Those who say we needn't care much about warming because it's a cyclical, natural phenomenon miss the point entirely. The issue isn't whether or not there's cyclical global warning every so-many tens of thousands of years or even eons.
We're living in a time when, even if that's so -- and it may or may not be so -- even if warming is a cyclical process, in the past we could not do anything to dent the warming and the harm it causes to our food supply, ocean levels, the chances for recurring and sustained dangerous and destructive weather, caused by or increased by those aspects and degrees of global warming that human activity can and does aggravate.
Now we can act for what ought to be three clear and obvious reasons:
1. First, now we know what humans didn't know the last time the earth warmed.
2. Second, now we have the choice, knowing what it does to us ecologically, to restrain our greed, to live not only in the interest of immediate profit-taking and instead use our sense and heart to sustain ourselves and those who come after us, because,
3. We have not just the knowledge and capacity for applied self-restraint, but we have some of the technology and methodology that can feed and power us without destroying what we have and have worked so hard to have.
This puts me in mind of the foolish plantation slave-holder class in the two generations prior to the Civil War.
Slave-holders largely knew, even by the 1820s and 30s, that rotating crops and letting fields lie fallow fairly often would better sustain their land as fertile land than if they planted cotton and tobacco year-in-and-out without swapping them out every couple of years for less nutrient-depleting crops... and, again, in some years not using some fields at all.
What slaveholders chose instead was a year-in-and-out high-yield cash crop paradigm that sapped their fields and left them, by the 1850s, with only one option: find a way to take Mexico after taking as many of the western territories of our continent as they could. As to raw economic survival, that was a prime reason that, along with its obviously closely connected immoral insistence on chattel-slavery, they began and fought a civil war that left 630,000 of us dead and, of course and ironically, if not justly, their farming lands burned.
We always have a choice. As to the earth, we have a choice, as the slaveholders had theirs: to change and act sensibly in the name of Justice. Acting for Justice, too, profits us.