This past August I spent a day hiking the Conrad Icefield (see figure 1), at 51° north latitude, North America’s southernmost icefield. While on the icefield, I recognized that without the grace and meticulous design of the Creator God of the Bible, our entire planet would be covered in ice, and advanced life would have been impossible. Now, a new geological discovery provides additional evidence that God designed the planet meticulously for us.
We are in an ice age now, more specifically an ice age cycle. For the last 2.5 million years, our planet has oscillated from 10 percent coverage by ice to 20–23 percent coverage, within either a 41,000-year or a 100,000-year period.
We have ice now. Given the fact that the Sun was a lot dimmer in the past (see figure 2), we would expect Earth to have been heavily covered with ice in its earlier stages, and as the Sun brightened, to have less and less ice coverage. Such is not the case. This oddity is known as the faint young Sun paradox.
Given how dim the Sun was in the past, Earth should have been a permanent iceball. An iceball is defined as a planet whose entire surface is covered with ice. Since ice reflects sunlight much more efficiently than liquid water or dry land, if Earth had been an iceball in the recent past, it would still be an iceball today.
Geologists have established that while Earth has never experienced an iceball event, it has on several occasions experienced slushball events. A slushball event is a glaciation that extends from the poles to within 5–15° of the equator, with icebergs populating the entire equatorial zone. The slushball events themselves are not permanent because greenhouse gases in volcanic emissions, plus methane released from methane hydrate deposits, always delivered enough greenhouse gases to, in due time, warm Earth sufficiently to melt the ice from any slushball event.
A big problem with this scenario lies in the qualifier “in due time.” Geologic records reveal that Earth recovered from slushball and other glaciation events much faster than one would anticipate, considering how slowly greenhouse gases are released from volcanic emissions and methane hydrate deposits. The rates also seem incapable of explaining why Earth for most of its history was ice free (see figure 3).
A recent paper published in the journal Geology helps resolve this discrepancy.1 A team of four Italian geologists explains how others have failed to recognize the contribution of subsurface calcite precipitation that enhances the emission of greenhouse gases from volcanic calderas. By taking this extra emission into account, the team established that the Campi Flegrei volcanic caldera emits a flux of 880 tons of carbon dioxide to the atmosphere per day. They also showed that this flux has been ongoing for the past 40,000 years. Since at least 100 such calderas are actively spewing out carbon dioxide, the team concluded that calderas, even during a time of relative quiescent volcanic activity, contribute a hearty fraction of the global budget of greenhouse gases to the atmosphere.
If geologists have overlooked such a large contribution of greenhouse gas emissions from calderas, it is possible that they have overlooked other important sources. Given how much more geologically active Earth was during geological periods and eras previous to the Holocene epoch (the last 11,700 years), it seems perfectly reasonable to conclude that the release of greenhouse gases from volcanoes and methane hydrate deposits explains why Earth never had an iceball event and why slushball and glaciation events were so rare throughout the planet’s history.
The emission of greenhouse gases from volcanoes and methane hydrate deposits does raise a fine-tuning issue, however. For Earth to sustain an abundance of life for 3.8 billion years it is necessary that the quantity of greenhouse gases in Earth’s atmosphere be continually fine-tuned. Too much will kill off all of Earth’s life; too little will do the same. Since the Sun’s luminosity continually rises throughout the history of life, Earth’s atmosphere needs to possess declining amounts of greenhouse gases so that the temperature of Earth’s surface would remain roughly constant in spite of the increasing luminosity of the Sun. Nothing other than the Mind of the One who knows the present and future physics of the Sun would be able to guarantee that Earth’s atmosphere continually possesses the just right amounts of greenhouse gases.
- Giovanni Chiodini et al., “The Geological CO2 Degassing History of a Long-Lived Caldera,” Geology 43 (September 2015): 767–70, doi:10.1130/G36905.1.