No one knows how the strongest greenhouse gas, water vapor, responds to
increasing temperatures.
But 'global warmunists' are sure rising carbon dioxide (CO2) levels in
the air increase the average air temperature, which increases the average ocean
temperatures, which increases water vapor levels in the air, which increases
the air temperature even more (a positive feedback) ... the cycle repeats, eventually resulting in
catastrophic runaway global warming.
The phrase “tipping point” is used to describe this imagined unstable
climate system dominated by positive feedback from water vapor (WV).
But ... there is no evidence this runaway warming belief is true -- climate
science is a young science filled with pretensions to great knowledge of
climate system behavior, even when the basic causes of climate change are
unknown.
If Earth's climate was really dominated by positive feedbacks, it would
have run out of control many billions of years ago, and we wouldn’t be here to
argue about climate change.
The United Nations originally defined climate change by starting with
the conclusion that man made carbon dioxide (CO2), a greenhouse gas, was the
primary cause of global warming.
The UN's Intergovernmental Panel on Climate Change (IPCC) was created to focus on man made CO2.
The effects of variations of water vapor (WV) greatly exceed the
effects of CO2 as a greenhouse gas -- even the IPCC agrees.
WV ranges from near zero in polar regions to 4% in the tropics, but is
difficult to measure globally.
Measurements began with satellite derived microwave
measurements that determine the amount
of WV dissolved in a column of air.
There are almost no WV data before 1950.
The average amount of WV in the air represents a balance between
surface evaporation (increases WV in the air), and precipitation (decreases WV
in the air).
We know evaporation increases with temperature, although we don't know
if one causes the other.
We don’t know much about how precipitation changes with temperature.
The important question is how do the effects of natural WV variations compare
with the effects of man made CO2?
No one knows.
From IPCC AR4: “The magnitude of the observed global change in tropospheric water
vapour of about 3.5% in the past 40 years is consistent with the observed
temperature change of about 0.5°C during the same period, and the relative
humidity has stayed approximately constant.”
The above quote means the IPCC claims WV changes have caused almost all of
the slight warming since 1975.
The IPCC claims rising man made CO2 causes a small amount of
atmospheric warming.
Atmospheric warming increases the WV level in the air, and causes the
oceans to release some of their dissolved CO2 into the air.
More CO2 and more WV = more warming.
And the cycle repeats.
The water vapor increase is claimed to greatly amplify (triples) the initial warming effect
of CO2.
This tripling is called a "positive feedback", and is claimed
to be the main cause of runaway global warming ... in theory.
Runaway global warming ... in practice ... has never happened in the
past 4.5 billion years of Earth's climate history, in spite of CO2 levels
higher than today most of that time.
The IPCC will not consider whether WV is the real climate controller.
The IPCC will not consider whether
WV and CO2 changes both RESULT from global warming caused by something
else, such as natural solar energy variations.
The IPCC starts with a conclusion that man made CO2 controls the
climate, so does not care about any other hypotheses.
The true cause(s) of climate change is still not known.
If WV levels were the climate controller, then climate change must be
natural, not man made, because humans have a negligible effect on changes to WV
levels.
But the IPCC will not study anything that affects the climate (average
temperature) that can not be blamed on humans burning fossil fuels.
There are small changes to 400 parts per million (ppm) of the greenhouse
gas CO2 every year.
There are much larger changes to 50,000 parts per million of the
greenhouse gas WV.
If you want to believe a greenhouse gas is the climate controller, an
unproven theory that I do not believe, then why not believe in water vapor, rather
than CO2?
Carbon Dioxide……… 0.04%…………. 400 ppm
Water Vapor……….…. 5.0 %……….. 50,000 ppm