Many people know about the dangers of global warming, but only few act.
The explanation, says Professor Andreas Ernst of the University of Kassel, has two parts. One, human beings get stubbornly comfortable in their habits. On the other, the human species is biologically programmed to act in its own best interests - and its members aren't very different from common rats on that point.
In addition, the overwhelming size and abstract nature of the concept - climate - dwarf any idea that an individual could have an impact through his or her actions.
In short, it's part of natural human psychological behavior to repress the consequences of climate change, Ernst said in an interview.
"We are, well, a little like rats, programmed by evolution to find advantages and exploit them," said Ernst, who is also spokesman for a panel on environmental psychology in the German Society of Psychology. "Short term advantages are preferred to the long-term variety."
Ernst made his remarks as a scientific panel prepared to release a United Nations report on global warming, part of a massive effort every six or seven years by the UN to gather consensus among thousands of world scientists.
This year's series has already raised alarm bells with the direst projections yet that polar ice caps will melt, sea levels will rise and one-sixth of the world population - including 1 billion people in Asia - will face severe water shortages by century's end.
But despite the severe warnings, humans are reluctant to change.
Roman Seidl, a fellow environmental psychologist at Kassel University, notes the widespread attitude: "My individual contribution on the climate issue is so small and irrelevant on a global scale - it doesn't matter whether I do something or don't."
In fact, it is true that reducing carbon emissions blamed for global warming depends on changing behavior across society, but even that conviction seems to be missing, Seidl said.
"Most people still don't have confidence in the ability of collective action to bring about change," he said.
Small sections of the population are aware of the issues, but most continue on their current paths.
The idea of climate is very "abstract" - despite efforts by environmentalists and the media to portray the urgency of the situation, Seidl noted.
"In addition, many people are burdened in their day-to-day lives by existential questions such as unemployment, problems at work or a car that has broken down," he said.
According to Hans Spada of the Institute for Psychology at the University of Freiburg, what's missing is cause-and-effect experience. Humans learn by making direct connections between actions and results - for example, when a high-speed turn into a curve results in an accident, or gets the driver arrested.
"Direct experiences contribute more to our learning than reports or projections," Spada said.
Another example of the short-term versus long-term effect is smoking. "Everyone knows that it damages your health. But the best lesson would be if one got ill immediately after smoking every cigarette."
Spada called for a brainstorming of new ideas about how to bring the message of collective change into daily life. Instead of relying on the momentary but only periodic shock of rising electricity and gas bills, there should be signals in hallways or rooms when some misstep has wasted energy.
Seidel added: "For those who are already convinced of the value of the environment, it's easier to grasp climate change and to acknowledge individual responsibility."
Those who act accordingly have a good feeling when they buy products locally, for example, saving carbon emissions and unnecessary transport.
Most people need to learn from their direct experiences - like the child who defies warnings and touches the stove. "But that doesn't work with the Earth's climate and its many billions of people. You can't rewind and replay," Seidl said.
That's why it's urgent to make clear that climate change is irreversible. "If we do nothing, there will be no way back," Seidl said. Families with small children are especially receptive to the message: "Climate change won't affect us, but our children and grandchildren."
An additional, crucial key to changing behaviour across society, however, is committed political engagement, said Ernst. The European Union could for example "turn the screws" incrementally to increase energy prices and reduce emission tolerance levels, he said.
In addition, the human tragedy and economic losses that resulted from Kyrill, the cyclone that formed over Newfoundland and blasted damage and death across Europe in January, and Hurricane Katrina, which levelled New Orleans in 2005, could help raise human consciousness about the huge problems of climate change, Ernst noted.