he (Arrhenius)suggested that the human emission of CO2 would be strong enough to prevent the world from entering a new ice age, and that a warmer earth would be needed to feed the rapidly increasing population. He was the first person to predict that emissions of carbon dioxide from the burning of fossil fuels and other combustion processes would cause global warming. Arrhenius clearly believed that a warmer world would be a positive change. From that, the hot-house theory gained more attention. Nevertheless, until about 1960, most scientists dismissed the hot-house / greenhouse effect as implausible for the cause of ice ages as Milutin Milankovitch had presented a mechanism using orbital changes of the earth (Milankovitch cycles). Nowadays, the accepted explanation is that orbital forcing sets the timing for ice ages with CO2 acting as an essential amplifying feedback.
Did you know that all data relating to CO2 in the atmosphere is restricted to 800,000 years?
All the rest of our information is based on scientific models aka conjecture.
Ice cores provide evidence for variation in greenhouse gas concentrations over the past 800,000 years. Both CO2 and CH4 vary between glacial and interglacial phases, and concentrations of these gases correlate strongly with temperature. Before the ice core record, direct data does not exist. However, various proxies and modelling suggests large variations; 500 million years ago CO2 levels were likely 10 times higher than now. Indeed higher CO2 concentrations are thought to have prevailed throughout most of the Phanerozoic eon, with concentrations four to six times current concentrations during the Mesozoic era, and ten to fifteen times current concentrations during the early Palaeozoic era until the middle of the Devonian period, about 400 Ma.
The Phanerozoic represents a relatively brief period of half a billion years (brief that is relative to the age of the Earth and the universe) that constitutes the age of multicellular animal life on Earth. During this time micro- and multicellular organisms left a detailed fossil record, and built up complex and diverse ecosystems, and life has evolved through countless transformations and millions upon millions of species
The spread of land plants is thought to have reduced CO2 concentrations during the late Devonian, and plant activities as both sources and sinks of CO2 have since been important in providing stabilising feedbacks. Earlier still, a 200-million year period of intermittent, widespread glaciation extending close to the equator (Snowball Earth) appears to have been ended suddenly, about 550 Ma, by a colossal volcanic outgassing which raised the CO2 concentration of the atmosphere abruptly to 12%, about 350 times modern levels, causing extreme greenhouse conditions and carbonate deposition as limestone at the rate of about 1 mm per day. This episode marked the close of the Precambrian eon, and was succeeded by the generally warmer conditions of the Phanerozoic, during which multicellular animal and plant life evolved. No volcanic carbon dioxide emission of comparable scale has occurred since. In the modern era, emissions to the atmosphere from volcanoes are only about 1% of emissions from human sources.So what evidence do we have that CO2 directly affects climate change?
We could start with the current scientific consensus. Of course consider this,
In 1938, G.S. Callendar argued that the level of carbon dioxide was climbing and raising global temperature, but most scientists found his arguments implausible.
Fast Forward to 1986
Would the climate changes expected to result from a doubled CO2 level, a level the world might reach a century ahead, in fact come upon them twice as fast — perhaps within their own lifetimes? The next year Robert Dickinson and Ralph Cicerone addressed the question with a calculation based on the new estimate of the effects of all greenhouse gases. They figured that by the year 2050 global temperature could rise several degrees, "and possibly by more than 5°C," if self-reinforcing feedbacks took hold. The 22nd century would be even worse.
We are still dealing with forecasts and calculations not evidence.
Did you know that methane is considered a significant greenhouse gas?
|After Ramanathan identified methane as a significant greenhouse gas, studies of its role in global carbon cycles accelerated. During the 1980s, scientists came to see that although the methane in the air comes largely from plants and animals, that did not mean human effects were negligible. For humanity was transforming the entire global biosphere. Specialists in obscure fields of research turned up a variety of biological methane sources that were rapidly increasing. The gas was abundantly emitted by bacteria found in the mud of rice paddies and in the guts of cud-chewing cows, among other places. And what about accelerated emissions from the soil bacteria that proliferated following deforestation and the advance of agriculture? Moreover, natural biological activity could be altered by the rise of CO2 levels and by global warming itself, making for complicated and enigmatic feedbacks.|| |
|The importance of all this was driven home by a tentative 1981 report that methane in the atmosphere was increasing at an astounding rate, perhaps 2% a year. The following year, a study of air bubbles trapped in ice drilled from the Greenland icecap confirmed that methane was climbing. The climb, radically different from any change that could be detected in past millennia, had started in the 16th century and accelerated wildly in recent decades.(20) By 1988, painstaking collection of air samples at many remote locations gave an accurate measure of the recent rise. The actual rate of increase was about 1% a year, bringing a shocking 11% increase of methane in the past decade alone. (Later studies found the rate of rise varying greatly from year to year. During the 1990s the rise levelled off, for uncertain reasons, but most scientists expected the climb must eventually resume). Each molecule of methane had a greenhouse effect more than twenty times that of a molecule of CO2. In addition, some of the methane was converted into ozone and water vapor in the stratosphere, where they would exert their own greenhouse effects. It seemed likely that the rising methane level was already having a measurable impact.|
Strange that CO2 is now the talk of the town and nobody mentions methane and climate change.
By 2009 many scientists believed the effects of nitrates had been seriously underestimated. Indeed, replacing fossil fuels with "biofuel" manufactured from corn might increase global warming, thanks to the emissions from soil bacteria stimulated by the fertilizers used to grow the corn. The more scientists studied the emissions of this and other nitrogen compounds such as nitrates, the more confused they got. Not only was it hard to measure how much was emitted, but the compounds reacted in complicated ways with smog chemicals, ozone, methane and CO2. Meanwhile nitrogen compounds fertilized plants and ocean plankton. Some of the interactions resulted in more greenhouse warming, while others removed greenhouse gases and would have a net cooling effect.
So, the complexity of the effects of N2O and methane on the atmosphere seem to show that scientists really don't understand what they pretend to understand.
What about those computer models you say?
Computer models offered only limited help. A survey found many differences among models in how they handled the chemical interactions among trace gases and between the gases and aerosols. Some models were afflicted with elementary errors of chemistry or computer coding. The best that could be said was that about half the models agreed reasonably well with observations and with one another, so that "some confidence can be placed in their predictions." The uncertainties made it hard to come up with defensible policies.
Now let's start to panic.
Having at some point accepted that CO2 is the main culprit of greenhouse effect/climate change, although reading the above you would wonder why, we now read this,
An international team of researchers has found that, since 2000, the rate at which CO2 has been pumped into the atmosphere is 35 per cent greater than most climate change models have allowed for.
The conclusions have serious implications for forecasts of how much and how quickly the world’s temperature will rise and mean that global warming will be harder and more expensive to control than feared. The results also mean that international efforts to bring CO2 emissions under control will need to be more far-reaching.