Skip to main content

Introducing engineering

Completion requirements
View all sections of the document

Figure 96 is a graph with the title 'Global Average Absolute Sea Level Change, 1880-2011'. The origin is a little above the bottom left hand corner. The horizontal axis, labelled 'year', ranges from 1880, to 2020. Intervening years are indicated at 20 year intervals and grid lines are placed at ten year spacings. The vertical axis, labelled 'Cumulative sea level change (inches)', has a range from -2 to +12 inches and is subdivided at 2 inch intervals. There are 2 traces labelled 'Trend based on tide gauges' and 'Satellite measurements'. Trend based on tide gauges: The trace starts at (1880, 0) and rises in a slightly concave curve to (2010, 9.5). However, there are small annual random fluctuations of up to about half an inch in amplitude and some evidence of longer cyclic variations, producing about one inch total variation from a perfect straight line. Above and below this line are two further traces which have not been labelled and which indicate the range of uncertainty of the measurements. It is greatest at the origin, being plus or minus one inch at the year 1880. The uncertainty steadily decreases to a value of plus or minus about a third of an inch in 2010. Satellite measurements: This trace starts at about 1992 and ends at 2011. For most of this period, this trace coincides with the trend based on tide gauges but it has dipped lower in the last few years ending at (2011, 9) i.e. about 0.5 inches below the trend based on tide gauges.

 5.8 Why renewables?