What allows nongovernmental organizations to play a major role in environmental issues?

NGOs or non-government organizations are organizations which are building by citizens and are free from governmental influence.

These organizations are non-profit means they work for the betterment of people with nothing in return.  

Their nature of being independent and run by funds and donations allows them to work for and play a role in environmental issues.

As I mentioned earlier, these organizations work for the people and their betterment which is another factor that gives them this right.

the relative standard reduction potential of the half-cell in which reduction occurs; more positive than the other half-cell. reduction is a chemical process in which electrons are added to an atom or an ion; it always occurs accompanied by oxidation of the reducing agent.