Climate change is on everyone’s mind’s lately, to the point where “climate fiction” is now a recognized subgenre — both within speculative fiction and without. Given my focus in this Patreon, however, I’m not going to attempt to spin scenarios about what our world might realistically look like in fifty or a hundred years, or how we’re going to respond to it; other people have already done that in far greater depth, with far greater knowledge of the subject, than I could hope to do.

Instead, we’re going to take a look at the climate changes humanity has already experienced, and what we’ve done about them.

Broadly speaking, we can lump these into two major categories: changes in precipitation, and changes in temperature. Furthermore, we can specify that, for it to count as “climate change” in a meaningful sense, it has to be a lasting alteration, not a brief one. Short-term change is weather; long-term trends are climate. And only the latter drives significant adaptations from society.

Of those two categories — please forgive the incoming pun — temperature tends to sneak under the radar. As we’re in the process of finding out, you can get significant alterations in weather patterns from global shifts of only a degree or two; in the days when no one had reliable thermometers marked with a systematic scale, that kind of shift was impossible to measure. And a gradual, large-scale drift like the one that produced the eras we term the Medieval Warm Period or the Little Ice Age happens on a timeline so slow, people are apt to notice it only across the generations: maybe your grandfather tells stories about how frost never used to strike after the spring equinox, or conversely, the ground had always thawed by then.

These changes are still significant! Agriculture depends on people knowing when it’s safe to put crops in the ground, and having enough time for them to mature before autumn storms or winter freezes kill them. As the average temperatures drift from what they used to be, harvests get poorer, because local customs are adapted to the weather patterns everyone expects. But as those patterns break, people will gradually change their customs to match, growing crops better suited to the conditions that now prevail.

Changes in precipitation can be a lot more calamitous. In this historical record, we most often hear about this as an issue of drought, when a persistent lack of rainfall across multiple years results in famine. It’s also possible, however, for the problem to go the other way; too much rainfall leads to flooding and crops drowning in the field. Or, in a worst case scenario, you get both: current theories hold that the decline of the Khmer Empire owed a lot to unpredictable shifts between not enough rain and far too much, which wrecked the stability of a society that depended upon sophisticated hydroengineering.

People can also adapt to changes in rainfall, of course, but it’s more difficult because the effects are more sudden. While unusual heat or frost can kill crops, a slow upward or downward drift in average temperatures gives you time to change from wheat to barley or vice versa, as you plant something hardier for the conditions. Droughts and flooding arrive more abruptly, and in between instances, you get good years where it seems like everything is back to normal. It’s only when you look back on the pattern that you can see where things started going downhill — and by then, quite a lot of people may have starved.

Attempts to engineer our way out of trouble are not a new phenomenon. The aforementioned hydraulic works, discussed in more detail last year, are all about trying to buffer against the vagaries of water being over- or under-supplied. Farmers can also insulate their fields with straw or attempt to shade them with taller plants, to mitigate the effects of heat and cold and reduce evaporation. But mostly, the response to this has had to take the form of changing our own behavior: planting something more tolerant of the conditions at hand, so that at the end of the day — or the season — we have something to eat.

I’ve been speaking of this primarily in terms of crops because that has been the overwhelming consideration — and also the only part even vaguely in human control. If climate shifts produce more hurricanes or tornadoes or blizzards . . . well, historically speaking, there is bugger-all people have been able to do about it. Even now, we can only do so much to fortify our houses and cities against those kinds of storms. And while it’s true that climate change can also introduce novel diseases, neither the people of the time nor historians looking back now can generally tell where exactly those epidemics came from. All people could do was hunker down and hope to survive, or migrate somewhere they hoped would be safer.

Because climate has historically been every bit as much out of our control as weather. While it’s true that human action can affect the globe, as we’re seeing right now, it tends to require a scale of influence we really only hit with the Industrial Revolution. Before that, our population was too small, our output of climate-changing factors too restricted. We have changed local climates through actions like deforestation, which can lead to desertification, but the biggest alterations have mostly come about through natural forces: volcanic eruptions, changes in ocean circulation, and the like.

I should note in passing a particular subset of (thus far fictional) climate change, which is the process of terraforming. Science fiction has long played with the idea that humans could deliberately alter the climate of a whole planet specifically to make it hospitable — and not just the climate, but the entire composition of the atmosphere and the biomes of the land and sea. Most novels have handwaved their effects into existence, caring more about it as a background device to allow for human settlement on other planets; only a few have really devoted attention to the mechanisms by which this might be achieved. If you’re interested in that end of things, I am definitely not qualified to help you! But it’s an intriguing question to explore — not least because the precursors to such ideas are being explored right now on our own planet.

Back to the home front: bear in mind that, more than any given set of conditions, the problem tends to be change. Some conditions are, admittedly, more favorable than others; mild temperatures and moderate rain — however those are defined for the region — are going to produce better results than the alternative. But humans are very good at adapting to the situation at hand, and thriving as much as possible under those circumstances.

It’s when the rug gets pulled out from under us that havoc truly results. Then the behaviors and patterns that protected us before suddenly become maladaptive. Even if the new situation is entirely survivable, we may not be acting in the best fashion to get through it. But figuring that out, and making the necessary changes, is easier said than done . . . and no, that isn’t simply a not-very-coded slam against all the inertia getting in the way of responding to our current climate crisis. People cannot easily abandon cities threatened by rising sea levels or the depletion of the local aquifer, or pivot their economy toward resources that better suit the new reality. That’s especially true of everyone at the bottom of the socioeconomic scale, for whom the immediate concern has to be their ability to get by today.

As I said above, these changes are mostly going to play out on a timescale that means we only see a snapshot of one moment along the line — or, perhaps, look back upon it in retrospect. (A few authors will have their story elapse over generations or centuries, but that’s not common.) Still, knowing that context can help set the stage for a plot . . . one with far too much relevance for us today.