The Copenhagen Accord (December 2009) underlines that climate change is one of the greatest challenges of our time and emphasizes the political will to urgently combat it, in accordance with the principle of common but differentiated responsibilities. Also, it recognizes that deep cuts in global emissions of greenhouse gases are required to maintain the temperature increase below 2 degrees C; the limit to prevent dangerous interference with the climate system. Unfortunately, the proposed emission reduction commitments (mitigation) submitted to the Accord fall short of required levels. From the analysis of the present situation, a significant global warming during the current century appears to be inevitable, with likely catastrophic increases of temperature (4 degrees C by 2100). Urgently, all countries should establish comprehensive adaptation programs. Furthermore, in order to alleviate the situation, it will be necessary to appeal to all the available mitigation options, including short lived compounds and atmospheric CO2 sequestration techniques. The participation of developing countries is crucial, as they currently contribute with similar to 58% of global emissions, which are growing substantially. On the other hand, to confront an eventual climatic crisis, it may be a good idea to develop a plan B. At present, several geoengineering proposals which could counteract warming in a relatively short time after implementation, such as injection of sulfur compounds in the stratosphere, are being discussed. This would give some extra time for mitigation options, the real solution. Obviously, the intentional alteration of the climate system could have negative environmental consequences, which should be fully investigated before proceeding.