National Geographic calls Ethiopia's Danakil Depression "the cruelest place on Earth." It's a desert wasteland, where temperatures can push past 120 F, where ancient and current lava flows impede movement, and where water is so scarce that that people build rock domes over the top of volcanic vents to trap and condense steam.
It's also a place where Ethiopian men and boys regularly travel in order to cut slabs of salt off of the surface of the Earth and haul them back to civilization. Salt flats like this occur when entire bodies of water totally evaporate. In the Danakil Depression, you'll also find salt towers and other formations caused by evaporation off of volcanic geysers and hot springs.
The photo above was taken by Reuters photographer Siegfried Modola, who traveled with a group of salt miners into the desert and then followed their haul all the way back to the marketplace. You can see his full slideshow of images online. I chose this one because it gives you a view of the salt as it's found on the ground, and the neat, rectangular blocks the merchants cut it into for shipping.
The spot is a favorite of photographers. I'd also recommend checking out the photos and story put together by Christina Feldt, who posted about the Danakil salt flats earlier this year. Read the rest
On Monday, I posted about an incredibly fascinating study linking the minerals that fertilize the Amazon rainforest to a specific corner of the Sahara desert in the country of Chad. That lake of sand—once an actual lake the size of California—is what keeps the Amazon green and verdant.
The interesting thing is that the study is actually not anything new. It came out in 2006. I heard about it from science writer Colin Schultz. Earlier this week, Colin went on News Talk 610 CKTB out of Niagara Falls, Ontario, to talk about how he stumbled across the study and why it's important far beyond simply connecting the desert and the jungle.
The interview delves into the subject in a lot more depth. In fact, it's a great demonstration of how reading a single research paper can be interesting, but doesn't necessarily give you the full picture of what's actually going on in science. Turns out, what we know about how dust travels to the Amazon has important implications for how we think about climate change and geoengineering. Also great: Colin comparing the volume of dust traveling from the Sahara to the volume of several Honda Civics. It's short, and very much worth listening to.
You can follow Colin Schultz on Twitter. BTW: He'd like you to know that when he says "bioengineers" in the interview, he means "geoengineers".
This is probably the most amazing thing I learned all weekend. The Amazon rainforest—with all its plant and animal life, and all its astounding biodiversity—could not exist as we know it without the patch of African desert pictured above.
The rainforest is amazing, but the soil it produces isn't very nutrient rich. All the minerals and nutrients that fertilize the rainforest have to come from someplace else. Specifically: Africa. Scientists have known for a while that this natural fertilizer is crossing the Atlantic in the form of dust storms, but science writer Colin Schultz ran across a 2006 paper in the journal Environmental Research Letters that not only produces evidence for a much larger trans-oceanic transfer of dust than was previously assumed ... it also pinpoints the exact (and astoundingly small) location where all the fertilizer in the Amazon is coming from.
The research paper, itself, is pleasantly readable, as far as these things go, so I'm going to quote directly from it. One quick note before I launch into this quote. The authors are measuring the mass of the dust in teragrams (or Tg). As you're trying to wrap your head around this, it might be helpful to know that 1 Tg = 1 million tons.
Read the rest
A total of 140 (± 40) Tg is deposited in the Atlantic ocean and 50 (± 15) Tg reach and fertilize the Amazon basin. This is four times an older estimate, explaining a paradox regarding the source of nutrients to the Amazon forest. Swap et al suggested that while the source for minerals and nutrients in the Amazon is the dust from Africa, it was estimated that only 13 Tg of dust per year actually arrive in the Amazon.