icebergs

About 8 years ago I took a trip to Newfoundland in June and got to see the icebergs.  Whether they were ice bergs from sea ice or land ice, I don't know.  At the time, I thought they were beautiful and was so excited to be in Newfoundland to see them.  Now, knowing what I know, they cause me anxiety - are they from land the ice of greenland that is being lost at a rate of 286 billion tons per year or from an ice shelf that is still attached by land or from sea ice. And again, from earlier in the course, less ice cover of the land and the oceans, means less ability to reflect back the radiation from the sun and more warming.  

The discussion question with regards to icebergs (or calving) in this section of the course was: How might processes like ocean and atmospheric warming cause mass loss from calving to increase? 

So first let's define calving.  This is where pieces of ice break away from a glacier that ends in a body of water (ie a land glacier extending into the ocean and then breaking away from its base). 

So how will ocean warming contribute.  Ocean warming can melt the underside of the glacier ice shelf (the part of the glacier now on the ocean but still connected to land glacier) weakening it and contributing to calving.  Atmospheric warming can lead to less snow fall and less ability of the normal summer time ice melt to refreeze back to the ice mass.  So with both loss of snow and less ice melt refreezing, there is less accumulation of mass and the glacier starts to spread out more to the edges of the land where they meet the warming oceans.  Atmospheric warming will also allow the lakes that form on the glacier itself more time to absorb more radiation (rather than reflect it back) which further warms them.  When they drain abruptly transferring heat to the interior of the ice sheet, the ice sheet can flow more rapidly to the edges (again meeting the warming oceans and leading to more calving.   

Reflections at the end of week 2

First reflection - it is taking me a long time to get through this course and unfortunately I will likely not finish it before it expires.  The reason - I always considered myself pretty "smart" in science when I was in school but I continue to struggle with the science as it relates to climate change. This is humbling but also makes me recognize how complex the science is and it seems to me that when there is topic that not only makes people uncomfortable talking about but is also really hard to understand, it is easier to just deny, distract or hope for the best without actually taking action. 

Second reflection - A sense of hopelessness has really settled in on me.  I really resonated with some of the thoughts expressed by the blogger of Above the Waffle who is also taking this course and who has a really well laid out and interesting blog in terms of what we are trying to "save" because it is us humans that have caused such horrible destruction so are we even worth saving (ie the planet and whatever life forms manage to survive the next extinction are probably better off without us).

I could go on but then I would likely be procrastinating the discussion questions for the end of week 2.  So here goes:

How does the climate vary naturally over millennial time scales?
Many factors have led to the natural variation of our climate over the last 4.5 billion years (ie the beginning of the solar system).  The intensity of the sun (burning brighter as time went on) could be considered one factor although the heat intensity of the sun doesn't seem to be as much as a factor as the gases (mainly carbon dioxide and water vapour) in the atmosphere that trapped the heat and radiated it back to earth to keep the surface warmer than if it was just relying on the sun's intensity alone (ie the blanket around the earth).Carbon dioxide seems to be the biggest factor.  Not only was it operating as part of the blanket effect, it would often combine with rain (the water vapour in the atmosphere) to form carbonic acid.  The acid would dissolve the rocks (a process called chemical weathering) releasing various ions (calcium, magnesium, sodium, potassium and carbonate).  The rivers would carry the ions to the ocean and shell building organisms would form calcium carbonate using the ions.  When the organisms died, they would sink to the bottom of the ocean and all the shells and sediment would combine to form more rocks.  So here we have a negative feedback loop which was a way the earth was self regulating its temperature "naturally".  Increased temperature would cause more evaporation of water reacting with more carbon dioxide and essentially removing more of it from the atmosphere to be stored in the lithosphere (thus reducing the blanket effect).The cooling of the earth with the chemical weathering and the creation of continents also lead to snow ball earth (the freezing of the earth 2.2 billion and 700 million years ago).  Here more ice cover continued to reflect back the sun's radiation so that eventually ice cover closed up from the poles to the equator.  However carbon dioxide again played a key role when over time, large amounts were released by volcano eruptions and since there was reduced water vapour (? was there any?) in the earth's atmosphere to combine with it, the carbon dioxide levels kept building up and thereby increasing the temperature until melting started to occur (and with further melting, more heat could be absorbed by the explored dark water rather than reflected back by the ice cover).

Can contemporary climate change be explained by natural variations?
There may be a few natural variations that has slowed the effect briefly but overall, the increased ability to have accurate data collection both for current and past indicators such as global temperature and ocean temperature and linking it to the graphs of carbon dioxide in the atmosphere and what we know is causing increased levels (burning of fossil fuels) that we have been producing as humans  shows that contemporary climate change is human caused.

What is the evidence for climate change?
I am basically using the NASA site which lay out 8 key facts that are concise and to the point:  Average temperature of earth increasing, average temperature of oceans increasing, shrinking ice cover, glacial retreat, decreased snow cover, sea level rise, artic ice decrease, extreme weather events and ocean acidification.  Again linking the highly advanced ways this data can be collected shows that the climate is changing and changing more rapidly then it ever has before