It Is All About the Ice (polar as well as glacial)

• "Secondary school" science refresher for global warming sceptics:
  
  
  1. Definition: one calorie of energy is required to raise the temperature of one gram of water by one Celsius degree (1°C).
     Alternatively: one BTU (British Thermal Unit) of energy is required to raise the temperature of one pound of water by one Fahrenheit degree (1°F).
      
  2. However, eighty calories of energy are required to convert one gram of "zero degree ice" into "zero degree water" (if you look it up, the actual value is 79.72 calories or 333.55 joules but I digress). This value is known as the specific melting heat of ice and is one reason why a small volume of ice can cool a larger volume of liquid. In a hand held container, the temperatures do not meet in the middle. Instead, the temperature of liquid drops toward the temperature of ice until no ice remains. Notice that the addition of eighty calories of energy to 0°C ice has not increased temperature; it has only changed the state from solid to liquid.
      
• Polar ice shelves and glaciers are melting at an unprecedented rate which means that they do a reasonably good job of slowing the rise of Earth's average surface temperature (although the CO₂ increase began with the beginning of the industrial revolution, things get far worse after human population quadruples between 1900 and 1999).
   
• Question: so what happens when the ice is gone?
  
  Answer-1: Instead of every 80 calories of thermal energy converting one gram of ice into water, it will raise the temperature of one gram of water by 80 degrees C. Higher temperatures will kill our oceans, increase the size and number of deserts (via affecting Hadley cells), flood most river deltas with salt-water storm surges, increase storm frequency and (to a lesser extent) intensity. Remembering that many river headwaters originate in mountain glaciers (six major rivers in Indo-China begin in the Tibetan plateau), the reduced river flow will reduce the food supply probably killing up to one billion people. (will subsistence farmers on the equator ever be able to buy food from developed countries?)
  
  Answer-2: Once the ice has melted into water, it will be very difficult (maybe impossible) to restore it to its previous condition. Why? From the liquid state you will require the removal of 80 calories to change the state back to ice. This might never happen again until the next ice age. (There is a high probability of the arctic polar ice cap totally melting because, unlike the Antarctic, there is no underlying continent)

  Recent bad news: The Wilkins Ice Shelf is comparable in size to the US state of Texas. Although it had been cracking for years, a Connecticut-sized portion began calving into icebergs in April 2009 (although the news media missed it because they were fixated upon the relatively smaller H1N1 Mexican influenza outbreak as well as minutia from Hollywood)

  1. http://www.esa.int/esaEO/SEMRAVANJTF_index_0.html (European Space Agency)
  2. http://www.coolantarctica.com/Antarctica fact file/science/global_warming.htm
  3. http://www.guardian.co.uk/world/2009/apr/05/ice-shelf-wilkins-antarctic
  4. http://news.bbc.co.uk/2/hi/science/nature/7984054.stm (with video)
  5. http://www.cbc.ca/technology/story/2009/04/28/tech-090428-wilkins-ice-shelf-antarctica.html
  6. http://www.ctv.ca/servlet/ArticleNews/story/CTVNews/20090429/ice_shelf_090429/20090429/
  7. A flotilla of over 100 icebergs endangers shipping lanes between Australia, New Zealand, and Tasmania. These icebergs were produced by high temperatures in 1998-1999 causing fractures of the Ross and Ronne Ice Shelves in 2000.
     1. http://www.telegraph.co.uk/news/worldnews/australiaandthepacific/australia/6768364/Giant-iceberg-heading-for-Australia.html
     2. http://www.ctv.ca/servlet/ArticleNews/story/CTVNews/20091201/iceberg_flotilla_091201/20091201
        
        
• Post Script: to make matters worse, melting ice is similar to flipping a switch: ice reflects 80% of incident sunlight back into space while water absorbs 80% of incident sunlight. This means that planet Earth is flipping from "reflecting mode" to "absorption mode" which could be the beginning of a thermal runaway effect. Additional environmental heat will do many things but here are just three:
  1. Drive the oxygen out of water thus killing the oceans. (Trout and Salmon prefer cold water because cold water is oxygen rich)
  2. Cause atmospheric oxygen to bind with minerals. Many deserts are reddish-orange due to the combining of oxygen with minerals (oxidization)
  3. Shorten winter so that disease bearing pests are not properly terminated each year.
     
     
• Many people claim the current warming trend is natural and they are partially correct. Earth's current orbital shape around the Sun is nearly circular (Eccentricity: 0.016710219) but is more elliptical during ice ages (elliptical eccentricity is one of three Milankovitch Cycles). Today, man-made green house gas emissions are amplifying a natural warming cycle which will push Earth's climate past the tipping point much sooner.
   

  Orbital Forcing 1) Orbital forcing is the effect on climate of slow changes in the tilt of the Earth's axis and shape of Earth's orbit (see Milankovitch cycles in the next section). These orbital changes modulate the total amount of sunlight reaching the Earth by up to 25% at mid-latitudes (from 400 to 500 W/m-2 at latitudes of 60 degrees). In this context, the term "forcing" signifies a physical process that affects the Earth's climate. 2) This mechanism is believed to be responsible for the timing of the ice age cycles. A strict application of the Milankovitch theory does not allow the prediction of a "sudden" ice age (rapid being anything under a century or two), since the fastest orbital period is about 15,000 years. The timing of past glacial periods coincides very well with the predictions of the Milankovitch theory, and these effects can be calculated into the future. 3) Scientists think Milankovitch Cycles enable/disable ice ages but climatic feedback loops are responsible for the actual flip. For example, Milankovitch warming causes the oceans to heat up which triggers the release of dissolved CO2, water vapour, and methane hydrates. These added greenhouse gasses raise atmospheric temperatures even higher which melt polar ice (changing albedo from light to dark) as well as melting of permafrost which releases even more methane.

