Culpability requires agency, awareness: that those who committed a vile act were aware of both the act and its vileness. A tornado destroys but it isn't a self-aware agent. Inebriation is often considered a mitigating circumstance in court, because the agent can be thought of as less aware of its actions. Ignorance of the law, though, has seldom, if ever, been thought to be a mitigating circumstance. Willful ignorance, or worse, disdain for the law has most definitely been considered an aggravating circumstance.
Some of us have known about global warming for at least a few decades. Some of us have known for nearly a century. We've known the law–the laws of physics as they relate to gases and heat in the Earth's atmosphere, in this case–for nearly two centuries: ever since the early experiments by the scientist Eunice Newton Foote on the warming effect of sunlight and the effect of the proportions of carbon dioxide in retaining solar heat. Yet here we are: planet Earth is on a path to raise average global temperatures by about 2C within a few short decades, with devastating consequences for its ecosystems and the well-being of humanity.
2C may not sound like a lot. But it's an average: some parts, such as land areas, heat up more than others, such as oceans (Seneviratne et al. 2016). And we humans live on land. And it's an average in more than one way: climate on average may not change dramatically, but that's because, as in the proverbial math joke, with one's head in the freezer and one's feet in the oven, on average the mathematician is fine. Some lands will become flooded; others, more arid. Overall, hotter air has more energy (think stronger winds) and hosts a larger absolute amount of humidity even if percent humidity wouldn't change, which means, when it rains, it pours. It is only a contradiction that a 2C global average temperature increase may result in more and heavier snowfalls in some places if one ignores the increased ranges and merely focuses on the averages.
Small changes in averages, with increased spread in the distribution of local climates, can push systems over limit points: thresholds, or points of no return, beyond which irreversible changes dramatically transform our environment. Some trees survive between e.g. 2C and 45C. A single day of temperatures above 45C or below 2C may kill it, even if the rest of the year remains only slightly off the former average temperature. Extremes kill. And once a member of an ecosystem is gone, its trophic links are broken: that is, its nurturing relationships with other plants, animals, fungi and bacteria are severed forever.
And hence a small change on an average can imply a dramatic change across the board: in the health of an ecosystem, in its resilience to perturbations (think forests recovering from naturally occurring hurricanes or wildfires), in its composition. Because there are dependency chains: some animals only feed on other, specific animal or plant species; some only feed on certain tree fruit; some flowers are pollinated only by one kind of insect; and so on. The loss of a single member of a community may start a domino effect on many others. The resulting ecosystem may remain impoverished for a while, or forever .
The largest threshold changes I have in mind are of a scale so vast as to be almost incomprehensible. The first is the North Atlantic ocean conveyor belt (the so-called thermohaline circulation): a current of low-salt warm surface water that flows from the gulf of Mexico to Europe, and responsible for the comparatively mild climates of Western and Northern Europe. Without it, the Baltic Sea would freeze solid every year, and Sweden and most of Western Europe wouldn't grow wheat. The countercurrent of deep salty cold water that flows back from the Arctic to the equator contributes to the overall temperate climate of planet Earth. Consider the alternative: a scorching hot equator (no cold water inflow) and a permanently ice-capped North Pole extending all the way to the Mediterranean sea, or New York City. It has happened before. And presently, the Atlantic conveyor belt has slowed down (Caesar et al. 2021): today it's at its weakest point of at least the last 1,600 years. Why? Because the Arctic is heating faster , and therefore the temperature gradient (i.e., the slope) from the equator to the pole is weaker.
The second threshold change to dread is the thawing of the permafrost. It's not only that some housing depends on the ground being hard for its foundations instead of soft, runny mud; it's that the permafrost traps huge amounts of plant and animal detritus (accumulated over thousands of years) that, because of the freezing, never got degraded into carbon dioxide. Once it thaws, bacteria come back to life, consume the detritus, and, as a byproduct of their metabolism, release carbon dioxide. The scary bit is the positive feedback loop that could be established: more dumping of CO2 would increase the global temperature further (the poles are particularly affected, with already average increases well over 2C) resulting in more thawing and more CO2 release. A situation that, like a chain reaction in an atomic bomb, would get out of control fairly fast . To make matters worse, the permafrost also stores big reserves of methane gas, which has an even stronger effect on global warming than CO2.
