The airport has closed its primary runway until Jan. 13 to repaint the numeric designators at each end and change taxiway signage to account for the shift in location of the Earth's magnetic north.
The closure of the west parallel runway will result in more activity on the east parallel runway and more noise for residential areas of south Tampa.
The busiest runway will be re-designated 19R/1L on aviation charts. It's been 18R/36L, indicating its alignment along the 180-degree approach from the north and the 360-degree approach from the south.
Later this month, the airport's east parallel runway and the seldom used east-west runway will be closed to change signage to their new designations.
The Federal Aviation Administration required the runway designation change to account for what a National Geographic News report described as a gradual shift of the Earth's magnetic pole at nearly 40 miles a year toward Russia because of magnetic changes in the core of the planet.