In brief, the “sustainability” issue of climate change is really the unsustainable way we emit greenhouse gases. When we burn fossil fuels, we are simply dumping our trash into the atmosphere, much like taking out your household trash and dumping it in the backyard. There are a lot of humans and we’re dumping 37 billion tons of waste CO2 into the atmosphere every year. There is a linear relationship between human released CO2 and the level of CO2 in the atmosphere and rising temperatures, and without limiting greenhouse gas emissions the earth will, within a century, become a really unpleasant place for humans and a great many other animals to live. But the temperature rise won’t stop there. So, the sooner we reduce emissions, the less ongoing future damage will be done.

Fortunately burning fossil fuels for energy is really ancient technology like the bow and arrow, bloodletting, and doing laundry on rocks by the river. We have better technology now. Nuclear is a great, fossil fuel free, way to generate energy, but is somewhat expensive. Fortunately, high tech windmills and solar cells generate electricity more cheaply than fossil fuels even without considering climate change and health costs. Solar doesn’t even require a grid, and unlike fossil fuels it’s widely distributed, and sunlight and wind are free. Unlike coal, oil or gas.

We’ve looked at some of the ways we can reduce CO2 emissions, and the good news is that the investment required, while substantial, is quite manageable. And the operational costs going forward are much lower in many cases. We looked at what it would cost to replace a coal power plant with a windmill and found that it pays to tear down even a fully depreciated coal power plant and replace it with windmills. The cost of electricity from windmills, including the capital cost, is lower than the operating cost of the coal plant. Thinking about what it would take to “decarbonize” a family brings the required investment into focus:

• Electricity: replacing fossil fuel burning power generation with renewables saves money, so cost is zero to your family (your electric rates stay the same)
• Switching from a gas-powered car to an electric or plug-in hybrid: You’re going to replace your car eventually and the price of electric cars (which are easier to build) will come down to match that of gas-powered ones. Operational costs (electricity vs gas maintenance) will be lower with the electric car. Zero cost to your family.
• Heating and cooling your home: heat pumps are already used widely in warm locations. In places where families use fossil fuels to heat their homes, heat pumps will have to replace furnaces. This can require a significant one-time investment of say $20,000 in the US, but government subsidies are available to cover much of the cost.

There are two problems with this rosy picture. While the capital costs are quite reasonable, we have assumed that they will be met over time. You won’t ditch your two-year-old gas car for an electric one until you feel the need for a new car. There will be a shortage of qualified heat pump installers, and they will be expensive. Windmills and solar fields can only be constructed so fast, and undepreciated gas-powered generation plants are sunk costs. In short, the quicker we want to reduce carbon emissions, the higher the net capital costs.

The other problem is political. This is not a book about politics, but we can’t ignore the strong ties between implemented policy and money interests. There’s a lot of money made from fossil fuels. There will be a lot of pressure to slow decarbonization, push ineffective carbon offsets, and adopt expensive technologies such as carbon recapture and hydrogen from fossil fuels.

The above discussion focuses primarily on CO2 emissions from energy production. We have also seen that there are less tractable greenhouse gas emissions from agriculture and land use.

That said, the greenhouse gas abatement curves we’ve looked at show that we have the technology to get to “net zero” emissions by 2050 at a reasonable cost when measured against country and world GDP. The problem in the end is more political than technical or even financial.