We humans have shown an exceptional ability to ignore known harms when these were delayed over the long term. Think of lead in gasoline: it was put there as an additive with anti-knock effects, improving the performance of internal combustion engines. Its inventor, the infamous Thomas Midgley, used it instead of ethanol because he couldn't patent the latter. While there were lead poisoning incidents throughout the development and early production of this gasoline additive, production, promotion and profits continued. The thought of spraying lead all over the country did cross the minds of those who promoted it, but nothing was done about it for decades, until regulations came into place to forbid its use. To this day, aviation (primarily small, private airplanes) still uses lead supplements in fuel. The removal of lead from car gasoline has been correlated with a decrease in violent crime all over the United States. Midgley himself fell ill from lead poisoning, twice. The ill-fated inventor then went on to develop chlorofluorocarbons (CFC), also known as Freon gas, which famously tore a hole into the planet's ozone layer, most prominently over Antarctica, and was later forbidden by more environmental regulations. One fridge in one lab has little to do with Freon leaks from fridges in every home of every family of many countries for decades. Scale matters, both for profits and for consequences.
Similarly, mercury has been used in gold mining operations for decades if not centuries, to separate gold from the rest of the ore. Such mercury fatally poisoned many rivers and then ended up in the oceans, and now we have to carefully watch which fish and how often we eat it, or risk mercury poisoning. It isn't helping that fish are often mislabeled in purpose (fraud), but such horrors are outdone by fish stocks being depleted nearly to extinction by overfishing. A small boat fishing with a net near the coast for village consumption and a factory freezer boat picking tuna out of the ocean at industrial scale and dropping all the "bycatch" dead back into the sea are two entirely different operations. Again, scale matters. It always did. The good news: as Enric Sala et al. (2021) have shown, protecting a fraction of the whole ocean from fishing (and dumping, and pollution) enables sea ecosystems to bounce back. There is hope, because we know what to do. Now we must push political action to realize this approach.
Who bears responsibility for trashing our planet? When my kids leave the living room like a dumpster, it's clear. There are proximate causes (my kids breaking havoc with cardboard, crayons, tape and scissors to build castles and theater stages). And there are ultimate causes (me allowing and encouraging such games to take place). In the case of carbon dioxide dumping into the atmosphere, it's not so easy. But our livelihoods are on the line, and therefore, like with lead additives and Freon gas, it's on us all to get our act together and push forward legislation and society-wide initiatives to clean our act.
Humanity has grown its numbers from about 1 billion in the early XX century to about 8 billion today, April 7th, 2021. Furthermore, a reduction in poverty and increased access to education and material goods has increased the proportion of us with access to carbon-emitting devices and activities. Whatever any one of us does, many of us, if not most, are doing it too. Scale matters. The upside is: whatever any of us does, many of us can do too, and this works just as well for positive effects. We can and we are fixing this mess. The economy continues to grow while decarbonising, that is, decoupling economic growth from CO2 emissions. What it will cost us: less than not doing anything at all.
Big petroleum corporations, also known as Big Oil (and its cousin Big Coal), have known that burning fossil fuels would ultimately result in steady increases in the percent of carbon dioxide in our atmosphere. For them, CO2 is an externality: a cost that is paid by the rest of us, rather than directly when e.g., purchasing gas at the pump. Keep in mind that, at least in the US, taxes on gas are directed towards funding road construction and upkeep, not cleaning up oil spills like the Exxon Valdez (another externality) or coping with increased medical care for respiratory illnesses related to road traffic or coal-burning plants (up to £11 billion yearly in the United Kingdom alone).
We've known for a long time what could happen. Evidence for the mechanisms of global warming emerged in 1824 (197 years ago), followed by further work in 1837 and later in 1856 by Eunice Newton Foote , with more evidence in 1861, and then the first model of climate change by Svante Arrhenius in 1896  who naively thought warming was a good idea.
