Written by Dr Dan Bebber | Updated: Dec 7 2009, 05:21am hrs
Prediction is very difficult - especially about the future

So Niels Bohr, Nobel Laureate in Physics, is supposed to have said about the difficulties of divining that which is to come. The world is a complex place, and determining the state of the world in coming decades might seem like a fools errand. Few anticipated transforming events like the recent global economic crisis, the terrorist atrocity of 9/11, or the collapse of the Soviet Union. However, while such social, political and economic upheavals are near impossible to foresee, certain fundamental trends in the physical state of the planet are clear and directional, and do provide firmer foundations for what coming decades might hold. Scientists have dubbed a new geological era, the Anthropocene, to describe the period of accelerating change that followed the advent of the industrial revolution at the end of the 18th century. It is this suite of changes, rather than the transient perturbations in economies and political systems, that will ultimately decide our fate.

What trends define the Anthropocene The clearest signal of all is the rapid change in the composition of the Earths atmosphere, which now holds more carbon dioxide, methane, and nitrous oxide than it has for millions of years. Other gases that have never been seen before are present in strong enough concentrations to alter fundamental atmospheric processes, such as the formation of stratospheric ozone. In response to these changes, global surface temperatures have risen by an average of 0.7C. The oceans have become more acidic as they absorb some of the additional carbon dioxide, glaciers and ice-sheets are melting ever-more rapidly, sea levels are rising, and weather is becoming more extreme in many parts of the world. Also, tropical forests continue to be cleared, fresh water and fertiliser use are accelerating, fisheries are collapsing, agricultural soils are eroding away. Material consumption is accelerating: there are more cars, more fast food restaurants, more international flights, more disposable goods. There are whispers that the era of easily available oil and natural gas is coming to an end. And behind all this, the growing human population, estimated to reach more than 8 billion by 2020, more of whom are living in growing cities. These trends show clear trajectories. We could be forgiven for simply extrapolating to a world devoid of tropical forests and coral reefs, with no viable fisheries, no fresh water or freely-flowing rivers, poor agricultural soils, and global average temperatures elevated by more than 5C.

Of course, such simple extrapolations ignore the complexities of human and planetary responses to change. For example, several tipping points, or discontinuities, have been identified in the climate system that could radically influence simple trends . Complete melting of arctic summer ice would remove an important mirror to the Suns energy, thus accelerating the rate of warming. For India, melting of Himalayan glaciers and disruption of the monsoon will cause dramatic shifts in water availability, affecting agriculture and livelihoods in the region.

Parallel discontinuities, or paradigm shifts, are possible in the socioeconomic sphere. For example, will people continue to overexploit fisheries, or hold to a system of sustainable quotas Will the throwaway society continue to feed the Great Pacific Garbage Patch (already half the area of India), or become less wasteful of resources Will consumption of meat, requiring many times the land area of vegetable production, continue to grow, or will people choose animal protein as a small supplement to a balanced diet

The most difficult choices of all relate to energy, both due to the strong correlation between energy use and most measures of wealth, and the derivation of most of our energy from greenhouse gas-producing fossil fuels. The energy company Shell sees three pressures: dwindling oil availability, climate change, and rapid growth in energy demand, forcing a choice between two alternative energy scenarios: Scramble and Blueprint. In the Scramble scenario, national governments respond to threats to energy security by nationalisation and a rush to capture fossil fuel resources. This can be seen in recent international disputes over rights to Arctic oil reserves. A lack of planning for the looming problems of climate change and dwindling supplies leads to disaster by the middle of this century. Change in the energy economy comes, but it is forced rather than planned. In the Blueprint scenario, governments, business, and civil society work together and plan for a low-carbon future. The role of government is to build a legislative framework in which new, efficient, low-carbon technologies can be developed and marketed successfully by business. Electric cars, the capture and storage of carbon dioxide from power stations, renewable energy from solar, wind and tidal sources, so-called third generation biofuels from algae, and woody biomass will all be vital in meeting future energy demands. The doctrine of unlimited consumption will need to be revised. The Earth can support what we need, not everything we might want.

Partnerships will be crucial in developing an effective blueprint. HSBC Bank, one of the worlds largest financial institutions, has been at the forefront of this approach. Through listening to the concerns of civil society, the bank has improved lending policies across the business. For example, only forestry companies engaged in sustainable forest management practices will now be supported financially. The HSBC Climate Partnership, launched in 2007 and comprising HSBC, Earthwatch Institute, WWF, the Climate Group, and the Smithsonian Tropical Research Institute, aims to tackle pressing issues such as the responses of forests to climate change, management of fresh water resources, and low-carbon cities.

Shell has found that the Blueprint scenario will not only avoid the societal upheavals inherent in the Scramble scenario, but will also reduce the growth in atmospheric greenhouse gases. Planning for a low-carbon future thereby delivers one. When must the decision between Blueprint and Scramble be made Research climate models suggest that greenhouse gas emissions must peak between 2015 and 2020, and must then fall rapidly to nearly zero, if dangerous climate change is to be avoided . The world must be completely decarbonised before the end of the century, and techniques that remove carbon from the atmosphere, such as aforestation, may need to be employed.

Every year that business continues as usual, the chances of catastrophic change increase. This is why the climate change conference in Copenhagen in December is so critical, for it could form the Blueprint for a safer future. We must remember that prediction is difficult, uncertainty remainswe cannot be sure what level of carbon dioxide is safe, nor how far the temperature will rise. The problem is one of growing risk, and the stakes are high. Time flies. We must choose now.

The writer is Head of Climate Change Research, Earthwatch Institute