A
Realistic Look at Global Warming
Much of the
alarmism surrounding the climate change issue results from climate computer
models that predict considerably higher temperatures in the coming decades as a
result of increasing atmospheric carbon dioxide. Carbon dioxide was part of
God’s “very good” creation. Plants “breathe” carbon dioxide, and there is
evidence that increased atmospheric carbon dioxide is causing more plants to
grow, even in dry areas. So even if CO2 is warming the planet today,
Christians have no reason to panic over this issue. Earth’s atmosphere is
subject to numerous intricate interactions, and we still don’t have a firm
understanding of its overall long-term sensitivity. We need to refrain from
jumping to conclusions based on skewed climate models and short-sighted
assumptions. To be sure, God has appointed man to be custodian of His Earth -
we should be good stewards of what He has given us, but we enter dangerous
territory if we presume to be able to control and shape to our will what God
has made
by Vernon R.
Cupps, Ph.D., and Jake Hebert, Ph.D.
Since the late
1980s, global warming has been hotly debated, with many arguing that Earth is
undergoing potentially catastrophic man-made climate change.
Is Earth getting
warmer? Is such warming, if real, dangerous?
And is it caused by
human-produced carbon dioxide (CO2)?
Or, to put it
another way, is catastrophic anthropogenic (man-made) global warming
(abbreviated as CAGW) real?
There has been a
warming trend for much of the 20th century.
In fact, ICR
scientist Larry Vardiman did his own independent analysis of three different
datasets and concluded that warming had probably occurred for at least the last
30 to 50 years.
But past warming is
no indication that such warming will necessarily continue.
In fact, there has
been an apparent pause in this warming trend for the last 18 years.
Nor does a warming
trend automatically prove that human activity is responsible.
A recent article in
Eos, however, attempted to establish as fact that human activities drive global
warming.
The author, Dr.
Shaun Lovejoy, did this by supposedly disproving the only alternative — that
observed warming is due to natural causes.
He calls those who
support this alternative hypothesis “denialists” because they supposedly deny
the obvious facts of science.
Lovejoy attempts to
show that increased amounts of atmospheric carbon dioxide are responsible for
an increase in global temperatures of about 1° Celsius over the last 125 years.
He does this by
making a plot of change in global temperature against a “stand in” or “proxy”
for radiative forcing due to atmospheric CO2 (Figure 1).
Radiative forcing
is an indication of a gas’s ability to affect the earth’s climate. (See the sidebar for
a more detailed discussion.)
Lovejoy argues that
there is only a one-in-three-million chance that natural causes could produce
this temperature rise, although he later acknowledges that a more realistic
estimate is one in a thousand.
A History Lesson
But are
long-lasting changes in climate really that unlikely?
Abundant historical
evidence shows that significant, long-term climate fluctuations lasting
hundreds of years have taken place.
These fluctuations
occurred long before human CO2 contributions became significant.
Even scientists who
believe that humans are causing global warming acknowledge that human
contributions to atmospheric CO2 were practically negligible until
the early- to mid-1900s.
Yet there have been
two significant changes in climate within the last thousand years — the
Medieval Warm Period (roughly 950–1250 A. D.) and the Little Ice Age (roughly
1300–1850 A. D.).
Because these
changes in climate occurred before humans could have caused them, the mere
existence of these two periods is a real problem for any attempt to dismiss the
possibility of natural changes in climate.
For this reason,
some who believe in CAGW have attempted to minimize the significance of these
past climate fluctuations, despite abundant historical evidence for their
reality.
For instance, one
of the best-known images in the global warming debate is the “hockey stick”
graph of Penn State University climatologist Michael Mann, so-called because it
resembles a hockey stick turned on its side with the blade pointing up.
The hockey stick
has been used to argue that the late 20th century was characterized by
unprecedented warming, since Mann’s statistical analysis significantly “cooled”
the Medieval Warm period.
However, Mann’s
work has been widely criticized, and a more conventional analysis indicates
that 20th-century warming is not unprecedented (Figure 2).
The Medieval Warm
Period and the Little Ice Age raise an obvious question about Lovejoy’s
reasoning.
If not one but two
significant long-term changes in climate have occurred within the last thousand
years, before humans could have influenced climate to any significant degree,
then perhaps such naturally occurring changes in climate are not nearly as
unlikely as Lovejoy claims!
Moreover, Lovejoy
seems to be underestimating the probability of natural changes in climate.
His argument
assumes that temperatures from hundreds of years ago can be known accurately to
within just one-tenth of a degree Celsius (0.1°C).
But these
temperatures were not measured with thermometers — not even crude thermometers.
Rather, they were
estimated from things like tree rings, boreholes, ice cores, etc.
Because these are
indirect estimates of temperatures, the true uncertainty is almost surely a lot
more than Lovejoy’s optimistic estimate of 0.1°C.
Using the same
reasoning he used, but with larger estimates for these temperature
uncertainties, would imply that significant natural changes in climate are much
more probable than he asserts.
An interesting side
note is that many evolutionists absolutely dismiss out of hand the possibility
that any observed global warming could be due primarily to natural causes.
For instance, the
National Center for Science Education has made advocacy of a belief in man-made
global warming a priority.
Yet even by Lovejoy’s
own calculations, the lowest probability he can estimate against recent warming
being the result of natural causes is one in three million (1 in 3×106).
Compare this to a
probability of 1 in 1×10106 that the simple protein insulin can form by pure chance.
