Greenhouse Gas Advantage (Steel Pallet)

How does a lightweight steel pallet compare against any plastic pallet on the Co2 carbon dioxide emissions factor?  (With acknowledgement)
A 25 Kg plastic pallet from anywhere costs about 150 Kg of greenhouse gas to produce because approximately 6 Kg of Co2  is produced to make 1 Kg of HDPE.  This does not include additional Co2 cost of any embedded steel.

It takes about 2.88 Kg of coal to produce 1 Kg of steel.  An equivalent lightweight steel pallet costs about 72 Kg of greenhouse gas, HALF that of plastic.  The steel in this case is less than 1mm thick.  Steel Wins.

Wood?  That stores greenhouse gasses does it not.   What would happen if left alone, substantially, or partially, and substituted with steel……