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Can someone ELI5 arctic tipping points or how close we are to runaway climate change?
As the various Arctic climate feedbacks show, we are fast approaching the stage when climate change will be playing the tune for us while we stand by and watch helplessly, with our reductions in CO2 emissions having no effect in the face of, say, runaway emissions of methane.
from this article: https://e360.yale.edu/features/as_arctic_ocean_ice_disappears_global_climate_impacts_intensify_wadhams
https://en.wikipedia.org/wiki/Atmospheric_methane
So methane is a very potent greenhouse gas, but it's also a quite unstable molecule, so it decays (to CO2 and water vapor) after a relatively short time.
This means human-caused release of methane (including the much-joked-about cow farts) does contribute to climate change, but in a way that if we got our act together and cut down emissions, the effects of it would go away within a decade or so.
The problem is that there are other, not human-caused (at least not directly) sources of methane emissions. The most notable of these is methane clathrate.
It's a form of methane that is a solid, like ice, but only underwater under extreme pressure. Here's the phase diagram, but that pushes the limits of "ELI5". This is the part of chemistry where our intuitive understanding of how substances behave breaks down, because it's based on atmospheric pressure and room temperature.
So you have a deposit of methane clathrate on the seafloor. If you heat the ocean up a little bit, that may "melt" this ice, causing it to bubble to the surface and into the atmosphere. That causes a little bit of global warming, enough to heat up the ocean a bit more, and cause a bit more clathrate to melt. This is a positive feedback loop.
Meanwhile, there are also methane deposits in Artic permafrost. A very similar feedback loop can occur. Bit of permafrost melts, releases methane, that causes a bit more warming, which melts a bit more permafrost.
Taken together, this has been called the "methane gun".
How close are we / is it happening already? It's really tough to say, but my suspicion is that yes, we're already in such a runaway feedback loop (or if we're not, we already have enough warming baked in from "normal" CO2 emissions that we will trigger the feedback loop within 50-100 years).
If we were in such a feedback loop, the evidence we would see would be unexplained methane releases observed from the ocean and sinkholes and craters in Artic permafrost.
thanks for the informative comment.
If I may ask, are you scared of what the future may hold?