It’s shock­ing for me (Robert) to accept that my home could be wiped out by greatly ris­ing seas. That’s because I live on a hill north of San Diego, 45 feet above sea level and more than a mile inland from the coast. Equally shock­ing to me (Dan) is that the cur­rent coast­line of my beloved Men­do­cino County, Cal­i­for­nia, could largely dis­ap­pear, a place where I spend week­ends with my daugh­ters explor­ing rivers that run inland, deep into wine coun­try. These inun­da­tions won’t hap­pen this cen­tury, but that is lit­tle solace. At the rate the world is going, land so dear to our hearts could slip under the sea and stay there for thou­sands of years.

That hurts. Most of us believe our homes, our towns, our cities will be here for cen­turies and mil­len­nia to come. And why not? In Europe and across Asia mil­lions of peo­ple live in cities that are thou­sands of years old. Indeed, inspired by Euro­pean per­ma­nence, Robert’s fam­ily built gar­den walls from stone and fondly looked for­ward to pass­ing on the land to hoped-​​for-​​grandchildren, and theirs, and so on.

That idea, how­ever, now seems flawed to both of us writ­ing this arti­cle. Strong, new research indi­cates that any­one or any­thing tens of feet above the sea today may one day face an unbeat­able force, whether a coun­try home near San Diego or a sky­scrap­ing condo in Miami. Although shore­lines are for­ever evolv­ing, these changes can be pre­dicted directly, and are due to need­lessly exces­sive car­bon diox­ide (CO2) emis­sions from a rel­a­tively brief, recent period of time.

How has the pub­lic not been made clearly and painfully aware of this? Why does fierce debate over cli­mate miss so glar­ing a threat? The mis­per­cep­tion, the wide­spread dis­be­lief and the fal­lacy are rooted in a grave error in our think­ing about time.


The many mod­els that have pro­jected sce­nar­ios about future cli­mate change gen­er­ally fore­cast only to the year 2100, or at times merely to 2050. As a result, pub­lic dis­cus­sions have been mostly about “X degrees of warm­ing” or “Y feet of sea level rise” to the end of this cen­tury. We have acci­den­tally but notably lim­ited our think­ing, caus­ing us to miss strik­ing impacts that arise beyond this lim­ited and arti­fi­cial, spe­cific time horizon.

It is fair to say that cit­i­zens and politi­cians intend for Miami, and indeed the whole State of Florida, to exist well beyond 2100. Same for New York City, Boston, Wash­ing­ton D.C., Lon­don, Shang­hai, Ams­ter­dam, Mum­bai and so on. Yet the same peo­ple dis­count stag­ger­ing losses these places face beyond 2100. That’s wrong, and immoral too.

That’s because a cru­cial frac­tion of air­borne car­bon from the indus­trial rev­o­lu­tion, plus that com­ing this cen­tury and next, will per­sist for tens to hun­dreds of thou­sands of years. The CO2 stem­ming from just 150 years ago to a mere two cen­turies ahead may com­mit the world by iner­tia to tens of thou­sands of years of impacts.

Any­thing going on for tens of thou­sands of years ahead essen­tially means “for­ever” on human time scales. These new data imply that we’re cre­at­ing a kind of for­ever legacy, one that poten­tially can’t be ever for­got­ten, or fixed, no mat­ter how far ahead we con­ceive of humanity.

We are doing our­selves a dread­ful dis­ser­vice by con­sis­tently fram­ing 2100 as essen­tially the last, final year of impacts. We’re think­ing in a blink­ered way decades out, while our foot is press­ing hard on a warm­ing accel­er­a­tor that has seri­ous impacts cen­turies out.

How, then, can we think about cli­mate and seas in truer time frames?

An admirable new paper by Peter Clark and col­leagues in Nature Cli­mate Change, titled “Con­se­quences of Twenty-​​First-​​Century Pol­icy for Multi-​​Millennial Cli­mate and Sea-​​Level Change,” illu­mi­nates the issue and helps point a way ahead. It addresses sea level rise in a longer term from a sci­en­tific perspective.

The authors first ana­lyze data that show how a major rise in CO2 and warm­ing from 20 mil­len­nia ago brought Earth out of an ice age. Air tem­per­a­tures con­tin­ued to rise over a long period from the Ice Age to the near-​​modern cli­mate that began some 11 mil­len­nia ago. From that time onward, CO2 lev­els and air tem­per­a­tures sharply lev­eled off.

