The Little Ice Age: How One Person Can Seriously Screw Up Planetary Climate

If you’re the kind of person who spends a lot of time exploring the Sketchy Science archive, you may have noticed a glaring omission in the topics of articles we have covered. Although we talk about issues of sustainability every now and then (geothermal, solar power, etc.) we have never written an article explicitly about human caused climate change. That is largely because every other science writer around has pretty much beaten that topic to death. The science is obvious to the point of being uninteresting. Everyone knows we are causing the planet to warm and should do something about it. Our job at Sketchy Science is to share weird and cool stuff you might never have heard of, not to tell you what you already know. With that in mind, did you know that some scientists believe that before we got started warming the planet, we may have accidentally dropped it into a mini ice age?

Before we get into the meat of the theory, we should add a disclaimer. This is just a hypothesis. It is supported by evidence and it makes intuitive sense, but the ideas are relatively new and are not widely agreed upon. However, it is a hypothesis that is just too cool to ignore (no pun intended).

You may have already heard of the Little Ice Age but in case you haven’t, it was a period from around the year 1500 to the mid 1800’s where the Earth gave humanity a bit of the cold shoulder. Following the blissfully balmy medieval warming period, the Little Ice Age was an increasingly frustrating time to be alive. Glaciers were growing, crops were freezing, and many people suffered through long, harsh winters following by short, cool summers. In a world where your options for indoor heat ranged from wood burning stoves to coal ovens, the Little Ice Age was a bummer.

Scientists have long wondered about the cause of this glitch in what has otherwise been a fairly agreeable 20,000 year stretch in Earth’s climatic history. Theories have ranged from a drop in solar activity to increased volcanic eruptions cooling off the atmosphere. What people didn’t begin to expect until around 2008 was that we might be able to point the finger at one person. He was an Italian megalomaniac whose genocidal tendencies have earned people in the United States a paid day off work. He is widely regarded as a deeply disagreeable human being who enslaved nations in search of gold. His name was Christopher Columbus.

So how could the no-quite discoverer of the Americas cause the global climate to cool? Well, when he moored his ship in the Caribbean way back in 1492, Columbus ushered in a period of unprecedented ecological change all over the planet. One of the most impactful and most well-known consequences of Columbus’ voyages to the new world was the introduction of European diseases like small pox, measles and a host of other deadly infections to Native American populations with no resistance to them. The outcome, as you probably know, was that within a few centuries over 95% of the indigenous people in North America were dead.

Before all this happened, people in the Americas were pretty busy manipulating the landscapes they called home. Of the many changes they wrought on their land, the one that relates to our topic today was their practice of burning large forested areas to create agricultural land and grasslands on which to hunt large game. As genocide and disease wiped out their populations, the people of the Americas could no longer keep up with the widespread burning program and it is believed that over the same period that so many people were dying off, an area in North America the size of California grew forests where there were no forests before.

Trees are really great things. They are nice to look at, provide us with shade on hot summer days, and they make a great place to build a fort to fall out of and break your arm. They also pull carbon dioxide out of the air and release oxygen. In 2014, this is nothing but good news; in the 1600’s, not so much. Ice cores from Antarctica which trap air bubbles from years gone by have shown that following the arrival of Columbus in the Caribbean, the level of CO­­_2­ in the atmosphere fell by 6 to 10 parts per million. That might not seem like much, but it adds up to about 17 billion metric tons of climate-warming gas locked up in trees instead of in the atmosphere.

Climate modelling computers have demonstrated that removing that amount of carbon from the air could explain most of the cooling of the little ice age. So next time you read about the disappearance of glaciers and sea levels rising, remember the man responsible for putting all that ice there in the first place. Then shake your head in disgust both at one of history’s greatest monsters (aside from Jimmy Carter) and at the modern world for messing things up in the total opposite direction.

Climate or Climb It? How changing weather builds mountains

It is easy to think of mountains as permanent features of a landscape. Don’t do it. That is what they want you to do. Let your guard down for one second and those craggy jerks will be on you like white on rice. Mountains change and they do it constantly. We all know about plate tectonics and how ancient sea floors are now some of the loftiest places on the planet. But did you know that climate can also shape mountains?

  

Recent research from the University of California at Berkley has revealed that California’s already substantial Sierra Nevada Mountains have risen 10 millimeters in the past 7 years. You might expect that this is due to things like earthquakes and tectonics plates crashing into each other, but that is only partly the case. The researchers have also suggested that California’s ongoing and increasingly severe drought has been causing the peaks to shoot upward.

The thing about the Earth’s crust is that it’s a lot more like a mattress than it seems. Put some weight on it and it will dent pretty easily. Take the weight off and watch it spring back up (if you have a few decades to spare). Much of North America’s crust is still rebounding upward in response to the removal of the weight of glaciers from the last ice age, a process called isostatic rebound. In California, glaciers are generally hard to come by, even during an ice age. The uplifting there is the result of water loss in the soil.

It may not seem like it it, but water is massively heavy stuff. It is even heavier than ice, which is why the "rocks" in your scotch float. A one meter by one meter by one meter cube of water weighs a ton. That means the bed of an average pickup truck could hold several thousand pounds of water. Imagine how much the rain water that falls on a mountain range in a year weighs and you can begin to understand why a long running drought might cause mountains to rise.

As water fluctuates and the Earth’s crust reacts, we can get into some pretty hairy situations. A growing body of research is providing evidence that changing rainfall and ice-melt patterns associated with climate change might even cause volcanoes to become more active (Capra, 2006; Deeming et al., 2010). Your classic stratovolcano is just a mountain with a lot of internal pressure. As the amount of ice or water on the overlying mountain changes, the magma chamber underneath can become unstable. When enough weight has been removed the effect is like taking the cap off a shaken up bottle of coke.

Even if the magma chamber doesn’t blow its top, melting ice can destabilize the soil in a slope and cause landslides. The massive landslide in Washington State on March 22, 2014 that killed 41 people came after a period of intense rain that weakened the slope which eventually failed.

Mountains are pretty uncool in that way. They can sit there for millions of years looking all rock-solid and majestic. They watch and wait as we build towns at their bases so we can enjoy the view, going about their natural processes of erosion and uplift at a pace that the human eye just can’t observe. Then one day, either because it has rained too much or not rained enough they are capable of kicking things into overdrive. The lesson in all of this? It’s okay to make friends with a mountain. You can even hang out from time to time. But don’t for a second think you can trust them. They’re more lively than they seem.

References:

Capra, L. (2006). Abrupt climatic changes as triggering mechanisms of massive volcanic collapses RID C-2371-2011. Journal of Volcanology and Geothermal Research, 155(3-4), 329-333. doi:10.1016/j.jvolgeores.2006.04.009

Deeming, K. R., McGuire, B., & Harrop, P. (2010). Climate forcing of volcano lateral collapse: Evidence from Mount Etna, Sicily. Philosophical Transactions of the Royal Society A-Mathematical Physical and Engineering Sciences, 368(1919), 2559-2577. doi:10.1098/rsta.2010.0054