The price drop in $ per kWh generated by solar, wind and hydroelectric, etc, has nothing to do with the growing concentration of greenhouse gases. You can look at greenhouse gas causing figures such as how many megatonnes of coal are burned each year, how many barrels of oil Canada exports to the USA each year, they're all on a steady climb.

The world has an inexorable thirst for energy. It's great if there are more watt-hours being generated by green sources, but at the same time, there is what seems to be an inexorable growth in pollution causing sources. Example: Look at how many cars are sold each year to the growing middle class in China and India.