What Do We Owe Our Planet?

SIXTY YEARS AGO, Anglican children used to sing, with some gusto, a hymn extolling the beauties of the Earth, from “Greenland’s icy mountains” and “India’s coral strand” to other examples of the Creator’s artistry. Two lines, however, suggested a glitch in the divine plan: our planet is a place where “every prospect pleases, / And only man is vile.” Caught up in our singing, we paid little attention. Few of us were budding deep ecologists.

If humanity were originally charged with the stewardship of a wonderfully designed world, as the story in Genesis claims, then it is easy to think we have failed in our responsibilities. We have modified the Earth’s surface — as well as the oceans and the atmosphere — in all manner of unattractive ways. But then, so have other species. Beetles have devastated elm trees around the globe. Ants have altered the vegetation and topography of regions they have invaded. Ivy, gypsy moths, and beavers have wrought their own kinds of devastation. Perhaps we have acted on a vaster scale than other species, but it seems unfair to charge Homo sapiens as uniquely vile.

If the idea of stewardship is taken seriously, it must be rethought.

Scripture offers nothing specific to guide our decisions about which modifications to allow or forbid. No biblical verse tells us whether to assist big cats in their pursuit of prey, or whether we should take the part of fleeing gazelles and zebras. How, then, should we make the inevitable choices? Through a laissez-faire policy? Through a commitment to the well-being of members of our species alone, ignoring the consequences for other animals, even for those recognized as having capacities for feeling and cognition? Or, despite the unreality of the Peaceable Kingdom, through an attempt to return to a world we recall — or romantically imagine — from some point in the past?

The choices we face are ethical choices and some are horribly wrong — like whether to turn the Grand Canyon into a giant landfill, use Canada’s Lake Louise for sewage runoff, embark on a program to eradicate the forests of the Amazon, or exterminate the great apes. Many people feel that such actions would not merely be tasteless but morally repugnant. What is the source of such repugnance? Do we owe something to Yosemite’s Half Dome that compels us to protect it from aerially sprayed graffiti? Or the redwoods from destruction?

Surely not. In the first place, inanimate objects (like an imposing rock face) have neither the will nor the capability to exercise rights, and the capacities of unfeeling organisms (such as trees) are only marginally better. To have a right to something depends on having a point of view, from which damage and loss can be recognized, or, at the very least, inchoately felt. Those who have written most penetratingly on behalf of rights — the late legal philosopher, Ronald Dworkin, for example — have limited their dispensations to organisms with sensory capacities.

And a further point typically goes unappreciated. Outrage provoked by the prospect of using the Grand Canyon as a rubbish dump is not matched by a similar attitude toward the plans of, say, a real estate developer whose projected housing complex on New Jersey marshland contains a site for the future residents’ garbage. On the contrary, we would be unlikely to regard any such development as an act of vandalism. (In the spirit of Woody Allen’s suggestion that the Creator was not responsible for certain parts of New Jersey, we would probably applaud the developer’s proposed transformation.) Of course, if other species, with different sensory abilities and adapted to different environments, possessed the cognitive ability to reflect on issues of preservation, their “aesthetic” choices might well be entirely different. Why, then, do the parts of nature that human beings find especially beautiful — such as the Grand Canyon — make an ethical claim on our powers of conservation?

One possible answer is that our outrage at a graffiti-covered Half Dome does not have to do with sympathy for the rock face itself, or for the small organisms that live upon it. Rather, scrawling or doodling on such a magnificent landmark would deprive human beings — some now living, many more who will live in the decades and centuries after us — of a prospect that would thrill or uplift or enrapture them. We have no moral obligations to the nonliving parts of our planet, however beautiful human beings find them. Our responsibilities are to other people, to whom we owe the chance to enjoy nature as we have done.

But such an answer may appear too anthropocentric, too negligent of the needs of the rest of the sentient world. Can human standards of beauty be the only criterion for making choices about our environment? Surely the case for the preservation of the natural world is more than aesthetic.

In many instances, the health of human populations may require conservation measures to protect whole ecosystems. Moreover, as the only species able to recognize the Darwinian struggle, we are the only available legislators, the sole judges of how the struggle might best go. Everyday decisions about planting crops and building settlements have always modified the pressures of natural selection, making life easier for some species and harder for others. As we come to understand ecological connections, we become conscious of some of these consequences. Responsible decision-making thus sometimes takes sides, as when we withdraw a promising plan because it would further endanger types of plants or animals we value (redwood trees or elephants, say). And sometimes the potential pains inflicted on other animals factor in our decisions. Nature may not be entirely red in tooth and claw, but the competition is fierce enough to ensure ample suffering throughout the animal kingdom. Hence, we might think, we should do what we can to mitigate the pain of animals, even if it means destroying an environmental feature — for example, a beautiful lake that confines and threatens the lives of an animal population.

