Hothouse Earth: It’s Worse than We Dared to Imagine

Steffen et al Hothouse Earth
It will take an “Earth System stewardship” ethic to steer earth systems to a ‘Stabilized Earth’ instead of rolling straight into the ‘Hothouse Earth’ trajectory we are already on. Graphic source: Steffen et al, 2018 http://www.pnas.org/cgi/doi/10.1073/pnas.1810141115

Average annual temperatures at the equator?  140+ degrees F.  Possible sea level rise? 196 feet.  How soon? It depends.

The 2018 paper Trajectories of the Earth System in the Anthropocene by Steffen et al is unbelievably depressing.  Will Steffen and Johan Rockstrom among other superstar scientists are making explicit what had been a distant concern: sometimes you don’t get a do-over. In the paper them argue that Earth Systems have already veered from the glacial-interglacial limit cycle (see cold blue basin in graphic above). That 14,000 year long stable planetary weather cycle that underpins modern agriculture and society is already behind us.  We’re on a trajectory of higher temperatures and higher sea levels.

So far humanity has been applying a linear mindset to the challenge.  We think that if we can reduce our CO2, then maybe we can stop warming and sea level rise.  No harm, no foul, right?  Right? Amirite?.  But what Steffen et al note is that the international goal to limit global climate increases to no more than 2-degrees C – even if we achieve it – may be too little, too late.  We are rushing towards a planetary threshold that may be closer than the 2-degree goal we’ve already set.  If we pass through that threshold we risk unleashing cascading self-reinforcing biogeophysical feedbacks that are capable of overwhelming our best of intentions. “These feedback processes include permafrost thawing, decomposition of ocean methane hydrates, increased marine bacterial respiration, and loss of polar ice sheets” that can “amplify temperature rise through changes in ocean circulation.” If unleashed, these natural systems that have been absorbing and entrapping greenhouse gases will become the dominant processes accelerating earth systems toward the “Hothouse Earth” state.

If we have any chance to avoid overwhelming our cities, coastlines, and food systems, it will only be because we work collectively at a global level to manage earth systems for a managed stability.  They call it a “Stabilized Earth.”  That requires transformation of our socio-economic systems, behaviors, technology, innovation, governance and values that can then deliver on essentials: deep cuts in greenhouse gas emissions; protection and enhancement of biosphere carbon sinks; efforts to remove CO2 from the atmosphere; and adaptation to unavoidable climate impacts already emerging.

This Stabilized Earth scenario seems an awful lot like a Hail Mary. Depressing.

Yet here we are.

It is time to mourn.  And it is a call to action.  The next chapter for the Earth Systems is not yet written but Steffen et al just published the outline.

As a young man I attended a Hopi dance at Second Mesa.  It was a whole neighboring village in this particular dance.  At the front were the elders, or the oldest that could still dance.  And then behind in a line that circled the courtyard was the rest of the village each younger than the ones before.  The elders in the front of the line.  The coming generation at the back.

The dance was not in 4/4 time.  It was a stutter step with drums beating a sacred rhythm with certain accent beats that shifted the dancers’ pausing, stuttering promenade around and around the courtyard.

It went on and on.  That same simple dance over and over.  Finally, it broke through to me:  I was watching the dance of more than that village.  I was watching the dancing of the ancestors before and the generations to come.  In front of the elders were the ancestors.  Trialing the youngest were the generations to come. But we could not see them. They were invisible.

And I was part of that dance, too.  I, like the dancers, am part of the visible generation.  Those of us in the visible generation can and must do the ceremonies.  We can raise the next generations.  We can keep the culture alive. We can move mountains. The ancients and the next generations  are still there dancing, too, but they can only watch and guide those of us who are visible.

It is on us, the visible generation to act now. In a way, it could hardly be a more important time to be alive.

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