Climate change: The basic science

- Take a deep breath. Not for meditation, although that's never a bad idea, but to notice the air. You're breathing in oxygen, of course, but other things as well. Almost 80% of the air is nitrogen and a tiny fraction is carbon dioxide or CO2, the same gas you breathe out and that plant's absorb to grow. Without that tiny bit of CO2 in the air, none of us would be here. CO2 molecules help make the planet livable by trapping heat. When sunlight hits the earth, some of the energy is reflected back towards space, but CO2 absorbs and re-emits some heat into the atmosphere. This is the greenhouse effect, and without it, our planet would be far too cold for life as we know it. It's a delicate balance. A planet with too much CO2 like Venus is too hot for life. For a long time, our climate has allowed life to thrive, even with large temperature swings during ice ages. But when the industrial revolution began, humans started burning fossil fuels like coal, oil, and natural gas. These are the largest sources of CO2 emissions, and we've added hundreds of billions of tons of CO2 to the atmosphere. The science of climate change and how it will impact us has been studied extensively by many thousands of scientists focusing on it for decades. There are obviously big questions about how such a complex system works and exactly how warming will play out, but beneath it all, the basic physics of climate change is simple. Humans have added much more CO2 to the atmosphere, and that extra CO2 is trapping a lot of heat. The effects are increasingly obvious. The oceans are warming and expanding, raising sea levels, hotter oceans fuel stronger storms leading to record flooding. In other regions, shifting water patterns and increased heat are causing severe droughts and larger wildfires. In short, CO2 is altering Earth's thermostat, and within a human lifetime, we're seeing changes that would normally take millions of years. At times, global warming can sound minor. What's one degree Celsius or 1.8 degrees Fahrenheit? But don't think of it like an extra degree, making a spring day nicer, it's much more like a change in your core body temperature. Spike a fever of just a couple degrees, and you feel crummy, a few more and you're in serious trouble. And if all of the science doesn't quite convince you, consider a more basic gut test. Think about where you grew up. Is the weather there the same today as it was 30 or 40 years ago? Global warming and climate change are often talked about in a politically polarized way, but this is not really a political issue. Of course, there are policy choices to be made about how to fight it, but at the core, this is a scientific problem for humanity to tackle. The good news is we have the technologies, innovation and creativity to do it. We just need the will.