Letters from climate change deniers cover the gamut from supposed incompleteness of the second law of thermodynamics to “… there is a growing body of scientific evidence that the planet is moving into another ice age.” and asked “…why are so many key politicians and multi-national special interest groups indoctrinating us with the dire warning of global warming?” Their answer: because “…these people stand to make huge profits from this new economic opportunity.” Huh? Guess he is not familiar with the humungous profits made by the banking and fossil fuel industries that are actually driving the disinformation.
From ice cores covering over 500,000 years we know a lot, including that the climate is
very sensitive to small energy inputs (forcings). Transitions between glacial and warm
periods were triggered by tiny fractions of a % changes in seasonal solar input, due
to cyclical variations in the earth’s inclination and distance from the sun, amplified by
powerful feedbacks that we are now triggering again. Over time changes in snow and ice
build up changed the amount of sunlight reflected back into space. As the earth warms
the oceans release CO2, which being a greenhouse gas causes the earth to retain more of
the sun’s heat. From the ice cores we know the composition of the atmosphere and the
temperature, and from geology we know the extent of the icecaps. Thus we can work
out the difference in forcing between the middle of the last ice age, when the mean global
temperature was 5 deg cooler, and the present extraglacial: 3.5 watts per square meter
due to the reduced ice sheets and 3 watts due to greenhouse gases. Thus we can calculate
the climate sensitivity as 5 deg per 6.5 watts or about ¾ deg per watt. A doubling of CO2
leads to a climate forcing of 4 watts, so the sensitivity to a doubling of CO2 is 3 deg. This is
not theory, this is empirical.
Our civilization developed in the unusually stable climate and sea level that has existed
since the last ice age, but we have already increased CO2 by 40% since preindustrial times, and the earth is obviously warming. In fact business as usual is guaranteed to double CO2 and bring us 3 deg, possibly substantially more, of warming this century.
So where is our climate heading? Certainly not to an ice age as claimed by Chris. The net
human caused forcing is already 1.5 watts per square meter, between 10 and 1000 times
larger than variations in solar forcing or other natural forcings. Over the entire surface the
human caused increase in energy input to the earth is 750 terawatts, the equivalent of the
heat release from several major hurricanes running all year every year! Humans are now
incontrovertibly in control of the climate, but scientists fear our control will be very short
lived – as little as just the next few years they warn!
The past climate record shows that in a warmer world additional feedbacks come into
play, such as release of methane ice from below shallow seas that can kick in runaway
climate change completely beyond our ability to claw back.
The last time the earth was 2-3 deg warmer than today, three million years ago, the ocean
was 25 meters higher, taking away the land now occupied by 1 billion people. The danger
can be much worse: scientists estimate the carrying capacity of a 4 deg warmer world this
century is less than 1 billion people!
So to answer questions: most climate scientists, but a small minority of politicians,
are issuing dire warnings because…well…what’s coming in our children’s time is dire. Is
this gloom and doom? No! This is reality! What will doom us is the gloomy and defeatist
outlook, stemming from the distorted self-interest of business as usual, combined with
the denialist ideologies of their apologists. In fact we have everything we need, if we can
inspire courage and generosity of spirit, to save our butts by rapidly deploying a low
carbon emission economy while creating fuller employment, and a safer and happier
Paul Taylor, PhD (from Germany)
Note names of some individual deniers have been removed.