An Emergent Crisis in the Global Arena. Washington DC; Climate Institute.
  8. See IPCC website
  9. Merchants of Doubt by Naomi Oreskes and E. M. Conway, 2010, provides a well-researched and chilling description of how a few influential US scientists deliberately obscured the truth on major scientific issues from tobacco and cancer to global warming.
  10. See Mark Lynas, Six Degrees that won Royal Society award for best popular science book of 2008.
  11. Quote from Sir Crispin Tickell.
  12. See e.g. John Stott, The Radical Disciple, IVP 2010, chapter 5; Lausanne Covenant, para 9; Ronald Sider, Rich Christians in an Age of Hunger; Dewi Hughes, God of the Poor.