All Things Sustainable

ecology, economy, community


3 Comments

Climate : The ancient and not so ancient past

The mini-moocs continue and this week we looked at past climate change, ancient and not so ancient. Looking far back into the formation of the solar system 4.5 Billion years ago we learn that the sun was much cooler than it is today and yet the earth was much warmer. There is evidence that the atmosphere had a high CO2 content and that blanket effect was responsible for the warmer climate. The question then became how did it change because if the earth had the same atmosphere today then as the sun grew brighter the world would become much hotter but in fact it is cooler.
Feedback loops
The answer lies in the “feedback loops” and the carbon cycle. As the world warmed evaporation, cloud formation and then rain reacting with the atmospheric CO2 created a weak acid. This acid rain, in turn, reacted with the rocks changing silicates to carbonates, removing carbon from the air into the earth via the rainfall, cooling the planet somewhat and balancing the climate. The carbon cycle also has a neat little trick that allows us to gauge the state of the ancient climate. It works like this, the carbonate that formed as part of the carbon cycle is used, together with calcium, to make shells for tiny sea creatures. When they die the shells fall to the ocean floor and build up into a deep layer of sediment where they can be preserved for millions of years. Now comes the clever bit that belongs to science – the ratio of the oxygen isotopes can reveal the temperature of the ocean when the shell was formed. Its all on web of course and too complex for a blog.
The Pelican
But feedback loops can destabilise the climate as well as balancing it. In fact it is postulated that about 2.2billion years ago and again at 700mllion years ago the earth became covered in ice and snow creating “snowball earth”. This time the feedback loops, rather than balancing the system, created runaway cooling. The trigger that set off the extreme cooling may not be clear but once the cooling got underway the mechanism is easy to grasp. Quite simply dark surfaces absorb heat and white ones reflect it. As the snow and ice spread more of the suns heat was reflected so the earth was cooling and more snow and ice were formed so more heat was reflected so…..
So how did we escape from the freezer? It seems probable that although the earth was frozen volcanic action was still putting CO2 into the air. Without rainfall there could be no weathering of the rocks (which were deep under the ice anyway) so the CO2 built up to a point where it was warm enough to start the melt. Once started the exposure of the sea and land absorbed the heat and raised the temperature by the same mechanism that caused the freeze but put in reverse.

The not so ancient bit of the story looked at how climate records can be inferred from data like isotopes (http://www.giss.nasa.gov/research/briefs/schmidt_01/), ice cores (http://www.earthobservatory.nasa.gov/Features/Paleoclimatology_IceCores/) and tree rings (http://web.utk.edu/~grissino/principles.htm#1), how the current warming differs from ancient warming events (it is happening much much faster) the effects of volcanic activity and aerosols in the modern era and archeological evidence of climate change.
The impact of volcanic action is interesting because it involves aerosols which vary greatly in their effect. They can block sunlight and cause cooling and light coloured particles can reflect the heat but black carbon can increase warming as can increased CO2 that may be pumped into the atmosphere. All a bit of a lottery I think.


Week 2 of the mini MOOCs

So this week as well as the Sustainability MOOC (Nottingham Uni) the Climate Change MOOC (Exeter Uni) kicks in, I am wondering how I will keep the two streams separate although it probably wont matter as they seem to me to be inextricably linked anyway, and as this is just a general interest exercise who cares if they get mixed? In some ways the Climate Change course looks a bit more challenging, it started out with a simple presentation that demonstrated how the earth warms using simple analogies. No problem there, shortly after that it gave us some links to IPCC (historical overview) and NASA (causes) then there was a piece on the atmosphere and the way the earth maintains its climate. Wonderful stuff about evaporation and rainfall has left me with an image of water molecules shimmying in space as they shake off the heat and condense into water droplets that form clouds and rainfall. I remember (from another source) a report describing how water is recycled multiple times through the Amazon rainforest as the winds carry it across the landscape, and a suggestion that something (I forget what and don’t still have the reference to check it out) something that is part of the forest transpiration enhances the ability of the clouds to form and produce rain.
At this point I took a break ad headed to the ocean to enjoy a little of the rather warm weather and maybe have a swim.
GE
The Sustainability MOOC also progressed, asking a little more from us this week looking at landscape and heritage. We were asked to offer comments on legislation covering these, there was no requirement that it apply to the UK. I focused on items like Abbott Point and expansion of the coal ports in Queensland, the necessary dredging and proposals to dump the spoil in the Great Barrier Reef Marine Park. These have been approved by the Queensland State Government and have a tacit approval of the Feral (sorry that should read Federal) Government. The Marine Park Authority has yet to approve them but it will be under intense pressure to do so. Another similar failure that comes to mind is the NSW government’s failure to protect prime agricultural land from Coal Seam Gas exploitation and the damage that it may well cause to the underlying aquifers including the Great Artesian Basin. I could have talked about the way the Unions turned the tide and changed the face of Sydney with black-bans on the destruction of certain buildings but the research was not at my fingertips so I stuck with the stuff I knew.
On the question of heritage I became very aware of how little I know about the local Yuin people even though I attended the Yuin Back to Country event recently. I know a little more about the history of the forests here having seen photos of the massive trees logged in the early days and a bit more still about Bermagui and its transformation from a fishing village to a tourist destination. The photo that follows was taken at the Yuin Back to Country Celebration held at the Tilba showground in the shadow of Gulaga, the mother mountain.
GE
The final thing I want to cover in this post is the description of a place that is special for me and what makes it special. That place is a small patch of remnant littoral rainforest on the edge of a lake close to my home. I have no claim on it, I was born half a world away but it speaks to me as no other place does. When you venture into it somehow it seem to wrap around you, the quality of sound changes and it is in some way timeless. I don’t have a photo of that place but here is one of the lake.
Bridge and Ducks


2 Comments

Week 1 of the Mini-Moocs

Nottingham Uni is part of the new MOOCS movement and I am trying out a couple of their free online courses not because I am totally incapable of sitting around with spare time on my hands but mainly because I want to know what the rest of the world is thinking about sustainability and climate change issues. I will be using this blog to see where they are going and explore how it changes my thinking. That is assuming I am not totally one eyed and immoveable.
Meanwhile back at the ranch so to speak I have a new delicacy for your consideration : pigface fruit.

Pig Face Fruit. Pigface is a ground covering succulent that grows near the coast, it has showy pink to purple flowers.

Pig Face Fruit. Pigface is a ground covering succulent that grows near the coast, it has showy pink to purple flowers.


This bush tucker grows wild in the area and a neighbour brought me some to try as I had never eaten it. He showed me how to split the outer layer of the fruit and reveal the succulent inner part. It tasted a bit like salty kiwi fruit. This is a sustainable resource I suppose but if everyone wanted to eat it I wonder how long it would last.
Once there were yam daisies that grew throughout Victoria I am told. It was a staple food for the local population before Captain Cook arrived but now the plant is rarely encountered because the introduction of sheep destroyed it. The sheep did well and Australia rode on the sheep’s back for many years but it certainly wasn’t a sustainable solution for the native people.
Conclusion: Sustainability is inclusive : you must include everyone and everything that is affected by your decisions. Not easy.