Big Oil companies knew all along too. As early as 1957, "H. R. Brannon of Humble Oil Company (now ExxonMobil)" understood the effect of CO2 emissions. And in 1959 Edward Teller further warned the oil industry about CO2 accumulation and its effect in elevating global temperature and sea-level rise by the end of XX century . And by 1982, the likes of ExxonMobil knew exactly how much CO2 was contributing and projected to continue to contribute to global warming, with eerie precision. And yet chose to do nothing: acknowledging global warming would undermine its business model and profits. And this continues to be the case.
Blame shifting, though, is an industry of its own. Have you noticed that "global warming" is nowadays more often than not referred to as "climate change"? This is the result of a deliberate campaign by the oil industry, muddling the waters of understanding via lobbying in the US Congress, because "climate change" can also mean, not accidentally, global warming by natural causes instead of the burning of fossil fuels . And it gets worse. When the burning of fossil fuels became unambiguously associated with CO2 emissions and their effect in global warming, Big Oil corporations launched a campaign to make consumers reconsider their choices and, in all, make consumers believe that their individual choices mattered a whole lot. Because it is partially true, the campaign succeeded. Guilt-tripping consumers is now the norm. Even low-key climate warriors will try to shame others because of e.g., the car they drive, instead of finding out what car did they actually drive, or why they are driving a car at all.
On consumer choices, there are staggering statistics. Half of all plastics ever made were produced in the last 13 years leading to 2017 (Geyer et al., 2017). And about half of all CO2 from burning fossil fuels ever emitted was emitted over the last two decades or so. Which means, it's us really. Not our forebears, but us today. The toys we bought, the road trips, the holiday and business flights, the purchasing of a car or the meats we've consumed daily over the last decade. We did it, we, humans alive today, pushed atmospheric CO2 to its current astounding heights.
After all the above, the reader won't be surprised to learn that plastic recycling was always a lie, the product of an advertising campaign to sell more petroleum derivatives. Nowadays it has become clear that plastics should be used the least possible (e.g., avoid phthalate exposure; Swan et al. 2015), and when disposed of, burn them (for e.g., medically contaminated material) or bury them in landfills: as awful as this sounds, it's far less bad than the alternatives. Only about 9% of all plastics ever made have been recycled (Geyer et al., 2017).
On cars, buying a second-hand gas-burning car is less environmentally damaging than purchasing a new electric car. That's because the mining of metals and oil for plastics, and the manufacturing of a new car, emit more CO2 than the gas burned by the car's internal combustion engine over its entire lifetime. Until new electric cars are manufactured using only renewable energy and carbon credits of some sort to compensate for emissions during e.g., steel manufacturing, this will remain true. And the industry, while presumably aiming at this (it's great PR), it's far from such goal. And never mind the pollution and environmental and health impact of particles emitted by rubber tyres.
The only environmentally friendly transportation choice is to not drive a car at all. But here, forces beyond the individual come into play, such as urban design. As Jane Jacobs famously described in her phenomenal book "The death and life of great American cities", local, well-structured and tightly knit neighborhoods have "eyes on the street" and are far safer, and also humane: its inhabitants are happier, with stronger community ties and life satisfaction. And, importantly, everybody walks or cycles, as services, employment and schools are all within the neighborhood. The antithesis are large city blocks that disrupt local dynamics, and of course the suburbs, with their suburban parkways, strip malls and large parking lots, all subservient to the car as the one and only mode of transportation. The city ordinances that regulate roads and parking requirements for businesses are as much to blame for global warming (and many other calamities) as the oil industry itself. Engage in local politics and push for change: it is worth every ounce of effort.
And big malls have been shown to be pernicious to not only local businesses but to the very cities they claim to serve. How the arrival of tax-subsidized malls nearly collapsed the local downtown businesses (despite the latter contributing far more in taxes), and the departure of said malls some years later left the city dependent on nearby cities for basic retail services, is but one example: the story of Brainerd, MN. Jane Jacobs could have predicted the fate of this town down to the date of its demise. And just like in biology, monocultures (malls) spell short-term profits (for the few) in exchange for near- to long-term collapse (of the entire ecosystem: all of us). Whereas in diversity there is enormous strength and resilience. Once the business links and know-how are gone, though, re-establishing them is as hard as bringing the forest back: it is not just a matter of merely planting trees; there is a long and well-know sequence of ecosystem transitions necessary to bring about a mature and complex forest, or a mature and business-rich downtown.
