Yes, insurers telling G20 to stop funding fossil fuels by 2020 will have an impact on renewable energy funding. The message that the insurers are sending to G2, and to the world really, is that it is unsustainable to continue using and relying on fossil fuels. In my opinion it is the insurers, worth $1.2 trillion, who will probably have more influence on the G20 as opposed to the scientists who have been recommending the end of fossil fuel use for years now.
Putting a timeline on the funding of fossil fuels will have an impact on the funding for renewable energy funding as money and research shifts toward finding more renewable energy sources. Change is expensive, but if G20 is forced to stop funding fossil fuels by a certain time, then they will likewise be forced to put money into other energy sources.
Yes, having insurers tell G20 to stop funding fossil fuels by 2020 will have a huge impact on renewable energy funding. People need some sort of fuel for energy. If fossil fuel usage diminishes greatly, then something has to replace it. The new fuel will be solar, wind, ocean currents, and other forms of renewable energy.
Although $1.2 trillion is an impressive number, the oil companies and the associated businesses are much, much larger. And as long as money is flowing from those companies to our government, there will be some excuse about why we need to continue to subsidize fossil fuels. The market will decide to abandon them long before governments.