• Based on the principle of utility, we should do the geoengineering.
Because if we can solve the problem of climate change, the negative influences that climate change brings will disappear and people won't suffer from it. In other words, it maximizes the utility of human beings.
• The negative responsibility refers that we are not only responsible for what we cause, but also for the things that I fail to prevent.
In this case, if we do the geoengineering to solve climate change, we fail to prevent the long term negative side-effect. So, we cannot do the geoengineering.