Today I watched the Rooster Teeth podcast earlier and at one point Burnie discusses the natural heating of the planet due to climate change. I have tried to stay fairly neutral about modern climate when I post my educational series on my profile about climate. This discussion, however, provides an important segue to discuss: natural heating of the environment.
The planet has warmed and cooled many times throughout its history. It has been very warm. It has been very cold. Whether or not you believe humans are causing climate change is irrelevant in Geologic time: it will continue to oscillate on its own long after the people alive now have turned into dust and ash. The causes of this oscillation are variable. Our atmosphere has a big impact, plate movements and tectonics cause changes, but so too does our orbit around the sun and the movement of the earth on its own.
Orbital parameters are the easiest point to discuss. The earth shifts in three major ways: 1) our orbit around the sun changes between circular and elliptical; 2) the tilt of the earth changes; and 3) the earth “wobbles” on its axis. These three movements are called the Milankovitch cycles after the work of Serbian scientist Milutin Milankovitch, or the Croll-Milankovitch cycles if we honor the works of Scottish scientist James Croll. These three cycles have specific names 1) is often called eccentricity, 2) is obliquity (or just tilt), and 3) is precession of the axis. At many times in Earth’s history, these have worked with and against each other to have varying degrees of effects. They can both work with and against each other given the variable timescales on which they occur. Eccentricity, for example occurs in cycles of approximately 100,00 years and 400,000 years (the 400k cycle being variations of multiple 100k cycles). Obliquity operates on a ~40,000 year cycle, with precession being the shortest at ~20-25,000 years. As we can see there will be times when all three overlap at once, or when 1 or 2 work against the third, etc.
What are the impacts of these cycles though? Primarily it is changes in the seasons or intensity of seasons depending. Eccentricity, for example is not just the change in shape of the orbit, but also the change in where the sun sits within the orbit. The change in shape changes where the sun sits relative to the equinoxes and solstices of the planet. Imagine a hula-hoop where the person in the middle is the sun. At some points the ring of the hoop will be much closer, and at others it will be further away. The close and far points are call perihelion and aphelion respectively. Now, currently perihelion occurs in early January, shortly after the winter solstice in the Northern Hemisphere. What this translates to is the Northern Hemisphere winter is closer to the sun than the Northern hemisphere summer. Consequently, the Southern Hemisphere summer is closer than the Southern Hemisphere winter. What this does is enhance the seasons in one hemisphere and mute the seasons in the other. In the above example Northern Hemisphere (N.H.) winters are made warmer, and summers are made cooler, muting them. While the Southern Hemisphere (S.H.) winters are colder and the summers warmer. You may wonder, if the N.H. winter is closer to the sun, why is it winter? The answer is obliquity.
Obliquity, or tilt, if how much the planet leans. The North and South pole are not perfectly perpendicular to the sun, they are tilted between 22.1 and 24.5 degrees. Now winter versus summer is just a matter of which hemisphere is tilted towards the sun versus tilted away from the sun at any point. N.H. summer is when the N.H. is tilted towards the sun, and the S.H. is when it is tilted towards the sun. Obliquity, then, controls which hemisphere gets which season. They change in the amount of tilt adjusts the intensity, with the 24.5 figure having more intense summers and winters.
Precession is the trickiest to visualize of the three Milankovitch cycles. The best way to describe it is like a top. A top is a small toy you could spin and it would remain standing straight until it began to slow and wobble until it eventually fell down and stopped spinning. Anyone who has seen the movie Inception has seen a top, it was the device Leonardo DiCaprio used to determine if he was dreaming. Precession is the “wobble” of the earth’s axis, like a top. Its primary effect is shifting when the equinoxes and solstices occur by changing where the axis is pointed. So the axis stays tilted, but precession is the sway changing where it aims. Precession tends to work most with eccentricity in terms of effects, either making eccentricity minimal or more powerful depending on timing.
Orbital parameters are fairly powerful effects and are often interpreted to be the main drivers of glacial versus interglacial (warm periods) cycles. But these are not the only answer. If they were, we’d expect the North and South Pole to be more variable between seasons, but also for the equator-to-pole temperature gradients to be more pronounced. The reason these factors aren’t as intense as expected is due to the atmosphere. Atmosphere moves raw heat from warmer to colder locations via temperature gradients, pressure gradients, and currents (e.g. jet streams). The movement of heat in the horizontal axis (relative to the surface) explains why the poles are warmer than expected based on the equator temperature gradient. Trace gases in the atmosphere cause the Greenhouse effect by trapping some outgoing radiation from the planet (specifically long wave radiation). I am glossing over this section because there are entire careers dedicated to atmospheric science, but the premise is that the atmosphere, and the oceans for that matter, are very effective at distributing heat across the planet.
