You actually can't say how much renewables are reducing carbon output, because you have no idea how much energy consumption there would be without renewables. If 100% of the growth in energy consumption is caused by increased use of renewable energy, then renewable energy hasn't reduced carbon output at all. We could have achieved precisely the same carbon output simply by reducing our energy consumption.
Those who do not understand the Jevons Paradox are doomed to destroy the planet. It's about efficiency, but it applies to anything that reduces the cost (by any metric we care about) of consumption.