There has been discussions of some risk factors related to an eventual collapse of modern civilization. Describe modern civilization from a Jared...

Most of the factors that Jared Diamond argues cause the collapse of civilizations involve ecology. I should note that this theory is controversial; many historians believe that other causes (such as outside invasion or failed political institutions) are more important than ecological sustainability in explaining civilizational collapse.

But given Diamond's theory, there are five things to worry about:
1. climate change
2. hostile neighbors
3. collapse of essential trading partners
4. environmental problems
5. failure to adapt to environmental problems

On a global scale, hostile neighbors and trading partners are irrelevant (unless we suffer alien invasion or colonize other planets I suppose).

So that leaves only environmental problems and our ability to adapt to them. Is there reason to be concerned about this? Yes, there is.

The Intergovernmental Panel on Climate Change releases a report every year about just how bad global climate change is getting, and how much we are contributing to it by our emissions of carbon dioxide and methane; and the results are rarely encouraging. The worst-case scenario estimates for what climate change will do to human society involve hundreds of millions of deaths, which is probably not enough to cause a total collapse of modern civilization, but would still literally be the worst thing that ever happened in human history.

Diamond characterizes the problem of warfare as "hostile neighbors", but internal war might actually be more important for civilizational collapse, and on a global scale all wars are internal. If the rush for scarce resources caused by climate change (such as oil or fresh water) triggers a nuclear war, that is a terrifyingly realistic scenario for total collapse of modern civilization.

The good news is there is a lot we can do about it, and much of this is already being done.

First, we can disarm nuclear weapons; that should probably be our top priority, because nuclear weapons are the number 1 way human civilization is most likely to destroy itself. Most political scientists believe this will only work if done multilaterally; personally I believe that there are ways to make a unilateral strategy effective by establishing a conventional deterrent that would punish the use of nuclear weapons without destroying entire cities.

Second, we can do a great deal to reduce the effects of climate change. Switching our power grid from coal and oil to nuclear and solar would dramatically reduce our greenhouse emissions, as would switching from private gasoline cars to electric public transit. Changes in farming practices---and a reduction in meat consumption, perhaps as a result of a steep tax on meat---would reduce methane emissions and deforestation. A carbon tax or cap-and-trade system is a good way to leverage market forces to reduce emissions without heavy-handed intervention.

There are also ways we can adapt to climate problems (Diamond's number 5), involving either geoengineering to halt the effects of climate change, physical infrastructure such as dikes and levees to hold back rising sea levels, and social programs such as refugee relocation to save people from regions that get destroyed by hurricanes, dried into deserts, or reclaimed by the oceans.

Are we doing enough of these things? Probably not. But we are doing some of them, and with enough public understanding and support we can do more. Even in the last few years there has been a significant shift in international policy toward reduced carbon emissions and better sustainability policies; if this trend continues we might be able to avoid that worst-case scenario after all.

Let's hope so; the stakes could hardly be any higher.