Examples - Long Term Trend

By looking at the long term trend, I can see that overall the amount of sea ice in the artic appears to be generally decreasing from an average of about 9.45 million square kilometres in 1990 to an average of about 8.37 million square kilometres in 2011.

This is an average decrease of (9.45 - 8.37)/21 = 51,400 square kilometres per year (3sf).

This decreasing trend appears to be quite constant, apart from a slight trough between 1995 and 1996.

(Possible contextualisation:

This yearly decrease in sea ice is significant, and could result in observable sea level rises. This could be catastrophic for low lying island nations around the world.)

The trend line in the recomposed graph shows a decrease in the number of penguins between the years 2000 and 2007.

In the beginning of 2000 the average number of penguins in the colony was 600, by the end of 2006 this average had dropped to 418.

Between the years 2000 and 2003 the average number of penguins remains constant at about 600. In 2003, however, the average number of penguins decreases sharply to 400 and remains at this number for the next 3 years, to 2007.

The trend line of the recomposed graph shows an increase in the average number of visitors from Australia.

At the beginning , in 1999, the average number of visitors from Australia is about 17,000 per quarter. At the end of this data, in 2012, this average had increased to 33,900 visitors per quarter.

The trend line in the recomposed graph shows an overall increase in the average monthly CIF values at Airports.

In 2000 the average monthly airport CIF value is $619,000. By the end of 2013 this average had increased to $836,000.

This average CIF airport total initially drops to about $550,000 per month in 2002/2003. It then starts to increase over the next few years, temporarily peaking at about $800,000 per month in 2009. It then suffers another drop in 2010, dropping to about $750,000 per month.

It then climbs to about $850,000 per month in 2011 before dropping back to $836,000 per month at the end of 2013.

By looking at the recomposed data I can see that overall the volume of wood removed from plantation forests has increased since 2000 from 4770 million m³ of wood on average per quarter to 7500 million m³ of wood on average per quarter in 2013. Each year the volume of wood removed from Plantation forests increased by 210 million m³ .

The increase in the harvesting of wood from plantation forests has not been constant. There appeared to be a 4-yearly cycle from 2000 to 2009 where the amount of harvested timber fluctuated between 5500 million m³ and 4500 million m³. From 2009 onwards there has a sharp increase in the volume of timber harvested. The amount of timber harvested has increased at the rate of approximately 600 million m³ per year from 2009 to 2014.