It is no secret that there is a massive disconnect between what the scientific community understands about climate change and what the general public understands. This has allowed our elected officials and those running for office (most recently the Republican candidate for Senate in Wisconsin) to get away with blatantly distorting the science, if not outright lying about it. This is perhaps the fault of scientists, who have often proved either unwilling or unable to explain their findings to the general public. Or maybe the media is at fault for refusing to accurately report on peer-review research.

When all of the available evidence is considered, it is impossible not to understand that climate change is primarily driven by human activity. The science that backs this up is relatively simple; I’ve found it to be easier to understand than any of the science I learned in high school. This makes me confident that, although my own area of study is biology, I can accurately present the research being done by climate scientists. I hope that what I write will help you to understand this crisis.

As I said, my own field of study is biology and, if the climate scientists won’t speak up, we must. The current extinction rate is 100 times higher than it naturally is and it will only worsen if we continue to burn fossil fuels.

With that introduction, I wish to begin by explaining how natural climate change occurs.

The key concept is that the Earth’s orbit around the Sun is not fixed. Every year, the point at which the Earth is closest to the Sun shifts very slightly, a mere fraction of a day. In fact, it takes 41,000 years for the cycle to complete itself. In other words, if the closest approach this year was August 17th at 9am EDT, then it would be 41,000 years before the date and time had slowly worked through the other 364 days of the year and returned to August 17th at 9am.

This matters because it is the most significant driver of natural climate change. When the Earth is close to the Sun during summer in the northern hemisphere, as in our example above, the Earth experiences a period of warming characterized by rising temperatures, increasing greenhouse gas levels, and the loss of ice caps. When the Earth is close to the Sun during winter in the northern hemisphere, the opposite is true; this is when ice ages occur. Temperatures fall, greenhouse gas levels fall, and the ice caps expand. At the height of an ice age, Lowell would be under about 1 mile of ice; it’s simply unimaginable. (As a side note, the reason why it is the northern hemisphere that matters is that most of the land mass on Earth is in the northern hemisphere).

So why does this happen? Well, let’s take the ice age example. A close approach during winter, say January, means that temperatures are warmer in winter and cooler in summer. Warmer weather means more precipitation; warmer weather in winter means more snow. Cooler weather in summer means that less ice melts. This combination of increased snow fall in winter with less melting in summer means that the ice caps can expand. The reverse logic applies to a close approach in summer.

One of the key things to remember is that the growth of ice sheets or the melting of ice sheets takes a very, very long time. We’re talking a minimum of thousands of years. This is an important point that everyone, scientist or not, has a difficult time with. It is easy for us to conceive of the Civil War ending 145 years ago. We can understand Rome being founded nearly 2,800 years ago. But what about the dinosaurs going extinct 65,700,000 years ago? Or the formation of the Earth 4,500,000,000 years ago? It is very hard to imagine and I’ll thus be returning to this theme repeatedly. The Earth moves on much longer time scales than humans experience, longer than we can even really conceive of.

Now, returning to natural climate change. I’m sure many readers remember that several decades ago some scientists began warning of global cooling. I’ve actually heard this used as a reason for ignoring scientists talking about global warming.

So why were scientists talking about global cooling?

The Earth’s closest approach to the Sun currently occurs in mid-January. Temperatures are supposed to be falling. The ice sheets are supposed to be expanding. We’re supposed to be entering an ice age. But we’re not.