How Lessons from Earth's Past Can Help Us Survive the Climate Crisis
by Michael E. Mann
The drying of the tropics during the Pleistocene period created a niche for early hominids, who could hunt prey as forests gave way to savannahs in the African tropics. The sudden cooling episode known as the “Younger Dryas” 13,000 years ago, which occurred just as Earth was thawing out of the last Ice Age, spurred the development of agriculture in the fertile crescent. The “Little Ice Age” cooling of the 16th-19th centuries led to famines and pestilence for much of Europe, yet it was a boon for the Dutch, who were able to take advantage of stronger winds to shorten their ocean voyages.
The conditions that allowed humans to live on this earth are fragile,
incredibly so. Climate variability has at times created new niches that
humans or their ancestors could potentially exploit, and challenges that at
times have spurred innovation. But there’s a relatively narrow envelope of
climate variability within which human civilization remains viable. And our
survival depends on conditions remaining within that range.
In this book, renowned climate scientist Michael Mann will arm readers with
the knowledge necessary to appreciate the gravity of the unfolding climate
crisis, while emboldening them—and others–to act before it truly does become
too late.
https://michaelmann.net/books/our-fragile-moment
Review by Court of the Grandchildren
be drawn from these events.
One of the most important lessons is that climate impacts are not all neatly reversible. For example, if we start to lose an ice sheet because of excess atmospheric CO2 and warming, just dialling down the CO2 back to its starting point will not magically renew the ice sheet in proportion.
This phenomena, called hysteresis, has played out many times over the course of Earth’s 4500 million year history.
Mann’s analysis shows that some of the gloomiest climate projections are unlikely to play out. Nevertheless he warns that “Dangerous climate change cannot be avoided. It’s already here. It’s a matter of how bad we are willing to let it get.” Global mean temperatures are already around 1.2oC above pre-industrial times. As Mann shows, we are potentially only a few points of a degree from destabilising the Greenland Ice Sheet.
On the other hand, Mann does not buy into the most catastrophic societal collapse scenarios as long as we take action. For example, his scientific analysis shows that neither runaway methane-driven warming nor an uninhabitable world are plausible in any scenario but total inaction. He concludes that even under a business-as-usual scenario, the warming of the planet is unlikely to exceed 3 degrees. But that’s hardly comforting because at that level of warming we can expect lots of loss of life, destabilization of societal infrastructure, chaos and conflict. It’s not a world we want to live in.
He acknowledges that there are lots of uncertainties but argues they are reasons for more prompt action rather than less.
What are these actions? Among them is to keep carbon emissions within definable carbon budgets. This means carbon emissions being brought to zero within three decades and getting halfway there within a decade if we are to limit rise to 1.5 degrees. Even if 1.5 degrees is exceeded, “there is no point beyond which we shouldn’t keep trying to limit warming. Every fraction of a degree matters.”...
https://courtofthegrandchildren.com/our-fragile-moment/
‘Our Fragile Moment’ Finds Modern Lessons in Earth’s History of Climate
While some might find the book dense, it offers illuminating
insights into our current crisis
Over four millennia ago, in the final days of the Akkadian Empire in Mesopotamia, a drought swept over the region, afflicting lands as far away as Greece and what’s now Pakistan. Probably driven by the eruption of a distant volcano, the drying climate devastated local agriculture. A contemporary text, The Curse of Akkad, noted that “the large arable tracts yielded no grain … the irrigated orchards yielded no syrup or wine, thick clouds did not rain.”
As once-prosperous farmlands collapsed in the northern part of the empire, people fled to the south. The southern Akkadians’ response? Build a more than 150-kilometer-long wall between the Tigris and Euphrates rivers, barring entry to any migrants. Soon after, history’s first empire crumbled, dying of thirst in the cradle of civilization.
Climate systems and civilizations are stable only up to a point. In Our Fragile Moment, climate scientist Michael Mann reminds us that today we are pushing the limits of both.
In the book, Mann looks back at episodes of global climate change over the last 4.5 billion years, from eras of deadly heat to wastelands of widespread ice. With each instance, he draws out lessons about what happens to Earth in periods of changing climate. Sometimes, the result is dramatic mass extinctions or geologic upheavals (SN: 8/28/15). Other times, as with the Akkadians, it’s societal collapse.
Earth’s climate system includes regulating forces that tend to buffer against small shifts in climate; ice caps and low clouds reflect sunlight and help cool the planet, for instance. But pushed too far, regulating forces can be overwhelmed, causing the climate to spiral out of control.
This was the case 55 million years ago. As a steady set of volcanic eruptions spewed carbon dioxide into the air, Earth warmed. The heat may have contributed to thinner and less reflective clouds. This in turn would have made the planet even hotter. Eventually, the low-lying clouds disappeared, and average global temperatures soared to 32° Celsius (90° Fahrenheit) in what is referred to as a Hothouse Earth (SN: 11/3/15).
