LAYING
TEN GLOBAL WARMING MYTHS |
Professor
R.M. Carter
Hon. FRSNZ
Marine Geophysical Laboratory (Node C)
Sporing Road South, James Cook University
Townsville, Qld. 4811, AUSTRALIAContact RMC
Myth
1 Average global temperature (AGT)
has increased over the last few years.
Fact
1 AGT
has remained steady, or slightly declined, since 1998.
Myth
2 During the late 20th Century,
AGT increased at a dangerously fast rate and reached a
high point of unprecedented magnitude.
Facts
2 The recent rate
of AGT rise has been between 1 and 2 deg. C/century, which falls squarely within
natural rates of climate change for the last 10,000
years. AGT has been several degrees
warmer than today many times in the recent geological past.
Myth
3 AGT was relatively unchanging
in pre-industrial times, has sky-rocketed since 1900,
and will increase by several degrees more over the next 100
years (the Mann, Bradley & Hughes "hockey stick" curve).
Facts
3 The Mann et al.
curve has been exposed as a statistical contrivance. There is no convincing
empirical evidence that past climate was unchanging, nor that 20th
century changes in AGT were unusual or unnatural.
Myth
4 Computer models predict AGT
will increase by 6 deg. C or more over the next 100 yr.
Facts
4 Deterministic
computer models do. Other equally valid (empirical) computer models predict
cooling.
Myth
5 Warming of 1-2 deg. C will
have catastrophic effects on ecosystems and mankind alike.
Facts
5 Ecosystems have
been adapting to climate change since time immemorial. The result is the process
that we call evolution. Mankind can adapt to all
climate extremes.
Myth
6 Human addition of carbon
dioxide to the atmosphere is causing dangerous warming,
and is generally harmful.
Facts
6 No human-caused
warming can yet be detected that is distinct from natural system variation and
noise. Any additional human-caused warming which
occurs will probably amount to less than 1 deg. C. Atmospheric carbon dioxide is
a beneficial fertilizer for plants, including cereal crops, and also aids
efficient evapo-transpiration.
Myth
7 Changes in solar radiation
cannot explain recent changes in AGT.
Facts
7 The sun's output
varies on many time scales (including that of the 11-year sunspot cycle), with
concomitant effects on Earth's climate. More than 50% of the 0.8 deg. C rise in
AGT observed during the 20th century can be attributed to solar change.
Myth
8 Unprecedented melting of ice
is taking place in both the north and south polar regions.
Facts
8 Both the
Greenland and Antarctic ice sheets are growing in thickness. Sea ice around
Antarctica is growing. Temperature is falling at the South Pole.
Temperature in the Arctic Ocean region is just now achieving the levels of
warmth experienced during the early 1940s, and the region was warmer still
(sea-ice free) during earlier times.
Myth
9 Human-caused global warming is
causing dangerous global sea-level (SL) rise.
Facts
9 SL change differs
from time to time and place to place; between 1955 and 1996, for example, SL at
Tuvalu fell by 105 mm (2.5 mm/yr). Global average
SL is a statistical measure of no value for planning purposes. The global
average SL rise of 1-2 mm/yr that has occurred over the last 200 years shows
little sign of increasing.
Myth
10 An
increase in AGT during the late 20th century has led to an increase in the
number of severe storms (cyclones) or in storm
intensity.
Facts
10 Meteorological experts are
agreed that no increase in storms has occurred beyond that associated with
natural variation of the climate system. The
argument that storms have increased in their intensity as a result of warming
remains the subject of strong dispute.