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Very generally, we are adapted to the climate we have. In the short term, almost any change has associated costs. If two regions with different climates simply swapped their climates, for example, both would have wrong-sized air conditioners and heaters, too many or too few snow plows and swimming pools, less-than-optimal seeds for crops, etc. All of these can be fixed, but not for free.
If changes remain small, there are likely to be winners and losers. Warming may make beach resorts happier, but ski areas less happy. Rare and endangered species, and people trying to live traditional lifestyles, may be pushed to the edge by even small changes. For most people, if you have winter that interferes with travel and other activities, air conditioners so you can work in the summer, and bulldozers to build walls against the rising sea, a little warming is not especially costly; if you lack winter, air conditioners and bulldozers, even a little warming is likely to make your life at least a little harder.
But, if the temperature continues to rise, and the big hotter-than-we-like belt around the equator expands towards the poles, life is projected to get harder for most people in most places.
There are real uncertainties, so things really may end up better than this. But recall that, because breaking is easier than building, we don’t see how raising CO2 greatly and rapidly will create Eden, but we do see at least a slight chance of huge and damaging changes.
Video: Reducing Risks of Climate Change Damage (2:59)
DR. RICHARD ALLEY: This is a fascinating figure from the IPCC. This is actually from the 2001 report. So this one goes back a little farther.
This part is CO2. And, actually, it's more CO2 as you move towards the left here. And that gives you more warming.
So this is how much warming you get for various possible futures. So far we're tracking on the high end. But we're really not sure where we'll end up in the long term.
And each of these over here, as we release more CO2, by late in the century, we get more warming. And so you can take the warming that you think we'll find and you can draw a line across. Maybe you think we're going to get three Celsius, because we're on the high end of the emissions. And so you draw the line across there.
Then what you see are various columns over here. So example one here is unique and threatened systems such as species extinction. If you are a rare and endangered species living in a little national park and now you need to migrate and there's cornfields in the way, even a little bit of warming is pretty bad for you.
And so you'll notice, this is going from orange up to red or into a more saturated color very, very quickly. Because even a little bit of warming causes a lot of trouble for unique and threatened systems.
If you're worried about when do we get more floods and more droughts, it doesn't take a lot of warming before you start getting to more floods and more droughts. And we'll be well into that before the end of the century. We're already seeing some of that now.
In some areas, poor people in hot places are already hurting now. Rich people in cold places-- it'll take more warming before they really get into trouble.
And because so much of the Earth's economy is in the rich people in cold places, you don't really worry about them until you get a good bit of warming. And this sort of, we killed the North Atlantic or dump the antarctic ice sheet, it takes a lot of warming until we get there.
And so in terms of the question, how much warming before we get into trouble, that bothers a lot of people, it depends what you're talking about. And for unique and threatened systems, for rare and endangered species, we're already pushing them hard, as well as for poor people in hot places.
The world's economy is not yet suffering hugely. But as the warming increases, it will tend to suffer more.
And the basic picture-- each degree of warming costs more than the previous degree and that the first degree didn't hurt a huge amount, because it's really only hurting the rare things and it's not hurting the economy. At some point, it starts to hurt the economy, too.
One way to look at the future is shown in the figure. Different things you might care about are shown by the different columns, and the risks from warming are shown by the increasingly orange-red (saturated) color going up in the columns. Another way to look at the issue is that damages are projected to go up faster than temperature; the first degree of warming is nearly free, but each degree beyond that costs more than the previous one did. The first degree has allowed us to test our models and learn that they are doing well; the next degrees really matter.
Please recognize that these projections do not include major human efforts to reduce emissions of CO2 and other greenhouse gases. And, we are certainly capable of making such reductions, or of adopting other approaches that might reduce the warming while supplying plenty of energy.
So, in the next Unit, we’ll look at some of the options. Then, we’ll return to Economics, Ethics and Policies that might address the paired issues of getting valuable energy for many people while reducing damages from climate change.
Activate Your Learning
The costs or benefits of changing climate depend on how much the climate changes. If the amount of change remains small, say 1˚C or so, who is likely to be most negatively impacted?
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