INSURANCE COMPANIES, politicians, and business people often use the expressions “natural disaster” or “act of God” to deflect responsibility for events beyond our control. Now, human activity and technology have become so powerful that we’re contributing to what were once natural disasters.

Tornadoes, storms, hurricanes, floods, pest outbreaks, heat waves, and even earthquakes are occurring with greater frequency and intensity than ever.

Some of this can be traced to human activity.

Greenhouse gases, large dams, and deep oil and water wells can all affect Humans appeared during the last period of evolutionary time, perhaps 150,000 years ago.

For most of our existence, we didn’t even know whether other humans lived on the other side of an ocean, desert, or mountain. We only had to worry about our own tribe.

Suddenly, we have become a geological force, the most prolific mammal on the planet, endowed with powerful technologies, impelled by an insatiable appetite, and supplied by a global economy.

Our numbers, technology, and global economy have made us a new kind of force on the planet. For the first time, we must ask, “What is the collective impact of 6.8 billion human beings?” As we answer that question, we’re left with the problem of responding to global threats that we’ve caused.

Many people harbour an understandable tendency to deny the reality of the crisis in the biosphere. After all, how can puny humans have such a massive impact on this large planet? Some also maintain a conceit that we can manage it with heroic interventions of technology.

But we’ve learned from past technologies — nuclear power, DDT, CFCs — that we don’t know enough about how the world works to minimize unexpected consequences.

The truth is that the only factor or species we can manage on Earth is us. We have no choice but to address the challenge of bringing our cities, energy needs, agriculture, fishing fleets, mines, and so on into balance with the factors that support all life. This crisis can become an opportunity if we seize it and get on with finding solutions.