How do they measure sea level?
An accurate measurement of sea level is very hard to pin down. But it is an important measurement for two main reasons: • By having an accurate sea level measurement, it is possible to measure the height of everything on land accurately. For example, calculating the height of Mt. Everest is complicated by sea-level measurement inaccuracies. • By knowing sea level, we can determine if the oceans are rising or falling over time. The concern is that global warming and other weather changes caused by man might be leading to an overall rise in sea level. If so, coastal cities are in big trouble. The problem with measuring the sea level is that there are so many things that perturb it. If you could take planet Earth and move it out into deep space so that the sun , moons and other planets did not affect it and there were no temperature variations worldwide, then everything would settle down like a still pond. Rain and wind would stop, and so would the rivers. Then you could measure sea level