Sea lev­els, which were 400 feet lower than today, did not stop ris­ing, how­ever. They con­tin­ued ris­ing long past when air tem­per­a­tures reached their plateau, ris­ing for another 8,000 years, climb­ing another 150 feet up to today’s height. The oceans did not achieve the near-​​current state that we all know as mod­ern coasts and maps until roughly 3,000 years ago.

The mere sliver (in geo­logic time) of cli­mate sta­bil­ity in the last 10 or so mil­len­nia has dearly helped human soci­eties and cul­tures to flour­ish. But the les­son is that seas are acutely sen­si­tive to CO2 and tem­per­a­tures, and they can have iner­tia lag­ging the car­bon cycle and cli­mate sys­tem. That means today’s oceans could go on ris­ing very long after CO2 might be steadied—even if human­ity takes deter­mined action to slow rises in CO2world­wide, or even decrease emis­sions. This thorny fact is not widely appreciated.

As Clark and his co-​​authors note, one-​​fifth to half of the air­borne CO2released by human indus­try so far and in the next 100 years will still be present in the atmos­phere by the year 3000. Com­bine CO2 per­sis­tence with the iner­tia of seas and it can mean sea level rise might go on at least 10 or more millennia—the unimag­in­able. There is no easy off switch to halt the ris­ing of seas, no mat­ter how much future soci­eties might wish it to end.

The oppor­tu­nity to go on ignor­ing this basic dynamic is now van­ish­ingly small. There’s already been a well-​​accepted 1.5 degree Fahren­heit increase in global tem­per­a­tures since 1900. That change alone seems to come close to the great­est vari­a­tions that have occurred over the pre­vi­ous 10,000 years.

The cur­rent rate of change is just as con­cern­ing. It had taken a long period, from some 21 mil­len­nia to 12 mil­len­nia ago, for atmos­pheric con­cen­tra­tions of CO2 to jump by 80 parts per mil­lion (ppm), from about 190 to 270 ppm. In that time span global tem­per­a­tures rose by an aver­age of 7 degrees F. We are on track to repeat that kind of increase over a much shorter period.

Keep in mind what that scale of change means. A dif­fer­ence of 7 degrees F sep­a­rates today’s “ideal” cli­mate from the extreme con­di­tions of an ice age. For a refresher, the Ice Age built ice sheets over Canada, New Eng­land, parts of the Mid­west­ern U.S., North­ern Europe and North­ern Asia. The Great Lakes were born when those sheets retreated. The melt­wa­ter retreat cre­ated Long Island in New York, and Cape Cod. Huge impacts were thus wrought by 7 degrees F; ice stood two miles tall over parts of North Amer­ica, and shaped the ele­va­tions of a con­ti­nent we know today.

Just imag­ine if there’s another 7 degrees F of global warm­ing ahead. Cer­tainly that would alter land, sea and ecol­ogy in scales and ways hard to fathom.

By look­ing back to Earth’s more dis­tant past we know that with a tem­per­a­ture rise of “only” 2 degrees to 5 degrees F warmer, seas could rise 15 to 65 feet, a level that would drown so much today. For a thought exper­i­ment, adding 5 degrees F of warm­ing is very imag­in­able, given cur­rent trends of increas­ing CO2. So it is rea­son­able to imag­ine seas 60 feet higher. That would ren­der all of Florida a mem­ory, almost all of New York City, much of the East­ern seaboard, parts of the West­ern U.S. and Gulf Coasts—and (Robert’s) acre of San Diego land that today is a mile from the present shore.

Mech­a­nisms by which this hap­pens are easy to fathom. Greenland’s ice sheet stores only 22 feet of poten­tial sea level rise, pos­si­bly ongo­ing for some 10 mil­len­nia. How­ever, the Antarc­tic ice sheet stores around 150 feet of poten­tial rise in that same time frame. Iron­i­cally, over the last dozen years, the East sec­tion of the Antarc­tic ice sheet annu­ally has gained some 175 tril­lion pounds of ice. But West Antarc­tic annu­ally has lost much more, some 275 tril­lion pounds of ice. (Green­land has aver­aged 600 tril­lion pounds of ice lost yearly, which is equiv­a­lent to10 bil­lion trucks a year cart­ing ice away).

We may be head­ing quite out­side of con­di­tions known in human recorded his­tory. Earth might even begin to exhibit changes of states that only can be guessed at. A new study, for instance, shows that net melt­ing is caus­ing Earth to slightly change how it moves on its polar axis. Days are get­ting just very slightly longer as ice melts at poles and redis­trib­utes that mass as water towards the equa­tor. A very tiny change in Earth’s spin may not be trou­bling, yet it helps to show the mag­ni­tude of changes pos­si­ble from CO2. Even dis­tant earth­quakes con­ceiv­ably can grow in size or fre­quency, as unbur­den­ing crust rebounds after los­ing tril­lions of tons of ice. That in turn also could mean increased vol­can­ism and tsunamis worldwide.

