Stories tagged water cycle

Apr
09
2010

By Our Hands: Cities are perhaps the most impressive mark humankind has left upon the face of planet Earth.
By Our Hands: Cities are perhaps the most impressive mark humankind has left upon the face of planet Earth.Courtesy anaxila

Throughout the ongoing debate about exactly how, to what extent, and the ethical implications, the indisputable fact remains that humankind has altered the planet. Back when the human population was only a few thousand strong and agriculture and cooked food were the latest inventions, it was easy for the Joneses to pick up and move camp when the water ran dry, the soil stopped producing tasty wheat, or the garbage piled too high in the backyard. The same can’t be said for the populations of world cities today.

Advances in public health, industry, and agriculture have blown the human population out of the brush. There will soon be 9 billion people on the face of planet Earth! Coupled with rising affluence, our ballooning population’s resource consumption and waste outputs are wrecking havoc on natural systems. New research (see several links below for more info) suggests that within a fixed amount of space, humankind is in danger of causing our own extinction and the only way out is to discard traditional ideas of industrialization and embrace sustainability.

No, silly...: Not THAT kind of tipping point!
No, silly...: Not THAT kind of tipping point!Courtesy Go Gratitude

The first step to bailing out humankind is to investigate how close to failure the world actually is. This was the point of a recent international collaboration: to calculate safe limits for pivotal environmental processes. The key idea here is that of “tipping points,” which can be thought of as thresholds or breaking points. Think about being pestered by your brother or sister: aren’t you able to put up with the annoyance for even a little while before you get so upset you retaliate? That’s your tipping point – the last straw that put you over the edge.

Led by Stockholm Resilience Center’s Johan Rockstrom, a group of European, Australian, and American scientists – including the University of Minnesota’s Institute on the Environment’s director, Jonathan Foley – identified nine processes reaching their tipping points. Three (climate change, nutrient cycles, and biodiversity loss) have already been pushed past their tipping points, four (ocean acidification, ozone depletion, freshwater use, and land use) are approaching their tipping points, and two (aerosol loading and chemical pollution) do not yet have identified tipping points because they require more research. The Institute on the Environment recently released a YouTube video addressing the conclusion of this new research:

Blissfully, there are things we can do to stop hurting the planet and begin patching its wounds. According to Foley’s article, we can’t let ourselves get any closer to the tipping points and piecemeal solutions won’t cut it because of the interconnectedness of the issues. Instead, we should focus on switching to low- or no-carbon fuel sources, stopping deforestation, and rethinking our approaches to agriculture.

There's No Place Like Home: It's worth keeping healthy.
There's No Place Like Home: It's worth keeping healthy.Courtesy NASA

The conclusions of this research have been well-accepted, but there has been some criticisms for 1) attempting to establish tipping points at all, and 2) for the appropriateness of the establish tipping points. If you would like more information, including commentaries, please check out the following sources:

Article in Nature: A safe operating space for humanity

Commentaries: Planetary Boundaries

Article in Scientific American: Boundaries for a Health Planet

Article in Ecology and Society: Planetary Boundaries: Exploring the Safe Operating Space for Humanity

Two questions to consider as you watch the YouTube video and take a look through the links and articles referenced above are:

1) What are the consequences of being past our tipping points?

2) How do the solutions discussed prevent us from reaching tipping points?

You are encouraged to post your thoughtful answers below!

Nov
09
2009

Floating Free on the Dead Sea
Floating Free on the Dead SeaCourtesy Courtesy of Ranveig at Wikimedia Commons
In anticipation for the Dead Sea Scrolls exhibit coming to the Science Museum of Minnesota, I found myself wondering, why do we call it the Dead Sea? The Dead Sea is the lowest place on earth and one of the saltiest bodies of water in the world, 6 to 10 times saltier than the Atlantic Ocean. Because the salt creates such a harsh living environment, the only organisms that will survive in the Dead Sea are bacteria and algae. Any fish that accidentally swims into the Dead Sea from one of the freshwater streams that feed it, like the Jordan River, would die instantly!

The sea is so salty because of evaporation. The high temperatures and low humidity in the region cause the water in the sea to evaporate very quickly, leaving behind all the dissolved mineral salts. Some salts sink to the bottom and some wash ashore leaving a salty crusty beach.
Dead Sea Salt Beach
Dead Sea Salt BeachCourtesy Courtesy of Isewell at WikiMedia Commons

Because of the high concentration of mineral salts in the Dead Sea, the water is more dense than both freshwater and the human body. This means that our bodies become buoyant, like a cork, and we can easily float on it. When you take a dip in the Dead Sea you can actually kick back and read a book like floating on a raft. In fact, it is hard to actually “swim” in the sea.
Dead Sea Salt
Dead Sea SaltCourtesy Courtesy of Xtall at WikiMedia Commons

The Dead Sea has been a tourist attraction since the time of Herod the Great in the 1st Century BCE. The Dead Sea isn’t just a novelty for “fun while floating” but the mineral salts have been used in Egyptian mummification, in agricultural fertilizers and even in modern day cosmetics. Check out these links to learn more about Dead Sea geography, how it was formed, how it is used by humans, and some of the issues it faces today.

http://www.extremescience.com/DeadSea.htm
http://www.wysinfo.com/Dead_Sea/dead_sea_overview.html