Expert: Philip Stahl - 1/10/2007

Question
I live in Milwaukee,WI. It's January and the temps have been around 40-50 degrees fareneheit. I can see the effects of global warming all around me happening rapidly it seems. Can the tilt of the Earths axis be directly related to global warming? If so, what is causing the Earth to go off tilt?

Answer
Hello,

There is absolutely no evidence that the tilt of the Earth's axis plays any significant role in global warming. All the evidence shows that it is the result of man-made greenhouse gases (particularly CO2) accumulating in the atmosphere.

This is also irrespective of the "Milankovitch hypothesis" (which postulates a number of orbital, other changes over long times) which - so far as most astronomers go - remains mostly in the realm of speculation, with little other than coincidental geologic evidence to support it.

In her book 'Greenhouse', Penguin, 1999, pp. 170-71, Prof. Gale Christianson notes (p. 171) that from the 'frozen record'of ice cores:

"Never has the Earth remained cool when the CO2 concentration was high", and conversely there is no record of an ice age except when CO2 levels dropped below some 200 ppm."  

Serious climate researchers (such as Gunther Weller – who was at the University of Alaska, Fairbanks when I was there in 1985-86) already believe we're in the first stages of a positive feedback, non-linear effect that is leading right into the maw of a possible runaway greenhouse.

The basis has already been described by Sagan and others: Melting of ice caps (already occurring) results in diminished albedo (reflection of solar radiation back into space), and a darker Earth surface - with more IR (infrared or heat energy) absorbed - enhancing global warming.

At the same time global warming is accelerated in the oceans, and both El Nino and La Nina are ramped up in the unfolding panorama of global warming (cf. S. George Philander in Eos, March 31, 1998, ‘Who is El Nino?’) . In the meantime, we have new evidence that the melting permafrost (e.g. in Alaska) is releasing 25- 100 times more greenhouse gas as methane and CO2.

As more ice melts from the polar regions, positive feedback proceeds faster. The overall (mean) ocean temperature continues to rise - ultimately becoming too hot for any marine life- and reaching equilibrium temperature somewhere in the next 500 years. All ocean currents, circulation systems will, of course, cease. With atmospheric circulation soon following (as on Venus) , all solar energy going into heating the oceans until their specific heat capacity is reached.

Few current climate scientists raise the specter of the runaway greenhouse - perhaps not to create overt alarm - but it is definitely there.

The relative contributions of the respective greenhouse gases can be given in a table as follows - in terms of time duration in the atmosphere, and power per sq. meter:

Greenhouse gases:

Carbon Dioxide >100 years, 1.3 to 1.5 W/m^2

Methane ~10 years, 0.5 to 0.7 W/m^2

Tropospheric Ozone 10-100 days, 0.25 to 0.75 W/m^2

Nitrous Oxide ~100 years, 0.1 to 0.2 W/m^2

Perfluorocarbon Compounds >1000 years, 0.01 W/m^2 (Including SF6)

Fine Aerosols:

Sulfate 10 days -0.3 to -1.0

Black Carbon 10 days 0.1 to 0.8

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As you can see from the above, CO2 is definitely the most efficacious contributor.

Using these inputs, the GCM (General Climate Model) has arrived at its prediction of an Arctic air temp. increase of ~5 C by 2100

This may actually be an *under-estimate* since dust and aerosol particles in the atmosphere are probably reducing the warming effect by up to 15% or more. If and when that particulate matter is removed, temps. worldwide will spike even further.

Even before the recent National Academy of Sciences report came out (basically validating that anthropogenic warming is real)  The American Geophysical Union had issued a much more cogent position statement than its earlier one in 1998. From the new statement (cf. Eos, Vol. 84, No. 51, December, 2003, p. 574:

"Human activities are increasingly altering the Earth's climate. These effects add to natural effects present over Earth's history. Scientific evidence strongly indicates that natural influences cannot explain the rapid increase in global near-surface temperatures observed during the second half of the 20th century.

Human impacts on the climate system include increasing concentrations of greenhouse gases, air pollution, increasing concentrations of airborne particles and land alteration. *A particular concern is that atmospheric levels of carbon dioxide may be rising faster than at any time in Earth's history, except possibly following rare events like impacts from large extraterrestrial objects*.

In terms of the last statement, this is a reminder that we’re approaching catastrophic climate change. Since the 'rare events' referred to here were two asteroid strikes that altered the Earth's climate - the last 65 million years ago, wiping out all the dinosaurs in a literal cosmic 'heartbeat'.

The AGU statement continues:

"Atmospheric carbon dioxide concentrations have increased since the mid-1700s through fossil fuel burning and changes in land use, with more than 80% of this increase occurring since 1900. Moreover, research indicates that increased levels of carbon dioxide *will remain in the atmosphere for hundreds of thousands of years.* "

This last is cognizant of the fact that CO2 accumulates because earlier depositions remain even as new burdens are added yearly! Thus, the CO2 warming we’re now experiencing is not the result of just one year – but 100 years’ accumulation. The process may be described something like a series with terms being added, viz: to describe the CO2 content now in the atmosphere, we must initiate the series with n= 1 (for 1906), viz.


CO2( 2006) = x_1 + x_2 + x_3 + x_4 +.............+ x_100

E.g. terminating at the last term 100 years later. Here each ‘x’ denotes the CO2 burden added for each year in succession.

Thus, the CO2 effect for a given year is not just for that year, but rather inclusive of the cumulative additions for all the years - starting up to 100 years before!

This means things can only get worse.

The AGU 2003 position statement goes on for another 12-14 lengthy paragraphs noting the complexity of the problem, but also the urgency in solving it or at least getting better predictions. It also suggests ways and means of doing this, e.g. "enhanced international research."

Now, while not everyone yet agrees we are approaching an emergency – most climate scientists of any repute argue that we cannot afford the luxury of waiting any longer for “absolute proof” to arrive. We must act now, or face dire consequences – and have future generations curse us forever for our inertia, inaction and fobbing responsbility onto natural agents or causes.

The bottom line, and most pertinent aspect of your question - is that we cannot blame ancillary external agents ("natural warming cycles", etc.) or processes on what is happening to the planet. It is time we recognized that, and began taking responsibility. We may not have much more time in which time to act.