Philosophy, is different to practice. It may inform and guide, but it can't be expected to prescribe.
Darwin shifted the understanding of extinction, and the idea of positive action to avoid extinction could be considered the beginning of ecology, the understanding of ecological systems so as to be able to take informed actions affecting them.
Peter Singer is notable for seeking to shift away from anthropocentric ethics. EO Wilson focused on sociobiology and eusociality, leading to multi-level selection as a challenge to neo-Darwinism. Margulis and Lovelock developed a system of ideas including symbiogenesis, autopoesis, and Gaia theory, which also challenged conventional ideas about ecology. These are philosophical developments, shifting the groundwork and framing definitions of biology and ecology.
Extinction Rebellion represent a modern iteration of environmental activism, along with school-strikes led by Greta Thunberg. These seek to shift environmental action to centre stage of government action, in response to the science. Extinction Rebellion advocate the philosophical step of reforming decision making with citizen assemblies, a type of sortition, or jury service, where a representative group are presented with evidence to make an informed decision on topics too complex for a population to have enough knowledge to make informed voter decisions about, or that has become too partisan for politicians to make practical compromises on.
Ecological science can provide information, like understanding that more species-diverse grassland is the more resilient to changes in climate, that relying on only 4 species for half of human calories while allowing their wild ancestors to dissappear is problematic, or by framing ecosystem services with ideas like blue and green infrastructure.
But where we put the balance between human and animal interests, environmental consequences to rich vs poor, what attitude we take to risks of irreversible changes like extinction and ecosystem collapse, must be the result of decision making by politicians and electorates, that depend on their whole cultural and philosophical framing. As Benatar notes, invariably at least until recent times, that has been focused on human needs, interests, and wellbeing as the arbiter, and this when examined is not flattering about human nature or our likelihood of creating a net-positive future for sentient beings, or even any future for large regions of humans.
It is interesting to note the expansion of granting legal personhood from chimps and dolphins as advocated by Singer, to environmental personhood, and growing calls for ecocide to become a globally recognised crime. The Community Environmental Legal Defense Fund in the US has helped support a series of these grants of personhood since 2006 including a Lake Eyrie bill of rights. Ecuador granted rights to nature in a 2008 referendum, which has been used to succesfully allow a river to act as plaintiff against a government highway project. And Maoris and Hindus have given rivers such protection in the last 5 years. This is part of a wider movement of rights of nature.
Astrobiology and leaving Earth, is likely to throw a sharper spotlight on how we are interpendent with other species, for instance when colonising Mars. Kim Stanley Robinson explores in his book Red Mars whether even without life the landscape of Mars might have some rights. And it's interesting to consider whether a future ecosystem there might attain legal personhood, and on what basis.
As we become able to perform genetic engineering, especially since CRISPR/Cas9, boundaries between species may reduce, including digital and biological transhumanism. This tends to support our knowledge of Earth's biology as an evolved toolbox, as a resource where it's worth preserving diversity for that sake, even where no current applications are known.
