Quick Points:

•  wind has already shown its ramp up capability several times in the last decade or so. with stable regimes the ramp up of the supply chain could border on the astounding.

•  PV has already shown its capabilities, can do rooftop globally very quickly , two decades if necessary.

•  all manner of efficiency technologies can do the same.

•  When there's a political desire to achieve something, it gets done. There is nothing in the way of a huge ramp up of sustainable technologies except modern civilization.

•  Whenever there's a hole, new developments fill it.

As a weird example, here's a report of a new technology allowing coal plants to be load following being done in 'Schland, from Der Spiggle.

Conventional power plants grind coal into dust, which is then blown into a boiler. But in Niederaussem, the pulverized coal is first stored in a silo, making it possible to control much more closely the amount that is later fed to the flame. German energy giant RWE originally built the silo in Niederaussem to make fueling its power plant easier. But the German energy revolution has lent the silo system an entirely new dimension.

A power plant with a silo can run on a low level if necessary. It can be powered down to 10 percent of its maximum output, a function that's impossible for plants without a silo. Even the most modern conventional facilities can go no lower than 35 percent of maximum performance. Operating at a capacity any less than that requires laboriously keeping the combustion going by burning oil or gas -- an option that's far too expensive.

Silos for storing coal dust represent just one of several new technologies that are helping coal-fired power plants shape up for the transition to renewable energy. Time is short. Germany's environmental revolution will mean major upheavals for coal plant operators, and the new electricity supply system will subject them to grim competition.
....
This new system leads to ever greater fluctuations in power generation, with output changing with every gust of wind and every cloud that flits across the sun. Hitachi Power, a Japanese company that builds power plants, estimates these fluctuations will double or triple by the end of the decade, while at the same time the demand for electricity from non-renewable sources will drop by half between 2010 and 2020.

Soon the demand for electricity will likely no longer be enough to keep all the existing coal-fired plants in business, and those that want to continue selling as much conventionally generated energy as possible in this shrinking market must be able to react quickly to fluctuations in supply and consumption. Once this was something only gas-fired plants were able to do, but coal-fired plants are now preparing to challenge them for the role of a flexible provider that can make up shortfalls. Coal and gas power, once partners, are suddenly becoming competitors in a shrinking market.

So Yes, in the mid-term, there will be ways to balance the system, and as long as some form of basic intelligence prevails, the goal of drastically lowering CO2 can be accomplished, even by using what's already built and dirty.

"Life shrinks or expands in proportion to one's courage." - Anaïs Nin