Today, with unchecked greenhouse gas emissions, we may face a similar, though less sweltering, spiral with the disappearance of our reflective ice caps (SN: 11/9/22).
But what makes current climate change different is its source — humankind — and our ability to stop it. This is a benefit that is unique to our changing climate. It comes with blame, but it also comes with agency.
That agency is an important source of hope for Mann. Melting ice caps could raise sea levels and displace some 40 percent of the global population. Rising heat could make swaths of the planet uninhabitable (SN: 5/8/20). But if we act, we can preserve a world that looks much like ours. The limit is not geologic or even technological, Mann argues; it is political.
Despite the far-reaching themes Mann weaves throughout the book, it may not be for everyone. There is a strong academic bend to the writing, which leans heavily on jargon. The book also features a dizzying parade of researchers, and Mann often emphasizes his connection to climate researchers and events, at one point reminiscing about how he “was known as a bit of a statistics guru.” The technical terms, acronyms, initialisms and self-referential tangents can distract from the book’s broader arguments and message.
Even though Mann’s dedication to precise academic language comes at the expense of some clarity, climate buffs will appreciate the deep dives into the scientific process. Many of the dense sections reward the reader with a satisfying tidbit of fascinating information or an illuminating insight. On occasion, I laughed out loud at Mann’s puns, jokes and barbs. (A reference to The Princess Bride’s ROUSs — Rodents of Unusual Size — landed particularly well.)
After journeying through the past, Mann brings us to the present and looks toward the future. Though past climates may offer lessons, those lessons only go so far. We are unlikely to bring about another Hothouse Earth, but the climate is warming faster than it has in millennia, thanks to human actions. If current climate policy holds, the best scientific predictions show things will be painful, but civilization won’t end. But climate scientists are not oracles. They can’t be sure.
That uncertainty, rather than being a cause for complacency, should spur us to action, Mann argues. “The impacts of climate change, no doubt, constitute an existential threat if we fail to act,” Mann concludes. “But we can act. Our fragile moment can still be preserved.”
https://www.sciencenews.org/article/fragile-moment-book-earth-history-climate
Perspectives on Time, Kenneth Silber
Mann was inspired to pursue a science career by watching Sagan’s 1980 Cosmos series while a freshman in high school, and he was an undergrad physics student at Berkeley a few years later when Sagan became embroiled in a debate about “nuclear winter” with Edward Teller, Berkeley faculty member and hydrogen-bomb inventor, who had a reserved parking space at the physics building, “an honor that was otherwise granted only to Nobel Prize winners.”
Mann’s career in geophysics and climatology has shown a style reminiscent of Sagan, in emphasizing communication with the public, and in gravitating toward contentious issues where science and politics intersect. Over two decades ago, Mann and colleagues published papers with “hockey stick” graphs showing temperatures spiking upward in recent decades compared to baselines over centuries and millennia. This brought criticism from right-wing think tanks and fossil-fuel interests, but contrary to claims that the hockey stick’s been debunked, it’s held up well as more data’s been collected.
In Our Fragile Moment, Mann seeks lessons about current and prospective warming through examining vast climate fluctuations that have occurred over the eons. Such episodes include the Paleocene-Eocene Thermal Maximum, or PETM, 56 million years ago, or 10 million years after the asteroid that brought the dinosaurs’ downfall. The PETM, starting from a baseline already far warmer than today, produced additional warming of some five degrees Celsius; this happened over thousands of years and was likely caused by carbon spewed from volcanic eruptions (though the alternative “Silurian hypothesis,” involving pollution by an ancient reptile civilization, may appeal to some).
The PETM, in Mann’s view, offers a mixed lesson for our own time. “Even when the planet was hotter than a worst-case fossil fuel emission scenario can plausibly make it, there was no runaway warming,” he writes. Fortunately, a massive methane belch from the seabed appears unlikely. But the news is not all good, Mann points out: “Even if PETM-level warmth is out of reach, a policy of total climate inaction could warm the planet up to the point where substantial regions would become uninhabitably hot for human beings—a hotter, more crowded planet with less food and drinkable water.”
Aided by the perspective of deep time, Mann, who’s long fought against denialists of human-caused climate change, cogently emphasizes that “the truth is bad enough” and shouldn’t be exaggerated. After noting positive developments such as the election of an Australian government pledged to emissions reduction, Mann writes: “Ironically, it is at this very moment of promise that a new obstacle has emerged. The greatest threat is no longer denialism—which is frankly untenable given the impacts that we can all see playing out in real time—but rather doomism, the notion that it is too late to act.”
