MOTR wrote on Mar 7^th, 2012 at 2:22am:


neither is there any logic in assuming that current warming MUST be the result of human co2 emissions!

Models are models, I generate computer models in my work too, however I do this to find an appoximate answer, I don't start with the answer then adjust the model until it reflects what I believe to be true.

Actually, the discipline of geology is full of people who have real doubts about AGW, but what would we know? we only study the Earth.. Oh and thats right..were in the pay of big Oil companies...lol, can you tell me where to send my invoice? I'm still waiting for my cheque

In conclusion - what does the geological record tell us about the potential effect of continued emissions of CO2?

Over at least the last 200 million years the fossil and sedimentary record shows that the Earth has undergone many fluctuations in climate, from warmer than the present climate to much colder, on many different timescales. Several warming events can be associated with increases in the ‘greenhouse gas’ CO2. There is evidence for sudden major injections of carbon to the atmosphere occurring at 55, 120 and 183 million years ago, perhaps from the sudden breakdown of methane hydrates beneath the seabed. At those times the associated warming would have increased the evaporation of water vapour from the ocean, making CO2 the trigger rather than the sole agent for change.

During the Ice Age of the past two and a half million years or so, periodic warming of the Earth through changes in its position in relation to the sun also heated the oceans, releasing both CO2 and water vapour, which amplified the ongoing warming into warm interglacial periods. That process was magnified by the melting of sea ice and land ice, darkening the Earth’s surface and reducing the reflection of the sun’s energy back into space.

While these past climatic changes can be related to geological events, it is not possible to relate the Earth’s warming since 1970 to anything recognisable as having a geological cause (such as volcanic activity, continental displacement, or changes in the energy received from the sun). This recent warming is accompanied by an increase in CO2 and a decrease in Arctic sea ice, both of which – based on physical theory and geological analogues - would be expected to warm the climate. Various lines of evidence, reviewed by the Intergovernmental Panel on Climate Change, clearly show that a large part of the modern increase in CO2 is the result of burning fossil fuels, with some contribution from cement manufacture and some from deforestation44. In total, human activities have emitted over 500 billion tonnes of carbon (hence over 1850 billion tons of CO2) to the atmosphere since around 1750, some 65% of that being from the burning of fossil fuels. Some of the carbon input to the atmosphere comes from volcanoes, but carbon from that source is equivalent to only about 1% of what human activities add annually and is not contributing to a net increase.

In the coming centuries, continued emissions of carbon from burning oil, gas and coal at close to or higher than today’s levels, and from related human activities, could increase the total to close to the amounts added during the 55 million year warming event – some 1500 to 2000 billion tonnes. Further contributions from ‘natural’ sources (wetlands, tundra, methane hydrates, etc.) may come as the Earth warms. The geological evidence from the 55 million year event and from earlier warming episodes suggests that such an addition is likely to raise average global temperatures by at least 5-6ºC, and possibly more, and that recovery of the Earth’s climate in the absence of any mitigation measures could take 100,000 years or more. Numerical models of the climate system support such an interpretation.

In the light of the evidence presented here it is reasonable to conclude that emitting further large amounts of CO2 into the atmosphere over time is likely to be unwise, uncomfortable though that fact may be.

hmm...so...whats the Null hypothesis to Anthropocentric Global Warming? That weather events stay the same as in the past? That there is no change? that weather remains constant and the climate holds within 0.1 of a degree globally averaged for 100 years?

If any of these things ever did happen, it would be highly unusual! Climate changes, always did, always will.

(I won't bring up the burgess shale if you don't try the "rate of change argument!")

There is no logic whatsoever to the argument that because climate changed in the past anthropogenic increases in atmospheric CO2 are not forcing current changes.
- MOTR

Absolutely agree Motr.  I find that the deniers consider that humans are either;
- too unimportant to have such effects, or
- somehow are divorced from the earth,above it, like we don't REALLY live here, and therefore we can do anything we like, without consequences.!!.

Its like some holy belief.!!! I shake my head in amazement at the Folly.!!

topend geo wrote on Mar 7^th, 2012 at 7:34am:


It is mischevious to suggest that proof of anthropogenic warming rests on computer models. There are numerous lines of independent evidence that do not rely on computer models. Computer models are used to test certain hypotheses and predict possible outcomes. The case for AGW does not stand or fall on the latest computer model. To suggest this shows a real lack of understanding of where other disciplines are at.

topend geo wrote on Mar 7^th, 2012 at 6:52am:


http://www.skepticalscience.com/images/recon_lj_with_others.png