Written by Sig Silber
An article entitled Hundred-Year Forecast: Drought recently appeared in the New York Times.
But droughts do not usually come with 100 year durations and I realize this is not exactly what the author was saying. Titles are often created by the editor rather than the author(s) and can be misleading.
If you take a group of climate cycles with different wave lengths and amplitudes and superimpose them, you get a pattern with large variations over time. Thus we can experience long periods of above average or below average temperature or precipitation, all part of the patterns that one expects to see. Those working with economic cycles have been dealing with this phenomenon for a very long time.
But what we have now is a grand experiment – adding greenhouse gases (GHGs) to the atmosphere. We have a good idea of the impact on secular temperature trends (and hence evaporation) and some idea about precipitation, but with a lot more uncertainty there. What does not seem to be well understood is how warming and more water vapor in the atmosphere impacts the various climate cycles. Are they unaffected (i.e. they are additive to the climate change secular trend)? Are they enhanced? Are they dampened? Is their duration changed and is the geographical area where they have an impact changed? Is the interaction among climate cycles changed?
On a worldwide basis, it can be dry in some places and wet in other places. Ocean evaporation does not stop. When air temperatures are warmer, you get more ocean evaporation and it can’t all just “stay up there”. If you read the IPCC reports you will notice that they project a wetter planet. I think the formula is one degree Centigrade translates into a 7% increase in the intensity of extreme precipitation events and a 2% increase in average precipitation. That does not tell us about the distribution of precipitation over a year or the distribution of distribution over the planet; But there will be more precipitation on a global basis – and more evaporation. So net water availability is a big issue.
Those who have an interest in this topic might have some fun playing around with this – http://www.climatewizard.org/
You may have to play around with it a bit (and check the right boxes) to have it show
A. Precipitation measurement
B. Global analysis area
Then pick any of the IPCC scenarios and time frames.
You will see that a lot of the World will have more precipitation. Some important areas will have have less and that is of significant concern. We will also definitely have more evaporation so the amount of water we have to work with is another story. That is the big issue for parts of the US where the net impact is projected to be negative.
Going the next step to project geopolitical and economic impacts is another layer of complexity. It is fairly unlikely that we will have both less water and more people in large areas. But it could happen. That could result in transfering more and more water out of agriculture into cities. But food has to be grown somewhere. As the size of the area projected to have less usable water to work with increases, I suspect that it is less likely that such an area will experience population increases.
Perhaps humans will evolve into smaller people. In the early Eocene, I think rat-sized was the optimum for mammals. A change in that direction might solve a lot of problems and may be how nature adapts. More likely, though, given the rapid rate of climate change, people will be forced to migrate.
Historically, migrations have not occurred peacefully. And economic activity shifting from one place to another causes economic imbalances. So it is likely to be a messy process. I think there will be winners and losers but some think even expressing that thought is inappropriate.
Time will tell.
I am fairly certain that our (the world’s not the U.S. alone) level of greenhouse gas emissions is not going to be reduced any time soon and probably will increase. I think the concept that people in developed nations are willing to give up even 10% of their current standard of living for the benefit of future generations is unrealistic. And the idea that those currently living at close to subsistence levels in developing nations are not going to seize their opportunity to try to achieve developed nation living standards is also unrealistic.
I do not believe that sustainability is programmed into the genetic structure of animals. Adaptation is. So it is probably more useful to focus on adaptation than bemoan the shortsightedness and villainy of others. Adaptation can be attempted on an individual basis and by small groups. Global sustainability requires large-scale cooperation and is unlikely to be achieved, especially if sustainability is defined as sustaining the status quo. It is a quaint and perhaps charming concept but not very realistic. And of course focusing on achieving sustainability delays adaptation.
Editor’s Note: Sig has a unique way of letting readers know about his posts. The following table conveys how this author wants a reader to process.
|Interpretation Key for this Post|
|Humor||No (except for the Eocene reference which actually may have some validity)|
|Criticism||Yes – NYT was sloppy in their choice of title for that article|
|Request for Action||Yes – Plan for adaptation|