Existential Threat

An article published in Nature states that civilization is in a climate emergency that requires urgent action.

[E]vidence is mounting that [tipping points in the Earth system — such as the loss of the Amazon rainforest or the West Antarctic ice sheet —] could be more likely than was thought, have high impacts and are interconnected across different biophysical systems, potentially committing the world to long-term irreversible changes.

[T]he clearest emergency would be if we were approaching a global cascade of tipping points that led to a new, less habitable, ‘hothouse’ climate state.

[C]ascading effects might be common. Research last year analysed 30 types of regime shift spanning physical climate and ecological systems, from collapse of the West Antarctic ice sheet to a switch from rainforest to savanna. This indicated that exceeding tipping points in one system can increase the risk of crossing them in others. Such links were found for 45% of possible interactions.

Update (December 7):  Although the phrasing is disputed by some scientists, U.N. Secretary-General António Guterres warns that "the point of no return is no longer over the horizon, it is in sight and hurtling toward us".

Meanwhile, Robert Hunziker reports on research showing that melting permafrost has changed the Arctic into a net emitter of carbon dioxide.

Update (December 15):  COP25 ends with no new agreements and Greenland's ice loss is seven times as much as it was during the 1990s.

Update (December 24):  Robert Hunziker points to an article about the Amazon at a tipping point and notes that since the first of three droughts starting in 2005, the rainforest has been a net carbon emitter.

Update (December 30):  John Vidal looks back on a "lost decade" in terms of action on climate change. Also, Sarah Ruiz-Grossman and Lydia O’Connor list seven numbers (and one conclusion) to summarize the state of the climate.

The past five years were the hottest ever recorded on the planet
Four of the five largest wildfires in California history happened this decade
Six Category 5 hurricanes tore through the Atlantic region in the past four years
Arctic sea ice cover dropped about 13% this decade
Floods with a 0.1% chance of happening in any given year became a frequent occurrence
There were more than 100 “billion dollar” climate disasters, double from the decade before
Meanwhile, we pumped a record 40.5 billion tons of carbon dioxide into the air in 2019
We’re ending this decade on track to warm a catastrophic 3.2 degrees Celsius by the end of the century

Update (January 5, 2020):  David Roberts thinks we need to be honest with ourselves.

We’ve waited too long. Practically speaking, we are heading past 1.5˚C as we speak and probably past 2˚C as well. This is not a "fact" in the same way climate science deals in facts — collective human behavior is not nearly so easy to predict as biophysical cycles — but nothing we know about human history, sociology, or politics suggests that vast, screeching changes in collective direction are likely.

What bothers me about the forced optimism that has become de rigueur in climate circles is that it excludes the tragic dimension of climate change and thus robs it of some of the gravity it deserves.

That’s the thing: The story of climate change is already a tragedy. It’s sad. Really sad. People are suffering, species are dying off, entire ecosystems are being lost, and it’s inevitably going to get worse. We are in the midst of making the earth a simpler, cruder, less hospitable place, not only for ourselves but for all the kaleidoscopic varieties of life that evolved here in a relatively stable climate.

To really grapple with climate change, we have to understand it, and more than that, take it on board emotionally. That can be an uncomfortable, even brutal process, because the truth is that we have screwed around, and are screwing around, and with each passing day we lock in more irreversible changes and more suffering. The consequences are difficult to reckon with and the moral responsibility is terrible to bear, but we will never work through all those emotions and reactions if we can’t talk about it, if we’re only allowed chipper talk about what’s still possible in climate models.

Exceeding one [temperature threshold] does not in any way reduce the moral and political imperative to stay beneath the next. If anything, the need to mobilize against climate change only becomes greater with every new increment of heat, because the potential stakes grow larger.

[I]t should mean getting serious about adaptation, i.e., preparing communities for, and helping them through, the changes that are now inevitable.

[S]hrinking of empathy is arguably the greatest danger facing the human species, the biggest barrier to the collective action necessary to save ourselves. I can’t help but think that the first step in defending and expanding that empathy is reckoning squarely with how much damage we’ve already done and are likely to do, working through the guilt and grief, and resolving to minimize the suffering to come.