Figuring out how to do that economically and at scale includes a number of research problems. How do we generate power, produce concrete, do metallurgy, transport goods, fly airplanes, etc. without greenhouse gas emissions? How do we capture and sequester greenhouse gas emissions? How do we develop closed-loop sources for chemical fuels? How do we store energy in the power grid?
Perhaps what you meant was that we have the technology to do it without completely abandoning industrial civilization--though maybe people will have to sacrifice some things, like eating meat, driving private cars, or living in climate-controlled private spaces. And maybe that's an easier sell. But it's also a false dichotomy. Developing the technology to reach higher levels of carbon neutrality more quickly and more economically can and must happen at the same time that we do what we can today. Building more renewable power generation can happen at the very same time that we prototype carbon capture systems for natural gas power plants, battery-electric vehicles, or Sabatier-process closed-loop carbon-neutral natural gas production (which, incidentally, is also something we'll need on Mars). We can build Generation III nuclear plants now while researching Generation IV nuclear plants to build later. We can work now on making all of our technology more energy-efficient while developing fusion power to deliver unlimited, carbon-neutral energy for generations to come.
However, the reality is that people like the current situation and prefer government intervention in favor of carbon emitters. This unfortunately leads to situations where subsidies to e.g. coal based electricity generation have to be matched by subsidies to zero carbon electricity generation just to have any impact at all.
Alternative technologies already exist but there is no reason to use them because conventional technologies are blessed by the government. Of course you can forcibly pump money into them and eventually get the result you desire but only at a higher cost.
In Germany people absolutely disliked the idea of a revenue neutral carbon tax where every tax payer would receive a share of the collected tax back at the end of the year. Instead the government introduced a minimum price on CO2 certificates which is basically the same thing except it is not revenue neutral but hey at least it's not a "tax" so the uneducated mob won't come after you. People think they understand taxes but when you show them something "complicated" like a cap and trade system they suddenly don't understand a single thing.
It's specifically about 'don't spend more money on X' (X being larger particle colliders) than about the specific examples A, B, C, of alternatives it mentions (climate research center, epidemic studies).
But yea, if we do our jobs, its work will be less significant. Let's try to make that happen.
Whether we build another giant particle accelerator or two (reminder: Not only CERN is interested, but China is already well down that path) is almost irrelevant if we don't fix our pollution and destruction of the ecosystems that allow Homo sap. to live comfortably (or, possibly, at all).