Yet evolutionists
claim that the insulin protein did somehow form by chance, even though such an
event is much less likely (by their own reasoning) than long-term natural
climate variation, which many of them confidently dismiss as an impossibility.
Why? Could it have
something to do with their worldview?
Lovejoy
quickly dismisses other factors that can affect climate, such as changes in
solar activity.
But mounting evidence shows that the sun can indeed
subtly influence weather and climate by affecting the number of cosmic rays
(energetic protons) entering the atmosphere.
In fact, the Ph.D. work of one of this article’s
authors found additional evidence for this possibility.
Also, increases in temperature can actually cause an
increase in atmospheric CO2 via releases from the oceans.
A well-known rule in chemistry called Henry’s law
states that the amount of gas that can be dissolved in a liquid decreases with
increasing temperature at constant pressure.
This is the reason a can of soda goes flat as it warms.
Indeed, some datasets show atmospheric CO2
increasing after temperature goes up.
So, are temperatures, particularly ocean temperatures,
causing an increase in atmospheric CO2, or are warmer temperatures
the result of increased atmospheric CO2, or is it some of both?
Another problem with the argument that human-produced
carbon dioxide could lead to climate catastrophe is that this argument
implicitly assumes that the concentration of atmospheric carbon dioxide in the
pre-industrial era was consistently much lower, about 270 parts per million
(ppm), than today’s value of about 400 ppm.
It also assumes that today’s value is truly abnormal.
Systematic measurements of atmospheric carbon dioxide
have been made at Mauna Loa Observatory in Hawaii since 1959, and these measurements
do indeed show an increase in CO2 from about 310 ppm to today’s
value of 400 ppm.
However, scientists also made thousands of measurements
of atmospheric CO2 between 1812 and 1958.
Although not as precise as the modern Mauna Loa
readings, many of these older measurements are estimated to have been accurate
to within 3% of the true values and were good enough to show a seasonal cycle
that is also apparent in the Mauna Loa measurements.
These suggest high values of atmospheric carbon dioxide
around the years 1825, 1857, and 1942, with the 1942 value comparable to
today’s value of 400 ppm.
Specialists are aware of these data but generally
dismiss them in favor of estimates of atmospheric CO2 inferred from
ice cores.
However, gases tend to escape from the cores after
their removal from the surrounding ice, which implies that such estimates will
tend to be lower than the true values.
Even so, there is evidence from a shallow Antarctic ice
core that amounts of CO2 may have been as high as 328 ppm within the
last hundred years or so.
But recent jumps in the amount of atmospheric CO2,
both before and during the industrial period, suggest that atmospheric CO2
can vary due to natural causes, not just human influences.
We have already mentioned one possible source for such
variation — warming oceans, which would release more CO2 into the
atmosphere.
The Climate Change Model Problem
Finally, much of the alarmism surrounding this issue
results from climate computer models that predict considerably higher temperatures
in the coming decades as a result of increasing atmospheric carbon dioxide.
Obviously, the particulars of different models will
vary, but a general overview is presented in the sidebar.
However, in the past these climate models have
consistently overestimated the amount of future warming, as shown in Figure
3.17
If one looks at these climate change model predictions
for the temperature anomaly from the present to 2050, they vary from 0 to
2.5°C, a significant disparity between models.
The observational data are very near 0 for the
temperature anomaly.
Clearly, there are major disagreements between
different models about any significant global warming.
But the data accumulated thus far seem to support the
models (hypotheses) predicting global warming of no more than 0.5°C through
2050.
It should also be remembered that carbon dioxide was
part of God’s “very good” creation (Genesis
1:31).
Plants “breathe” carbon dioxide, and there is evidence
that increased atmospheric carbon dioxide is causing more plants to grow, even
in dry areas.
There are also indications that the pre-Flood world may
have had more atmospheric carbon dioxide than we do at present, and this
increased CO2 may have contributed to a much more temperate pre-Flood climate.
So even if CO2 is warming the planet today,
Christians have no reason to panic over this issue.
So many variables affect Earth’s climate that it’s
difficult to see how a computer model can accurately predict future changes,
especially given our present imperfect understanding.
Earth’s atmosphere is subject to numerous intricate
interactions, and we still don’t have a firm understanding of its overall
long-term sensitivity.
If we want a realistic assessment of climate change, we
need to
1) do our homework and learn from history,
2) continue to study the data with great
diligence, and
3) refrain from jumping to conclusions
based on skewed climate models and short-sighted assumptions.
To be sure, God has appointed man to be custodian of His
Earth.
We should be good stewards of what He has given us, but
we enter dangerous territory if we presume to be able to control and shape to
our will what God has made.
The law of unanticipated consequences inevitably intervenes.
Drs.
Cupps and Hebert are Research
Associates at the Institute for Creation Research. Dr. Cupps received his Ph.D.
in nuclear physics at Indiana University-Bloomington. Dr. Hebert received his
Ph.D. in physics from the University of Texas at Dallas.
The
Institute for Creation Research
(ICR) wants people to know that God’s Word can be trusted in everything it
speaks about—from how and why we were made, to how the universe was formed, to
how we can know God and receive all He has planned for us.
After 50 years of ministry, ICR remains a
leader in scientific research within the context of biblical creation. Founded
by Dr. Henry Morris in 1970, ICR exists to conduct scientific research within
the realms of origins and Earth history, and then to educate the public both
formally and informally through professional training programs, through
conferences and seminars around the country, and through books, magazines, and
media presentations.
https://www.icr.org/article/realistic-look-at-global-warming/
No comments:
Post a Comment