2 ms·

The total mass of all cars in the world is on the order of 2e12 kilograms. Since most routes cancel, drop that by an order of magnitude or two. The mass of the

The total mass of all cars in the world is on the order of 2e12 kilograms. Since most routes cancel, drop that by an order of magnitude or two. The mass of the ice melting just from Greenland in a year is 2e14 kilograms. (Edit: the car mass number was 1e3 too small, thanks to mikeash for correction.) Edit2: the car mass number was right, but both numbers should have been in tonnes. Now it's right. I should sleep now.

mikeash 11y ago
There are about 1e9 cars in the world. Your 2e9kg figure is off by about three orders or magnitude.
- semi-extrinsic 11y ago
  Ah, crap, you're right.
mturmon 11y ago
As another data point, the annual groundwater withdrawal from the Colorado river basin is estimated at 5.6 km^3/year over 2004-2013. (http://onlinelibrary.wiley.com/doi/10.1002/2014GL061055/abstract http://onlinelibrary.wiley.com/doi/10.1002/2014GL061055/abst...) Since 1m^3 is 1000 kg, that's 5.6e12 kg/year in that one basin. The above groundwater figure (and other water-related quantities, like snowpack and reservoir storage) are pretty much at the edge of what can be detected by current gravity-based techniques using GRACE (https://en.wikipedia.org/wiki/Gravity_Recovery_and_Climate_Experiment#Discoveries_and_applications https://en.wikipedia.org/wiki/Gravity_Recovery_and_Climate_E...). Figure 2 in the linked paper (if you have access) shows a nice sinusoidal-like graph of mass in the Colorado basin over this time period. It's a monthly measurement, so daily mass flows like cars would not be present (even if the measurement were precise enough to get at them).
semi-extrinsic 11y ago
So this is quite interesting: could it be that the total volume of ore excavated per year is comparable to the total volume of new seawater from melting ice? It looks like 5e13 kilograms of ore are excavated per year [1]. At an average density of <5 kg/l, that is the same volume as 1e13 kg of water, or 1/20 times the meltwater from Greenland. No solution to rising oceans :( [1] http://www.ilocis.org/documents/chpt74e.htm http://www.ilocis.org/documents/chpt74e.htm
- mturmon 11y ago
  OK, I read this and I had some disbelief. It starts with a total of 23 billion tonnes of ore, and ends with a volume equivalent to 1.5 meters of the whole country of Switzerland being excavated per year. That seemed high, but it turns out that independent estimates of just coal excavation are 8 billion tonnes per year. So my disbelief was wrong. And then, looking at it the other way, this makes it evident how much burning all that coal could change global CO2.
mc32 11y ago
Thanks for the quick napkin math. Great to see it distilled for easy comparison, however, wouldn't glacial melt also be characterized by some cancelling out effect?

mikeash 11y ago

There are about 1e9 cars in the world. Your 2e9kg figure is off by about three orders or magnitude.

semi-extrinsic 11y ago
Ah, crap, you're right.

mturmon 11y ago

As another data point, the annual groundwater withdrawal from the Colorado river basin is estimated at 5.6 km^3/year over 2004-2013. (http://onlinelibrary.wiley.com/doi/10.1002/2014GL061055/abstract http://onlinelibrary.wiley.com/doi/10.1002/2014GL061055/abst...) Since 1m^3 is 1000 kg, that's 5.6e12 kg/year in that one basin. The above groundwater figure (and other water-related quantities, like snowpack and reservoir storage) are pretty much at the edge of what can be detected by current gravity-based techniques using GRACE (https://en.wikipedia.org/wiki/Gravity_Recovery_and_Climate_Experiment#Discoveries_and_applications https://en.wikipedia.org/wiki/Gravity_Recovery_and_Climate_E...). Figure 2 in the linked paper (if you have access) shows a nice sinusoidal-like graph of mass in the Colorado basin over this time period. It's a monthly measurement, so daily mass flows like cars would not be present (even if the measurement were precise enough to get at them).

semi-extrinsic 11y ago

So this is quite interesting: could it be that the total volume of ore excavated per year is comparable to the total volume of new seawater from melting ice? It looks like 5e13 kilograms of ore are excavated per year [1]. At an average density of <5 kg/l, that is the same volume as 1e13 kg of water, or 1/20 times the meltwater from Greenland. No solution to rising oceans :( [1] http://www.ilocis.org/documents/chpt74e.htm http://www.ilocis.org/documents/chpt74e.htm

mturmon 11y ago
OK, I read this and I had some disbelief. It starts with a total of 23 billion tonnes of ore, and ends with a volume equivalent to 1.5 meters of the whole country of Switzerland being excavated per year. That seemed high, but it turns out that independent estimates of just coal excavation are 8 billion tonnes per year. So my disbelief was wrong. And then, looking at it the other way, this makes it evident how much burning all that coal could change global CO2.

mc32 11y ago

Thanks for the quick napkin math. Great to see it distilled for easy comparison, however, wouldn't glacial melt also be characterized by some cancelling out effect?