Final answer:
Environmental Security is the APEX activity addressing procedures for operational environment description, including national security threats, supporting planning mechanisms. Key environmental issues include global warming and deforestation, affecting resources and therefore national security.
Step-by-step explanation:
The APEX activity that addresses procedures for describing the operational environment, including threats to national security, and supports both deliberate planning and crisis action planning is Environmental Security. This branch focuses on a wide array of environmental issues that can pose significant challenges on a transnational scale and can affect national security. Important concerns in this area include global warming, deforestation, and the potential conflicts arising from the scarcity of vital resources.
As demonstrated by the Cape Action Plan for the Environment (CAPE), which has expanded into a comprehensive 20-year implementation program, the proactive engagement in environmental security measures can include the protection of biodiversity, promotion of sustainable use of resources, and the enhancement of local institutions and capacities.