On Tuesday, President Barack Obama announced new measures to combat global warming.
Vigorous discussions about whether these are the best policy responses are almost sure to follow. These discussions are likely to be more productive if they start from the solid scholarship showing that we will be better off if we respond wisely to the coupled challenges of energy and environment.
Our use of fossil fuels produces roughly 40,000 pounds of carbon dioxide per person per year in the United States, and data clearly show this CO2 accumulating in the atmosphere and oceans.
The warming influence of the CO2 is well-understood based on well-tested physics discovered more than a century ago and explored extensively by the Air Force after World War II for reasons such as sensors on heat-seeking missiles.
The Earths temperature continues to rise despite a slight dimming of the sun and increased blocking of some sunlight by particles from dirty smokestacks and volcanoes.
If you wanted to warm a meal of leftovers in your microwave, you could heat all the dishes at the same time. Or you could heat the chicken first, then the potatoes and then the peas. Each individual dish would heat faster, although taken together you wouldnt save time.
The Earth is somewhat similar: Over the past decade, warming of the air has slowed as more heat has transferred into the deep ocean, and the previous decade saw accelerated air warming with less going into the deep sea.
But the Earth does not have the option of eating one dish cold. The recent slowdown in warming the air bought us time, but our CO2 is still pushing us toward hotter temperatures in air and water.
The first degree or so of warming is enough to confirm our scientific understanding, but the costs are still relatively small. But, as temperatures move outside the range of past experience, the costs go up, with each degree of warming projected to cost notably more than the previous degree.
Initially, the losers are mostly poor people in hot places or people not yet born but the damages are projected to spread to affect almost everyone.
We must pay to dispose of the almost 1,000 pounds of trash per person per year that we generate in our homes, but the damages from the roughly 40 times more CO2 from our energy system are paid by society and not by those burning the fossil fuels.
This subsidy for fossil fuels distorts markets, leading to inefficiency.
We have chosen to outlaw some actions that harm others, such as using your neighbors yard as an outhouse. We enjoy the good we get from the energy stored in fossil fuels, so serious modern efforts to reduce the damages from CO2 emissions do not contemplate similar bans.
Instead, these efforts focus on leveling the playing field by removing fossil-fuel subsidies. And, because fossil fuels have been boosted for decades by government-funded research and targeted tax breaks, similar help is often suggested for renewable energy sources.
The great body of scholarship showing damage from CO2 points to ways forward. Responding to this challenge of the environment, while recognizing the value of the energy we now get from fossil fuels, can lead to solutions that increase the size of the economy and the number of jobs while improving national security, preserving endangered species and respecting the Golden Rule by avoiding damage to future generations and to poor people in hot places now.
Richard Alley is Evan Pugh professor of geosciences at Penn State. Michael Mann is distinguished professor of meteorology. Both are associates in the Earth and Environmental Systems Institute.