Dumb Question Dept.: If Earth is a Closed System and We're Running Out of Water, Where's it All Going?
by Jeremy Elton Jacquot, Los Angeles on 08. 3.07
Ed. note: This is the first post in the "Dumb" Questions series of posts that TreeHugger is writing to provide answers to some basic questions about the environment and all things green. We realize that many of these questions/answers will seem, well basic, to most of you, but please bear with us: we just want to make sure that everybody is on the right page! After all, what's the fun in having you read our posts if you get stuck on a basic premise?
To answer this question, it helps to first have a rudimentary knowledge of the planet's hydrologic, or water, cycle. The water cycle, in essence, describes the processes by which large quantities of water move continuously through the Earth's oceans, land and atmosphere over short and long time scales. It is primarily dominated by the oceans — which account for 96% of the planet's water and where 86% of global evaporation takes place — though it has no defined starting or ending point.
Being a closed system, the water cycle depends on an equal number of inputs and outputs to function — which can include, but are not limited to, snowmelt (melted water flowing from glaciers and ice caps) and precipitation on one hand and evapotranspiration (water transpired from plants and evaporated from the soil) and surface/subsurface storage of water in lakes or aquifers on the other. In general, more water is often stored in reservoirs — like the oceans — than moves through the water cycle. This is especially true during warmer climactic periods when, as a result, average global sea levels tend to rise. Colder climactic periods, on the other hand, are characterized by the formation of more ice caps and glaciers — which come to accumulate a significant portion of the Earth's water supply.
If this is then the case, how can we account for the fact that we keep on hearing that we're running out of water? For one thing, the tremendous and unprecedented rise in our global population — especially in lesser developed countries — has put significant pressure on our finite supplies of freshwater. Whether it be through our contamination of some of the water supply, our relentless urbanization or our aggressive extraction of its reservoirs for agricultural irrigation, anthropogenic influences have sparked major variabilities in the Earth's water cycle whose implications we do not yet fully understand.
As was exemplified this summer by the unusual weather patterns that afflicted various regions of the world — prompting catastrophic floods in parts of Britain and severe droughts in Africa and the southwestern parts of the United States — climate change will come to play an increasingly important role in shaping the future of the planet and its water cycle. According to the IPCC's latest climate model projections, the water cycle will intensify throughout the next century as annual precipitation continues to rise in the already wet near-equatorial and high latitude regions while continuing to fall in dry sub-tropical regions — trends that can neatly be summarized by the following expression: "the wet will get wetter and the dry drier."
More broadly, the increases in global temperatures we are witnessing — which have already helped trigger the rapid and large-scale melting of ice sheets in Greenland — will continue eliminating valuable freshwater buffers (like glaciers) and contribute to ever rising sea water levels. These rises, in turn, may result in some saltwater bodies encountering once isolated freshwater bodies, contaminating them and making them inaccessible to us for our needs. This will only spur unsustainable practices such as the continued drilling and extraction of water from underground wells.
The likelihood of more unpredictable positive feedback loops arising as a result of our actions and the changing climate could worsen an already dire situation.
Based on projections made by the International Water Management Institute, freshwater shortages are likely to become more prevalent among poorer, rapidly developing countries in Africa and Asia by 2025 — a consequence of overpopulation and poor water infrastructure. Developed countries in Europe and North America will not see a serious threat to their water supply because of their wealth and technology, and because many of their populations are expected to decline over the coming years — thus better aligning them with their needs. These are only projections, of course, so we may end up facing a much harsher reality in 2025 — or, hopefully, a more pleasant one if we do a better job of addressing the underlying problems.
Well, that about does it for this episode of TreeHugger's "Dumb" Questions series. Hopefully this post was of some use to those of you still perplexed about the planet's water cycle and the state of our current and future supply of freshwater. We could've gone on (there's a lot more where that came from) but thought this was enough for a primer.
We're sure that some of you will have more questions about some of the topics we tackled (and, more likely, didn't tackle), so feel free to fire away in the comments or, better yet, in this forum thread!
