I'll resolve to a percentage split based on the input of a climate expert I know.

Climate change doesn't have to be "fixed" by 2065, just under control and on track to be solved. Think about how the Ozone Layer hole was solved with an international ban on HFCs, but the hole has taken decades to actually heal. e.g. this chart should be trending comfortably downwards in forty years' time.

Feel free to suggest more answers.

DEFINITIONS:

• Geoengineering - e.g. emitting particulates into the atmosphere which will reduce Earth's albedo

• Emissions Reductions - e.g. Smokestack Scrubbing, Hybrid/Electric Cars, Low-Energy Washing Machines, LED lights replacing incandescent bulbs.

• Consumption Reductions - e.g. Vegetarianism, Subways and Bicycles instead of Automobiles, Less packaging on consumer goods, people turning off the lights when they leave their homes.

• Total Technological Paradigm Shift - Any technological development that turns climate change into a trivial problem. If humans all upload their brains into computers and so no-one consumes physical goods anymore, or if asteroid mining makes us so rich that direct air capture costs pennies, if a superintelligent AI computes a simple scaleable solution, etc.

• Human Extinction - Also encompasses massive population declines but I went with the punchier title.
  
  THE FINE PRINT:

• Many of these options occupy different layers of the process, and so could stack on top of each other, e.g. International Cooperation might create a global Carbon Tax which would lead to more Renewables. In that case, the percentages are allocated to the one deemed to be the driving force. The spirit of this question is: where would today's climate R&D dollars get the most bang for their buck? So if a superintelligent AI invents a bacterium that processes all CO2 in the atmosphere into O2, this resolves to Total Technological Paradigm Shift not Carbon Capture or Bioengineering, because in retrospect, your R&D dollars were best allocated into $NVDA rather than carbon capture technologies, even though carbon capture was the proximate cause of the carbon decline.