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Following the Ice: Is this Global Warming?

The views expressed are those of the author and are not necessarily those of Scientific American.

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From the mess tent, we can hear huge boulders crashing through rapids half a kilometer away. The boulders sometimes sound like approaching footsteps, and as we’re all just a tiny bit nervous about an unlikely polar bear visit, conversations trail off and we listen.

In the four years our camp has existed on this glacial river, more meltwater is spilling out from beneath Leverett Glacier than we’ve ever seen. What’s more, the river has spilled over its banks and is now eroding a glacial moraine near our camp that was likely pushed there in the 1700’s during the Little Ice Age. It’s only June and the river is still rising.

Ben Linhoff sampling the stream formed by glacial melt early in the season.

Ben Linhoff sampling the stream formed by glacial melt early in the season.

The Greenland Ice Sheet is the most impressive thing I’ve ever seen. Looking out over its seemingly endless expanse of white, grey, and black textures of crevasses and rolling hills of ice, one feels close to infinity. On my last trail run, I ran to the top of a small mountain surrounded on three sides by the ice sheet. I was wearing running shorts and a tee shirt; the sun was bright and a steady wind coming off the ice kept the mosquitoes away. I sat down on a slab of granitic gneiss and leaned against a warm boulder. The wind was surprisingly balmy and humid, despite having just crossed the Greenland Ice Sheet. I closed my eyes and soaked in the heat and sun. Later that day I reformatted my air temperature graphs from last year’s season to fit the data collected this June. The y-axis had to be expanded by 10 degrees.

Can we say this year’s warm weather is because of global warming? It’s not for certain, and it’s important not to ascribe one especially warm season or year to global warming. It’s probably more important not to write off global warming as a hoax when it snows in Washington, D.C. This is particularly true in the high latitudes (the Arctic and Antarctic) where temperature variability between years is higher than anywhere else. In the tropics, there is very little variation between years (or even seasons) compared to the much larger variations nearer the poles. However, while average temperatures have climbed in both the tropics and the high latitudes, the arctic and Antarctic have warmed significantly more. In general, the closer to the poles, the greater the increase in average temperature but also the greater the variation between years. Last year we had snow in the middle of June and only a handful of days with bad mosquitoes. This year in early June, it was often unbearably hot in our tents by 5:00 a.m. while outside, millions of mosquitoes swarmed around our tent doors, waiting for us to give into the heat and step outside.

Global warming refers to increases in average temperature over the entire globe over a period of decades, not in one location or over one year. I don’t think this point can be made often enough. While we cannot say one warm season is the result of global warming, I think the fact that our ice-melt-fed river is spilling out of its banks and eroding things that have clearly been there for centuries seems worth noting.

Finally, although scientists have been trying to beat the public over the head with this concept for at least two decades, it’s probably worth pointing out again: There is widespread, broad consensus among scientists, not just about global warming, but also about what’s causing it: burning fossil fuels.

I wouldn’t be surprised if someone reading this decides to disagree in the comments. There is a very vocal and surprisingly incensed group of people who think the climate is not changing or that it’s all just natural variation. All I can say is that the so-called climate change deniers have views completely at odds with what the mainstream scientific community agrees on. Rest assured, the global warming controversy exists outside of the scientific community.

When I’m not collecting samples and keeping equipment running in camp, I’m cramming for my qualifying exams for my chemical oceanography Ph.D. in the MIT/WHOI Joint Program. Much of our exam focuses on the carbon cycle and CO2. Because the ocean is the largest sink for CO2 produced from burning fossil fuels (on time scales that affect people), a large part of my exams are focused on tracking fluxes of CO2 in the ocean and then determining its fate (What happens to CO2 once in the ocean and how long will it stay there?). For many years the faculty at MIT and Woods Hole have written qualifying exams that focus on making sure we understand (in excruciating detail I might add) the central role the carbon cycle plays in marine chemistry and Earth’s climate. Because most of us who come out of the program will spend our careers as scientists, the exam is at least partly designed to ensure we are prepared to research and understand the profound way people are changing our planet by adding CO2.

