We are starting a
project next week and the topic is "change". We have chosen
the subtopic "global warming"
Do you have the time to
answer a few questions in writing?
1. What is behind
global warming?
2. What can we do to
prevent global warming?
3. If we don't do
anything about it, how does it affect us and our descendants?
4. What will happen in
the future, and what are the alternatives for us, if the Earth
becomes unlivable?
5. How can we save
Earth if it isn't too late?
RESPONSE
Dear Students:
Dr. Singer was not
available to answer your questions. I have worked with him for the
past seven years, and he approved this response to you.
You ask some very good
questions, which require answers with some detail. Science advances
by asking good questions, providing answers that may or may not be
correct (guesses), then testing the guesses against all hard
evidence, that may or may not support it. If the strongest evidence
does not support the guess (the hypothesis), then the guess must be
discarded or changed.
The climate has been
warming and cooling for hundreds of millions of years. For over two
million years, the globe has usually been cold, with long ice ages
interrupted by short warm periods of 10 to 15 thousand years. We live
in one such warm period of about 10,000 years. The longer periods of
cooling (and shorter periods of warming) have been explained as
resulting from a changing of the orbit and tilt of the globe in
relation to the sun, known as the Milankovitch cycles.
Within the
generally-warm past 10,000 years, there has been shorter periods of
modest warming and cooling. During a warming period, agriculture
began and with it, civilization. The most recent cooling period is
known as the Little Ice Age. It occurred between about 1300 to 1850
and was very hard for those living in Northern Europe and China,
where we have written records. In Europe, many died from starvation
and associated diseases because crops did not ripen. The Nordic
settlements in Greenland were wiped out. Great storms occurred in the
North Sea, killing thousands of people living in the low countries.
It is thought this cooling period was caused by a weaker intensity of
the sun, which resulted in increasing cloudiness and corresponding
cooling.
Understanding what is
behind the current warming of the last century or so, requires a
complete understanding of what created periods of warming and cooling
over the past 10,000 years, which we do not have. The earth’s
climate is extremely complex. It can be described as the result of
two fluids in motion interacting with the land. The fluids move in
response to the heat generated daily by the sun.
One of the fluids is
the ocean, which transports heat on the surface from the tropics to
the poles, where it escapes into the atmosphere and to space. A
famous surface ocean flow is the Gulf Stream, which keeps Northern
Europe much warmer than the corresponding latitudes of Canada. The
other fluid is the atmosphere, which transports heat from the surface
to the upper troposphere by convection, from which heat can escape to
space by radiation. We simply do not understand the movements of
fluids sufficiently well to explain exactly how these systems work.
Adding to the
complexity is the rotation of the earth, which changes the intensity
of solar energy hitting any specific location on the globe. That
varies both daily and seasonally, which adds to the ever-changing
motions of the atmosphere and the oceans. It may take hundreds of
years before these complex motions are fully understood.
In answer to your
question: What is behind global warming? We simply do not know in
detail, but can guess, then look at the evidence.
Over 100 years ago,
scientists wondered why the surface of the earth does not cool as
rapidly at night, as many thought it should. An explanation, since
then well tested, is that some gases in the atmosphere delay the
transport of heat from the surface to space, keeping the earth warmer
at night. These gases are called greenhouse gases, the most important
of which is water vapor. Deserts, with low atmospheric water vapor,
cool more rapidly at night than humid areas at comparable latitude.
A lesser greenhouse gas
is carbon dioxide which humans emit by burning fossil fuels. But
research by different laboratories have shown that adding carbon
dioxide to today’s atmosphere will cause only a small warming,
nothing to fear.
Prior to the time when
satellite measurements began (1979), the surface thermometers that
indicated warming were largely on land, mostly located in the US,
Western Europe, and other Westernized areas. The coverage was not
global. Surface temperatures may indicate what is occurring in the
atmosphere, but are influenced by many other human activities such as
building cities, land clearing, and farming. For over 38 years, we
have had the benefit of accurate temperature measurements from
satellites that cover nearly all the earth, including oceans.
Meanwhile, computer
models, known as General Circulation Models, have been used with
relatively little success. Built into them is the assumption that the
slight warming caused by CO2 will be amplified into a much greater
warming due to water vapor. The principles of the scientific method
demand that real data from observations be used, and for a computer
model to be valid, it must reproduce the observed data. Any warming
caused by increased greenhouse gases will be stronger in the
atmosphere than on the surface.
Satellite measurements
of temperature trends in the atmosphere have been studied intensely,
including even tiny corrections for drifting orbits. Furthermore, the
temperature trends are double-checked by using four different sets of
atmospheric temperature measurements, taken with different
instruments, carried by weather balloons; and all closely agree. Now
stretching over 38 years, these show a modest warming trend.
From this evidence, we
can conclude that: unless compelling evidence indicates otherwise,
the warming influence of greenhouse gases, especially carbon dioxide,
has been greatly overestimated; efforts to reduce greenhouse gases
will not prevent global warming; carbon dioxide-caused warming will
be modest; and the Earth will not become unlivable from carbon
dioxide warming. Life began on this planet when the atmosphere was
far richer in carbon dioxide, and far poorer in oxygen, than it is
today.
Starting in 1972, Landsat satellites have been taking images of the
earth. They show that the earth is greening with increasing carbon
dioxide, becoming richer for life. Thousands of experiments show food
crops grow better in atmospheres richer in carbon dioxide than the
atmosphere today. Indoor plant nurseries routinely increase the
carbon dioxide concentration of their air to three to four times that
of today’s atmosphere.
Through the wonder of
photosynthesis, using energy from the sun, green plants convert
carbon dioxide and water into oxygen and carbohydrates (food). All
plants and complex animals depend on this food. We should praise
carbon dioxide, not fear it.
To directly answer your
questions:
- What can we do to prevent global warming? Nothing. The main cause is natural variation, which we cannot prevent.
- If we don't do anything about it, how does it affect us and our descendants? You and your descendants will live in a world richer in carbon dioxide, which is a benefit to plants, the environment, and humanity.
- What will happen in the future, and what are the alternatives for us, if the Earth becomes unlivable? Life began on earth with the atmosphere many times richer in carbon dioxide than today. The earth will not become unlivable from carbon dioxide-caused warming.
- How can we save Earth if it isn't too late? The earth does not need saving, but it needs good stewards. You can help by not polluting with trash, not wasting energy, and living healthy lives.
Best wishes,
Kenneth Haapala,
President
Science and
Environmental Policy Project
December 22, 2017'
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