If you see a friend heading for trouble and know there is only so much you can do to hold them back, what do you do? Do you throw your hands up in despair and turn your back on them, or make every effort to help, not least preparing to support them should disaster come? The answer to this question seems obvious to me, yet this simple logic of care is frequently dismissed in the debate about protecting the planet and its many inhabitants from the threat of climate change.
In the plodding but powerful film An Inconvenient Truth, Al Gore notes wisely that many people go from denial of climate change to despair in one quick step without even pausing to consider their personal scope for action.
This is spot on: I increasingly hear people flippantly saying "we're all doomed" and getting on with their energy-intensive lives without any engagement with the moral responsibility of protecting current and future generations from the grief, pain and loss that climate change causes.
To tackle this problem we need to be more realistic about the future we face. Climate change is already happening and the speed of change is much greater than anyone anticipated. We are already dealing with extreme weather events and matters are going to get much worse. Severe storms, heat waves, flooding and drought will soon be commonplace. Crucially, therefore, we have to act now not merely to reduce these impacts but also to prepare for them. However serious the changes ahead may be, we will only be "doomed" if we refuse to imagine, and prepare for, this future.
For house design, this shift in perspective has radical consequences. The combination of increasingly severe weather and an escalating energy crisis will seriously affect electricity, gas and water supplies. We will all have to face regular - and sometimes prolonged - losses in these services. Rather than hoping we can fix such problems with generators in the shed and tankers of fuel and water, we should be designing buildings to cope on their own, an approach known as "passive survivability".
Although the green building movement has barely begun to face these issues, there is a near-perfect congruence of traditional green design with design for passive survivability. In fact, remembering what life is like during a power cut is a good way of defining the priorities of green building. For starters, you want to stay warm, so a well-insulated, draught-free building with minimum energy losses is a priority. In increasingly hot summers you will also want to stay cool, so external shading, natural ventilation and thermal mass - heavy materials that dampen temperature swings - are all important considerations. You should also make the most of the sun's energy: lighting your interiors, trapping heat in the fabric of the building, providing hot water or even generating electricity yourself. If you collect the rainwater that lands on your roof, you will have a good buffer if the mains supply shuts down.
However, our biggest challenge is likely to be the massive refugee populations that ensue from lowland flooding across the planet.
The per capita carbon emissions of the inhabitants of the Ganges Delta barely register, so when these poorly resourced people confront the full impact of Western fossil fuel burning, we had better be ready to fulfil our moral obligations to them.
* If you are looking for ideas on sustainable living, head for the Homes4Now show in Great Malvern this weekend ( www.malvernhills.gov.uk/homes4now).
* GREAT BUY
The Refugee Council fights to change British attitudes to refugees. Their book, Credit to the Nation, is excellent. £7.95 ( www.refugeecouncil.org.uk, 020-7346 6738).
* GREAT WEBSITE
Al Gore's website, www.climatecrisis.net - includes a useful list of carbon-cutting actions that can be taken in the home. See how many you can tick off.