Climate Change Feedback Loops

Doing some “back of the envelope calculations,” we’ve estimated that the river discharging from the glacier is carrying about 400,000 metric tons of sediment per day to the ocean (Ten grams of sediment/liter with a discharge rate of 470 cubic meters/second: feel free to stop reading and try the math!).

The high latitudes (including Greenland) are warming much faster than the rest of the planet.

The high latitudes (including Greenland) are warming much faster than the rest of the planet.

That’s a lot, but what’s really interesting about glacial meltwater is that this sediment load is composed of extremely fine-grained, freshly broken rock material that is primed to consume CO2 through chemical weathering reactions. Although rock weathering is thought to ultimately control Earth’s CO2 budget on time scales of millions of years, photosynthesis—something probably much more familiar to everyone—is the most important sink for CO2 on year-to-year time scales.

Surprisingly, glaciers may also play an important role in driving photosynthesis in the world’s oceans. Glacial meltwater, icebergs, and wind-blown dust from glaciated landscapes can all carry essential nutrients (especially iron) to nutrient-starved regions of the ocean (Raiswell et al., 2006). These glacial nutrient sources can fertilize the ocean, stimulate photosynthesis and ultimately cause the consumption of atmospheric CO2. If you are scratching your head thinking, “So more glaciers can lead to more CO2 taken out of the atmosphere which would cool the planet, grow glaciers cause more icebergs, more CO2 consumed, more cooling,” then you’re on the right track and have identified something called a feedback loop.

Scientists are wondering if, during the ice ages, glacial-fed phytoplankton blooms in the Southern Ocean (the ocean surrounding Antarctica) helped keep CO2 levels at a minimum, which helped keep the world in a freezer. Basically, the glaciers themselves may have stimulated photosynthesis and kept global CO2 levels low, which then grew more glaciers and so on, until some external force threw off the balance. This external force would’ve been episodic changes in the amount of sunlight reaching Earth’s surface (called the Milankovitch Cycles). Once the timing and intensity of the sun’s heat changes (or humans release too much heat trapping CO2), another feedback loop can take over.

Consider permafrost. Permafrost is a thick layer of subsurface soil in polar regions that remains frozen year-round. While you may have heard of permafrost you may not have realized that permafrost contains vast quantities of carbon that was frozen in place thousands of years ago. As the planet warms, and permafrost melts, this ancient carbon becomes food for microbes that transform that carbon into CO2 gas and methane (CH4), which warms the planet, melts more permafrost, producing more CO2 and CH4 (see Frey and Smith, 2005). Ice cores taken from the Antarctic Ice Sheet give us a datable record of the atmospheric CO2 concentrations through time. These records tell us that ice ages are often ended by sharp, fast upswings in CO2. This upswing could very well be the release of CO2 from melting permafrost.

For many scientists, the questions are more immediate. How are glaciers affecting climate today? Will the world’s shrinking glaciers produce more or less icebergs, meltwater, and windblown dust and will this help or hinder photosynthesis in the ocean? One interesting hypothesis is that as Antarctica’s ice sheet collapses, a temporary increase in icebergs in the Southern Ocean could help fertilize marine phytoplankton and slow global warming as the blooms consume CO2 through photosynthesis. Or not. For now, I think the jury is still out regarding the role the world’s ice will play in the changing climate.

There are many of CO2 feedback loops, and glaciers and permafrost are just part of a few of them. Serious accounting skills are required to understand the delicate balance between all of the world’s CO2 feedback loops, as well as all the sources and sinks for CO2. All we know for sure is that much like the natural variations in the sun’s intensity, burning fossil fuels is heating the planet and could set off a CO2 feedback loop with unforeseen consequences.

For what it’s worth, over the last four years in our camp in Greenland, all the nearby ponds have rapidly shrunk and we suspect melting permafrost beneath the water is causing them to drain (think of their bottoms falling out). Meanwhile, as noted in the above post, we may be on our way to a record-breaking melt year that may be part of a larger trend.


Frey, K.E., Smith, L.C., 2005. Amplified carbon release from vast West Siberian peatlands by 2100. Geophys Res Lett 32.

Raiswell, R., Tranter, M., Benning, L.G., Siegert, M., De’ath, R., Huybrechts, P., Payne, T., 2006. Contributions from glacially derived sediment to the global iron (oxyhydr)oxide cycle: Implications for iron delivery to the oceans. Geochim Cosmochim Ac 70:2765-2780.

