Once the permafrost starts to melt, it will cause a positive feedback loop causing all trapped methane to rapidly be released, doubling the amount of greenhouse gases in our atmosphere. It's literally a ticking bomb. I worry about it.

This just in: permafrost has already been melting for a little while now.

Nice nitpick. I am of course referring to the fact that the ongoing melting of the permafrost will soon reach a point where methane will start to be released on a terrifying scale.

But then again, methane has a short half life in the atmosphere.

then again, this is not a process that can be stopped once started and there more than enough methane to have dramatic consequences.

then again this is one reinforcing feedback loop among several others.

Are you familiar with the concept of planet albedo, and how it is changing on earth due to melting polar cap? Ever heard of ocean's anoxic events and their consequences ?

And the list goes on.

Yes yes

The reason I'm citing this is not because I think we shouldn't worry, but because if the methane is released (and this depends on the release speed as well) we might have a period with an atmosphere with high concentrations of methane, then a sudden reduction.

Runaway greenhouse gas concentrations and higher temperature might trigger (the reason being we know some things, but we don't know everything) a runaway CO2 capture process. It sounds SciFi, and it probably is, and it seems Nitrogen is a limiting factor. But I wouldn't say it is impossible. Or it could be possible with human help.

Then at the end of this period we could end up with less CO2 in the atmosphere, with oil running out and the clathrates emptied.

Yes, it's hard to know. But pushing too hard on extreme projections is too easily gamed by deniers.

Sure, but there's a lot of it there.

And even after it's 'short life', it just breaks down into a less potent greenhouse gas.

Yes, there's that too :(

Most of the worlds largest cities are near the coasts. And weather systems hundreds of km from coastal areas are still affected by things like ocean currents that affect the temperature. E.g. weather in large parts of North Western Europe is substantially warmer than you'd expect because of this.

So on one hand expect large scale migrations and/or massively expensive programs to mitigate the problems. On the other hand expect far more extreme weather far inland.

The idea it will only affect coastal cities is a dangerous one.

>Most of the worlds largest cities are near the coasts.

There are some cities (New Orleans, Venice, Boston to an extent, to name a few), which are highly vulnerable to sea level rise, but most coastal cities are at high enough elevation that a sea level rise of a few meters wouldn't be the end of the world - it would require better levees, dikes, etc.

Contrast with such risks as increased capability of biological warfare, the persistent risk of nuclear warfare, or, ecologically, declining natural forestation and vegetation due to heavy use of land for cultivated agriculture.

As for extreme weather, it's not like the Earth naturally has less extreme weather at colder temperatures. Warmer temperatures will cause changes in weather patterns, and some places are getting more extreme weather than before, but there is no reason it will be net worse for the whole world.

Not that simple. It's not just about managing a few meters, but managing a few meters increase in worst case. E.g for London a few meters is a minor problem in normal situations, but a few meters in worst case situations have potentially dramatic impact on costs to upgrade the Thames Barrier, and will have dramatic impact in terms of how large areas downstream of London will get flooded if the Thames Barrier needs to be closed.

A lot of cities face issues with follow on effects like that.

It won't be 'the end of the world' if its just a few meters, but it is still enough that cities like London face multi billion flood defence upgrades, and towns housing hundreds of thousands will face increased flood risks as a consequence of anything done to upgrade the defences.

And you're severely underestimating the direct damage. Many of the highest population density areas in the world are at risk,and many of the areas at worst risk are also among the poorest, like Bangladesh.

As for extreme weather, yes indications are that we're heading for more overall extreme weather, not just changes.

There’s a lot of money to be made by government contractors who are prepared.

The problem is how quickly and where to people from costal areas will relocate. And how new climate will affect food production.

Try not living in the past and regurgitating media nonsense. Global warming is what global media uses to brainwash people away from the problem. Climate change is the real thing and real deal.

Inform yourself and learn that one of the current issue we face is a continental increase of temperature and shift inseason that would make agriculture impossible in about 50 years.

There are reinforcing feedback loops that will push the change past a threshold where cascading effects would make life on earth surface near impossible.

Life on earth is a complex interdependent system and the larger animals are the first to go, guess what's next now that elephants, whales, tigers, and pretty much every animal larger than humans is on the brink of extinction.

It won't make life on earth's surface impossible. At worst everything largish (plus some other stuff) will die off and open up the environment to new life (maybe a new cephalopod world order?). Remember, all of this CO2 was once in the atmosphere during the carboniferous and other periods. Nature doesn't give a damn about us and will just roll with the punches we're throwing and crush us like it has other times when life totally fucked the environment up.

On the contrary, agricultural output goes up with increasing temperature.