timdennell’s Recent Comments

• Click here to view comment in original post

  Thermal expansion and sea level rises

  For bailsout - H2O has many peculiar properties. At 4°C H2O expands on heating or cooling. As H2O cools, it contracts - until it starts to freeze - then, because it forms rather large crystals it's volume suddenly expands This is why precipitation that falls as snow can be  many inches thick, the same amount of H2O falling as water wouldn't occupy the same volume of space. If ice is cooled further after it has completely frozen, it will contract again.

  Like all materials H2O also expands when heated (thermal expansion). With H2O this occurs between 4°C and 100°C. A simple school experiment is to take a Pyrex flask of water at room temperature and heat it gently, measuring the rise in water level as it heats. Another is to fill a screw-top (to prevent evaporation) glass container with warm water and mark its surface level on the side. Then place in a fridge for a few hours then see if there's been a change. Invariably the level will now be a little lower. (Perhaps by only a mm or so if a small container, so exact measuring is important.)

  NB: All household hot water heaters require thermal expansion tanks to provide a safe place for expanded heated water to go. (Most water meters are installed with devices that prevent backflow, this creates a closed system.) For example, water heated from 32ºC to a thermostat setting of 60ºC in a 40 gallon hot-water heater will expand by almost half a [US] gallon (1.8 litres). This is because when water is heated, its density decreases and its volume expands. Since water is not compressible, the extra volume created by expansion must go somewhere. Pipes in a home may burst unless there is somewhere for the expanded water to go. There are temperature/volume tables to help engineers work out how much a volume of water will expand by at any given temperature.

  With seawater salinity differences within the oceans will affect the local water density and thus the expansion rates of local sea levels, but have little effect on the overall global average sea level change.

  Mary, above, was absolutely right in pointing out that areas most at risk are those affected by storms. Even a small rise in sea levels can affect the size of a storm surge. A storm surge is primarily caused by the extremely high winds that accompany a hurricane. This wind pushes the water towards land, building it up into huge waves. At the same time, the low pressure caused by a hurricane also causes the water level to rise up in the lowest-pressure spots and to sink in areas of higher pressure, exacerbating the wave build-up caused by the winds. So even a small increase in the volume of seawater can lead to bigger storm surges than before reaching further inland than previously. As well as the devastation this causes, longer term effects include salt contamination of the ground which affects crop productivity. Given how many subsistence farmers live in delta and low lying areas of India, SE Asia and China this could have major impacts.

  Even small rises in sea levels also will cause greater penetration of salt into coastal water tables. I understand that some previously healthy Palm trees in Florida are now being killed off because salt has contaminated more of the water table. A small rise in sea levels can have a bigger impact than you'd first think.On Umbra on sea-level rise posted 1 year, 4 months ago 7 Responses

• Click here to view comment in original post

  Psychology of the climate chage debate

  I think this raises some important issues, not just relating to the climate change debate, but about how people relate to the world and adapt to new information and circumstances.

  We're all products of the culture we were raised in and carry, often unconsciously, values, assumptions and beliefs from that upbringing. And we can hold often conflicted thoughts and feelings about issues. Part of myself, for example, would really like to be told that the global warming issue is a false alarm, simply because the implications are so disturbing; I recognise that feeling writ much larger in many sceptics (Some are obviously desperate to disbelieve it.) I have got rid of my car, yet that is the lifestyle change I find hardest to accept, even though I can walk to work. It does limit what can be done; I can see why so many find they cannot take that step, alternatives are not readily to hand. We need to be aware of motes and beams. It may also help us engage in more constructive debates.

  All people are likely to resist new knowledge or information that contradicts existing information. It's why messages received during early years tend to become deeply embedded and often continue to shape a viewpoint throughout adult life, particularly if reinforced by a frequent `topping up' of messages. Islam is a good example of such belief control and re-enforcement, but any religion would suffice.

  When faced with information that threatens existing knowledge or values people try to resolve the resulting internal conflicts by angrily attempting to deny outright the problem (`climate change isn't happening'), seeking some reason to discount the information, (hence the emphasis placed by sceptics on `secret agendas' e.g. `eco-fascist world governments') or grasping at simplistic, but emotionally gratifying, alternative solutions (`All the planets are getting warmer' etc.), projecting their anxiety and attention onto some unrelated but containable problem or activity or indulging in deliberately wasteful behaviour (displacement), trying to shut out all information (suppression), seeking scapegoats or simply retreating into fantasy. All these are symptoms of an unconscious defence mechanism characterized by refusal to acknowledge new information that is painful to acknowledge.

  And all of us will do some of the above at some point in our lives, often in a work, relationship or 'life-crisis' setting.

  Jungians would cite an individual's tendency to project their `Shadow' onto those they see as the enemy or who are causing the feelings of `dissonance'. The Shadow is the personification of all the `bad stuff' in the human unconscious that we deny in ourselves and project onto others in order to interpret them as `not -us' or `enemies'. And the Shadow is a part of all of us (anger, hate, fear etc.) however noble we see ourselves being.

  If people cannot accept the new information, but cannot ignore it, they attempt to adapt the old paradigm to fit - however badly - the new one. Creationists attempting to shoehorn more and more information into their Biblical paradigm - dinosaurs in the Garden of Eden - is one example.

  Some people relate emotionally to the Climate Change issue in an unhealthy way, possibly reflecting their underlying world-view. Their main response is one of fear, feeling helpless and of having lost control (existentialist angst) together with fear of change and of the unknown. For some it produces a fear that this is may be some form of retribution or punishment for humanity's hubris, that the certainties we thought we had, or expected to have, have been destroyed. Over the top apocalyptic language is likely produce these feelings in others along with paralysis and inertia. It makes the issue appear too overwhelming and hopeless to even begin engaging with.

  I believe what we're all aiming is for is to be aware of - and have some language to describe - both our unconscious and conscious (rational) sides in order to assess how we're responding to information (e.g. are we more likely to believe something because we want it to be so?); hopefully then to be able to make reasonable, and value-neutral, judgments based on the evidence presented.

  This is important because intense emotions undermine peoples' capacity for rational decision-making (or argument), even when they're aware of the need to make careful decisions. When formulating public policy, when people are angry, afraid or euphoric they tend to favour simplistic, symbolic and emotionally satisfying solutions to problems over more complex, yet effective policies.On How the two are related posted 2 years, 3 months ago 10 Responses