How can we reduce the amount of greenhouse gases that humans emit?

Answer

Changing the way we make and use energy is an enormous challenge that will take decades, and a lot of resources and willpower, to accomplish.

What level of resources? It is hard to say for sure, but the Stern Review, a well-respected recent study on the economics of climate change, says it could cost as much as $2 trillion per year to stave off the worst effects of climate change by the year 2050. That is a huge number — but inaction is likely to cost even more. According to the Intergovernmental Panel on Climate Change, or IPCC, climate models suggest that if we keep burning fossil fuels on a “business-as-usual” basis, people around the world will experience dislocations for which the economic, environmental, and human costs will be huge.

Sea-level rise projected by the climate models would require relocating whole cities, which would be costly. Providing water to the estimated 500 million people whose supplies would fall below sustainable thresholds would be costly. Feeding the world’s population, as changing weather patterns put severe pressure on agriculture, would be costly. Based on the Stern Review, it is estimated that by the year 2050 the cost of adapting to climate change could be anywhere from $10 to $40 trillion per year.

The year 2050 seems far in the future, so it is tempting to delay action on climate change for a while. Unfortunately, the longer we wait to start, the more expensive it will be. It is kind of like losing weight — if your goal is to get down to 150 pounds, it is a lot easier if you start dieting when you weigh 160 pounds rather than wait until you weigh 220 pounds. The same goes for climate change — it is easier, and cheaper in the long run, to tackle the problem before it gets too far out of hand.

Fortunately, there are ways of slowing the rate at which we add greenhouse gases to the atmosphere that actually save money. These are familiar ideas like switching to more efficient cars, heating and air conditioning systems, light bulbs, and appliances; and putting better insulation in homes and buildings. But these actions can only take us so far. To reduce emissions of heat-trapping greenhouse gases to a relatively safe level, experts on the economics of energy and climate believe we’ll have to do much more—like make a transition from the extensive use of fossil fuels to using lots more wind and solar energy. And, if we continue to use fossil fuels to generate electricity, then we must capture and sequester — that is, bury — the greenhouse gas emissions.