Your "primer" leaves the question unanswered. The water ISN'T going anywhere. It is still here.
You seem to infer that sea water is "unusable" but your own article shows that most of our fresh water comes from ocean evaporation. In warmer climate scenarios, won't this evaporation continue, replenishing rivers and lakes (even if ice and snow are gone)? Saying that the oceans will somehow "contaminate" our water implies that the oceans now are somehow "outside" the fresh water system.
There are real reasons why we need to be concerned about availability of fresh water without making up such nonsense. Fresh water is going to be an issue because too many people are going to need it, not because it is stuck in the ocean. Desalination plants and evaporation technologies have been around for decades. You can purchase filtration systems off the shelf that allow you to drink sea water. The problem with water isn't that it is salty, it is that there is only so much. The more people we have, the less water we each get. Likewise, the more water we pollute, the less we have to drink.
The hydrologic cycle isn't going to shut down due to climate change (unless the planet gets too cold for evaporation or too hot for condensation--neither is likely). Even polluted water still follows this cycle. No, the real problem is that demand is quickly outpacing our finite supply.
From a geologic perspective--this isn't really a problem. Those who don't get the water they need won't survive, the population will crash, and the remaining people will continue on. Not a rosy picture from a human perspective, but it is exactly what will happen if we don't approach this rationally.
Keep things rational please.
It is a strong point about the oceans contaminating freshwater supplies. As you point out, desalination facilities have been around for years and the natural process of evaporation does the same. The problem is the cost in energy to do this. Los Angeles, for example, is right on the ocean. Yet it is a lot easier to ship in the water via the Los Angeles Aqueduct.
To quote wikipedia, "Desalination typically requires large amounts of energy as well as specialized, expensive infrastructure, making it very costly compared to the use of fresh water from rivers or wells (bores)."
http://en.wikipedia.org/wiki/Desalination
It's not just contaminating freshwater with salt water. Raise in the oceans can flood cities and contaminate the fresh water with chemicals and other unwanted impurities in addition to salt water.
The problem is not just the increase in population, but also getting fresh water to where it is needed. If the population in the US and other developed countries do decline (and all else being equal), then the lowing of available fresh water a little bit won't matter to us. More will be needed in developing countries, where the population will likely continue to increase.
I have held an idea that a part of it is related to the following...
and, I preface this with saying I am an armchair scientist at best...
1) Mass cannot be created or destroyed.
2) Water has/is mass
3) Humans are composed of roughly 62% water
4) The planet, in addition to polluted fresh water sources, has the 'matter' of water being used in human bodies as populations rise.
5) Human population growth is contributing to the decline in water, as the mass of the water is contained in the body until death.
Without doing the math, a growing population of humans made up of 62% water HAS to impact somewhere, but, I do not know if scientifically this can be proved or supported. No matter what, oil is going to seem really, really unimportant if we do not have water.
Why not let me run water pipes like i do oil pipes for you. I can do it across the land from Alaska to the Great Plains. Ever heard of desalination, funny GE has. If earth is 70% ocean ie water, take salt out and drink up.
If you post such nonsense, it will just fuel the irrational right wing and give them more fodder to say there is no environmental problem. Please consider your political footprint as well as your carbon footprint.
Interesting read.
Maybe a "dumb comment", but when you show graphics such as the "projected water scarcity in 2025", could you provide a link to a bigger version of the graphic so we can actually read the writing on it.
Thanks.
Marc P.
Another problem, with global warming, is that acid rain is a direct result of CO2 in the air which reacts with water to form carbonic acid (also what's bubbling in your soda.)
http://en.wikipedia.org/wiki/Carbonic_acid
Actually Earth looses millions of liters of water every day due to solar winds.
I don't get it; it doesn't have to be expensive to desalinate ocean water. A solar still is very cheap and easy to build. If people are dying of thirst living in the desert, shouldn't they be encouraged to live closer to the ocean? There's no shortage of water; our planet is covered in it.
It reminds me of New Orleans. Why are they rebuilding? It will only get flooded again.
