Newly discovered greenhouse gas '7,000 times more powerful than CO2'
theguardian.com
theguardian.com
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.
https://en.wikipedia.org/wiki/Water_vapor#Water_vapor_in_Ear...
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.
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.
http://unfccc.int/ghg_data/items/3825.php
A 100-year GWP of 7000 seems typical for the type of chemical described in the article. Nevertheless, it's good we are identifying them.
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.
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.
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.
[0] https://en.wikipedia.org/wiki/Terraforming_of_Mars#Use_of_fl...