These threats may be on long timescales but there’s an acute need for sci­en­tific knowl­edge, mea­sured in and across mil­len­nia, to seep into our global discussions.

August 2016 was the planet’s warmest month on record, by a lot. It was the 16th month in a row that a monthly heat record fell, way beyond any such streak in 137 years of record keep­ing. Arc­tic tem­per­a­tures were an eye-​​opening 20 degrees F above nor­mal. With rel­a­tively extreme lev­els of heat cov­er­ing the Arc­tic, ice lev­els in the win­ter there were the low­est ever recorded. Nights have stayed warmer world­wide, too, mak­ing heat waves tougher to endure. This hap­pened along­side the largest, single-​​year jump in atmos­pheric CO2 con­cen­tra­tions ever recorded. The level is now over 400 ppm and ris­ing. And the global ocean reached record warmth as well.

So what does all this mean for sea level rise?

An inter­na­tional panel in 2013 had given sce­nar­ios for rise in this cen­tury mainly based on straight­for­ward expan­sion of warm­ing oceans. They only allowed for a small influ­ence from marine ice-​​sheet insta­bil­ity, known as MISI, pri­mar­ily on the assump­tion that Antarc­tic ice sheets were too sta­ble and vast to irre­versibly shrink this century.

The report pre­sented an opti­mistic lower-​​end CO2 sce­nario that assumed strong actions would be taken later this cen­tury to reduce CO2 emis­sions, and which pre­dicted an esti­mated 1 foot of rise (0.3 to 0.6 meters) by 2100. The higher-​​end esti­mate, based on cur­rent trends con­tin­u­ing and lit­tle strong action this cen­tury to reduce CO2, led to 3 feet of rise by 2100, with the rate increas­ing rapidly to between one third to over half of an inch (8 to 16 mil­lime­ters) per year dur­ing the last two decades of this cen­tury. Such a rate only a cen­tury hence could be up to 10 times the 20th cen­tury aver­age rise and might pos­si­bly approach what had occurred around end of the Ice Age, when seas rose rapidly.

In the three years since that major report, three new papers on ice-​​sheet dynam­ics have shown that our prior under­stand­ing was incom­plete, and that MISI mech­a­nisms may be much more exten­sive across the Antarc­tic. The enor­mous Pine Island Glac­ier in Antarc­tica, for exam­ple, is thin­ning and retreat­ing at a quick­en­ing rate. Mech­a­nisms in newer mod­els show that mass loss from unsta­ble retreat may poten­tially become sig­nif­i­cant, sooner than expected. Some early col­lapse may be start­ing at the Thwaites Glac­ier now. Unex­pected col­lapse of the Antarc­tic marine ice sheet could cause pre­vi­ous upper esti­mates of sea level rise to be exceeded not long after the end of this cen­tury. Although the timescale is uncer­tain, more rapid col­lapse could occur in a rel­a­tively short time period of two to nine centuries.

NASA’s DC-​​8 flies over the crack form­ing across the Pine Island Glac­ier ice shelf on Oct. 26, 2011. Credit: NASA GODDARD SPACE FLIGHT CENTER, FlickrCC BY 2.0

Fur­ther­more, an impor­tant paper released in 2016 notes marine ice cliffs may be becom­ing insta­ble, another mech­a­nism for yet more rapid retreat through 2100. A dif­fer­ent paper, out in March, shows sea lev­els could start to rise much more than was fore­cast in the prior lower-​​end sce­nar­ios. It indi­cates that more than 40 feet of rise may poten­tially come just from Antarc­tica by 2500, in accord with higher-​​end sce­nar­ios for CO2.

The point here is that 2100 shouldn’t be regarded as a ter­mi­nal year. To do so is folly, a fal­lacy in think­ing. Life goes on, peo­ple do not end there, and seas will not sud­denly halt their rise then.

Sci­en­tists are nat­ural skep­tics, not prone to dra­ma­tize their find­ings. But cause for abun­dant hope is fad­ing. That ought to stretch our think­ing. Lis­ten­ing to the sea and this emerg­ing sci­ence should mean adjust­ing ideas about what’s wise. The pale­o­cli­mate record indi­cates that in peri­ods of melt­wa­ter, or ter­mi­na­tion of the last glacial period, seas pos­si­bly might have risen at an astound­ing rate of a foot per decade, or 10 feet per cen­tury. There is no rea­son to say it can’t hap­pen again, or rise by faster rates. Given aggres­sive CO2 trends, it must be considered.

