The Green Party is by no means a single issue party, but it rightfully recognizes climate change as the single biggest existential threat to the long-term survival of the human species. It aims to radically and immediately address this existential threat to the human species and to at the same time preserve and expand the greatest legacies of the enlightenment, liberal, and socialist traditions. It doesn't ignore, obfuscate, and deny the existence of the problem-- which is itself a well-known and established scientific fact, as does the Republican Party, nor does it give empty lip-service and uselessly menial reforms as does the Democratic Party. The Green Party and the Libertarian Party are the only really rational parties that exist today in my view, and while the Libertarian Party is rational on a lot of the issues the Green Party is rational on nearly all of the issues.
The ecological crisis is a social crisis, and as such it can only be solved through social means. The domination of nature by man has its prerequisite in the domination of man by man, in the ability for an individual to profit off the destruction of the natural world, or of the community. Wherever there is a incentive to destroy the natural world, even the prerequisites to all other human wealth, prosperity, and life for short-term profit, it will be utilized by those with the power to do so. The existence and domination of an economic system based on a philosophy of endless growth, of profit for the sake of profit, is incompatible with an ecological society once the prerequisites to all human life and prosperity are existentially threatened by such a system. Such an economic system is the cause of the present crisis. The Green Party stands against such a social order. In that regard it is a manifestation of rationality in an otherwise irrational society.
The Green Party is an ecosocialist party, and the adjective 'eco' could just as easily be preceded by the words "libertarian" or "democratic" as it aims to give the community (and not a centralized, overarching, bureaucratic state) real democratic control over its own political and economic affairs on the basis of assured individual and political liberty, to reclaim the word "politics" in the Hellenic sense of the word. It is necessary to remake human society to be one in harmony with the natural world if humanity is to survive and thrive.
The Green Party has a rich tradition in promoting the ecology movement since long before I was born. It's focus on building bonds with the community at the grassroots level is precisely what is needed today. It's ten key values embody the ideals any rational or humane society ought to aspire towards. Obviously in a country dominated by two parties it is extremely difficult to organize politically and garner popular support, but it's a worthwhile endeavor, and one that absolutely has to be done for the above mentioned reasons.
"I'd rather vote for what I want and not get it than vote for what I don't want and get it" -Eugene V. Debs
"To speak of 'limits to growth' under a capitalistic market economy is as meaningless as to speak of limits of warfare under a warrior society. The moral pieties, that are voiced today by many well-meaning environmentalists, are as naive as the moral pieties of multinationals are manipulative. Capitalism can no more be 'persuaded' to limit growth than a human being can be 'persuaded' to stop breathing. Attempts to 'green' capitalism, to make it 'ecological', are doomed by the very nature of the system as a system of endless growth."
-Murray Bookchin (Remaking Society)
“Human beings are much too intelligent not to have a rational society; the most serious question we face is whether they are rational enough to achieve one”.