There are two sides to the arguments over whether the 2 degree Celsius limit is the right one to have for the planet. Leading climate scientists, particularly Professor Jim Hansens, argues that there will be catastrophic consequences with a 2 degree limit, and we should aim for 1 degree. Others say that it is too costly and unfeasible to try to achieve the 2 degree limit, and we should instead try a bottom up approach to climate change mitigation. A 2 degree warming might see up to 6 meters of sea level rise. It might also cause slope amplifying feedbacks, such as the Amazon forest dying off from drought and causing the release of massive amount of CO2 into the atmosphere to further aggravate climate change, or the release of CO2 that is currently buried in the permafrost of the tundra that is melting. However, there are those who claim that staying within the 2-degree limit is too difficult. Evidence points to the fact that this is feasible even assuming business as usual, economic growth and development, using technologies that are already commercially available or that simply need more R&D to be deployed at a scale necessary for deep decarbonization. This needs to be acted upon quickly. The cost of mitigating climate change must be compared to the cost of climate change itself, and models to do this often do not take into account the direct impacts on the environment and human health of climate change, what are called non-market impacts, and the true responsiveness of the climate system to greenhouse gas emissions. Climate change modeling frameworks must also take into account ethical judgements on the distribution of income and how to treat future generations, as well as social impacts of climate change. GDP is too narrow an indicator, but estimations of the costs of climate change mitigation can be done by looking at the resource costs of measures or to use macroeconomic models to explore the system-wide effects of the transition to low common economies. This video is part of the module The 2-Degree Limit.

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