Exploring the warming – Cryoconite and Albedo

I was reading my copy of this month’s National Geographic which has a great feature on the melting Greenland glaciers and I started thinking about how often this subject is ignored when people discuss the merits of climate change (so often simplified to ‘global warming‘). Not the melting of glaciers, but one of the key causes of melting glaciers; The albedo of the Earth and the effect our burning of enormous amounts of black carbons has on it.

Even if you spend little to no time researching climate change or it’s causes, it’s been impossible to escape some exposure to it, and from that exposure, most people will tell you than climate change is happening because of CO2 and other greenhouse gases. That is one part of it, one very crucial part of it, but many people are unaware of how large the issue is, or how complicated it can be. Because of that, it is often frustrating to deal with climate change deniers because of how limited their attack on the issue is, they’ll crow about the divergence problem and how scientists are all part of a massive conspiracy until they’re blue in the face, but they will rarely tackle many other sides of the issue. For instance, I have never ran across deniers talking about carbon’s effect on the Earth’s albedo.

What is the albedo? In astronomical terms, albedo is measurement of how much light is reflected off of something back into space. In other words; an astronomical body’s brightness. Light materials reflect more radiation than dark materials and objects. Dark materials absorb more radiation than light materials and objects. As you learned in school, objects have color because they absorb different frequencies of the visible spectrum, and reflect others into our eyes and blah blah blah, we see color.

The oceans grow warm because their dark blue color absorbs much of the radiation the sun throws at us, the arctic is bitter cold because most of the heat thrown at it from space is reflected back by the very bright snow. Bright white clouds reflect light back into space, the dark pavement and buildings we build everywhere absorb heat. Even the contrails left by jetliners are a significant source of reflected light as shown by the grounding of all flights on September 11th.

So that’s albedo. Maybe you can see where this is going already if you don’t already know.

The burning of fossil fuels releases CO2 into the atmosphere, and those large quantities of CO2 trap radiation in our atmosphere warming up the planet, but there is another mechanism at play that is very rarely discussed in my experience.  I think will come into play a lot more frequently in coming months and years, however. When fossil fuels burn, they release black carbon into the atmosphere, also known as soot. When this soot is kicked up into the atmosphere, it is pulled into the strong, turbulent winds of the upper atmosphere and they are blown all over the globe. Unlike CO2, this soot settles out of the atmosphere onto the ground in relatively short order.

White glacier with high albedo on the left; dirty, lower albedo glacier on right.

A lot of the soot, settles in the cold areas of our planet, combining with dust and minerals sucked up from all over the planet which also happened to fall there. This combination of particles forms a gritty substance called cryoconite. The critical part here is, than these cryoconite granules only become dark when soot is added to them, and even more important-

“Even though cryoconite is composed of less than 5 percent soot,” he says, “it is the soot that causes it to turn black.” The darkness decreases the albedo, or reflectivity, of the ice, which increases the absorption of heat; that in turn increases the amount of melting.” – Nat Geo feature [link]

It doesn’t take a lot of this soot to have things turn south really quickly. This is dangerous because as mentioned above, these dark additions to the otherwise very, very bright glaciers, cause them to heat up. As they heat up, they speed up melting, which stimulates more heat absorption due to the uncovering of more of these cryoconite granules with the additions of new ones. It starts a positive feedback loop, or a point of no return; Once a tipping point is reached, it spirals out of control and nothing can be done about it.

Holes melted in glacier by cryoconite deposits.

This is not exclusive to glaciers, it applies to sea ice as well. As regions of once permanent sea ice melt, the dark ocean waters below them are exposed to sunlight which heat those waters up, which stimulates further sea ice melt. Another feedback loop.

These feedback loops are so dangerous not because we’re afraid of losing all of our ice (well we are, many ecosystems are dependent on the ice), but because of the effects a large amount of cold freshwater pouring into our oceans would mean. It would raise sea levels world wide, and more importantly even, would be the slowing of the gulf stream, which has a very violent history.

Climate change is much more complex them some deniers would have you believe. It is a giant interlocking machine of independently changing variables, many of which we are tinkering with to dangerous levels.

I suggest reading the National Geographic article linked above if you’re still reading. It’s an interesting look at the phenomenon. Go buy the magazine if you want to see some absolutely stunning picture to go along with it.

Advertisement

About this entry

You’re currently reading “Exploring the warming – Cryoconite and Albedo,” an entry on Reasoned Assault

Published:
June 3, 2010 / 3:01 am
Category:
Environment, Skepticism
Tags:
, , , , , ,