The study, published in the journal Geophysical Research Letters, found PFTBA was 7,100 times more powerful at warming the Earth over a 100-year time span than CO2.
Concentrations of PFTBA in the atmosphere are low – 0.18 parts per trillion in the Toronto area – compared to 400 parts per million for carbon dioxide. So PFTBA does not in any way displace the burning of fossil fuels such as oil and coal as the main drivers of climate change.
Dr Drew Shindell, a climatologist at Nasa's Goddard Institute for Space Studies, said:
"This is a warning to us that this gas could have a very very large impact on climate change – if there were a lot of it. Since there is not a lot of it now, we don't have to worry about it at present, but we have to make sure it doesn't grow and become a very large contributor to global warming.".
edit - is cool research, but the headline here is very badly judged.
Still, if it is in fact 7,1000 more powerful at warming the earth, wouldn't a concentration of 0.18 ppm have a greater impact on the climate than 400 ppm of CO2? Not sure if the math is that simple, but it's not obvious to me why there has to a much greater concentration for us to worry about it compared to CO2.
Parts per million versus parts per trillion. Assuming the math is that simple (I think it is), CO2 is the larger contributor by five orders of magnitude.
Semi-offtopic: water vapour is by far the most powerful atmospheric greenhouse gas per unit volume and as a whole, many times more 'powerful' than CO2. Hardly anyone mentions it because it is not something we can change.
That's worth some elaboration, though: the water vapor in the atmosphere is (to a very, incredibly rough approximation) a system where the average global vapor concentration oscillates tightly around an equilibrium point. More than that, the average residence time in the atmosphere is a bit over a week. So when you say we can't change it, it's very true in one sense: if we vaporized the Mediterranean into the atmosphere, well before a month had gone by it'd have precipitated back to the liquid state on the Earth's surface.
On the other hand, what you said could be misunderstood to mean that human activities have no effect on the average water vapor concentrations, and that'd be inaccurate. The equilibrium point is determined in large part by global temperatures: the higher they are, the more water vapor is pulled into the atmosphere. And we do have a mechanism to increase atmospheric temperatures: CO2.
CO2 by itself is fairly limited in terms of temperatures: doubling its atmospheric concentrations only increases average global temperatures by about a degree, which is simple to calculate and more or less undisputed. But what really kills us (and where uncertainties creep in) is in the positive feedback loops, the biggest of which is water vapor. A degree increase in temperature from CO2 alone results in an additional couple degrees of increase in temperature due to the effects of increased water vapor.
Combine a couple of those positive feedback loops, and you've got a problem.
Yes, but that's almost a separate issue. Water vapor is a limited feedback: if you double CO2 concentration, the additional water vapor will increase temperatures further, but only enough to induce a fraction of the original amount of increased water vapor to be sucked into the atmosphere. If this weren't the case, small deviations in the amount of water vapor in the atmosphere would cause even greater deviations, leading to runaway global warming until other, negative feedbacks grow large enough to counteract it; in other words, we must be in a stable equilibrium, as an unstable equilibrium would have already collapsed into a nearby stable one.
Methane clathrate guns aren't the same: the idea there is that we've not historically explored the relevant parameter landscape (oceanic acidity + temperatures). People hypothesize that, if we're not careful, we can stumble into a saddle point where a small delta propels us away from our current equilibrium and toward one with much higher mean surface temperature.
All of this is to say that water vapor feedbacks are well established, while a methane clathrate gun is just a speculative hypothesis.
On the contrary, deforestation has a huge effect on the water cycle. Most people don't realize that if you're more than ~200 km inland most of your precipitation comes from transpiration by plants upwind instead of evaporation.
How do we know? Oxygen isotopes. Basically, the differential fractionation of oxygen (and hydrogen) isotopes in water during evaporation vs. transpiration allows you to trace where your rainfall comes from. http://www.nature.com/nature/journal/v496/n7445/abs/nature11...
Also, don't cut down forests thinking it'll fix global warming. Overall they have a net cooling effect. What you'll do instead is create deserts downwind.
This is a many-page plot point in Kim Stanley Robinson's Mars Trilogy. Highly recommended to all interested in the colonization of Mars.
14,000 kg would be equal to 98,000 tonnes of CO2. Trivial amount of heating, esp. since atmospheric forcing is weaker on Mars since the Sun is further away.
Incidentally the Mars Trilogy is some of the best hard sci-fi out there. Absolutely not to be missed.
I reread it a year or two back, and it's standing the test of time very well, in spite of the fact that Red Mars was first published almost 21 years ago and the story begins in the 2020s.
According to the wiki article on the topic ([0], citing [1]), you could get significant terraforming of Mars with something on the order of 39 million tons of CFCs. One Falcon rocket can carry 14 tons there, so that would naively 2.8 million Falcon launches, at a current cost (@$100MM/launch) of $280 trillion. (And surprisingly little terrestrial CO2 emissions -- only about 3 billion tons).
As ealloc points out [2], this particular fluorine compound isn't very different, as a greenhouse gas, from the other CFCs these estimates are based on.
Well, the Martian atmosphere is apparently around 25 teratonnes, so I would be surprised if a warming effect from the addition of 14,000kg of any known gas at martian air pressure and temperature would be either measurable or in any sane way even calculable.
The melting point of Fluorinert is -50 C. The average temperature on Mars is, if I recall correctly, -50 to -60 C. The material would tend to precipitate out over the poles and stay there. Another source of warming would be required for it to produce any long-term effects.
It's worth checking what people have already calculated, e.g. the wiki article on the topic [0]. There's large amounts of CO2 ice on Mars which could be "evaporated" to create a strong greenhouse effect. Someone thought of orbital space mirrors as an elegant method to do this -- to heat the polar ice caps and sublimate enough to create a runaway greenhouse. Fluorocarbons would take about 10^8 tons, so that might be vaguely plausible.
Does Mars have an atmosphere to insert the gas into? How much mass does a planet need to support an atmosphere? A quick check on Wolfram suggests that Earth has 10 times the mass of Mars. Does a planet need to be Earth or Venus sized to hold onto the air?
Mars does have an atmosphere, but it's thin. As for holding onto the air, it all depends on what kind of timeframe you're talking about. The Moon, for example, has no atmosphere because it's too small. But if you magicked into an existence an Earth-like atmosphere on the Moon, it would persist for something like a million years before it all drifted away. Mars would do even better. That kind of timescale is probably plenty for human purposes.
Earth's retention of its atmosphere also owes a significant amount to its planetary magnetic field, which deflects solar radiation that would otherwise energize molecules in the upper atmosphere enough to escape the gravity well.
Add the biggest amount of C and H you can on a molecule with it remaining a gas (easier on Mars than on Earth). Then, replace some of them with N and O, in a way that you create the biggest diversity of shapes you can.
The study, published in the journal Geophysical Research Letters, found PFTBA was 7,100 times more powerful at warming the Earth over a 100-year time span than CO2.
Concentrations of PFTBA in the atmosphere are low – 0.18 parts per trillion in the Toronto area – compared to 400 parts per million for carbon dioxide. So PFTBA does not in any way displace the burning of fossil fuels such as oil and coal as the main drivers of climate change.
Dr Drew Shindell, a climatologist at Nasa's Goddard Institute for Space Studies, said:
"This is a warning to us that this gas could have a very very large impact on climate change – if there were a lot of it. Since there is not a lot of it now, we don't have to worry about it at present, but we have to make sure it doesn't grow and become a very large contributor to global warming.".
edit - is cool research, but the headline here is very badly judged.