People moved by this thought should ponder another Darwinian lesson. An environmental change can produce a cascade of effects on selection pressures with far-reaching consequences. Our knowledge is limited, as we know from our efforts to eradicate diseases by exterminating the insects that spread them. Indeed, contemporary environmentalism was born from our vivid awareness of the damage done by the well-intentioned use of chemical pesticides. Any grand attempt to do what a benevolent Creator might be expected to have done — to minimize animal suffering as a whole — is beyond our abilities. If we therefore think in more modest terms, we might take on a human-sized project, focused on lessening the sufferings of animals with whom we have close relations — for instance, those we have domesticated. The aesthetic concerns leading us to preserve mountains and forests and coastlines might then also be expressed in efforts to maintain species we find attractive or impressive or appealing. So we might try to save the bonobos and the polar bears and the koalas. Like Candide, we would thus be cultivating our own garden.

After all, most of the time, when we move beyond our local interactions with domestic animals, we have little clue about how to proceed. To be sure, we should abandon cruel practices, providing decent lives for laboratory animals, forbidding cockfights, and reforming our zoos. Yet when we think about ecological policies, the effects on the sufferings of nonhuman animals are generally incalculable. A better rule of thumb might thus be to focus on human welfare — in which appreciation of the natural world plays a role.

All this said, however, when it comes to the major problem arising at this stage in the history of our planet — namely, climate change — all such ethical considerations are in fact aligned. However we balance the claims of future human beings and sentient nonhuman animals, a change affecting the well-being of most of them (including those species we most value) demands our trying to prevent it.


On an exceptionally hot day in the summer of 1988, the eminent scientist James Hansen informed Congress of the perils of a warming world. Since then, the graph depicting yearly average temperature steadily tilts upward, with a remarkably high fraction of the hottest years on record occurring in our (still young) century. Other measurements record melting ice, rising sea levels, and increasingly frequent extreme events — droughts, heat waves, wildfires, and intense storms.

The reality of global warming was only one part of Hansen’s message. He also warned that human activities were responsible: specifically, by way of the emission of “greenhouse gases” — carbon dioxide, methane, and nitrous oxide — into the atmosphere. These greenhouse gases share an important property. As their concentration in the atmosphere increases, more heat is reflected back to the Earth’s surface, increasing average planetary temperature. This greenhouse effect was identified in the late 19th century, and the underlying physics and chemistry are as well established as are the elementary parts of those subjects learned by schoolchildren. About this there really can be no doubt. You should feel the same about the greenhouse effect as you do about the identification of water with H2O.

Long-range studies of average planetary temperatures and atmospheric concentrations of greenhouse gases have shown a remarkably fine-grained correlation. Of course, as schoolchildren also learn, correlation does not imply causation. Here, however, we know the underlying mechanism for the observed pattern: the greenhouse effect predicts that as the concentrations of these gases increase, so too should the mean temperature. Does that settle the issue? Not quite. For even though increased emissions are playing a causal role, they might only be a small part of the story. Perhaps something else is going on that swamps the effects of human behavior.

All sorts of possibilities are routinely touted by those interested in denying human responsibility for climate change. Some of these people suggest that variations in our planet’s orbit play a crucial role. Others point to variation in sunspot activity. During the past decades, the climate science community has been unusually conscientious — and unusually patient — in exploring these alternative explanations. It turns out that none of them is capable of accounting for the correlation. As in the plot of a well-crafted murder mystery, there is a victim and a list of possible suspects. One of those suspects had motive, means, and opportunity; none of the others did.

If the climate scientists are correct, then the verdict is clear: the culprit is us. Since the Industrial Revolution swung into high gear (with an agricultural revolution to follow), we have significantly changed the Earth’s climate. Even if we were to amend our behavior overnight, this change would continue for some time. And the longer we continue our current practices, the more dramatic this change will be.

If the climate scientists are correct … Some skeptics seize on this proviso. Our president has talked darkly of global warming as a “hoax” and a conspiracy emanating from China. Such diagnoses are at best naïve, and more likely inspired by economic interests. Consensus among climate scientists is international and almost universal. How exactly has such widespread agreement been manufactured and sustained? No scientist has the power of coercion, the ability to make each of his fellows an offer he can’t refuse. The findings of climate science have gained acceptance in the way scientific findings usually do: by means of rigorous and public corroboration. Moreover, the rewards for any young scientist who explodes any widely accepted article of current lore are enormous — a Nobel Prize and an assured place in future textbooks. Even if all climate scientists were devoid of moral scruples, no source of funding could outweigh the lure of joining the grand parade of luminaries who overthrew once-current orthodoxy — not to mention the worldly rewards likely to be showered on the debunker by a grateful consortium of fossil-fuel executives.


