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NASA Contrails Presentation Begs Some Questions
By Rosalind Peterson
While searching the NASA website on July 31, 2008, I found a link to David Duda's (Hampton
University/NASA LaRC), PowerPoint presentation on 'Contrails' (no date provided for presentation). |
The
presentation provides pictures of interest and information on contrails.
This presentation does not answer critical questions about persistent jet contrails but it does provide the
following information:
- "…Contrails have been around for a long time! They were first described in the scientific literature in
1919…"
Since no jet engines were in existence in 1919, this means that contrails must have been
formed by smoke.
- "…During World War II, contrails sometimes littered the skies during aerial combat…"
This statement is
true but the contrails would have been created by smoke and other sky obscurants used during WWII.
It should be noted that there were only a handful of jet engines in small experimental aircraft at that
time in England and Germany. These jets were not used in combat as far as can be determined by
extensive historical research.
- "…Persistent contrails occasionally cover large areas. Like cirrus clouds, contrails contribute to global
warming…"
We currently estimate that contrails add an additional 0.5 to 5 percent warming to the
greenhouse gas effect…” Water vapor is a green house gas.
- "By 2050, the warming due to contrails may be 2.5 to 25 percent of the current greenhouse gas
warming…"
Why aren't we curtailing all jets leaving persistent jet contrails now in order to eliminate this
threat to climate change? No answer to this question in the presentation. If we are serious about
reducing global warming why isn't this issue addressed at the state or federal level, especially in
California?
- This presentation fails to discuss the climate change produced by persistent jet contrails when they turn
into white haze and man-made clouds.
NASA noted in an October 2005, newsletter that increasingly persistent contrails may turn into manmade
clouds that are:
" …trapping warmth in the atmosphere and exacerbating global warming…"
NASA goes on to state that " …Any change in global cloud cover may contribute to long-term changes
in Earth's climate. Contrails, especially persistent contrails, represent a human-caused increase in the
Earth's cloudiness, and are likely to be affecting climate and ultimately our natural resources…"
- The pictures in this presentation are also of interest. There is only one date 2002 on a satellite picture
in the entire power point presentation. Thus, there is no way to date this presentation or the pictures as
no credits are given for them.
- This power point presentation does not provide information on why jet contrails, produced by jet
engines, have only persisted in their present form since the late 1980s.
- This presentation addresses contrails in a general manner which includes smoke and other types of
contrails produced for air shows and skywriting. It also mixes propeller engine and jet engine contrails.
The discussion by NASA and other entities should be on the type of persistent jet contrails which
persist and exacerbate global warming, produce white haze and man-made clouds. These are the
ones which may negatively impact agriculture production and change our climate.
- Duda asks "What are contrails" and defines other terms pertaining to contrails: " …Also known as Vapor Trails, Jet Trails,
'Chemtrails'…"
This is limited contrail information and does not address the problems they create.
View the PowerPoint presentation here
Link to NASA site here (PDF version of PowerPoint presentation)
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