In 1896 the Swedish professor and founder of modern physical chemistry, Svante Arrhenius, completed a complex number-crunching exercise, according to which if the amount of CO2 in the atmosphere were reduced by a half, the temperature in Europe might decline by 4-5°C, in correspondence with an ice age. As an explanation for the conundrum of the ice ages, this notion could only hold water if a mechanism for such large changes in atmospheric composition might be found in the real world. A colleague of Arrenhius, Arvid Högbom, had investigated the cycling of carbon dioxide in nature, through geochemical processes, including emissions from volcanoes and uptake by the oceans, but in his reckoning he also included the emissions of CO2 from factories and other industrial processes, such as cement manufacture. Stacking up the numbers, he realised that human activities were adding CO2 to the atmosphere in a quantity and rate equivalent to all natural processes of absorption or emission of the gas. As it was put, a decade later, we were "'evaporating' our coal mines into the air'.
This succinctly expresses my understanding of the situation: that human (anthropogenic) emissions of CO2 are causing the global temperature to rise, and the consequences of this are likely to be catastrophic. There are complexities, however, and for example, some parts of the world appear to be warming and others cooling. Some regions are getting wetter and others drier. Substantial parts of the Antarctic (peninsular and western sheet) are melting, as has been the case for 7,000 years, but other parts in the East are actually getting thicker. I would suggest that these phenomena may be explained in part by changes in the way the heat energy from the sun is being redistributed around the globe. Undoubtedly, there are complex and holistic phenomena at work.
In some parts of the world sea-level is rising in others it seems to be falling. This could be partly due to faulty measurements. There was a play "The Heretic", which challenged the politics of climate change, performed at the Royal Court Theatre in London, and which I wrote about on Forbes:
Within the plot of the play at least, in one case, the land appeared to be falling rather than the sea-level rising, and in another, both land and sea were rising together, thus disguising the reality of sea-level rise, but within the plot, a university department would lose a lucrative grant if they told the truth.
I have no doubt that an elevated level of CO2 should increase the temperature of a solid massive object such as the Earth, with an atmospheric mix of gases including CO2, in accord with some calculations I have made made in collaboration with a German Engineer, Alexander Koewius: http://www.koewius.de/Website/Climate_Change.html.
However, the Earth system is complex, and for example, rather than the planet "frying", another scenario is that the melting of ice in the Arctic will switch-off the Atlantic Conveyor (of which the Gulf Stream is a part) so that Northern Europe experiences an effective ice-age. http://shadow.eas.gatech.edu/~kcobb/abrupt/alley07.pdf
Irrespective of the reality of anthropogenic global warming is the far more immediately pressing issue of a imminently failing supply of cheap liquid fuels for transportation. If it is true that we may expect a decline in the availability of cheap crude oil, and hence diesel and petrol fuels, upon which essentially all world transportation, manufacture and the production and transportation of food, and thus global growth depend, the news on the CO2 emission front must be good. If we have less cheap oil and fuel to burn, our carbon emissions will necessarily fall. This however is the least of our worries. If we can't find alternative fuels or the means to live at a lower energy consuming lifestyle then our civilization is condemned. We will have no choice but to curb our carbon emissions, and to do so by design rather than by default is the most pressing issue for humanity.