We put greenhouse gases into the air by burning fossil fuels. We can replace fossil fuels and take greenhouse gases out of the air using renewable energy.
Today we can build solar energy plants whose cost to build are several times less than the value of energy they create over their operational life. There are millions of square kilometres of desert areas suitable for solar installations. With solar panels of 15% efficiency, we can generate all the primary energy the human race currently uses with 1,000,000 square kilometres of the desert or less than 5% of desert areas. We can use some of the energy to replace burning fossil fuel. We can use some to take greenhouse gases out of the atmosphere while creating valuable products such as liquid fuel, building materials, foods, plastics. In doing this we will reverse global warming.
Assuming one panel is 1.6 square meters we need 625,000 panels to cover one square kilometre. Last year the world produced about 250,000,000 panels or enough to cover 400 square kilometres. Last year production more than doubled. If it continues doubling then in eight years enough panels to cover 250,000 square kilometres will be constructed each year. History tells us that each doubling of capacity reduces unit costs by about 15% so after eight years the cost of panels will drop to one-quarter the current price.
We can do this, and we can fund the construction from the value of future energy output.
The main barrier to doing this is not technical nor economic nor even directly political. It is the way we allocate capital through the use of interest-bearing money. If we replace interest as the way we give investors returns and repay them with more energy instead of money, the funds to build and deploy solar farms will be available as we remove the cost of interest.
Removing the time value of money will increase the economic output of human-kind because renewable energy is highly profitable.