The last ice age on Earth ended about 11,000 years ago, but it was only a few squalls compared to the so-called scenarios of the globe. Scientists believe that the Earth has experienced several such periods, when the entire surface was covered with ice and snow. A new MIT study points to a potential mechanism of events on the Snowball that could help explain the development of complex life. It can also affect the search for exoplanets around other stars.
The ice age is simply a period during which global temperatures drop enough for polar ice caps and alpine glaciers to expand. The land of the Snowball is on a completely different level, and this makes it difficult to identify the causes. Researchers have long speculated that this has something to do with a decrease in sunlight or a drop in retained global heat, but the MIT team specifically points to “caused by the rate of icing” as the root cause.
The data show that all you need for the Snowball Earth is a fairly large drop in solar radiation reaching the planet’s surface. Interestingly, modeling by graduate student Konstantin Arnscheidt and geophysics professor Daniel Rothman shows that solar radiation does not have to fall to a specific threshold to launch Snowball Earth. Rather, it simply needs to be reset quickly in a geologically short period of time.
As the ice cover increases, the planet reflects more light, and icing becomes an “escape” effect. That’s how you get to the “Snowball” scenario, but fortunately for us these periods are temporary. The planet’s carbon cycle is interrupted when ice and snow cover the entire surface, and this causes the accumulation of carbon dioxide. Eventually, this leads to a warming trend that pulls the Earth out of the snowball period.
Research suggests that solar radiation could decrease quickly enough to cause global glaciation. For example, volcanic activity can precipitate particles in the atmosphere that reflect sunlight before it comes to the surface. It is also possible that biological processes can change the atmosphere, creating more cloud cover to block the sun.
The two suspected Earth periods of the snow globe most likely occurred about 700 million years ago, which is a notable time in the history of the planet. This is also when multicellular life exploded in the world’s oceans. Then, perhaps, the Snow Land cleared the way for the development of complex life. It may be the same on other planets. Finally, we can see exoplanets around distant stars in the “living zone” covered with ice. This does not mean that they will be icy forever, and big things can come as they thaw.
Credit top image: Stephen Hudson / CC BY 2.5