The Case for a Creator - Lee Strobel [98]
“You see, greenhouse gases, like carbon dioxide, absorb infrared energy and help warm the planet. So they’re absolutely crucial. The problem is that their concentration in the atmosphere needs to be regulated as the sun slowly brightens. Otherwise, the Earth would not be able to stabilize its surface temperature, which would be disastrous.
“Plate tectonics cycles fragments of the Earth’s crust—including limestone, which is made up of calcium, carbon dioxide, and oxygen atoms—down into the mantle. There, the planet’s internal heat releases the carbon dioxide, which is then continually vented to the atmosphere through volcanoes. It’s quite an elaborate process, but the end result is a kind of thermostat that keeps the greenhouse gases in balance and our surface temperature under control.
“What’s driving plate tectonics is the internal heat generated by radioactive isotopes—Potassium-40, Uranium-235, Uranium-238, Thorium-232. These elements deep inside the Earth were originally produced in supernovae, and their production in the galaxy is declining with time because the supernova rate is declining with time. That will limit the production of Earth-like planets in the future, because they won’t generate as much internal heat as the Earth does.
“This radioactive decay also helps drive the convection of the liquid iron surrounding the Earth’s core, which results in an amazing phenomenon: the creation of a dynamo that actually generates the planet’s magnetic field. The magnetic field is crucial to life on Earth, because it shields us from low-energy cosmic rays. If we didn’t have a magnetic shield, there would be more dangerous radiation reaching the atmosphere. Also, solar wind particles would directly interact with the upper atmosphere, stripping it away, especially the molecules of hydrogen and oxygen from water. That would be bad news because water would be lost more quickly.
“Now, remember how I said that plate tectonics helps regulate global temperatures by balancing greenhouse gases? Well, there’s also another natural thermostat, called the Earth’s albedo. Albedo refers to the proportion of sunlight a planet reflects. The Earth has an especially rich variety of albedo sources—oceans, polar ice caps, continental interiors, including deserts—which is good for regulating the climate. Whatever light isn’t reflected by Earth is absorbed, which means the surface gets heated.
“This is self-regulated through one of the Earth’s natural feedback mechanisms. To give you an example, some marine algae produce dimethyl sulfide. This helps to build cloud condensation nuclei, or CCN, which are small particles in the atmosphere around which water can condense to form cloud droplets.
“If the ocean gets too warm, then this algae reproduce more quickly and release more dimethyl sulfide, which leads to a greater concentration of CCN and a higher albedo for the marine stratus clouds. Higher cloud albedo, in turn, cools the ocean below, which then reduces the rate at which the algae reproduce. So this provides a natural thermostat. 40
“On the other hand, Mars lacks oceans, so it doesn’t have this albedo component. It only has deserts, small polar caps, and very thin, occasional clouds. So Mars is far less capable of adjusting its albedo as its more eccentric orbit takes it closer and then further from the sun. That’s one of the reasons why it experiences larger temperature swings than Earth.”
Giant plates of shifting rock that precariously balance greenhouse gases; decaying radioactive isotopes acting as a life-sustaining underground furnace; an internal dynamo that generates a magnetic field which deflects cosmic dangers; precision feedback loops that unite biology and meteorology—I had to pause and marvel at the complex and interconnected processes that orchestrate our planet’s environment.
And that was just the beginning. I knew Gonzalez could go on and on about scores of other fine-tuned