Climate change is happening, and I’m watching it happen. I’ve been watching it for a couple decades, as I grew up in the wild forest of a steep and rainy valley. Of course, I was raised by slightly fundamentalist Christians, and homeschooled, so from the beginning I was told that climate change wasn’t real, that global warming was not a thing. I spent many days of my childhood free and innocent, exploring and imagining my way through our own wilderness of trees and moss and ferns.
In later years the argument shifted to “it’s real but not caused by humans”, probably because reality wasn’t conforming to their previous claims, as I eventually noticed. I watched our once gushing sweet well water, pumped up from 265 feet below the surface, slowly dwindle from summer to summer until there were days that the ground simply had no more water to give and the pump would stop, waiting for more liquid so it could safely run again. Once the pump didn’t shut off and it burned out and had to be replaced.
I watched as our winters in the mountains grew warmer, and threatened our water supply for the summer by melting the snowpacks with rain instead of adding more ice. I watched summer come earlier, drying out the forest, bringing drought and wildfires. I watched snowfall become rarer, then punctuated with intense storms that piled up to three feet of snow, which buried my Porsche entirely–all that could be seen was the antenna. Then more record heat, and another winter with no snow.
One day in my town last August I couldn’t see the mountains half a mile away due to choking smoke from a fire about forty miles to the east. Both Seattle and Portland and many places between were affected by the smoke that week as fires burned all over the state. The rainforest caught fire for the first time that anyone knows. These fires were the result of an extreme drought and the hottest year on record, which was in the process of breaking the hottest-year record set by the previous year. We’ve been doing that repeatedly in recent decades. Then comes 2016, which is breaking the record again. Our creeks dried up. All the grass turned brown for months, and leaves fell off the trees in August.
The global temperature has been increasing steadily for over a century, and in the past few decades the rate of temperature rise has itself risen. Nobody denies this…or perhaps I should say that nobody who understands what they’re talking about denies this, because the data is easily accessible and sources are plentiful. Search and read for yourself if you really want to understand. I’m going to try linking good sources, but I always double-check them so you should too.
What most people now are divided on is whether human activity is the cause of that temperature rise, and whether or not it presents a threat to our societies or survival. It is these questions which we must consider seriously, without falling for conspiracies or emotional arguments. They are important questions, so we want to be sure that we err on the side of caution. If there is a chance that it could be a threat to us, then we should understand it and take action to protect the well-being of our fellow humans.
I’m not going to address arguments and conspiracies against climate change, because usually that’s a waste of time. What I want to do here is present, in my own words, my best understanding of the data and research regarding climate change, carbon dioxide, and how it relates to humans. I am attempting a presentation of the facts, not my opinion, so if you have a different set of facts there’s really no point arguing about opinions.
The idea that increased levels of carbon dioxide could cause the planet to warm was first proposed way back in the 1800’s, after the mathematician and physicist Joseph Fourier calculated that based on its distance from the sun, the earth should be colder than it is. He proposed that the atmosphere acted as an insulator, and within a few decades people were looking at carbon dioxide as one of the key molecules for insulation of the planet.
Long story short, it turned out they were right. Carbon dioxide traps heat by absorbing infrared radiation, as John Tyndall found in the middle of the 19th century. He speculated that fluctuations in water vapor and carbon dioxide could change the global climate, which at the time was just becoming a field of study as people discovered and explained the effects of glaciation in past cold periods.
Then, in the late 1890’s, infrared absorption measurements were used to estimate how much of an effect the gas has on global temperature. Swedish scientist Svante Arrhenius calculated that removing half of the carbon dioxide in the atmosphere would be enough to trigger an ice age, and doubling it would warm the planet about 5-6 degrees Celsius. He realized that human emission of carbon dioxide from burning coal would contribute to warming the planet, but at the rates of the time it would be a slow change. His calculations were not perfect but they were the beginning of many decades of careful research.
