Climate change is bad. Melting glaciers are also bad. However, both these things lead to something called "dead water." From a nautical perspective, this is also bad because it stops a ship in the middle of the ocean. But it is so, so cool to look at.
As glaciers melt, they release massive amounts of fresh water into the ocean. Some of this water gets mixed into the seawater immediately. Some of it collects in pools above the existing salty water. The difference in salinity, and the resulting difference in density, keeps the two pools of water separate, with the less-dense fresh water covering the salt water.
A person in a boat going over the ocean shouldn't notice a difference between stratified fresh and saltwater and the regular sea — at first. Then, after a traveling normally for a little while through the layered water, their boat will slow, or even stop, seemingly without cause. As the sailor tries to maneuver the craft around, it will either fail to respond to their steering at all, or exaggerate their turns wildly. It will seem as though the boat is being held back, or pushed around, by powerful forces, but the surface of the ocean will remain calm and unchanging. Sailors who strayed into stretches of water like this call it "dead water."
Recently, scientists simulated dead water in the lab. It was as simple as stacking up water with different levels of salinity, marking the less-dense level with dye, and dragging a toy boat across the surface of the "ocean."
The process is easier to see than to describe. The boat creates a wave in the lower, saltier level of water. This wave isn't visible on the surface, but follows the boat. The problem starts when it overtakes the boat, and the boat "fall backwards" into the trough of the underwater wave. The boat isn't dragged under, but its progress is halted Meanwhile, the surface looks smooth, and gives the passenger no clue as to what's happening underneath.
Image: Christopher Michel
[Source: Mattieu Mercier]
DISCUSSION
Okay, fine, let's discuss the funny comments here.
Large and fast amounts of climate change are difficult for biological organisms to adapt to. As a biological organism, I will admit that I might be biased (I'm a bit of a chauvinist when it comes to wanting my species to not go extinct), but, yes, large and fast climate change is really bad. Next question.
Yes, the modern Left's primary ideology is that humans should take responsibility for their actions. This used to be an ideology of the Right, but apparently when faced with too much responsibility, they think the best solution is to ignore things. I don't know how intelligent of an idea that is.
This would take a lot of work in basically undoing emissions of the past few centuries. But! You're right in one sense. Large and fast climate change, in a global cooling direction, would also be really bad for humans.
No. All available evidence argues that during the Holocene (the past ~12000 years, the time period in which human civilization has existed) there was a slow natural cooling trend from about ~6 thousand years ago. The amount of warming that has occurred within the past 2 centuries only occurred because humans started adding large quantities of a greenhouse gas into the atmosphere.
Yep! You're totally right. The science that says that greenhouse gases heat up planets has been demonstrably proven to have been fabricated. Svante Arrhenius totally just fudged all his experiments a century ago. Actually, rather than H2O and CO2 and CH4, Earth's atmosphere retains heat by unicorns using magic. True story.