Sea level observations come from measurement by satellites and, as Carter notes, a network of tide gauges around the Australian coastline operated by the Bureau of Meteorology and similar gauges internationally.
These observations show that rates of sea-level rise around Australia range from 2.6mm a year to 9.5mm a year since the early 1990s, compared with the global average rate over a similar period of about 3.2mm a year.
Variation in sea levels from region to region is to be expected, as Carter also notes, but continuing analysis indicates the dominant trend around Australia for the past 20 years is upward and above the global average.
The global average of observations is near the high end of the Inter-governmental Panel on Climate Change model projections over the same period, indicating that the range of model projections encompass changes that have occurred, and indeed that the models may be underestimating observed changes.
Bruce Mapstone, chief, CSIRO Marine and Atmospheric Research, Hobart, Tas
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Sea level
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For the sea level change associated with the current episode of global warming, see current sea level rise.
For other uses, see Sea level (disambiguation).
Mean sea level (MSL) is a measure of the average height of the ocean's surface (such as the halfway point between the mean high tide and the mean low tide); used as a standard in reckoning land elevation.[1] MSL also plays an extremely important role in aviation, where standard sea level pressure is used as the measurement datum of altitude at flight levels
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........Ice shelves float on the surface of the sea and, if they melt, to first order they do not change sea level. Likewise, the melting of the northern polar ice cap which is composed of floating pack ice would not significantly contribute to rising sea levels. Because they are lower in salinity, however, their melting would cause a very small increase in sea levels, so small that it is generally neglected.
Your "simple science" is wrong; sea level and rates of rise vary around the planet. Long-term influences are water temperature (warmer water is less dense - levels will be higher) and gravitational effects due to crustal thickness and density, and the nearness or otherwise of large land masses. Large land masses "pull" the water towards them, increasing the adjacent levels.
ReplyDeleteBTW -if you doubt my motives in making this comment, read the comment I just posted here:
http://junkscience.com/2012/02/07/bob-carter-scientific-research-drowning-in-a-sea-of-alarmism/