Then our population ballooned from an already high one billion to seven billion. We now have released so much carbon dioxide into the atmosphere that the concentration is over 400 ppm, a significant increase over 19th century levels, and we have the capacity to nearly quadruple that number. Ice core data shows a pretty steady fluctuation over the past 800,000 years between about 180 and 300 ppm. These fluctuations in carbon dioxide match global temperature changes due to Milankovitch cycles and the ensuing positive feedback loop that results when slight changes in solar radiation trigger environmental changes that increase carbon dioxide, which in turn absorbs more radiation and adds more heat. Or the reverse during cooling periods. I mentioned these cycles when I talked about varves several months ago, since their effects can be seen in the millions of layers of the Green River Formation in the western U.S.A.
So we have learned the mechanism by which carbon dioxide absorbs heat, verified that it naturally tracks along with global temperature and amplifies small temperature variations from other causes, showed that our emissions have raised the concentration higher than it has been for a very long time, and measured a sudden and unnaturally fast rise in global temperature over the past century. Additional methods of confirming these facts are available to anyone who still remains skeptical.
Where do we go from here? It’s a difficult question to answer because we really have no precedent for what we have done to the planet. There’s no example in the history of humans that’s comparable, and a lot of other factors were different when you look far enough back to find a similar level of carbon dioxide.
For one, sea level was much higher, which could become a bit of a problem for humans since a majority of us and our large economic centers are near sea level. Obviously warming global temperatures will cause sea level rise because there will be less ice on land. This is an immediate threat for island nations and other sea-level populations, as the sea level has already risen almost 20 centimeters along with temperature and carbon dioxide since the 19th century. Several areas have already lost land, dealt with saltwater spilling over into their groundwater, experienced record flooding, and more. You can easily find recent information about these ongoing issues in Florida, Louisiana, and other areas.
What other consequences are there of warming temperatures and higher carbon dioxide? One effect is increased acidity of oceans, which absorb carbon dioxide from the atmosphere and form carbonic acid. This has also been an ongoing trend, and is harmful for some of the species that are vitally important to ocean ecosystems, because it can weaken or dissolve shells and exoskeletons. The possible effects of making the ocean uninhabitable for those species is not really known, since the change in pH we have caused is, once again, without precedent.
Another concern is that western North America has experienced megadroughts in the past, and California especially has been struggling with a multi-year drought recently. There are many factors involved, but a simple one is the relationship between temperature and the maximum moisture content of the atmosphere. As temperature goes up, the atmosphere can hold more water, which means less falls back to the ground as rain. Water vapor is also a more potent greenhouse gas than carbon dioxide, and can further amplify the heating effect, but it does hit a ceiling. The problem is that the ceiling rises with temperature, so the higher the temperature rises the greater the effect will be.
There is a lot more I could cover, but this is quite long now. The facts are there, and now I suppose each of us has to decide if the risks are enough to care about. We have many ways of quantifying these various risks, but people and models do disagree sometimes. One important thing to keep in mind is that the rate of change is unnaturally fast, which prevents many organisms from adapting. A collapse of certain populations could have a domino effect and we are already in the midst of a major extinction event caused by our actions.
For myself, I think about the scale of the possible impact, the fact that these changes could trigger events that threaten the lives and well-being of most humans alive right now and the billions who will probably come later. Maybe we’ll be fine, but maybe we won’t. The majority say we won’t unless we change. A minority disagrees. In my understanding, that minority among people who really know the science is tiny. They’ve been pushed by political and social forces to downplay the risks, for decades, because people don’t like hearing that they need to change their way of life. But we might have to.
Why not err on the side of caution? The changes we could make to stop using fossil fuels are demonstrably better for us and the planet in plenty of other ways, even if they aren’t necessary to save ourselves from forced mass migration and global instability. It might be a good idea to refrain from radically altering the global environment until you get solid evidence that it won’t have serious unintended effects, especially when almost everyone who understands the science agrees that serious problems are possible, if not likely.
For anyone interested in responses to specific arguments against climate change, here is a site that references numerous sources and provides clear explanations for a wide variety of details.