When they worked out how the ice would disappear, they failed to take both methane quantities and political inadequacy would affect the warming of our globe. With the past century alone accounting for 0.8 degrees C. of warming, the rate of warming must be slowed. One of the little known reasons is that we don't know how to cool the ocean depths, once we have caused them to warm.
According to the latest open access review by James Hansen of Columbia University, our projected and almost inevitable 2 degrees C. of warming will be a disaster, and slow climatic feedbacks make it likely we will exceed the 2 degrees easily. With 17 illustrious colleagues they review all evidence in PLoS ONE's Assessing "Dangerous Climate Change": Required Reduction of Carbon Emissions to Protect Young People, Future Generations and Nature. Some of our own material on climate change (and failing conferences).
When reforestation and better agricultural technique kick in, the net land use carbon of the past could be demolished. CCS (carbon capture technology) can be regarded as a possible help, but the progress on such old technology is painful. If, as some models show, we have in fact produced twice as much carbon as we thought, reduction of land use carbon will be more difficult. However, the potential for more carbon absorption in many ways can be nothing but useful, once it is achieved.
Calculations make for a 3 degree C. rise in earth temperature, given only the current situation. If nations continue to us coal, gas, oil and now shale I, the end is never reached. We simply heat up in our own pollution. The methods of optimistically calculating fossil fuel reductions and net results may cause us distress in the future. What is clear is that rapid carbon emission reduction must begin now. From Europe to China, North American shale oil and Australian coal, thee plug has to be pulled. Profit from the use of fossils is an obvious motive. That has to be removed from the international companies and even the individuals caught up in the net.
We have no idea of whether "new" factors will be negative or positive for global warming. What we do know is that the risk so far has proved to be wrong. If we risk it any further, our descendants are still stuck in a world of warming for centuries. As the researchers here put it, "as one of these climate forcings increases, it increases the others. The good news is that, as one of them decreases, it tends to decrease the others."
Government is the essence. We have politicians who will tell you today that they want to go nuclear, to save carbon. Even worse, some want to make profits from cheap and simple tar oil and shale gas. What makes it cheap is the mass of events that are recorded every time somebody sticks his pipe in the ground. Inherently unsafe, the costs are enormous, in both health and ensuring safety for local and other communities. James Hansen and his many colleagues believe political feasibility is the crime we all have committed against us. These so-called "leaders" have to stop following fossils and drop them for renewables with slogans involving job creation, new technology and the improved human condition. It is totally misleading to announce that fossil fuel extraction is the only way to create jobs.
When the UN HQ opens its doors to climate again in September, it will be to create an "atmosphere" literally for Paris 2015. Like the 1997 Kyoto Protocol it may lead to climate deterioration and injustice for the planet. We have to follow Norwegian leads and not Poland. We must emit like the Pacific islands and not the US. Russia has to stop using the Arctic as a productive backyard and every country has to improve attitude. Without all of this, the future is certain.