Venus: Earth

1
Venus Earths Hot Future?
2
Overview

• Similarities to Earth
• Differences from Earth
• Current situations of both planets (recap)
• The dry runaway greenhouse effect
• The wet runaway greenhouse effect
• How they relate to Earth
• Skeptics of either/or scenarios on Earth
• An example of it already happening

3
Similarities

• Orbital radius is 70 that of Earths.
• Planetary radius is 95 of Earths.
• One of the inner rocky planets
• Has similar mass and density.
• Surface features of highlands and lowlands.
• Abundant atmosphere.
• Geological processes still continue (volcanoes,
  etc)

4
Akna Mountains

• Venus Northern Hemisphere (radar imaging)

5
Differences

• Makes one axial rotation every 243 Earth days.
• Orbits in retrograde motion.
• Tilted 177.4 degrees compared to Earths 23.5
  degrees.
• Atmosphere 90 times more massive than Earths.
• Very high atmospheric concentration of CO2
• Has very low amounts of hydrogen.

6
Current Situations

• Venus
• Barren wasteland
• Avg. Temp of 900 F
• 96.5 of atmosphere is CO2
• No water
• Clouds of sulfuric acid
• Behaves as it was expected to

• Earth
• Supports life
• Avg. Temp of 57 F
• 0.04 of atmosphere is CO2
• Abundant water
• Clouds of water vapor
• Deviates from expected behavior

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Why is this so?

• Venus and Earth both formed approximately 4.5
  billion years ago and given their similarities,
  should have turned out the same, but they do not.
  Why didnt they?
• How is it that Earth can support life when Venus
  is completely hostile to it?
• The answer Global warming.

8
Two Runaway Greenhouse Effects

• Dry Runaway Greenhouse Effect no liquid
  water.
• Wet Runaway Greenhouse Effect liquid water
  present.

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Dry Effect

• Venus was closer to the sun and this proximity
  didnt allow water to condense.
• Since no water condensed, carbon dioxide could
  not be taken out of the atmosphere by oceans.
• Outgasing from the planet (through volcanoes)
  would continue to increase amounts of CO2 and
  water vapor in the atmosphere.
• This heating leads to whatever water vapor
  present to rise to the top o the atmosphere.
• It is broken in oxygen and hydrogen molecules by
  ultraviolet light.
• Lighter hydrogen escapes into space, oxygen left
  recombines with other elements like sulfur and
  oxygen.
• The planet loses hydrogen, and in effect loses
  all the water it had and becomes the inferno that
  it is today.

10
Wet Effect

• The water on Venus did condense into oceans.
• Higher temperatures than Earth would cause it to
  evaporate large amounts of water into the
  atmosphere.
• It would not precipitate back since the temp. was
  so high and oceans gradually vanished.
• The higher temperature also caused rocks to hold
  carbon less effectively and carbonates would
  eventually undergo processes releasing their
  stored carbon.
• As more water vapor enters atmosphere, the
  temperature rises even more and when the oceans
  were completely gone, water vapor again starts to
  rise to the top of the atmosphere
• They are then broken up by ultraviolet rays and
  hydrogen escapes into space while oxygen remains
  and recombines.
• The planet STILL loses all its water even if it
  once had liquid oceans.

11
Earths Greenhouse Effect

• Greenhouse gases on Earth, carbon dioxide,
  methane, ozone, and water vapor raise the
  temperature of the planet.
• Without the greenhouse effect, the planet would
  be -13 F, with it, it is about 55 F.
• Most of the greenhouse effect comes from carbon
  dioxide which is responsible for 57 of the total.

12
Venus Relevance to Earth

• Human activity is increasing greenhouse gas
  concentrations.
• Every year 6 billion tons of carbon dioxide alone
  are put into the atmosphere.
• In the past 133 years, avg. global temp. has
  risen by 0.5 C or 1 F.
• By 2100 it is expected to rise anywhere from 1.5
  C to 5.5 C (2.7 F to 10 F)
• This may or may not be enough to trigger a Wet
  Runaway Greenhouse Effect

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Venus Relevance to Earth (cont.)

• A Wet Runaway Greenhouse Effect on Earth would
  require that the majority of the oceans around
  the world evaporate more water than they get back
  through precipitation.
• The average temperature where this is occurs is
  more than 80 F.
• Currently, the highest ocean surface temp. at any
  given time usually does not rise above 87 F.
• The average ocean surface temp. varies between
  50 to 60 F (closer to the 50).
• If by 2100 the average global temp. rises by 10
  F then the average surface temperature could
  possibly rise to about 70 F, this is much closer
  to the doomsday number of just slightly over 80
  F.
• If this process were ever to start, it would be
  impossible to stop given the vast energies
  involved in it.

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Venus Relevance to Earth (cont.)

• All the water would evaporate into the
  atmosphere, fueling more global warming until all
  the oceans were gone.
• At this point, water molecules in the atmosphere
  would move closer to the top of the atmosphere
  and get broken apart by ultraviolet rays.
• The reason ultraviolet rays would affect them
  more at that point than now is because there
  would be virtually no ozone layer left at this
  point.
• Global warming contributes to the destruction of
  ozone.
• Once the water molecules were broken up, hydrogen
  would escape into space, just like on Venus and
  oxygen would remain to recombine with other
  elements.
• If this sounds similar to Venus, it should.
  Venus, in becoming the 900 F inferno that it is,
  follows and expected path of progression while
  Earth is the anomaly, not the other way round.
• The only things preventing Earth from fulfilling
  its expected outcome are the carbon cycle, since
  oceans remove a great deal of carbon dioxide and
  keep it in check and life, since many organisms
  (such as shellfish) create carbonates in the form
  of shells and help take carbon dioxide out of the
  atmosphere.
• This is a very delicate process that can be
  easily upset.

15
Skeptics Arguments

• Skeptics of either scenario happening have some
  facts to try and support their claims.
• One compelling argument they make is that carbon
  dioxide is only 0.04 of the Earths atmosphere
  and, to date, humans have contributed only 3
  directly.
• Although 6 billion tons of CO2 may be released
  every year into the atmosphere by humans, 200
  billion is released by natural processes in the
  same time frame.
• But their one flaw is that they fail to realize
  how fragile the system is and how narrowly Earth
  avoided becoming a second Venus.
• A disruption of the carbon cycle that keeps
  global temperatures in check could change

16

• This

• Into

17

• My planet!

• This!

I mean
18

• This.

• Venus (view from space)

19
Example Already Happening

• In fact, a very localized scenario of the wet
  runaway effect has already occurred.
• In May of 2002, scientists discovered an area in
  the Pacific Ocean to the North East of Australia
  that exhibited a runaway effect.
• This location was warm enough year round to
  continually evaporate more water vapor than
  precipitated back to it.
• Luckily, since it is only a localized area,
  surrounding parts of the ocean compensate for it.
  If the entire planet were to runaway, however,
  there would be no other areas to compensate.
• This one example shows that we could very well be
  close to the entire planet running away.

20
Conclusion

• Action must be taken now to avoid the Venus
  outcome happening on Earth.
• If it is indeed the one planet that supports
  life, human beings have a great responsibility to
  preserve it.
• Hope everyone has a good winter break! ?