Photos by Chris Linder


Previously in this series:

Following the Ice: Greenland
Following the Ice: In the Beginning
Following the Ice: Glacial Dam
Ice Day: Like a nice day, but not

Ben Linhoff About the Author: Ben Linhoff studies glaciers and chemical oceanography in the MIT/WHOI (Woods Hole Oceanographic Institution) Joint Program in Oceanography where he is a second year PhD student. He writes about glaciers, the arctic, climate change, and adventures. Follow on Twitter @FollowingTheIce.

The views expressed are those of the author and are not necessarily those of Scientific American.

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  1. 1. Carlyle 5:14 pm 07/12/2012

    What causes my scepticism is primarily driven by the proposed solutions. For example, Australia has just imposed a $23.00 per ton carbon (dioxide) tax yet excludes nuclear power, diverting billions of dollars to alternative energy schemes that inevitably fail. There will be no effect on global climate whatsoever as a result of this tax. Energy intensive industries are being driven off shore to countries like China who will use the ore we sell them, processed with the coal we supply them, using dirtier plants than the ones we are closing, as well as all the extra fuel consumed shipping the raw products thousands of miles unnecessarily.
    The linkage of what may prove to be some good science, to harebrained schemes coupled to wild exaggerations that inevitably focus on ill effects, with barely a mention of the positive effects of the .8 degree Celsius in global warming that has occurred over the past 150 years.
    The science has been captured by the Green movement whose main objective, social engineering, is using climate change as the medium to achieve goals that have nothing to do with the health of the planet.
    If scientists wish to regain respect & credibility in the climate field they need to vigorously dissociate themselves from exaggerations & all non solutions to energy production with less polution. Also to acknowledge the benefits that a Co2 enriched atmosphere can bring as well as the possible ill affects.

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  2. 2. geojellyroll 6:08 pm 07/12/2012

    Environmnet Canada…cooler conditions this past Spring over most of the Arctic and western Canada. Vancouver has coolest June on record.

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  3. 3. Plantiful 6:10 pm 07/12/2012

    Carlyle: the carbon tax is not the solution, it is simply a means of trying to address the solution, which is to slow the introduction of carbon dioxide into the atmosphere. One of the main reasons that renewable energy is not being used is that fossil fuels are so cheap, and the complete cost of their use is not being paid for (i.e. the externalised cost of the added CO2 in the atmosphere- the cost of this is just starting to be paid for in lost lives and increased insurance payments for increases in frequency and intensity of weather-related disasters).
    The intents of this carbon tax economic tool are several: 1) raises cost of burning fossil fuels, 2) makes renewable energies more competitive, 3) increases awareness of conservation of fuels/energy (electricity, oil, coal, etc…). Where this money goes is up to the government, and that is where any fault in the system exists: the money should be used to get a renewable fuel / technology running so that it can be self-sustaining economically (to scale).
    A global carbon tax would prevent manufacturing from going to countries where the tax does not exist, but that is a matter of international diplomacy, which both China and especially the corporate-owned United States government would quickly prevent.
    There will be no positive effects from a temperature change of +0.8°C, especially since this change has occurred in such a drastically small amount of time (geologic scale). It is anticipated that we are looking at +2 to +6 °C by 2100. Even +2 °C over 200 years is scary. Yes, plants may grow a little faster with more heat and CO2, but any benefit will by quickly negated by increased droughts, floods, and fires.
    The science has not been captured by the dark and mysterious ways of the “Green Movement”. Anything “green” is maligned by images of the hippy movement in the 1960′s. It may help to think about sustainable living in a new manner: if it is not sustainable, it ends. How do we want our current society to end / change? I would prefer a change that is a known where we have some control, over something that is a headlong, rush into the unknown, and perhaps such a change that it can be likened to an end.
    Exaggerations serve no one but the media, which seeks fear to sell their story / product.
    Wonderful technologies that can be used economically today include:
    1) Solar Hot water heaters (why burn oil/coal, when the sun is out nearly everywhere),
    2) the simple clothesline (clothesdriers use the most energy of laundry)
    3) reel-style lawnmowers (get some quiet exercise),
    4) LED and CFL lights (1/8-1/4 energy of incandescent)
    5) fans instead of the A/C (where applicable),
    6) brooms and rakes (more exercise!) instead of the now ubiquitous (at least in U.S.)blower,
    7) get rid of the SUV and buy an efficient car, hybrid, or electric car (if you have the money). Rent the SUV when driving the football team somewhere- the rent is cheaper than filling up the SUV for all trips.

