Related Rule
United Kingdom of Great Britain and Northern Ireland
Practice Relating to Rule 43. Application of General Principles on the Conduct of Hostilities to the Natural Environment
The UK LOAC Manual (2004) states:
Methods and means of warfare should be employed with due regard for the natural environment, taking into account the relevant rules of international law. Damage to or destruction of the natural environment not justified by military necessity and carried out wantonly is prohibited. 
United Kingdom, The Manual of the Law of Armed Conflict, Ministry of Defence, 1 July 2004, § 12.24.
In the conduct of attacks against targets on land, the manual states that “[t]he natural environment is specially protected”. 
United Kingdom, The Manual of the Law of Armed Conflict, Ministry of Defence, 1 July 2004, § 12.26.
In its chapter on maritime warfare, the manual provides:
Methods and means of warfare should be employed with due regard for the natural environment taking into account the relevant rules of international law. Damage to or destruction of the natural environment not justified by military necessity is prohibited. 
United Kingdom, The Manual of the Law of Armed Conflict, Ministry of Defence, 1 July 2004, § 13.30.
Under the UK ICC Act (2001), it is a punishable offence to commit a war crime as defined in Article 8(2)(b)(iv) of the 1998 ICC Statute. 
United Kingdom, ICC Act, 2001, Sections 50(1) and 51(1) (England and Wales) and Section 58(1) (Northern Ireland).
In a briefing note in 1991, the UK Foreign and Commonwealth Office declared that Iraq’s attacks on Kuwaiti oil fields were “a deliberate crime against the planet”. 
United Kingdom, Foreign and Commonwealth Office, Briefing Note: Oil Pollution in the Gulf, June 1991, reprinted in Marc Weller (ed.), Iraq and Kuwait: The Hostilities and Their Aftermath, Grotius Publications, Cambridge, 1993, p. 338.