Will such ideas lead to sound pol­icy deci­sions? They should, but prob­a­bly will not. Con­sider that likely lev­els of CO2 could make a folly of putting bil­lions or tril­lions of dol­lars into armor­ing coast­lines. One can imag­ine an enor­mously long and expen­sive wall, say 10 feet high, being topped in a cen­tury or two. And one can’t even imag­ine sea­walls able to han­dle oceans going 50 feet higher and rising.

Costly walls might make slightly more sense if ris­ing seas could be counted on to sta­bi­lize, or retreat from know­able heights, and do so in a year mean­ing­ful to our species. Since nei­ther is the case, cap­i­tal that might be spent on armor­ing might instead be deployed in smarter ways. Arguably, rather than spend­ing enor­mous yet finite cap­i­tal on costly “hard­en­ing,” it would be bet­ter to put resources into avoid­ing CO2emis­sions, and grow­ing renew­able energy in the first place. Pre­ven­tion rather than cure. That brings up the next part of this story: What, then, should we do?


One recently cel­e­brated ini­tial step was the Paris cli­mate agree­ment, spelled out in Decem­ber 2015. Although pun­dits thought it would take years to rat­ify the accord, by Octo­ber 2016 the needed thresh­old of 55 nations that also rep­re­sented 55 per­cent of global emis­sions had rat­i­fied it, putting it into effect.

Mov­ing from hope to real and dif­fi­cult action has under­mined prior aspi­ra­tional agree­ments, how­ever, such as the Kyoto Pro­to­col. Paris is an impor­tant start, as is a recent amend­ment expand­ing the Mon­treal Pro­to­col to cover hydro­flu­o­ro­car­bons, but the world is crit­i­cally short on time and the means to ver­ify reduc­tions, and on finance for the nec­es­sary actions to achieve those reductions.

Paris, more­over, isn’t bind­ing. It is no treaty, and it lacks penal­ties. And per­haps most impor­tantly the for­mal goal of 2 degrees Cel­sius (3.6 degrees F) for an “upper limit” on “allow­able” warm­ing is in truth a legal fic­tion, a mere balm for present lead­ers, since the planet is on a clear path to blow right past it.

Fur­ther­more, sci­ence sug­gests this 2 degrees C of warm­ing is far more dan­ger­ous than the nego­tia­tors seem to think. Warm­ing with much higher seas for mil­len­nia can be already baked in, even at a hoped-​​for 2 degrees. That is why the Paris Accord left many sci­en­tists shak­ing their heads in despair. There is an enor­mous gap between how quickly the sci­ence says car­bon emis­sions must fall to stay within 2 degrees C, and what global agree­ments like that from Paris may aim to require.

Inter­na­tional equity is impor­tant, too. West­ern nations have already burned through much of the world’s total allow­able car­bon budget—the amount of car­bon the world can burn before the planet is likely to cross the 2-​​degree thresh­old. This is pro­found, and vex­ing. Devel­op­ing nations like China and India bear lit­tle blame for fuels burned for a cen­tury till now, and they may unsur­pris­ingly argue for growth based on carbon-​​spewing indus­try of their own.

Yet repeat­ing our same carbon-​​path is now unaf­ford­able given the global car­bon bud­get. The phys­i­cal car­bon ceil­ing is wholly unyield­ing. The chem­istry and physics of warm­ing can’t be bar­gained with or pled to. There­fore, although the Paris cli­mate accord is good as a first step, the need now is for ongo­ing real action and a strong, con­tin­u­ing com­mit­ment to progress to a 1.5 C tar­get. If we act as if Paris and the Mon­treal Pro­to­col amend­ment are the major end­points, not a begin­ning, that will put off real solu­tions until it is too late.

There are also pit­falls along the way if we don’t make cli­mate solu­tions an ongo­ing process. “Cap-​​and-​​trade” sys­tems for car­bon emis­sions in the­ory can begin a tran­si­tion to market-​​based mech­a­nisms but they have already been gamed by many par­tic­i­pants because caps are not rig­or­ous and dimin­ish­ing. A very hard look is needed at how nat­ural gas is imple­mented: Can a plant be built today and be decom­mis­sioned by 2050? So-​​called “clean coal” is expen­sive, untested, unwieldy and unwork­able, yet it is raised as a panacea. (Lost coal jobs are indeed a con­cern wor­thy of much atten­tion, how­ever). Non­starters like geo­engi­neer­ing are sug­gested in some des­per­a­tion, at least in the long term, yet they defy moral­ity and could worsen a spi­ral­ing ocean acidification.