    We do nearly all of this, and our electric bill is 200-400 kWh/month, and we burn about 300 L of oil / year for heating hot water in the winter. That saves money too!

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  4. 4. jctyler 8:06 pm 07/12/2012

    @plantiful: disregard comments 1 and 2 = heartland-type “sceptics” = waste of time

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  5. 5. icowrich 8:28 pm 07/12/2012

    Carlyle: I’m pretty much where you are on the topic, except I don’t see how my frustration with politics should blind me to the science. There are, as far as I can see, four questions that must be answered.

    1. Is the Earth warming?
    2. Is man responsible (whether in whole or in part)?
    3. What are the true costs to the above warming?
    4. What, if anything, can we do about it?

    It seems to be that 1-3 have been answered.

    1. Thermometers across the globe can’t all be lying so consistently.
    2. It is uncontested that CO2 levels have risen rapidly and that we are the ones releasing CO2. It is also uncontested that CO2 traps heat. This can be demonstrated easily in high school chemistry lab.
    3. Costs are trickier to assess, but it’s pretty clear that they do exist and that they are rather massive.

    It’s only the final point that a mystery, at this point:

    4. We don’t know whether costs of remediation are greater than the costs of global warming. This is a legitimate point of dispute.

    All of the time we waste “debating” 1-3 (when the science is clearly in) is only relegating sensible doubters to the background. I happen to think that artificially limiting carbon emissions has the (also incontrovertable) effect of limiting economic growth. It is economic growth that ultimately leads to the kind of innovation that will one day solve the warming crisis. Do you want efficient solar panels that can truly compete with coal and gas? Do you want efficient wind and hydrothermal? You won’t get it by slowing industry.

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  6. 6. scientific earthling 2:33 am 07/13/2012

    Please, please guys do nothing. Life will return to earth after the sixth extinction runs its course. There is a massive benefit for the planet and all life if the most viscous, ignorant life-form is lost in this extinction.

    Celebrate the extinction of the Homo sapien. The most evil life-form to ever exit in this corner of the universe.

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  7. 7. Steve3 5:14 pm 07/13/2012

    Geojellyroll — Even if you text is true (and I have no reason to believe anything you write) you’re writing about weather- not climate.

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  8. 8. Steve3 5:18 pm 07/13/2012

    icowrich “It is economic growth that ultimately leads to the kind of innovation that will one day solve the warming crisis.”

    Can you tell me why you think economic growth leads to innovation ?
    It might be the other way around innovation leads to growth or there may be no causal relation.

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  9. 9. CherryBombSim 9:39 pm 07/13/2012

    “Finally, although scientists have been trying to beat the public over the head with this concept for at least two decades.”

    Ben says two decades, but I was in his boots FORTY years ago, studying atmospheric physics and stomping on glaciers. Without any temperature data at all, we knew damned well what would happen if you doubled the partial pressure of CO2. (At least to a first order approximation) There was no controversy. (We did have CO2 data, and were fairly certain where it was coming from.)

    At the time, I was living in LA, and it was just about the time when pollution was so bad that everyone agreed that it was so horrible that it needed to be fixed, and it was. I think humans will deal with the temperature thing, but only when it gets really, really bad.