  Milankovitch Cycles 1) Precession is the change in the direction of the Earth's axis of rotation relative to the fixed stars, with a period of roughly 26,000 years. This gyroscopic motion is due to the tidal forces exerted by the sun and the moon on the solid Earth, associated with the fact that the Earth is an oblate spheroid shape and not a perfect sphere. The sun and moon contribute roughly equally to this effect. 2) The angle of the Earth's axial tilt (obliquity) varies with respect to the plane of the Earth's orbit. These variations are roughly periodic, taking approximately 41,000 years to shift between a tilt of 22.1° and 24.5° and back again. When obliquity increases, the temperature difference between winter and summer increases. 3) The shape of Earth's orbit around the Sun is an ellipse and  eccentricity being is a measure of the departure from circularity. The shape of the Earth's orbit varies from being nearly circular (low eccentricity of 0.005) to being mildly elliptical (eccentricity of 0.058) and has a mean eccentricity of 0.028. The major component of these variations occurs on a period of 413,000 years. A number of other terms vary between components 95,000 and 125,000 years, and loosely combine into a 100,000-year cycle. 4) The result of these waves combine to enable glaciation cycles with an average period of 100,000 years. (feedbacks from greenhouse gases actually throw the final lever; Volcanoes introduce a randomness which can go either way). Within this cycle you will find an average interglacial period of 15,000 years. Milankovitch Animations: http://www.wwnorton.com/college/geo/egeo/flash/18_2.swf http://www.sciencecourseware.org/eec/GlobalWarming/Tutorials/Milankovitch/

  
  
  Food For Thought: the current warming trend (which started 11,700 years ago at the end of the previous ice age) has enabled the human population to grow to its current size of 6.9 billion. Things got worse with the beginning of the industrial age and the invention of steam engines. The current level of trapped solar energy is too high so humanity must employ geoengineering along with "CO₂ reduction" to lower the average temperature so we can maximize agricultural production. Some time in the distant future, humanity will use geoengineering along with "CO₂ production" to prevent the temperature from getting too low as we enter the next ice age. Think of both interventions on our part as a cosmic survival test.
  
  
  
• So with Milankovitch cycles causing the largest changes, are man-made (anthropogenic) green house gases of little consequence? No.
   
  Ice cores from Greenland (Century Station) and Antarctica (Vostok Station) provide scientists with an atmospheric history going back 400,000 years and 600,000 years respectively. During previous interglacial periods, natural warming occurred first which then triggered the oceans to release dissolved CO₂ (some sources say there is one molecule of CO₂ in the atmosphere for every 50 molecules dissolved in the oceans; the amount released would depend upon the temperature (think warm beer)). With the current interglacial, industrial CO₂ was released ahead of the warming. When our oceans release dissolved CO₂ this time around we will get a double dose. Maybe this is already happening and may be one explanation for the blue spike in the diagram on the right.
  
  p.s. While ice cores trap samples of atmospheric gas, other climate proxies like stalactites, stalagmites, and sediment cores do not. Nevertheless, these three methods do support the theory of Milankovitch cycles as far as temperature and water are concerned. Indian Ocean sediment core "Vema 28-238" is probably the best sample of the lot.
  
  
• 71-minute video by Gwynne Dyer from TV Ontario titled "Climate Wars":
  http://www.tvo.org/TVO/WebObjects/TVO.woa?video?BI_Lecture_20090509_834122_GwynneDyer
  Click here for a mini-Review of his book
   
• 60-minute video interview with author George Monbiot ( Heat: How to Stop the Planet from Burning )
  http://www.tvo.org/TVOsites/WebObjects/TvoMicrosite.woa?b?9076471184378400000
   
• 10-minute lecture by Isaac Asimov in 1989 ( Isaac Asimov - Threats to Humanity Part 1 ) where he states that the discovery of Global Warming was the most important scientific discovery of 1988.
  http://www.youtube.com/watch?v=LO0sCs8jI4k
  
  
• To learn more about Milankovitch and climate cycles, read the no-nonsense book "The Discovery of Global Warming" by Spencer Weart.
   
  http://www.aip.org/history/climate/cycles.htm
   
  If you don't want to but the book, you can access it online for free here:
   
  http://www.aip.org/history/climate/
   
  Caveat: You may need to increase text size via the "Control - Scroll Wheel" hack in your browser (hold down the "CTRL" key on your keyboard while rolling the scroll wheel on your mouse to zoom in or out)
   
• Are there other factors affecting climate? Yes. While things like Milankovitch cycles drive climate over tens to hundreds of thousands of years, other factors can cause changes over the course of tens to hundreds of years. 
   
  • Solar Cycles (Wolf Minimum, Sporer Minimum, Maunder minimum, and Dalton minimum) are all periods when the Sun released less energy and the Earth cooled quickly. For example, the Wolf Minimum was responsible for the start of the Little Ice Age.
     
  • Volcanoes can heat or cool depending upon what they emit (CO2 adds to the greenhouse gases, while SO2 and H2SO4 can make clouds very reflective)
     
  • El Nino heats North America while La Nina cools it.
     
• All models are close approximations but they still have their uses. For example, many people do not know that "one" of the reasons for moving to the heliocentric system was that the mechanical models based upon epicycles were too complicated to build and reset while the models based upon the Copernican system were simpler. I recently learned that Maxwell built a mechanical model while developing his theory of electromagnetic unification. Using computers to build climate models have convinced many model researchers to insert code they didn't previously think was important. Until more is known about things like "solar science" and "the apparent randomness of volcanic explosions", I fear the current models are closer to doing a jig-saw puzzle. But even a jig saw puzzle is better than groping in the dark.