Tectonics. Now this is the one people often underestimate. Why” Well, truth be told is takes massive amounts of time to have an effect, and when it does it is primarily by affecting the atmosphere and in particular the ocean. Ocean currents are incredibly powerful forms of heat transfer. Our current system is situated well to our modern continental positions, with the North Atlantic being of huge importance. You see, the North Atlantic is a heat dump. Warm currents run up to around Iceland, give off heat to the air, then have a massive downwelling to form what we call the North Atlantic Deepwater formation (NADW), this heat dump is what keeps places like Iceland and Scandinavia from being as cold as parts of Siberia. Now, tectonic can interrupt these current systems by moving the plates and the continents. South America and Africa used to be connected, the NADW runs right through that gap on the way to the Antarctic, but warm waters also travel north through here as well, meaning were those continents still connected there, the climate of Western Europe would be drastically different from today due to different movements of oceanic heat and water. Additionally, tectonics can interfere with winds and cause changes within the continents. The Himalayas are an example. Winds blowing off the Indian ocean are warm and full of water vapor, they hit the mountains and are pushed up, which causes clouds and rain to fall (complex processes I may discuss at a later date). Dropping rain here makes the wind that goes to the other side of the mountains dry leading to what we call a “rain shadow” on the downwind side of a mountain range. This effect can be seen in North America as well. The Rocky Mountains cause a rain shadow wherein the west side has much higher precipitation, while the east has much less. This example of tectonics does not even address the roles of volcanoes, which have complex roles in introducing both ash and greenhouse gases to the atmosphere, but also arise from tectonics.
I mention all of the above given that they are natural processes that balance and interact with each other through time. There are always other factors to take into account (e.g. sunspots on solar output), but entire careers have been made discussing the innumerable ways different earth and space variables interact to make our climate.
So how does this relate to the RT podcast?
Well, above I tried to outline how nature shifts itself regarding climate. There have been extremes of cold and warm in antiquity. An example of very warm conditions for example comes from the Cretaceous where there were crocodiles found at the North Pole. Crocodiles, for those not versed in reptilian biology, need to keep their temperatures around 77 degrees Fahrenheit, meaning they need fairly warm conditions in order to survive. To find them at the North pole is significant, meaning it was much warmer in the Cretaceous. This warmer period was due largely to a more greenhouse gas intensive environment causing warming, so it was a lot of the atmosphere being involved. This all relates to Burnie’s comment about the changing conditions possibly killing us.
Well the earth is constantly in a balancing act between the inputs of climate. Fundamentally, even if we go back to Cretaceous levels of heat the planet itself won’t “kill us” because when it warms the equator is one of the least affected zones, all the heat does is 1) move equator-ward climate regimes pole-wards and 2) cause heat changes to affect winds, currents, etc. Fundamentally, even if we had those conditions today, the big thing of note is that where rain occurs, where plants grow, and things like sea level will change. Humans will be able to survive quite easily, but where we live will be drastically affected. Cities like New York will be negatively impacted or even uninhabitable depending on the sea for example. Areas with drought may become drier, areas with rain may flood more. You remember the planes in Phoenix getting grounded a year or two back? Things like that will affect human society as well. The exact changes are extremely hard to predict.
One thing is clear. We are not killing the planet. The planet (as in the big spherical body) existed before life formed its first shred of DNA. It will exist long after until the sun expands and consumes everything we were, are, and will become. What is changing is how and where people and other animals may live on the Earth. Our trash problems are an example of humans affecting stuff, but that is not the point here. Regardless of if people are causing climate change or not. Eventually climate will change, and our species will face it.
Now, that said, it is worth it to invest in things like clean energy. Even if you don’t think humans are causing change, fossil fuels are of limited supply. Even if they last a millennium, they will run out eventually, so it makes sense to transition off of them while we can. If we do, we can say: even if climate does change, we are not actively working to cause said change. There are plenty of benefits.
The moral of this story is climate changes and will continue to change. Humans will be able to survive even if it does, but society and current population levels likely will need drastic restructuring. I know this is a bit of a nitpick on a single comment, but I want to inform and share information with people. Ultimately, however, I agree with the sentiment, and hope we can change our energy uses to prepare for the future.