SkS Analogy 19 - A table full of crystal and ideal temperature
Tag Line
A table stacked high with delicate crystal is beautiful to look at, but impossible to move without significant breakage.
Elevator Statement
Stack crystal plates, bowls, glasses, and figurines on top of each other on a table. Done by a skilled artist it is a pleasure to look at. But try to move this delicate work of art from one place to another. The faster you move it the more damage there will be. The more crystal that is placed on the table and the higher it is stacked, the more precarious it is to keep balanced, and the more breakage occurs if the table is moved.
If the table had been placed at a different location before stacking the crystal, it could have been filled with the same crystal and created a similar, beautiful masterpiece at a different location. But stacking the table full of crystal and then moving it to a new place causes significant breakage.
So it is when we populate Earth with 8 billion beautiful people, inhabiting all of the available habitable zones, and then alter the location of the habitable zones through rapid changes in temperature, precipitation, and storms. Increasing the average temperature of the earth is not so much the problem as is the rate at which we are changing the temperature. The faster we raise the temperature, the faster climate changes, the quicker that habitable zones move, and the less time there is to adapt (i.e., move from one habitable zone to another).
Some ask rhetorically what Earth’s ideal temperature is. This is like asking what a table’s ideal location is. Damage occurs to the crystal on a table not because it is or is not in the ideal location, but because the table is moved after it is fully loaded with delicate crystal.
To minimize breakage, a table stacked high with crystal must either be moved extremely slowly, or left in its current location.
Climate Science
The current climate is the one to which humans have adapted themselves for the past 7000 years. This period has been marked by unusual stability of global temperature and sea level (Hansen and Sato, 2011). The climate during which human civilization developed is not necessarily the “best” nor “ideal” climate for human civilization to flourish: it is simply the one nature handed us at the end of the last glacial cycle and the one on which we built our cities and ports, carved out agriculture, established protected forests ... We settled down from our early life as nomadic bands of people. We should not assume that this stability will endure arbitrary pressure from 8 billion people.
A few of the critical factors for civilization to flourish are
- Stable sea level for international commerce to be driven by ocean-going vessels traveling from the shores of one country to the shores of another.
- Severe weather limited in scope and duration so as not to disrupt too much of earth’s societies at one time. This allows the unaffected to offer assistance to the affected.
- Stable temperature, hydrology, nutrients, and populations of pollinating insects for successful agriculture.
During 100,000-year glacial cycles global average temperature varies by 5°C and sea level varies by 120m. During the last 2000 years, up to the start of the industrial revolution sea level varied by less than 0.5m. In geological terms a variation of 0.5m is remarkably stable.
International commerce has benefited from stable sea level. Since the start of the Industrial Revolution Earth has warmed by 1°C. The goal of the 2015 Paris Accord is to keep warming to less than 2°C. Although there is much debate about the magnitude and speed of future sea level rise, because there is about 66m of sea-level rise locked up in the world's ice, and because we've built settlements right up to edge of the oceans, even a "modest" sea level rise of 1m by 2100 will cause enormous problems and require expensive adaptation. And sea level will continue to rise after 2100. What impact will this sea-level rise have on international commerce? We can build floating harbors, but adaptation to continuously rising seas will be expensive.
How many days of freezing weather, how many hail storms, or how many floods are required to kill a crop? Successful agriculture requires fairly benign conditions over an entire growing season, meaning the temperature must remain in a relatively narrow range, hydrology must remain in a stable range, and there must be pollinators. How will the changing climate affect the preconditions for successful agriculture?
In the best case, the loss of agricultural productivity in one zone will be offset by a corresponding increase in productivity in another zone. Even in this “best case” scenario, however, if national borders separate these offsetting zones, movement of people from one zone to another will likely imply significant social disturbance, and with it, human suffering. Few people or organizations freely give up their “gains” to offset the “losses” of others.
In the worst case, in addition to shifting zones of acceptable habitation and agriculture, we will suffer a net global decline in fertile agriculture zones, causing suffering beyond the confines of the locations where the redistribution is occurring. The Russian drought of 2010 caused Russia to ban grain exports. When such a ban occurs, as a minimum, countries depending on grain imports would likely see price increases and food shortages. But the effects could be much more severe as people struggle to feed themselves and their families.
Just as rapidly moving a table stacked with crystal will cause much damage, rapidly increasing temperature through greenhouse gas emissions will cause much damage to human civilization.
Hang on, “It’s going to be a bumpy ride.”1
Footnotes
1. Reference to statement made by talking head in the movie "Harry Potter and the prisoner of Azkaban."
References
James E. Hansen and Makiko Sato (2011), Earth's Climate History: Implications for Tomorrow, NASA Science Briefs.
Posted by Evan on Thursday, 7 March, 2019
