AS AN ENGINEER it has eluded me for years how to translate the picture of a blanket of carbon dioxide around the globe to something more susceptable to visualizing and understanding what is really happening.
The "blanket" around the spherical globe is really composed of many rivers, complex flows that determine the climate.
It is possible to concieve of the blanket not as many rivers but as a single infinite river, for the spherical blanket is indeed infinite. A single river, coming into equalibrium with the planet over eons is easier to visualize. It widens and narrows, has large still pools and running rapids, tributories and drainage but over time has setteled into an equalibrium that we once could count on to stay within certain boundaries.
However, first with the beginning of agriculture perhaps 10,000 years ago, mankind began contribution small additional amounts of carbon dioxide. However, this amount was negligable until about 1860 with the industrial revolution and the introduction of fossil fueled steam power.
Fossil fuel burning grew enormously in importance from that time until today and carbon dioxide, that began at an average value of about 240 ppm has now grown to over 410 ppm, so the river has become about 70% larger.
However, it is not the size of the river that matters but the size of the disturbances it creates as it flows through space and time. It interacts in different ways in different places with highy concentrated effects in some places, and nearly none at others.
However when it does interact, the results are usually catastrophic in drought, storm intensity, unpredictability of flow, floods, and, of course melting at the poles and sizzling heat in places already very warm.
It is not just the sum total of all the effects that is most worrisome, but the potential of the larger river triggering self-reinforcing warming for example by melting the tundra and releasing methane, a far more powerful greenhouse gas.
But that is still not the whole story.
The further down the river we go, the less we can predict its behavoir, and so we face something I (astonishingly) rarely hear discussed and that is risk management.
Some risks are manageable, perhaps a power outage. Others such as flames from an engine on an airliner at 35,000 are not. You would likely recover from the first. The second could be terminal. So the question for the earth is weather there is a possibility for a "terminal" scenerio, and the answer is simply yes. Why? Simply because there is no way of positing an absolutely definite no. The climate process is not predictable and it is possible to envision catastrophic mechanisms coming into play.
WHEN YOU ARE DEALING WITH YOUR ONLY PLANET you have to do everything possible to avoid the engine fire at 35,000 feet, even if it should cost trillions of dollars. My own eyes (and those of Microsoft Excel) see "exponential" in NASA temperature data.
However, I have not seen "planetary" listings in the realestate section of my local paper.