This essay was originally published on July 25 2019.

In 1830 Congress passed the Indian Removal Act, designed to appropriate to the United States lands occupied by aboriginal Americans. The Supreme Court ruled it unconstitutional, but the army under Commander in Chief Andrew Jackson acted anyway. Now a lightning rod for condemnation of the expropriation of indigenous property, Jackson was an agent of demographic pressures and a lust for the resources found on tribal lands.

The result of this land grab and ethnic cleansing was the Trail of Tears, a highway of the dispossessed, en route from their homelands to less favorable situations away from the population centers of the European-Americans and their recently created nation. Those with the means self-deported; those who moved late moved in large numbers and suffered terrible losses.

Nearly two centuries later, we face the prospect of forced relocations on a scale that is difficult to fathom. This New Trail of Tears will involve humans on every inhabited continent, and it will impact countless other species as well. This time, the driving force is all humanity, agents of climate change through our greenhouse gas emissions.

A major consequence of climate change is the global rise in sea levels due to the melting of glaciers and the polar ice caps as well as the expansion of warmer oceans. Accompanied by more violent storms powered by the warmer atmosphere, rising seas will have a profound impact on coastal areas. Flooding is already common in coastal Florida; with just the few feet of sea-level rise expected by the end of the century, sizable portions of Miami and Fort Lauderdale will be inundated. “Superstorm” Sandy brought this lesson home to New York City in 2012. In a bitter echo of the original Trail of Tears, Native Americans are already being forced to leave their island homes in Alaska and on the Gulf Coast.

Other low-lying coastal cities will be affected similarly. The economic impact will be enormous: Miami alone is spending 400 million dollars over the next few years to combat sea-level rise by reinforcing seawalls, improving drainage, and installing pumping stations, in an effort destined to be obsolete within a few decades if the current trajectory of carbon dioxide emissions continues. The human impact will be similarly enormous. Those with the means will self-deport; those who move late will do so in large numbers and suffer terrible losses.

Our planetary fellow travelers are being affected just as we are. Warmer winters have reduced the mortality of the Mountain Pine Beetle, resulting in the destruction of a close to a hundred million acres of pine forest in the Mountain West. Trees don’t migrate to escape environmental threats, but their range can expand northward, given the proper soils and other requirements and absent obstacles such as human appropriation of land. Thus even the trees are on the move, and already there is talk of human-assisted migration to assist them in their northward travel. Some plants and animals will move uphill; the cooling rate of 3.5 Fahrenheit degrees per thousand feet of elevation provides relief.

But this trudge along the New Trail of Tears is lined with a gauntlet of perils: the area of the globe shrinks with increasing latitude, and the available area of mountains shrinks with increasing elevation. Competition for livable space will be fierce, and the refugia to which many species will be confined as their range shrinks will become extinction traps for some. Barriers to movement, both inadvertent and intentional, can be death sentences to those migrating. Roads and other human structures have dissected the landscape, either preventing motion or making it treacherous. Rivers and seas impede human migration, and border walls seek to prevent it altogether. But the migrations will continue and even increase against all odds; when life in one location is not viable, there is no other option.

Like forests, coral reefs are threatened and probably doomed, as the vast 2016 bleaching event in the Great Barrier Reef made clear. And while some northward retreat of these great oceanic nurseries is possible, there is nowhere to run to escape the acidification of the oceans that accompanies the increasing atmospheric concentration of carbon dioxide. Fish can and do migrate, as have the herring in the North Atlantic. They have left behind some of their predators, glued to their habitats by instinct as surely as the corals are fixed to the ocean floor. For example, the Atlantic puffins of Maine are now hard pressed to feed their offspring with the herring gone. These birds do not migrate in response to the change, even if their chicks are starving. They will either substitute fish arriving from the south, or their range will contract to the remaining viable colonies farther north.

The New Trail of Tears is occurring and will occur in time as well as in space. Times of plant flowering, insect appearance, and bird nesting have moved forward in the year throughout the northern hemisphere. There is no guarantee that these events will remain synchronized as this process continues. Already there is evidence that this phenological synchrony has been disrupted for many food-chain relationships. For example, black guillemots in Alaska initially benefited from the increased likelihood of eighty frost-free days to raise their chicks but now are declining once more due to the recession of the pack ice upon which they depend for their food.

Additional perils await migrating humans. In a fully-settled world with modern notions of property rights, space is not easily made for refugees, as we have seen repeatedly when people have been obliged to move to escape privation or war. Indeed, privation and war are often closely connected, as the Syrian refugee crisis reminded us. Both will be potentiated by the growing impacts of climate change.