Today, oppor­tu­nity lies in imple­ment­ing clean, green economies of solar and wind power, and energy effi­ciency, and geot­her­mal and hydropower when eco­log­i­cally friendly. The chal­lenges of ocean acid­i­fi­ca­tion, frag­ile ecosys­tems and climate-​​induced migra­tion all point to the need to scale up the truly clean energy econ­omy at an excep­tional pace.

We sup­pose that pos­si­bly we all could close our eyes and hope that, say, lead­ers in China go even big­ger on clean energy while drop­ping coal entirely. But China is cut­ting back on its ambi­tious solar goals.

We could hope for “neg­a­tive emis­sions” by suck­ing CO2 from the air and seques­ter­ing it into stone far below ground. That’s tech­ni­cally fea­si­ble in cer­tain basaltic rock regions, but the process is extremely expen­sive, and it is dif­fi­cult to see this being imple­mented at a global scale. And that is where the rub is: CO2 dump­ing is free, today, and CO2 seques­tra­tion is costly.

There are steps that make sense. Car­bon taxes—including rev­enue neu­tral ones where other taxes are reduced—can work because they send unam­bigu­ous economy-​​wide sig­nals. Car­bon account­ing across the pub­lic sec­tor, and for com­pa­nies wish­ing to do busi­ness with local to national gov­ern­ments, can edu­cate and start the move­ment to full car­bon pric­ing. Strong crossover poli­cies, such as those link­ing car pur­chases to low-​​carbon goals, also accel­er­ate the process.  Finan­cial divest­ment from fos­sil fuels—which has been a chal­lenge to implement—is another nat­ural place to begin.

We must con­sider, then, oppor­tu­ni­ties that har­ness viable tech­nol­ogy and eco­nom­ics. For exam­ple, a sim­ple, trans­par­ent car­bon tax could be key. It could help get us near where we’ve got to be and has­ten green energy. Even many big busi­nesses are now call­ing for a car­bon tax. A sim­ple tax that’s adopted widely could be very sig­nif­i­cant. But in the U.S. a car­bon tax goes unmen­tioned in polit­i­cal debates.

One way or another, if lead­ers are going to get real on cli­mate, they have to end fos­sil fuel sub­si­dies, then phase out fos­sil fuel use, all while imple­ment­ing clean, renew­able energy for elec­tric­ity gen­er­a­tion and trans­porta­tion. We should do this for our grand­chil­dren and for their grand­chil­dren. And because it is patri­otic, will make us stronger and is far less dis­tort­ing to our inter­ests than fos­sil fuel dependence.

These moves are not bur­dens. They are oppor­tu­ni­ties. Get­ting closer to 100 per­cent renew­ables could be achieved more read­ily than most peo­ple say. It can make nations stronger and more resilient, and add jobs. In some places like Cal­i­for­nia, China, Den­mark, Ger­many, Kenya and Morocco, renew­able energy is pro­gress­ing faster than in oth­ers. But nowhere is it fast enough.

We two authors have spent most of our careers advanc­ing renew­able energy and sus­tain­abil­ity, address­ing cli­mate both in the­ory and prac­tice around the world—in acad­e­mia, the pub­lic sec­tor, the pri­vate sec­tor and as entre­pre­neurs. Yet noth­ing cur­rently gives us great hope that very harsh sce­nar­ios for cli­mate change and sea level rise, last­ing for mil­len­nia, will be com­pletely avoided.

Look­ing at rates of CO2 emis­sions, and at inter­na­tional actions that lean toward lofty words about future cuts over real action with teeth today, opti­mism does not spring to mind. In a mere cou­ple of cen­turies, humans will have com­mit­ted Earth to new cli­mate regimes and higher seas never seen in our his­tory, that will poten­tially last millennia.

And we will have done it all, know­ing the likely consequences.


Cap­i­tal­iz­ing on Solu­tions that Can Make Eco­log­i­cal and Eco­nomic Sense. Robert J. Wilder in Jour­nal of Alter­na­tive Invest­ments, Vol. 7, No. 2, pages 80–84; Fall 2004.

Sav­ing Marine Bio­di­ver­sity. Robert L. Wilder, Mia J. Teg­ner, Paul K. Day­ton in Issues in Sci­ence and Tech­nol­ogy, Vol. 15, No. 3 (Spring 1999).–3/wilder

Lis­ten­ing to the Sea: The Pol­i­tics of Improv­ing Envi­ron­men­tal Pro­tec­tion. Robert J Wilder. Uni­ver­sity of Pitts­burgh Press, 1998.