Scientist Suggests a Cosmic Solution to Global Warming
As An Alternative to Drastically Slashing CO2 Emissions, Nudge the Earth
The basic idea was recently suggested by Matteo Ceriotti, Lecturer in Space Systems Engineering at the University of Glasgow, and involves changing the Earth's orbit to reduce the amount of solar energy reaching its surface when the sun, billions of years in the future, becomes much hotter and expands.
While his proposal was addressed to a problem billions of years in the future when remaining on Earth would become impossible, the basic concepts of changing an object's orbit are well known; indeed, the science fiction film "The Wandering Earth," now on Netflix, dramatizes, in an unrealistic and cinematic-type way, one such attempt.
Ceriotti admits that his proposal, aimed at moving the Earth from its current orbit to one 50% further from the sun [from about 93 million miles to 139 million, a distance of 46 million], similar to Mars', while theoretically possible, is clearly not feasible with today's technology.
However, Banzhaf notes that providing a remedy for the more immediate problems of gradual global warming, on a time scale now being considered by many governments and scientific bodies, would require a much less drastic change in orbit which might in the near future become feasible, especially considering the huge costs and major modifications in life style that the alternative of reducing carbon emissions would entail.
The recent and very important UN Intergovernmental Panel on Climate Change report analyzed what will happen when the Earth gets even slightly warmer than pre-industrial levels.
The UN put the cost of a mere 1.5°C [2.7°F] increase in temperature at $54 trillion in today's dollars, while a 2.0°C [3.6°F] increase will cause $69 trillion of damage, and a 3.7°C [6.7°F] increase will cause a stunning $551 trillion in damage. To put these costs into context, the latter figure represents more than all the wealth now existing in the entire world.
According to NASA, Earth's global temperature in 2013 averaged 14.6°C [57.3°F], or 287.75 on the Kelvin scale where 0°K is absolute zero. Thus, an additional 1.5 degrees on the Celsius or Kelvin scale (the units are identical) would mean an increase in average temperature of only about 0.5% [from 287.7K to 289.2K].
Banzhaf notes that the amount of sunlight (heating energy) falling on the surface of a planet is roughly inversely proportional not to its distance from the sun, but rather to the square of its distance from the sun. Thus, moving a hypothetical planet in an orbit 50 million miles from the sun to one twice as far [100 million miles] away would cause the amount of energy falling on its surface to be only one fourth - not one half - as great.
Using these figures, it appears that it would be necessary to increase the average distance of the Earth from the sun by only about 0.3% [290,000 miles out of about 93,000,000] to reduce the heat energy equivalent which various surfaces on the planet are receiving by 1.5°C or 1.5°K.
While this represents only a very rough approximation, it does suggest that changing the orbit by this relatively tiny amount could be possible using both existing technology, and new technology likely to be discovered in a few years if such efforts can be funded by hundreds of billions of dollars.
Ceriotti and others have noted that there are many well known ways to change the orbits of bodies in space, and some have been used to help redirect interplanetary probes, as well as studied just in case it ever becomes necessary to deflect an asteroid from getting so close to the Earth as to cause serious problems.
These alternatives for changing orbits, some of which appear to be equally applicable (though on a much larger scale) to possibly nudging the Earth into a slightly more distant [by 0.3%] orbit, include:
* an electric thruster, and in particular an ion drive, which works by firing out a stream of charged particles that propel the body forward;
* using a focused light beam such as a laser to change the Earth's velocity;
* a huge solar sail floating in space near the Earth; and
* using a gravitational sling shot; a well-known technique for two bodies to exchange momentum and change their velocity with a close passage, and one used several times by spacecraft.
Some suggest that nudging large asteroids into new orbits, which could then cause a cumulative sling shot effect over many years, might be the most feasible alternative - both technologically and economically - in the near future.
Indeed, it might be possible to exploit so-called "Δv leveraging" in which a body such as a large asteroid can be nudged slightly out of its orbit and, as a result, many years later it could swing past the Earth, providing a much larger impulse to our planet.
In theory, and perhaps in practice, large asteroids could be nudged out of their current orbits and into those in a position to help sling shot Earth by techniques such as a nuclear blast on the asteroid's surface, having an unmanned spacecraft collide with an asteroid at high velocity, or a combination of both.
While Banzhaf is certainly not proposing that we abandon plans to limit greenhouse gases in favor of a cosmic nudge strategy, he does suggest that this novel idea be considered and evaluated also.