Related Rule
New Zealand
Practice Relating to Rule 45. Causing Serious Damage to the Natural Environment
Section B. Environmental modification techniques
New Zealand’s Military Manual (1992) states:
Parties to the [1976 ENMOD] Convention have undertaken not to engage in any military or hostile use of environmental modification techniques which would have widespread, long-lasting or severe effects as the means of destruction, damage or injury to any other States Party to the Convention.
“Environmental modification techniques” are defined by ENMOD as any technique for changing, through the deliberate manipulation of natural processes, the dynamics, composition or structure of the earth, including its biota, lithosphere, hydrosphere and atmosphere or outer space. Care shall be taken in warfare to protect the natural environment against widespread, long-term and severe damage. This protection includes a prohibition of the use of methods or means of warfare which are intended or may be expected to cause such damage to the natural environment and thereby to prejudice the health or survival of the population. 
New Zealand, Interim Law of Armed Conflict Manual, DM 112, New Zealand Defence Force, Headquarters, Directorate of Legal Services, Wellington, November 1992, §§ 505(2)–(3) and 614(2)–(3).
[emphasis in original]