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SYSTEMIC STUFF ( + occasional nonsense ) IN THE NEWS . . . . DECONSTRUCTED FOR POSSIBLE MUTUAL BENEFIT
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MEMES |
![]() Rising sea-levels:The ice caps are melting, the Earth is getting warmer, sea levels are rising. These statements are all now accepted by most scientists as fact. The news headlines usually read something like ‘ Low lying nation’s existence threatened as sea levels are set to rise this century ’ They are rising – but how much, how fast ? The current estimates vary wildly, but the worst possible scenario would be around 1cm per decade. That’s 1m per century, which for a nation like Tuvalu, which is only 3 or so meters high, is a lot. Looking at it from another perspective however, that’s 1mm per year. So, a country like the Netherlands, for example, which is in a much worse position, level-wise, than Tuvalu, will need to heighten all the dykes which surround their country - by 1mm every year. Doesn’t sound too problematic ? The headlines also seem to miss the point that the oceans tend to have waves. Even the tamest ocean will have notoriously unpredictable waves several metres high battering the shore on a permanent basis, but the low lying nations aren’t swamped every other week. To put it into perspective, during the last ice-age, which was only 300 or so lifetimes ago, the sea level was some 30metres lower than it is now ! So the Earth is well and truly used to vast sea level variations, and pretty rapidly too. The current worst-case estimate, 1mm per year, although a challenge, won’t be a disaster.
Reader Rob H , from Australia, points out the possibility of positive feedback mechanisms which could dramatically increase the rate of change : " Sea Level rise predicted at 1mm/yr (as discussed yr website) is probably calculated upon gradual and constant warming (gradual ocean heating, gradual ice cap melting etc). This does not take into account positive feedback mechanisms which accompany climate change to either colder or warmer regimes. From the evidence it seems that world climate leaps from one stable position to another accompanied by catastrophic changes in sea levels."
Editor's comment: There is also of course the possibility that negative feedback loops ( e.g. more heat > more water evaporation > more clouds >. less sunlight > cooler temps ) could slow the change. But at the moment (2006) no-one on the planet has the answers. In this case, let's hope the 'negative' outweighs the 'positive'.
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