Slashdot Mirror
Peer-Review Process Confirms Contrails Climate Effect
An anonymous reader writes: "According to NPR, researcher David Travis (who was mentioned in two previous articles has been published in today's issue of nature as confirming jet contrails effects on the earth's climate. The publication of this paper in arguably the most prestigious peer-reviewed scientific journal of all should help serve to assuage the spurious doubts many slashdotters voiced back in May."
"today's issue of nature"
should be: "today's issue of Nature". Nature is a science magazine.
(This is another example that shows us that dropping out of high school is a terrible thing.)
You're misunderstanding or reading into the results. The result is that contrails hold heat like greenhouse gases, or yes, like a cloudy day. That's all it said. It wasn't trying to say that jet contrails do any of the funky chemistry that greenhouse gases cause.
BTW, CFC-Ozone reactions aren't really greenhouse gas related. Think more about CO2 and methane.
If tits were wings it'd be flying around.
I could agree that contrails are bad and I'm willing to acknowledge that global warming is a problem, but I'm worried that there's some bad science happening here. Maybe I've missed something, but just because the temperatures where different on those 3 days from averages during the same month over the past 23 years, how can you assume this was caused by the absence of the contrails? Wouldn't you need to be able to repeat the experiment several times before you could rule out a fluke? "Travis's team compared the average daily high and low temperatures over North America from 11 to 14 September 2001, with climatic records from 1977 to 2000, matching the weather over those three days with similar weather in September from historical records."
"I thought they were the dominant species..."
It just means that it passes the giggle test. Sometimes it doesn't even mean that. (Nature had its transgenic corn thing and Science had its bubble fusion recently.) It's a big mistake to confuse the imprimatur of a science journal with acceptance by the scientific community.
Bzzt. Naive. Global warming affects all climate zones. Some naive Canadian journalists have naively suggested that global warming would benefit Canada, because areas too cold for farming would now become arable. Or they have suggested it would be good for the summer tourist industry. Dim.
But the effects are proving unpredictable. Will there be enough rain? Currently arable areas are experiencing drought. I have already written here about the shocking results of the Repeat of Henry Larsen's voyages through the Northwest passage. The first traversal of the Northwest passage, in 1903, took Amundsen three years, because of the ice. Larsen's first trip took him 850 days, because of the ice. The vessel that repeated the voyage in 2000, easily traversed the passage, from Vancouver to Halifax in just 100 days, and encountered almost no ice...
In the high Arctic the soil is frozen year round. Normally the top six inches or so melts long enough for plants to grow during the brief Arctic summer. But the soil below that top six inches remains frozen.
Now it is melting, and this is a terrible development. This article says:
But now the permafrost is melting, releasing eons of stored carbon. Much of this carbon will be released as Methane, which is 30 times more damaging than Carbon Dioxide.
The scientist being interviewed estimated that recently thawed rotting vegetation from melting permafrost represented 3% of the amount of carbon flowing into the atmosphere from the combustion of fossil fuels.
Global warming frightens me. And now I have learned of yet another reason to worry.
Baloney.
First of all, if the analogy holds any water at all (excuse the pun), then locally, contrails are equally as significant as a really cloudy day.
The destructive nature of greenhouse gases has been piped loud and clear regarding the CFC-Ozone reactions that allegedly occur in emitted fossil fuels in the high atmosphere. Here [ucsusa.org] is a decent description of the process.
Take a look at the link you yourself provided.
Humans have damaged the ozone layer by adding molecules containing chlorine or bromine that lead to ozone destruction.
Nothing there about fossil fuels or jets. Read a little more and you'll learn those "molecules" are gases which are released on the ground.
No. Ozone depletion and global warming are separate problems, though some agents contribute to both."
Total atmospheric warming? I think water vapor contributed a bit more than carbon dioxide to the total greenhouse effect.
There have been many loud things said about greenhouse gases, but apparently not clearly enough.
If I understood the article correctly, jet contrails, locally counteract global warming, shifting the temperature down 1.8 degrees centigrade.
Nope. You read it wrong. They compared the difference in temperature between night and day. The existence of jet contrails are correlated to a smaller difference in temperature -- presumably, the days were cooler, and the nights were warmer than normal.
The idea is that sunlight bounces off the top of the contrails during the day, and reflects back into space. Thus, less energy is added to the environment during the day, which means that the jets have the immediate effect of cooling the earth, but only during the day.
However, the heat radiated up from the ground also gets reflected right back to the ground, just as if you'd put a big blanket over the earth. This has the effect of generally warming the earth, during both day and night.
So, there are all sorts of questions which are, hopefully, outside the scope of an article like this. I'm not sure, because I've only read the brief linked writeup, not the real paper published in Nature. Reading the paper costs money to read, and I'm cheap.
The questions I immediately have is: do the contrails have the net effect of increasing or decreasing the total amount of energy stored in the earths environment, i.e., do they actaually cool or warm the earth? Which has a bigger effect -- the light reflecting off the top and into space, or the heat reflected back onto the surface? What are the magnitudes of each of these effects across different seasons? What are the effects across different regions of the world? What effect does this actually have on the climate -- rainfall patterns, regional mean termperatures, or regional temperature variance.
Slashdot is jumping the shark. I'm just driving the boat.
But CFCs are greenhouse gases, though this has nothing to do with the CFC-Ozone reactions.
Lars T.
To the guy who modded me down from perfect to terrible Karma - Apple haters still suck
Since contrails dissipate after a short while and planes fly more during the daytime than during nightime wouldn't the reflective effect tend to be stronger than the retentive effect?
And I'm supposed to believe that this "obviously proves" something? They would be a lot more believable if they included other possible causes that they were able to DISPROVE. Smells like somebody is grasping at straws to get their grant renewed.
Obviously, the contrails can initiate cloud formation and cause a local affect, but whatever premature energy transfer occurs (condensation, precipitation, absorption, reflection) would have occured eventually. Looking at the big picture, the amount of energy introduced into the atmosphere by an aircraft is insignificant, even though it can initiate a significant weather event. It's a "robbing Peter to pay Paul" kind of thing.