The increasing frequency of extreme weather events, droughts and floods is in line with what climate scientists have been predicting for decades - and evidence is mounting that what's happening is more severe than predicted, and will get far worse still if we fail to act.

More than any other time in history, the 1990s will be a turning point for human civilization.

Human use of fossil fuels is altering the chemistry of the atmosphere; oceans are polluted and depleted of fish; 80 per cent of Earth's forests are heavily impacted or gone yet their destruction continues. An estimated 50,000 species are driven to extinction each year. We dump millions of tonnes of chemicals, most untested for their biological effects, and many highly toxic, into air, water and soil. We have created an ecological holocaust. Our very health and survival are at stake, yet we act as if we have plenty of time to respond.

The terrible part of this looming catastrophe is that people have been working on solutions for years and have developed concrete steps to massively reduce our energy use, while stimulating whole new industries and technologies that are more efficient and affordable.

We must pay greater attention to keeping our bodies and minds healthy and able to heal. Yet we are making it difficult for our defences to work. We allow things to be sold that should not be called food. Many have no nutritive value and lead to obesity, salt imbalance, and allergies.

We have altered the physical, chemical and biological properties of the planet on a geological scale. We have left no part of the globe untouched.

It is clear that while science provides insights into the complexity of the world around us, those insights...present a fractured mosaic rather than a seamless whole. There are profound limits to science that must be recognized if we are to minimize the destructive consequences of using the powers provided by scientific discovery.