This isn’t likely to be a problem for a while, because of the carbon dioxide we’ve already dumped into the atmosphere and how much more we’ll continue to for the time being. But if civilization continues I’m sure that by a century from now we will no longer be dependent on fossil fuels. At that point we’ll presumably have the ability to regulate the total concentration of carbon dioxide in the atmosphere, and thus the average global temperature. But what should it be? By the year 2113 the people of Russia and Canada may be quite happy with how long their wheat growing season is, and being able to navigate freely through the Arctic Ocean. Would they actually protest restoring the Earth to its “natural” temperature? What is its natural temperature- how much CO2 was in the atmosphere before 1700? Before then Europe and North America were in what climatologists call the Little Ice Age. IS there a “right” temperature for the planet to be?
There’s no one real “right” temperature. The immediate problem though isn’t the temperature so much as the effects of its changing; whatever the endpoint is, the change is going to cause a lot of hardship and probably death, and kill off quite a few species.
And of course there’s the question of what the future climate will actually be like; we’ve never existed in a climate as warm as what we’re heading towards, and can only guess at what’ll be like. For example, for all we know it may not be amenable to agriculture; it might produce too many powerful storms and too much unpredictable weather. Obviously if we can’t feed ourselves we’ll want to cool the world back down if we can. Or if for example the “hypercane” scenario turns out to be true and we start seeing continental scale hurricanes.
Although it seems likely that we won’t be able to. From what I’ve heard over the years once we transition to a warmer climate it should be a stable situation lasting for millions of years. It’ll be much harder to change back than it was to get there.
Well, at least Greenland will be lovely.
Science Writer Peter Hadfield on the warming seen in the past in norther Europe and Greenland.
Back in the medieval warm period America got so much drier that experts called the conditions then a mega drought, so much for the grain belt.
The rest of the world does not live in Greenland, Canada or Russia, and as I observed before there is going to be a wild period of weather before it settles into something more predictable, and unless the usual nationalistic tendencies are not reduced it is not unreasonable to expect many to suffer as they can not move to those new nice weather locations.
Do your sources for this believe it to be true because we won’t be able to significantly lower GHG concentrations, or that doing so would be ineffective (because of some other feedbacks that would be slow to undo: changed albedo from melted glaciers, for example)?
How about, roughly what it’s been over the last 10 000 years, so we can plausibly maintain our agricultural economies?
IIRC (it’s been a long time) it’s because heating up the world would move it out of the present Ice Age (we are still in an Ice Age, just an interglacial period) into one of the warmer periods which are the historical norm.
That covers a lot of temperature range. Even in the last 2500 years it’s varied a lot. It wasn’t until 1980 for example that average temperatures exceeded the Medieval Warm Period. In the last 10,000 years it’s varied even more: Holocene climatic optimum - Wikipedia
And? Why couldn’t we reverse the process and move back into an interglacial?
No.
There is a temperature that is best for 21st Century humans to live in. Generally, it’s the same temperature that supported the build up to our current technology/lifestyle. What needs to be avoided is not a particular temperature (given a reasonable range, of course) but rapid changes to temperature.
Changes that occur over a 50-100 year period are going to cause problems vastly different than changes that occur over 500-1000 years.
There is no “right” answer, but IMHO this is the “best” answer. Rapid change is hell on economies.
Yes, it’s a wide range, but it’s a very narrow range and a remarkably stable climate compared to what preceded it.
I think it was Guns, Germs, and Steel where I first saw the argument that agriculture developed in this period because of it’s unusual stability and moderateness. It’s quite possible that without a widely and quickly varying climate in preceding eras, humans might not have evolved at all: brains adapt more quickly to changing challenges than genomes do. But while we may have had the brains to develop agriculture for over 50K years, we didn’t have a stable enough climate for it to work long enough to matter.
In any case, eventually we’ll have technological tools to tweak the climate. (We may already – e.g., Dubner’s garden-hose piping sulfur to the upper atmosphere.) When we do, it’ll be a very hot international topic: who benefits? What do we optimize for? Preservation of the recent climate will be the default, but of course that will be challenged.
Obviously the optimal range for humans is what’s occurred, without the extremes for the last 10,000 years, since that’s one of the large factors that have allowed us to spread across the globe, to thrive and to massively accelerate our civilization.
The issue with the current global warming isn’t so much the warming itself, it’s the rapidity of climate change that could lead to such potential harm. The current warming, even the projected warming are all within the normal variation (i.e. in the past it’s been just as warm or warmer on earth as it is today or even as it’s projected to be with global warming), but it’s the speed of that change that is unprecedented and potentially disastrous.
Should be for what? Human civilization? Like I said above, for us I’d guess that, leaving aside some of the extremes and outliers, the temperature variation we have experienced in the last 10,000 years seems to be optimal for us.
You’d need to think about what qualifiers you want to put with this or the question makes no sense. The planet itself doesn’t care what the temperature is. From the Earths perspective it’s gone from molten lakes of liquid rock to a snowball Earth, from an atmosphere of almost pure carbon dioxide to one much richer in oxygen than today’s Earth. So, there IS no ‘right’ temp for the Earth.
Unfortunately, the rapid change is the one thing we won’t be able to do anything about. It’s happening already, and would continue to happen even if we completely stopped emitting CO2 today. The best that can reasonably be hoped for is that within a century or so we’ll stop making things worse.
There is no right temperature, the problem is the pollution and the speed of increase.
Remember that old song of the little girl claiming that “everything you can do I can do better”?
Imagine that this is about making it even worse, we have to do more and soon to prevent even more dire scenarios.
http://thinkprogress.org/romm/2010/12/25/207242/the-ghost-of-climate-yet-to-come/
Actually that would help the Northern lands. Canada would become more productive.
Africa on the other hand is always going to suck because of tectonic movement of the Himalayas. As they move upward it affects the weather patterns east of them.
I don’t think agriculture is the real concern. It’s the loss of land due to rising oceans.
On the other hand there’s speculation that Europe may get quite a bit colder due to disruptions in ocean currents. And in both cases they’ll be dealing with a major die-off of their wildlife that can’t adapt fast enough.
correction, I should have said WEST of the Himalayas. As the mountain range moves upwards, it has slowly affected the arid lands of Africa.
While that might be true I would think losing land would be the biggest short term problem.
Personally I think the transition to lower co2 emmissions will naturally lesson the problem but if push comes to shove we could add high altitude screening to lower the temperature. No country wants to lose massive amounts of productive land.
If you can think of a solution that doesn’t involve dismantling industrial civilization, or passing global sumptuary laws, I’d like to hear it.
Remember that the whole Pleistocene cooling is something of an aberration, against the backdrop of a steadily warming Sun. There are feedback loops with very long time delays. Glaciers are slow to melt … but they will also be vary slow to reform.
Is it even understood what caused the Pleistocene cooling? I’ve heard that the closing of the Panama Isthmus had something to do with it.
(BTW, it will be straightforward for man to add cooling pollutants to the atmosphere, and I think he will do so when the adverse consequences of warming become clear. Unfortunately, this will not solve all habitat degradation problems.)