Climate Primer #5: The Fourth Planetary Boundary – Climate Change

So climate crisis is the defining issue of the 21st century, but here “climate crisis” really means “the intersecting crises that threaten to broach key planetary boundaries and hence make the Earth less/unlivable (for humans).” So far, posts have addressed the planetary boundaries of stratospheric ozone depletion, biodiversity loss, and toxic substance contamination. The title of today’s post (paradoxical as it may seem), points to just the problem that prevailing nomenclature creates in trying to think about the planetary crises now confronting human societies. Can climate change really be simply one of the components of climate crisis? For now, yes, because there is no better, widely-accepted terminology for addressing these matters. When I write “climate crisis,” I now refer to all of the intersecting planetary crises, whereas, here – following the Stockholm Resilience Center (whose description follows) – in using “climate change,” I mean only that:

Recent evidence suggests that the Earth, now [approaching 420 ppm] CO2 in the atmosphere, has already transgressed the planetary boundary and is approaching several Earth system thresholds. We have reached a point at which the loss of summer polar sea-ice is almost certainly irreversible. This is one example of a well-defined threshold above which rapid physical feedback mechanisms can drive the Earth system into a much warmer state with sea levels metres higher than present. The weakening or reversal of terrestrial carbon sinks, for example through the on-going destruction of the world’s rainforests, is another potential tipping point, where climate-carbon cycle feedbacks accelerate Earth’s warming and intensify the climate impacts. A major question is how long we can remain over this boundary before large, irreversible changes become unavoidable.

Even in this reduced form, it’s a doozy, and is almost certainly the most capacious (and hence the defining) of the nine planetary boundaries in the SRC’s schema, so perhaps it makes sense to think about climate crisis as synecdoche: Just as “White House” stands in for “the presidential administration” and “DC” for “the US Federal Government,” so too, perhaps “climate crisis” means “climate change, but also all of the other planetary crises which threaten the future of organized human life on Earth.”

A key aspect of the SRC’s description above is its emphasis on feedback loops and thresholds beyond which changes will become “irreversible” (over humanly-meaningful time horizons). I plan to address both of these issues in detail in future posts, but, in the meantime, if you’re feeling energized by all this (because despair and hopelessness are not options), you might consider donating to support the long-standing struggle of the Wet’suwet’en people against the Coastal GasLink pipeline. Sometimes, battles seem un-winnable until you win them, and with pipeline projects stalled and canceled across the country in the face of fierce popular opposition (and plummeting fossil fuel prices); popular support growing for a Green New Deal, or something like it; and the US oil majors getting hammered financially (such that ~$400 billion – a lot of money, but a small fraction of all the pandemic-related Federal stimulus spending – would suffice to nationalize Exxon Mobile, Chevron, and ConocoPhillips), there’s never been a better time than now – other than any time in the last 70 years – to confront, break, dismantle, and repurpose the power and infrastructure of the fossil fuel giants.

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