The Syrian migration crisis provides a compelling model of what might happen on an ever broadening scale as the consequences of climate change take hold in the coming decades. Unsurvivable heat waves may strike the Middle East before the end of the century, forcing people to move. Increasing immiseration will precipitate migration, but it may also trap populations, as a 2011 report by the U.K. Government Office of Science pointed out. The U.N. is taking steps to shore up its 1951 Refugee Convention, which lacks provision for environmental refugees, but opposing these efforts are powerful anti-immigrant movements taking hold all over the world at a moment when climate-induced migration is set to climb.

Most migrants do not cross international boundaries, but they are not necessarily more welcome than international migrants. In the U.S.A., precedent is provided by the dust bowl migrations, which displaced millions. Most traveled west; “Okies” headed for Los Angeles in 1936 faced a “bum blockade” established by the Los Angeles police. Although memory has faded with the passing of the generation that was hardest hit, ample evidence in photographywriting, and song reminds us of the human cost of this human-induced disaster. Suffering on a Grapes of Wrath scale edges nearer as surface water and water table levels fall in the arid, now more heavily populated American west. How ironic that mechanisms such as the thousands of Conservation Districts, created to ensure that poor land management practices do not create another such disaster, are now targets for cuts. The New Trail of Tears will be littered with the abandoned property, both literal and figurative, of those forced to focus on the immediate term.

Heat can attract as well as repel. While species and peoples are fleeing the heat at lower parallels, the warming of the Arctic and the melting of the polar sea ice is attracting humans to the newly available resources there. As nations jockey to exploit these resources, they all but ensure a nasty feedback loop: further disturbance of the fragile tundra and extraction of the petroleum or minerals below will accelerate the warming that has powered this northward migration in the first place. The irony of the situation seems to have escaped the notice of world leaders. As they push poleward, competing interests will encounter one another with increasing frequency, fueling conflict. A more survivable approach for all the inhabitants of the globe would be to declare the polar region an international scientific study area, off limits to resource extraction. Can such an approach prevail in the face of hand-wringing about stranded assets by those who envision short-term gain from their exploitation?

In any disruption there are winners and losers. The world is a complex place, and it is beyond difficult to distinguish them in detail in advance. But we know the broad outlines of the categories. As usual, the biggest losers will be the weak: those already struggling, already few in numbers, or specialized to niches that are being extinguished. The “winners,” as usual, will be the strong: the wealthy, who possess the resources to move; the numerous, who can tolerate great loss and survive; and the generalists and opportunists, who are prepared to exploit new situations as they arise.

The failure so far of the Paris Climate Accord to bring about significant change in carbon emissions shows that more immediate concerns trump good intentions. The agreement demanded immediate bold steps to forestall future calamity, along with further commitments in the near term to meet the goal of holding the global temperature increase to 1.5 Celsius degrees. Three years have elapsed, and the response so far to this call for action, to which nearly all nations agreed, is anything but encouraging. Meanwhile, the current refugee crises, though mere dress rehearsals for the migrations to come, are proving a severe test for social and political institutions.

The public, the media, and our political and thought leaders need to engage in more than speculation about whether or to what degree a storm was caused by climate change or whether the migration of Syrians or of Central Americans was influenced by climate change. Not only are such arguments sterile — which straw broke the camel’s back? — they are becoming increasingly irrelevant as it grows harder to ignore the impact of climate change on the lives of those already living at the margins, such as those working small coffee plantations in Honduras. A lack of individual awareness of the serious and pervasive consequences of human-caused climate change has been locked with the missing public discussion in a mutually reinforcing vicious cycle in recent years.

Our remaining hope is fed by the knowledge that public opinion can change rapidly. Demands for action have grown dramatically even within the last year, led principally by a young generation of citizens and politicians increasingly aware that its members will be the ones to walk the New Trail of Tears. Older generations are currently an impediment: less likely to suffer great harm, and more invested in current economic arrangements, their members generally urge “moderation.” But moderation in its present form means stalling for time, and each passing day of inaction will end up requiring more drastic future action. Can a public tipping point be achieved before a geo-ecological one precipitates a New Trail of Tears?

Brian Stewart is a Professor of Physics at Wesleyan University who specializes in the dynamics of small molecular systems. For twelve years, he has delivered an annual “Earth Week Rant” that documents the complex web of environmental issues we have created and urges action.