All the world’s nations ought to have come this far in their understanding of the condition of our climate and its causes — and for a brief shining hour it appeared that they had. Although most serious commentators maintain that the Paris Climate Accord of December 2015 failed to demand enough, it was an important first step, bringing together all but two of the world’s nations. When the United States, which under the Obama presidency had played a major role in crafting the agreement and coaxing reluctant nations to join it, withdrew its support, this appeared at first sight to be an act of monstrous ethical dereliction.

Is that judgment too harsh? The first form of skepticism — climate change is not happening, or, if it is, we are not responsible for it — has been conclusively rebutted. Still, those who resist action can find a second reason for dragging their feet. Perhaps the impact of a higher global mean temperature (and more acidic oceans) will not be too bad — not bad enough to justify the economic disruption involved in modifying our industrial and agricultural practices. If cities have to be built away from shallow coastlines, and agricultural production moved poleward, maybe all this can be managed while engaging in business as usual.

These comforting conclusions are often supported by pointing out, correctly, that predictions of the extent to which the Earth’s average temperature will increase usually allow a range of possibilities. Some climate scientists suggest that, by the year 2100, the temperature will increase between two and five degrees Celsius above pre-industrial averages; others think the gain will be between three and seven degrees Celsius. Skeptics focus on the lower ends of the forecasts, proposing to wait and see how large the changes are before engaging in what they often call “precipitous action.”

Unfortunately, once the miner’s canary has drooped, it is already too late to avoid the danger. To delay amending our ways until we reach the upper limit of what many experts consider manageable — two degrees Celsius, say — is to ensure that temperatures will climb even further, into a threatening range. And we should be aware that the year 2100 has no special significance. Unless emissions of greenhouse gases are reduced at some point, the world will almost certainly be five degrees hotter in the future than it was for our 19th-century ancestors. It makes little difference whether that moment comes in 2089 or 2134 or 2172.

It will be a moment that brings terrible challenges to the lives of billions of people, and to many nonhuman animals as well. The last time the Earth was that hot — in the Eocene Epoch, some 50 million years ago — there was no ice on the planet, and crocodiles and alligators flourished within the polar circles. A few animal species will have a field day, but the parts of the world in which close to half of human beings now live will become uninhabitable. Working outdoors in much of Africa and Southern Asia will become impossible for large parts of the year. No continent will go untouched.

Yet to think in this way, in terms of constant effects, is to underrate the magnitude of the problem. In considering climate change, many people become fixated on the averages. But as those who have lived through recent heat waves and floods and droughts know all too well, the extremes are what cause the most suffering. And as the averages rise, so do the extremes. In a hotter world, yesteryear’s extreme heat becomes much more common and new extremes unprecedented. The situation will be exacerbated if, as some theorists suggest and as the increasing frequency of extreme climate events seems to confirm, the new distribution is more skewed toward the perilous tail.

Nor are the episodic effects of climate change, the storms and fires and floods and droughts and heat waves, isolated phenomena. They interact with one another and affect the relationships between human communities. Recurrent droughts are likely to generate conflicts over remaining water sources. Unbearable conditions will cause waves of migration on a scale our species has never seen. Dirty, hungry, parched, and diseased, the wanderers of the future will spread infections in the places where they seek asylum. Changing ecological relationships will enable the eruption of new diseases.

Nobody can calculate the probability of any individual scenario. But there are so many dire possibilities that it would be foolish and irresponsible to assume we can avoid all of them. We should not simply “wait and see.”


Yet many who resist climate action are moved by an important ethical point. Recognizing today’s human suffering by way of extreme poverty and deprivation, they oppose diverting resources to cope with (so-called) “nebulous” threats to our descendants. No duty of stewardship should blind us to the needs of the billions now living who are afflicted with disease and danger. Should we allow the possibility that such a compassionate understanding figured in the apparently cavalier decision of the Trump administration to withdraw from the Paris Climate Accord (though it has not so far been expressed in any ambitious program for remedying global poverty)?

Properly understood, this ethical argument does not support climate inaction. Nor could it serve as a basis for bidding adieu to Paris. Imagine a thoroughly dedicated climate policy, one determined to expend all available resources on transitioning to a world in which greenhouse gas emissions were reduced to zero. Although acting in this way would embody a splendid concern for future generations, it would be blind to the human needs of the present. Equally, a decision to do everything we can to remedy present suffering would be blind to the plight of our grandchildren (and any people who may come after them). We have two duties, and since our powers are limited it is likely impossible to discharge both of them perfectly. Such is our ethical predicament: how do we balance our duties to our descendants against our responsibilities to our contemporaries?