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  10. 10. alyceobvious 12:19 pm 07/17/2012

    thank you for sharing this important piece. as a former scientist and current communicator about scientific and sociological concepts, i believe that it would be very effective to shift the climate dialog slightly in order to emphasize the underlying concern stated here by the author – the burning of fossil fuels.

    please see my related article “[climate] change is dead, long live change” published in truthout in march of 2010, but more pertinent than ever:

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  11. 11. bdddriller 12:44 pm 07/19/2012

    As SATAN surredered to God in Nov.2001 and is back in HELL,his body energy will keep the core moltin so it never cools and we end losing our protective magnetic feild like whats happened to Mars,You see God was having a problem with planets he was creating,their cores would cool and as a result they would lose their protective magnetic feild this will never happen to the earth as SATAN is perficly desighned needing nothing but giving a magnetic feild forever,this is Gods solution to this problem.Regards rik

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  12. 12. bdddriller 12:50 pm 07/19/2012

    Everybody knows that crude oil is from millions of years of dinosuar poop as everything was wiped out in the firestorm that wiped out the dinosuars 76 million years ago and everything in North America and possibly the globe was burnt so I don’t think you are going to get a lot of oil from charred dinosaurs as everthing that could burn ,burnt.

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  13. 13. bdddriller 1:00 pm 07/19/2012

    The drivers in Europe have caused the rains to fail in Africa for ten years now,and the drivers in North Americas have dried out the rainforest in South America so bad that frogs and others of their spieces can’t live there anymore and the rainforest is dying the lungs of the earth will be gone,then we will only have the plants and the oceans.There will be some temporary relief as the water from the melting North pole is obsorbed but once thats gone it is going to get real hot and so dry that plants won’t have enough rain to grow.The only solution is to pressure the leaders into switching us over to natural gas as fast as posseble.This is our only hope.Regards,rik

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  14. 14. bdddriller 1:06 pm 07/19/2012

    The problem with burning oil is not the cumbustion thats only elivating the global temperature but the oil smog its this thats dehydrating the globe and we are using atmousphere way faster then its being created so over time if we are not watching what we are doing we will run out of air as it can’t support us and machines so I think its time for our leaders to lead and we will follow as our culture allows.Regards,rik

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  15. 15. bdddriller 1:23 pm 07/19/2012

    As the oldest rock in Canada is 4.5 billion years old the true age of the earth and the Canadian sheild is only 3.5 billion years old it was created by the speed of Gods sheilded,time capibule spaceship.The speed of the ship impacting at lake bikail in kazikstan USSR.The sheild displaced the force of the impact and all the moltin rock till he exited at Hudson Bay in Canada the bow of the sheilded ship creating James Bay.It broke the arctic islands off the North Am erican plate and they were shifted close to where they are today.As there is no plate activity up there thats how they were formed.The force of the impact was so great that it pushed the earth south so far it exposed antarctica to space,space freezing it 3.5 miles thick.The angle of this impact gave us our twentyfour hour day rotation from east to west.The speed of the ship is classifyed but lets say the whole impact happened in one billionth of a second for aguments sake.Regards,rik

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  16. 16. bdddriller 1:28 pm 07/19/2012

    As SATAN is now back in HELL as of November 2001 this is your global warming but we still need to leave all the oil thats left for the gyro desighn of the earth as we know what happens to machines when they run low on coolant or oil just think of the earth as a complex machine,maybe you can understand this consept better.Regards,rik

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  17. 17. bdddriller 1:47 pm 07/19/2012

    I want somebody to core a major river bed silt layer to see if thier has been other ice ages.God says they happen every 12,000 years and the next one is 400-2,000 years away.As well as seeing if there has been other ice ages you should also be abil to tell how long they last.God says a long time,When he talks like this it could mean a few hundred to a few thousand years and as God knows this time line like no other we should look at the sedimentry record to see what hes talking about.Regards,rik P.S. As God is as old as the big bang we should listen when he talks as its for our own good.rik

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  18. 18. bdddriller 2:01 pm 07/19/2012

    The ore bodys and the water of both types balance out the magnetic feild,plants need this so you can have what you need but you have to leave some for the earth.Oil is a coolant and lubrication for plate movement.We all know what happens to machines when they run low on either coolant or oil.If we are not careful ice ages always start the same elivated temperature cuasing clouds to form blocking and reflecting the sun lowering the global temperature.We need the entire atmousphere to freeze,then it will warm up gradually.Just hope some of our children make it or the future isn’t going to be too frendly.If you are wondering what happens to a area that takes all the oil out just look at the weather Texas has now and for the last decade.Regards,rik

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  19. 19. bdddriller 2:19 pm 07/19/2012

