Sometimes you will hear it said that the evidence is ambiguous. It is not. More than one hundred years of study, on perhaps the most pressing issue in science, points to a clear correlation between rising CO2 levels, rising temperatures, and the explosion of the human population in the last 150 years or so, coinciding with the industrial revolution. For the entire history of humanity -- hundreds of thousands of years or so since the dawn of what we typically call a human -- the population was very low. It was not until the mid-19th century that the population reached 1 billion people. Today, it is more than 7 billion.
This exponential rise in the human populations begins at the beginning of the industrial revolution. And as our lives improve, our population swells, and our technology enjoys an exponential growth. In short order we are able to produce millions upon millions of machines that spew obscene amounts of carbon into the air. This carbon remained below the Earth's surface for millions of years -- deposited over millions of years -- but today we are devouring it at an insatiable rate, dumping our waste products into the air and into the ocean. There is no natural mechanism that could have released such enormous amounts of carbon into the environment all at once. It required the human catalyst for rapid change.
It's clear by now that the explosion of the human population feeds, and feeds on, the growth of technology, and this technology is almost entirely fueled by these ancient deposits. It is the lifeblood of our modern society. How could it not be a major signature of our impact on this planet?
The connection between humans and climate change, then, could not be any clearer. In the physical sciences, most of the time, you can trace a causality back through a sequence of events, piecing together where something came from. In this case, we measure increasing levels of carbon in the air, and we must explain where it's coming from. There has been no uptick in volcanism, no rapid change on the Earth other than the explosion of the human presence. Humans must be responsible for the rising carbon in the atmosphere. But where is it coming from? There is only one possible source: the vehicles and power plants that burn ancient carbon deposits. Ever wonder what's coming out of the exhaust pipe in your car? Well, it can be measured, and the verdict is unambiguous: carbon monoxide and carbon dioxide. It all goes up in the air.
Does it just evaporate into space? There's no way that's possible; the molecules would have to be incredibly energetic to reach escape velocity. No, they simply settle into the air for a long, stable existence. The measurements reflect this, and the way this change to our atmosphere affects the situation is clear. More carbon dioxide results in higher temperatures. This correlation between more greenhouse gases and higher temperatures is well demonstrated, and it is clearly reflected in the history of past climates. It's just physics and chemistry.
So, it's not any better to say you believe in global warming but doubt its cause. In both cases, you're ignoring the evidence.
But there are real consequences. There is an economic impact that looms very close on the horizon. There is the very real possibility that we consume our resources to such a gross extent that we do long-term damage to the world we depend on. There is the chance that we set up an unforeseen, climatic feedback loop which we are unable to reverse. We may interrupt the food chain in unexpected ways, setting off massive extinctions. This is the cost of our luxurious lives.
But the long-term solution is not austerity. We cannot well standby and say that we are the generation for which human progress stops. We humans could never abide by such a nonsensical idea. It could not be implemented even if anyone wanted to. The ultimate goal is not that we should enjoy fewer lights, fewer drives, fewer comforts. No, we want all of these things; we always have and we always will. That's why the choice now is clear: we must harness clean and renewable energy. It is abundant, affordable, sustainable, and dependable. It's the right thing to do.
It means honoring the mantle that has been bestowed on us by our ancestors, and is owed to our progeny, to guard well the Earth we call home. It means living free of air pollution, free of dangerous changes to our environment, and free to live in harmony alongside the other creatures of the Earth, evolved, as we were, over billions of years. They are far too lovely for us to be so cavalier about their existence. Any extinction caused by humans is a rueful and dreary event. It ought not happen.
Just imagine a world free of the drug of nations, fueling global tensions and wars. Free to grow without guilt, empowered to protect the world and pursue our own interests at the same time. It is achievable.