Some people think that the answer is easy. Doing everything we can to ensure the growth of the global economy, they say, is the best we can do for both present and future humanity. That confidence reiterates a complacent neglect of the impact of climate change. Economists are divided on whether the last century’s dramatic increase in global productivity can continue through coming decades, even in the absence of climate change. But when we take into account the expected disruptions that extreme weather events will bring, a policy of continuing business as usual is almost certain to leave our descendants economically ill-equipped to face the challenges of the future. Nor should we be consoled by the optimistic suggestion that some technological breakthrough will allow us to continue guzzling fossil fuels with impunity. To be sure, science sometimes provides for human needs. But would you want to bet the human future on discovering a timely fix?

We have no choice but to face the dilemma with all the clarity and sensitivity we can muster. There simply is no way around the ecological imperative. Only a fully cooperative effort to decrease global emissions of greenhouse gases as rapidly as possible will prevent the great perils to come. As that collective venture is pursued, the needs of people — and entire nations — who have not so far shared in the benefits of industrialization must be addressed, if for no other reason than that they must be recruited into the war against our new common enemy: atmospheric carbon and its equivalents.

In large outline, it is evident what must be done. Wherever human beings are currently pursuing their goals in ways that emit greenhouse gases, they will have to change their ways. Sometimes that may be achieved by amending the processes employed, so that the gases are no longer emitted; sometimes it may be done by using alternative processes, most evidently by replacing dependence on fossil fuels with alternative sources of energy; or, if neither of these options is feasible, a last resort would be to abandon the goals themselves.

Is it possible to develop a detailed “best solution” to our dilemma? No, it is not. The many-sided uncertainties of the future thwart firm predictions about the kinds of climatic emergencies we will face, about economic growth, about the effects of climate mitigation policies, and about future social and political consequences. We know only the direction of our ethical responsibilities. To secure a habitable planet for our descendants we must sequester carbon or replace existing fossil fuel consumption with renewable energy alternatives — or else simply give up some of our current goals. In our ignorance of the effects of detailed policy proposals, humanity can only experiment with different possibilities. We must try to find what works — where “working” is assessed both by the reduction in emissions achieved and by people’s continued ability to pursue the things that matter most to them. If we assume sufficient cooperation, then if different nations were to undertake different experiments, our chances of finding a route to a sustainable world would multiply.

Given sufficient cooperation: there’s the rub. Social experiments usually have large impacts on the lives of those who practice them (or on whom they are practiced). Part of our ethical duty lies in protecting those whose lives would otherwise be disrupted by the measures we try out. Our responsibility to the people who are alive now means there must be safety nets within and across nations. The grotesque inequalities of the present world should be reduced, not intensified, by our attempts to ward off threats to our descendants.

The temper of our times, alas, is hardly conducive to cooperation. Skepticism about international cooperation is rife, as is evident from Brexit and vows to “make America great again.” The final Paris Climate Accord in 2015, with its recognizably inadequate targets, was the product of jockeying for economic position. That has been the sorry state of climate negotiations. Nations have come together as if their cooperative efforts were merely transient, to be adopted with the aim of improving their economic position for the post-cooperative future. To negotiate under the assumption that, once the threats have been addressed, cutthroat economic competition may be resumed is a recipe for failure.

So, is there hope of fulfilling our ethical responsibilities? I end, as I began, with a religious frame. Pope Francis’s call to environmental action, sounded in his encyclical Laudato si’, was quickly echoed by spokespersons for other major world religions. Starting with their preferred religious ideals of human stewardship, all of them converged on a plea for cooperation, reminding their audiences to focus on what matters in human lives. But it is not necessary to invoke — or to invent — any such religious ideal. The challenge humanity faces today is to build a world in which more people can live rewarding lives. That will require restraining our appetites for trinkets and baubles, recognizing the absurdity of gilded follies built to advertise supposed successes. At the core of such religious arguments is a humanistic theme shared also by secularists. Our ethical duties to one another require us not to let the human population grow beyond the limits of available resources, and to distribute those resources so that all people have opportunities for meaningful lives.

What do we owe to our planet? Strictly speaking, nothing. What we owe to one another, however, is nothing less than a world in which human lives can continue to flourish and in which flourishing is more widely shared and enjoyed, and nonhuman suffering is as limited as we can make it. This carries us directly to the ecological imperative. Let us hope we can find the wisdom to discharge our debt.


Philip Kitcher is John Dewey Professor of Philosophy at Columbia University. He is the co-author (with Evelyn Fox Keller) of The Seasons Alter: How to Save our Planet in Six Acts (W. W. Norton) as well as author of Science in a Democratic Society (Prometheus Books).