1.5 watts does not seem much. A light bulb of this power just about simulates twilight, and an LED around twice as much light. However, the long term effects due to the 1.5 watts per square metre of increased radiative forcing from the sun since the pre-industrialised era, are overwhelming in both senses.
Human activities, in particular the burning of coal, petroleum and gas to gain energy as well as the unrestrained erosion of forests, have deposed an enormous amount of greenhouse gases in the earth’s atmosphere in the last few centuries. The concentration of carbon dioxide (C02) is already somewhat more than a third above the pre-industrial level and is therefore higher that any period in the last 15 million years of the earth’s history. Simply put, CO2 and other climate-changing gases from civilised sources keep more and more of the sun’s warmth from the atmosphere, and increase the natural greenhouse effect. Due to this, the 20th century already saw an average global temperature rise of approximately 0.8 degrees.
This is the dilemma of humanity in the 21st century. Today’s natural resources and land use, which were the basis of a mid-term, rapid development of wealth, carry the inherent, long term potential of destroying this wealth. This is because unchecked climate change would change living conditions on earth in a fundamental way. It is unlikely that our civilisation, which in the changeable history of the climate has experienced a paradisiacal stable phase since the end of the last ice age approximately 10,000 years ago, can withstand such changes.
In the area of earth system research and sustainability science, great progress has however been made in the last centuries. Through this, we are beginning to understand the boundaries of the secure planetary environment in which we are able to live without destroying the living foundation of future generations. The era of the “geonaut” has begun.
The start of the solution to the climate problem can be easily formulated – and much less easily put into practice: greenhouse gas emissions have to be reduced within this century to zero. But which technologies in all relevant areas of economic growth can be separated from the non-sustainable use of finite resources? And how can we be sure that simply a small section of the exploding world population will implement the transition to sustainability?
Talented young researchers can still create the cognitive basis necessary for the “great transformation” of our industrial metabolism. The science scene in Berlin/Brandenburg offers a corresponding intellectual glacis with its numerous institutes, such as the Geo Research Centre Potsdam, the Technical University Berlin and the Potsdam Institute for Climate Impact Research, which is currently being added to by the excellence Institute for Sustainability in Potsdam.
The sustainability crisis is the decisive challenge of human beings in this century. It will demand huge efforts from us but will also possibly introduce the transition to a more stable and just world society - if we are very lucky and use our intellect.
Professor Hans Joachim Schellnhuber CBE
Potsdam Institute for Climate Impact Research, Director
