The impact that humanity is having on climate change is directly related to the fact that there are so many of us. Add on top of our shear numbers the fact that we treat the planet harshly and it is clear why we are moving toward a global crisis.

Consider some facts about the growth of human population. Humans have been on the planet for hundreds of thousands of years. It took until 1804 for our numbers to reach 1 billion. It took another 123 years to reach 2 billion in 1927. It only took another 33 years for us to reach 3 billion in 1960 and 14 years to reach 4 billion in 1974. That means that if you are older that 40 the world’s population has doubled in your lifetime. There are now 6.6 times more of us now than 200 hundred years ago. It is also during these 200 hundred years that the Industrial Revolution occurred, bringing with it the use of fossil fuels for powering our societies and economies.

It is not clear, and has been open to debate as to what the “natural” or “perfect” level of human population is for the earth. What is the global number that could be sustained indefinitely in a perfect and interrelated manner on Earth? There is no correct answer to that question. It is clear that a few hundred million of us living lives of hunters and gatherers and limited agriculture would probably not over burden the planet. Since that milestone was passed more than a millennium ago we must now look at how many there are of us, how we conduct ourselves relative to impact on the biosphere, and, given that there are 6.6 billion of us, how must we adapt all our behavior to have a future on this planet that is sustainable and might go on for centuries.

Humanity did not even consider this equation until recently. There was no global council 100 years ago discussing the need for slow growth from the 2 billion population level at that time. We did not, as a species, make any conscious decision about managing our numbers as it might relate to the capacities of our spaceship earth. Quite the contrary our history has been one of ever greater numbers. Create large families to till the farm and work the family business and to offset infant mortality. Create ever larger populations to fuel our economies based upon unlimited growth. Large families and endless growth has driven us. The perception was that resources were infinite and there was therefore no need to consider the fact that constant growth and expansion might one day come up against finite resources and threaten our very existence. It could be argued that the photo of a lonely Earth floating in infinite blackness that was sent back by the Apollo spacecraft in 1969 was the first image that suggested a finite planet to us all. But of course we have more than doubled our population since then.

Since we did not manage our growth, we now are confronted with the consequences of mindless growth. What that means we must collectively decide, and soon. We really have only a few options. The first is to accept zero planetary population growth. The second is to end all burning of fossil fuels by finding replacement energy sources that are renewable. The third is to use innovation, invention and new technologies to change how we live and how we interact with the planet. The fourth is to accept that what we have brought with us from our collective past can no longer be the norm. We might have to give up ideas of unmanaged growth, fresh food, fish and all sorts of things we accept as part of the human experience. If we haven’t been able to manage our numbers, we must manage how our species lives. I don’t like it, you don’t like it, but we have birthed ourselves to a number that our precious spaceship can no longer sustain.

It has been said that if all of the earth moves up to the energy consumption level of the developed countries we would need three planet earths’ worth of fossil fuel resources to sustain us. James Lovelock, the visionary scientist who first suggested the Gaia theory, that the planet is a single, complex, interrelated organism has recently spoken with despair. He sees the climate change that is occurring as Gaia moving to rid itself of the virus that is the human species, in order to protect itself. We have become the virus that threatens Gaia. He has suggested that the climate disruptions ahead will shrink the 6.6 billion of us down to 500 million by the end of the century. He has suggested that it might already be too late to alter that scenario. In other words, since we didn’t manage our species growth, Gaia is stepping in to do it for us.

We must act now. Debating whether there is global warming and whether we are contributing to it is no longer an option. It is, as was pointed out in the last column, an issue of risk management. The incremental steps discussed by our so called leaders will not be enough. Collectively we must mobilize and change how our species conducts itself. We must make it very personal to get this underway. Think of it this way: if Lovelock is even remotely close to being right, then if you know someone under the age of 10, or if you envision grandchildren, actions taken today might save their lives. You are responsible for future generations even having a chance. We all are.