Summary so far: to keep average global temperatures within 2°C by 2100, we’ll need to be a lot more energy efficient, reproduce less (not exceeding 9 billion by century’s end), and get really good at increasing agricultural productivity so that lots of land can revert back to the wilds. Scenarios associated with RCP2.6 show how this might be possible. In a typical RCP2.6 scenario, carbon capture technology would greatly reduce the GHGs produced by coal and natural gas. Bio-energy and renewables would also play a part – but not more than is already expected per current trends. And later in the century, nuclear energy would make a comeback.
Check out the following chart. On the right is an energy mix consistent with staying within 2°C by 2100. On the left is a scenario that assumes carbon capture and storage basically won’t happen.
It's obviously essential to make carbon capture and storage happen. On a huge scale.
Staying within 2°C by 2100 would also require that we do everything we can to reduce population growth. Which means to educate the women of the world, insure sufficient economic development to absorb their precious skills, and promote a global culture of female empowerment so that no woman has sex or bears children unless she wants to. Sorry mister: you ain’t having none except on my terms.
Anti-GMO activists would also need to be marginalized or see the error of their ways. More GM Agriculture = less land for agriculture = more reforestation and wild habitat.
Between major advances in carbon capture and storage, expansion of nuclear energy, female empowerment, and intensive, sustainable agriculture, staying within a 2°C rise by 2100 is within the realm. It is feasible.
Now, if only...
Reference:
van Vuuren, Detlef P. et al (2011) RCP2.6: exploring the possibility to keep global mean temperature increase below 2°C. Climatic Change; 109:95–116 DOI 10.1007/s10584-011-0152-3