There is no anthropomorphic global warming

"In your case, you argue that co2 is a green house gas and can be proven to be a warming agent. I do not disagree. Where I disagree is whether or not this co2 is causing today's warming. In most historical episodes of warming, co2 trails temperature. If it was a forcing agent, one would expect the exact opposite. Co2 has been much higher in the past and temperatures were lower: http://www.nolanchart.com...... "In fact, 450 million years ago when we were in the depths of the coldest period the Earth has had in half a billion years, CO2 levels were 10 times above today's! Even using the last century as evidence for a dependent relationship is meaningless. 65% of the warming this century occurred in the first three decades, and then, while CO2 levels continued to rise, temperatures fell for four decades in a row." ============================================================================== http://environment.newscientist.com... Ice cores from Antarctica indicate that at the end of recent ice ages, the concentration of carbon dioxide in the atmosphere started to rise only after temperatures had begun to climb. There is uncertainty about the timings, in part because the air trapped in the cores is younger than the ice, but it appears the difference might at times have been 800 years or more. This shows that rising CO2 was not the trigger that caused the initial warming at the end of these ice ages – but no climate scientist has ever made this claim. It certainly does not challenge the idea that increases in CO2 heats the planet. CO2 is a greenhouse gas because it absorbs and emits frequencies of infrared radiation. Physics tells us that gases with this property trap heat radiating from the Earth, that the planet would be a lot colder if this effect was not real and that adding more CO2 to the atmosphere will trap even more heat. Furthermore, CO2 is just one of a group of greenhouses gases, and greenhouse gases are just one of many factors affecting the climate. There is no reason to expect a perfect correlation between CO2 levels and temperature in the past: if there is a big change in another climate "factor", the correlation will be hidden. It takes around 5000 years for an ice age to end and, after the initial 800 year lag, temperature and CO2 concentrations in the atmosphere rise together for a further 4200 years. What seems to have occurred at the end of recent ice ages, some factor - most likely orbital shifts - caused a rise in temperature. This led to an increase in CO2, resulting in further warming that caused more CO2 to be released and so on: a positive feedback that amplified a small change in temperature. At some point, the shrinking of the ice sheets further amplified the warming. Models indicate that rising greenhouse gases, including CO2, explains for about 40% of the warming as the ice ages ended. The figure is uncertain because it depends on how the extent of ice coverage changed over time, and there is no way to pin this down precisely. The ice ages show that temperature can determine CO2 as well as CO2 driving temperature. Sceptics - not scientists - have seized upon this idea and claim that the relation is one way, that temperature determines CO2 levels but CO2 levels do not affect temperature. Higher temperatures lead to more CO2 and more CO2 leads to higher temperatures. There are multiple limiting factors that kick in, the most important being that infrared radiation emitted by Earth increases exponentially with temperature, so as long as some infrared can escape from the atmosphere, at some point heat loss catches up with heat retention. To put it simply, we have altered the way natural feedbacks systems operate via the way we change the planet's surface and atmosphere. That is the difference to "450 million years ago". This is the error in your argument. You are basing climate change purely on CO2 entering the atmosphere. Climate change is vastly more complex than that, and human influence is equally more diverse than that simple aspect. However since your sole argument is based on CO2 we will continue. Ice cores show that carbon dioxide levels in the atmosphere have remained steady between 180 and 300 parts per million for the past half-a-million years. In recent centuries, however, CO2 levels have risen sharply, to at least 380 ppm. Human emissions of CO2 are small compared with natural sources. The fact that CO2 levels have remained steady until very recently indicates that natural emissions are usually balanced by natural absorptions. Now more CO2 must be entering the atmosphere than is being absorbed via carbon "sinks". The consumption of terrestrial vegetation by animals and by microbes (rotting) emits about 220 gigatonnes of CO2 every year, and respiration by vegetation emits another 220 Gt. These amounts are balanced by the 440 Gt of carbon dioxide absorbed from the atmosphere each year as land plants photosynthesise. Likewise, parts of the oceans release about 330 Gt of CO2 per year, depending on temperature and rates of photosynthesis by phytoplankton, but other parts usually soak up just as much and are now soaking up slightly more. Human emissions of CO2 are now estimated to be 26.4 Gt per year, up from 23.5 Gt in the 1990s http://www.ipcc.ch... So are we to blame for the CO2 increase? There are several lines of evidence. Fossil fuels were formed millions of years ago. Therefore they contain virtually no carbon-14. Because this unstable carbon isotope, formed when cosmic rays hit the atmosphere, it has a half-life of around 6000 years. So a dropping concentration of carbon-14 can be explained by the burning of fossil fuels. Studies of tree rings have shown that the proportion of carbon-14 in the atmosphere dropped by about 2% between 1850 and 1954. After this time, atmospheric nuclear bomb tests ruined this method by releasing large amounts of carbon-14. Additionally fossil fuels contain less carbon-13 than carbon-12, compared with the atmosphere. These fuels are derived from plants, which preferentially take up the more common carbon-12. The ratio of carbon-13 to carbon-12 in the atmosphere and ocean surface waters is steadily falling, clearly showing that more carbon-12 is entering the atmosphere. Frankly your argument so far is based solely on the link to CO2 and temperatures. CO2 is not the only greenhouse gas neither is fossil fuel burning the sole reason for their increase. Deforestation removes natural carbon sinks, draining swamps releases large amounts of stored CO2 and methane. Similarly greenhouse gases are not the sole reason climate change is occurring. Factors relate and feed off each other; warmer air, warmer ocean currents etc. CO2 feeds off temperature, temperature feeds off CO2. It is flawed to say that humans are the sole reason for climate change because clearly it plays to natural systems. It is equally mistaken however to say that humans have had no substantial impact at all. Which brings us to "it is not true that anything that can cause warming is in fact causing current warming." that being self refuting rubbish. Clearly it has a cause(s). Recommended: http://www.ipcc.ch...