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  8 billion flights

  We humans took 8 billion individual flights last year. How many of your share of that number were a necessity?On When is it necessary, and what are the alternatives? posted 2 years, 8 months ago 39 Responses

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  cheat neutral

  If we have to do a carbon intensive activity like flying is it better to do nothing to mitigate its destructive repercussions or is it better to try and make up for some of the damage?On If you are fooling around on your spouse, offset your cheating with CheatNeutral! posted 2 years, 9 months ago 8 Responses

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  some more possible problems with Caldiera work

  
  Just to add a couple of points to the above discussion. I plant offset trees in temperate latitudes for a living so I'm inevitably biased against the recent research by Caldiera etal indicating that treeplanting outside the tropics may warm us.

  1. The modelling in question appears to take no account of the emissive effects of alternate land uses. It posits the temperature effects of mature forest canopy vis-a-vis bare ground/pasture.To explain this. The land we are planting on was hitherto used as pasture for methane generating ruminant animals. Methane is more than 20 times more 'warming 'than CO2 and the U.N. estimates that human agriculture is responsible for 18-19% of all anthropogenic ghg emissions. When we replace grazing pasture with trees we get the added benefit of a reduction in atmospheric methane concentrations. No account of this is taken in this research and this is in my view a critical error.

  2. Global climatic modelling of this kind can help us to understand in outline terms, the complexities of the interactions between oceans, forests and the atmosphere. However it can never accurately predict the temperature effects of treeplanting on a local or even regional level. To give an example. The land we are planting on is north facing. The reason for this is simple. North facing land in the northern hemisphere is generally cheaper than south facing land because it receives less solar insolation and is thus less productive agriculturally.  At this time of year the sun doesn't even touch the land we work on!  What this means is that the warming effect of a mature forest canopy, in terms of its reduced albedo (reflectivity) as envisaged by this model does not really apply.

  3. If I understand it correctly, The model uses a 'slab' or uniform representation of the earths oceans. i.e. The oceans are given  a uniform temperature and there is no attempt to incorporate the complexities of the planets ocean circulation in the calculations. Obviously this is quite a gross simplification of what is one of the main drivers of global climate. Given that the earth is 70% water- covered and the deep-sea currents undeniably influence our climate on a massive scale , I feel this to be an area of inevitable inaccuracy.

  4. The model posits the temperature effects of mature, natural, forest canopy, covering entire areas of the planet. Now this is never going to happen. We need land for a myriad of other uses so forests can never cover all the surface, however much some of us may want this. There will be massive breaks in the cover that will allow 'albedo cooling'. Furthermore we are planting managed woodland and so can tailor our planting to minimise the envisaged warming effect of a close canopy. As mentioned above, we can plant on north facing slopes. We can select species such as Ash that are inherently more reflective than say, Beech or Oak as they only retain their leaves for 5-6 months of the year and these leaves are in any case slender and shiny. Also we can manage the woodland to  improve its albedo by leaving open spaces, planting the trees further apart and by ensuring a wide diversity of tree types. The result of this is that the trees will mature at different rates and thus be harvested at different times so ensuring that rather than having one complete area of mature canopy, we have a dynamic situation where individual trees are cut down and replaced as they mature. This means that the woodland will never represent the dense mature canopy that this model is based on.

  5. The logical development of this research (however much the authors may cavil at this) is that, if serious about attacking global warming, we should consider cutting down trees in temperate and boreal zones. They can't have it both ways. Either trees are cooling in temperate regions or warming. If they are warming then they have to go! This to me is the most dangerous repercussion of this work.

  Meet the new climate criminals - deciduous trees in temperate latitudes!

   On Football's biggest day will be carbon neutral posted 2 years, 9 months ago 19 Responses