Move the people dying of dehydration closer to the ocean, preferably to a spot above sea level. Teach them how to build a solar still out of a few dollars worth of scrap.
Why isn't this seen as a solution? There's no profit in it it. Much more profitable to build expensive centralized infrastructure and cities in the desert. Now the people must pay for water for the rest of their lives. Much more civilized and profitable!
It's amusing you think Earth is a closed system. Material is coming to the planet around the clock, meteors being an obvious example. You think material doesn't leave Earth because you've never seen an atmosphere burn off into space. It's not a fast process. Water is one of the first things to go.
@Patrick McGonegal
you said
"You seem to infer that sea water is "unusable" but your own article shows that most of our fresh water comes from ocean evaporation. In warmer climate scenarios, won't this evaporation continue, replenishing rivers and lakes (even if ice and snow are gone)? Saying that the oceans will somehow "contaminate" our water implies that the oceans now are somehow "outside" the fresh water system."
This is answered in the article. "In general, more water is often stored in reservoirs — like the oceans — than moves through the water cycle."
@humanfly
you said
"Move the people dying of dehydration closer to the ocean, preferably to a spot above sea level. Teach them how to build a solar still out of a few dollars worth of scrap."
What about when the areas near oceans become overpopulated as they inevitably would if you moved everyone there? What about agriculture, which in my opinion, is a bigger concern than water for people. I don't think solar stills are going to cover our needs for agriculture.
Solar stills are very cheap to build. You could build them on the ocean on modular rafts. Lay an underwater pipeline to pump the freshwater back to the land based agriculture, as your demand increases, add more stills.
For that matter, why not have people live on houseboatsif you're worried about overpopulation along the coast? Most of the planet is covered in water; why not live on it? Then you'd solve your water and your space problem for quite some time.
I went to school for geography. I've been told that we are polluting too much water. I even wrote an essay about it. I called it "We are pollution too much water". I am what you call an expert.
www.dibussolo.com
You are falsifying the statements made during the study by the IWMI and what figures are actually representing in the map. From the IWMI website.
" This means that they will not have sufficient water resources to maintain their current level of per capita food production from irrigated agriculture—even at high levels of irrigation efficiency—and also to meet reasonable water needs for domestic, industrial, and environmental purposes. "
This study also only included 118 of the possible maximum 244 countries in the world (depending on what sources you use there are 192 UN member states. It is really dissapointing to me that you falsify the facts and adjust other peoples work to suite your needs.
Im reminded of somethiing from school :dissolving a salt in a solution needs energy, although thousands of times lesser than it takes for desalination. So i personally hope there will be a breakthough technology to increase the efficiency by a factor of 20.
I believe suggesting that there isn't a water scarcity problem is rediculous. I'm an Environmental Engineer from Australia and we've just (and still are) experiencing the worst drought since records were kept. We have some extremely harsh water restrictions and are investigating all the options, including desal. I personally believe that it is a direct result of global warming and the increasingly erratic and extreme weather events. Whilst it may be somewhat attributed to the normal El Nino weather pattern, I feel it has been exaserbated by global warming.
In contrast to droughts, more extreme weather events result in some areas getting their entire yearly rainfall in one or two events a year. Resulting in flooding and limited available usable water.
Has anyone considered the impact of millions of gallons of water being thrown in the garbage can a day in the form of bottled water. I lands in a land fill and never goes back into circulation.
Paul Franz, finally somebody has expressed the same idea I've been telling my friends for years, the one about water stored in the body of humans and that the more humans there are,the more water is walking the streets of the world.
This might qualify as a dumb question, but here goes anyway; what happens to the water that the oil companies use to bring up the last drop of oil from their oil wells?. Is it left in the well or is it brought back up, cleaned up and reused?. If water is left buried, my mind tells me that if oil didn't percolate through the soil, and stayed undergroung for millions of years, so will the water, and that probably accounts for a few gallons of water that humans will never use again. Also, some years ago I read an article that stated that every day, we get water from space, in the form of ice chunks as big as houses that as soon as they hit the atmosphere become water vapor.