“Impermanence is a principle of harmony. When we don’t struggle against it, we are in harmony with reality.”―Pema Chödrön
If you live in a place where it is currently winter and have found yourself trudging through the snow these past few weeks, I’d like to invite you to imagine a world where ice is everywhere, all year round. According to the “Snowball Earth” hypothesis, this was the case 2.1 to 2.4 billion years ago, when scientists estimate that our planet was entirely frozen over—from pole to pole.
Snowball Earth occurred during what’s known as an “icehouse” period, one of two states that climatologists and glaciologists use to describe the planet. Icehouse states are defined by the capability of ice sheets to form; within them, there are colder glacial periods (ice ages) and warmer interglacial periods, times when the ice sheets build up and times when they retreat. The other state is called a “greenhouse” state, in which no ice sheets are able to form anywhere.
Since its inception, the Earth has alternated between these two states, each of which lasts for millions of years. Scientists estimate that there have been five periods in each state. For approximately 11,500 years, we have been living in the Holocene, an interglacial period of the planet’s current icehouse state, which began 34 million years ago. The five ice ages that have occurred all had one thing in common: they eventually ended.
The history of our cryosphere carries within it the wisdom that nothing stays frozen forever, that all things melt eventually (on our planet, at least). In studying it, we begin to understand that few things are as intimately entwined with time as ice, a harbinger of two of nature’s most imperative principles: patience and impermanence. Incidentally, it is the impatience that underlies our modern world that is forcing us to realize that none of it is permanent, and that time is running out to avert unprecedented alterations to our planet’s natural cycles.
Two weeks ago, a journal called The Cryosphere published the most comprehensive study of ice loss to date, calculating what we’ve lost across the last few decades, from the Greenland and Antarctic ice sheets, Arctic and Antarctic sea ice, and glaciers around the globe. It found that the rate of ice loss we are experiencing is now in line with the IPCC’s worst case scenarios. In the 90s, we were losing around 800 billion metric tons of ice per year; today, it’s 1.2 trillion tons. Between 1994 and 2017, we lost a staggering 28 trillion tons.
Scientists estimate that, without human-made global warming, the interglacial period we’re in would last for another 55,000 years before eventually giving way to another glacial one. Instead, we appear to be barreling head-first toward a human-induced greenhouse period. As geophysicist Henry Pollack writes, “Nature’s best thermometer and most unambiguous indicator of climate change is ice. Ice asks no questions, presents no arguments, reads no newspapers, listens to no debates. It is not burdened by ideology and carries no political baggage as it crosses the threshold from solid to liquid. It just melts.”
Impermanence offers both a chilling wakeup call and cooling balm. For a society coming up on a year in quarantine, it’s a comfort to know that nothing lasts forever. For the climate movement, it’s more than that: it’s a reminder that nothing is solid or set in stone, that it’s possible to change the world. That the world itself has changed many times. As Thích Nhất Hạnh says, “Thanks to impermanence, everything is possible. Life itself is possible.”