    Man will evole to a point and the lifespan will increase to a point so that man will be abil to keep God company as he is recreating himself in man,thats whats going on,and the future looks good now as SATAN and his DEMONS are back in HELL.Man has a really good future but this is the most cridicul time he has to live to evolve and he has to have the wisdom to keep everything alive with him as everything is interconected.Time is a good teacher but man has to learn that there are somethings you just can’t force.Regards,rik

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  20. 20. bdddriller 2:23 pm 07/19/2012

    You see God doesn’t hate anybody,but creating SATAN and HELL was the only way that he could get a magnetic feild to last till our sun goes super nova but that won’t happen for anouther six.five billion years.Regards,rik

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  21. 21. bdddriller 2:45 pm 07/19/2012

    God in a sheilded,time capibule spaceship impacted at lake bikail in kazikstan USSR the speed of the ship created a vacume that sucked out mantil rock creating the Canadian Sheild.The mantil rock that was sucked out creating the Canadian Sheild and the rock that was sucked out of the earth created a chamber we call HELL.And as SATAN surrendered to God in NOVEMBER 2001 and has been back in HELL ever since elivating the temperature to close to what it is today,this is your global warming as its the energy given off by his bodys energy feild that will keep the earth moltin and hot so it never cools and as a result lose its protective magnetic feild as whats happened to Mars and every other planet ever created you see SATAN and HELL are gods solution tho the problem as after a couple billion years the planets core would cool and as a result it would lose its protective magnetic feild.Mars is a good example as the solar winds have stolen the atmousphere and surface water,Of all the minerals Gold is the only mineral to stand against the solar wind and I wonder if that is why its Gods favorite mineral.Regards,rik P.S. Sorry for the spelling and the grammar but not much earth schooling.

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  22. 22. bdddriller 2:58 pm 07/19/2012

    What Man needs to do in the future is take a ballard power cell out to the edge of the asteroid belt and trade it for a old but better desighned spaceship,one with a better drive system then oil as you are limited by range and durationYou see getting water is such a pain in space as first you have to find a planet that has water and then hope that the natives let you take water as sometimes the reaction you can get is not te best.Then you have to achieve orbit and get your bareings and go on your way but with the ballard power cell you can make your ownwater and the electricity you generate can go to your sheild as it can never be too stong as asteroid collision debris is everyware.The space station should have a skin of pressure sencors so the folks will have a idea when and if you build it right how big and how fast you were hit becuase that will determine how you are going to respond,sometimes you have to obort your mission if you can’t seal your hull breach.Reagaeds,rik

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  23. 23. bdddriller 3:12 pm 07/19/2012

    Also in the future man is going to build a ore refinery at the edge of the asteroid belt so you can prosses asteroids of interist that your scout ships have diamond drilled and catologed so you can finaly fill your periodic table.Keep in mind rare mineral types can be shipped as is but as they are usualy radioactive need special treatment and long term unprotected exposure isn’t recomended.The star freighters can take sea water out in their hull,eposure to high sound waves seperates the hydrogen and oxigen out and it burns at 2500C hot enough to melt any mineral the only problem is that in space water freezes so you will need a special anti freeze that you can burn and not be bad to breath as you are going to need atmousphere for anyhing to burn.The now empty freighters can now transport back to earth for everyone.There is other things I know but have to take a break.Regards,rik

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  24. 24. bdddriller 7:48 pm 07/19/2012

    For Canada we need to build a big inch pipeline from the east arm of great slave lake in the northwest territories to Alberta Canada as it is 400-1200 ft deep on the east arm of the lake and refreshes every winter and all the water sheds are intact.So in ten years as all the glacier fed rivers are going to dry up farmers and folks will have a water source in the pipeline.Goverment can charge a small user fee to pay for building and maintaining it but every year after harvest it should be drained and you should run a x-ray pig thru it so you can keep up with the maintenance as running water is so corrosive and its to big to bury and it will be to expensive to cut thru the bedrock till you are out of the frost zone.It will be better to use it only in frost free months.Regards,rik

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  25. 25. Kyell Luca 5:10 am 09/15/2012

    Iam new to this blog and stuff,so i dont have any idea to share my thoughts about this post, can you help me.?

    seo company

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