The IPCC is not perfect, but they are not being dismissive of anything and to act like you know something they don't is downright laughable.
You can laugh if you want. It wouldn't be the first time in the history of science that the consensus is wrong.
I want to make clear that I have great respect for everyone who have dedicated their lives to understand the climate and how humans fit in it. They are true experts and their strict knowledge is a extremely valuable asset of mankind. Their work is great and if we can save ourselves from climate change it will be in large part for the work people like the ones at the IPCC have done warning us about climate change. Even then, they are wrong about the risks of climate change.
I don't think the IPCC is wrong because they are lying or because their data is faulty. They are wrong because they are not framing the problem correctly. For example humanity. The IPCC takes human population for granted, yet the data says we are a fluke. What we have seems permanent but it is unique and new. The kind of climate change we have unleashed is also new and unique, because as far as I know, this much CO2 has never been emitted this fast.
Another example, methane. I don't think methane will be our killer. The complete loss of ASI during summer will be.
If the reaction to the loss of ASI is more warming then GHG's will be released from all available sources at rates proportional to the additional warming. That's on top of human induced warming. However, at that point warming will be the least of our problems. Weather chaos caused by the destabilization of the oceanic and atmospheric currents will end humanity as we know it, specially with leadership with blinders on. Plenty of people will survive this. My bet is more than the average human population over the last ten thousand years, probably even a billion in places with good governance and climate luck.
If the reaction to the loss of ASI is cooling (a very possible event) then I just hope there is enough time to evacuate the north hemisphere. It will be buried by snow for the rest of our existence. Methane will be safe and sound for 130k years during the next glacial period (give or take a few millennia) until the next interglacial. It will eventually become a fossil fuel. Hopefully the next species that learns how to use it learns about our mistakes before it is too late for them.
Or maybe the reaction is both. Very hot during summer in the North Hemisphere, periodically unlivable. Very snowy after equinox and after the summer heat is dissipated into space, the ocean
the permafrost and snow.
The 2015-2018 global heat spike gave us just a preview of what happens as the Arctic melts. The hurricanes, the fires, the floods, the droughts, the heat waves were not coincidence.
There is no way to overstate the risks. What risk we face? We risk losing everything. The likelihood of such event? Given the known unknowns, way too high. Given the historical human population way too high. Given the association of warming with mass extinction events, way too high. Given the association of recent warming and natural disasters, way too high. Given the resistance to do something about climate change, way too high.