If commuting by car and a culture of throw-away plastics are the proximate causes, suburban design with its car culture and the regulations that impose it are the ultimate causes. Fighting the latter is hard. Blaming the individuals for the former is easy. But what choice do we, individual humans, have, but to live our lives as best we can, within the constraints and tensions that we find ourselves immersed in. And yet, we can do a lot. For example, we can support politicians when these want to end subsidies to oil industries. It is astounding, in 2021, to learn that Big Oil is the recipient of billions of dollars in subsidies. Along with the divesting movement (the withdrawal of investments from funds that include fossil fuels in their portfolios), ending Big Oil subsidies is a clear path ahead with overwhelming support. All it takes, as always, is the will to push ahead, the courage to say enough is enough, and convince our elected representatives that it is in their best interest, in addition to ours, to end such subsidies. And politicians always like a fight they know they can win easily while retaining support from the electorate.
What we can do, as individuals, is to know. To be informed. And to spread the word, to inform our family members, our friends, our acquaintances, our colleagues. Collective action matters. Pick an issue with immediate impact onto your local community and make it your own, and push ahead relentlessly. And remember: a determined, small group of individuals is the only force to ever have changed the world.
We've known for centuries about global warming and its causes. Now that we know that we know, we can't claim ignorance. We know the laws (of physics). And we know that we have no choice: either we act or we diminish, taking down with us the world as we know it. Another world may emerge from our mess, but not with us in it. We are to blame for causing global warming: we did it, knowingly, and recklessly, kicking the can down the road again and again all in the interest of the profits and advantages in the here and now, but not without a bad conscience. Because we knew. But we are also to praise. For our efforts to redress our ways, for our inventiveness, our resourcefulness. The rise of renewable energy has been extraordinary. The establishment of nature reserves, noteworthy and impactful. Let us continue. And let us be swift, for it is not too late (yet), and there is everything to gain.
- See a summary of Foote's contributions to the effect of carbon dioxide in absorbing solar heat here: "How 19th Century Scientists Predicted Global Warming" by Clive Thompson, 2019.
- "On the influence of carbonic acid in the air upon the temperature of the ground". Svante Arrhenius, 1896. Philosophical Magazine and Journal of Science 5(41):237-76. PDF
- See "Early oil industry knowledge of CO2 and global warming", by B. Franta, 2018, a letter to the editor on the contributions and early knowledge of the oil industry on CO2 and global warming. And also see this piece (2018) on Teller attending the centennial of the US oil industry and telling them, in their faces, that CO2 accumulation threatened to melt the poles ice caps and submerge all coastal cities.
- It got so confusing that there are even papers about this, e.g. "Talking about Climate Change and Global Warming", Lineman et al. 2015.
- "Warming of the arctic ice‐ocean system is faster than the global average since the 1960s", Zhang 2005; "Arctic Ocean surface warming trends over the past 100 years", Steele et al. 2008.
- A similarly concerning positive feedback loop is the loss of Arctic ice: the higher the Arctic temperatures, the less ice (white, reflective) and the more ocean water (darker, absorbent of sunlight) and the more heat retention rather than reflection: a change in the albedo. It's been predicted that the Arctic will be completely ice free in summer within mere decades: "A sea ice free summer Arctic within 30 years?", Wang and Overland, 2009. Some countries welcome this, as it opens the Northeast passage for boat traffic: an abhorrent outcome which would only bring pollution and trouble to an already sensitive and troubled Arctic ecosystem.
- A similar phenomenon has been recorded for cities. From the razing and salting of Carthage by the Roman armies in the Third Punic War, to prevent further continuation of Carthage; to the lynching and destruction of businesses in the Tulsa massacre to destroy a thriving Black community; and the killing of the city's leaders–the rich, clergy, businessmen–of Novgorod, a city then of similar stature to Moscow, by Ivan the Terrible. All had the effect of grinding to a halt any further developments. Whatever remained of these cities could not go on.