Are emission goals feasible?

President Obama says that we'll reduce our nation's greenhouse gas emissions. Compared to 2005 discharges he set lowering 2020 air pollutants by 17 percent. By 2050 it'll descend by 83 percent. While encouraged, I question its feasibility.

First I read a description from John Sterman at MIT. Too few people, he realizes, grasp the danger and consequences of failing to reverse global warming. His bathtub analogy explains the peril to nonscientists.

His tub contains our entire atmosphere. For most of human existence the volume of greenhouse gases entering the bathtub through its faucet equaled the amount going down the drain. That is, carbon dioxide from burning fossil fuels and decomposing plant material in recent millennia was fully absorbed through plant photosynthesis (e.g., trees. algae).

But so much carbon dioxide is produced today that plants and the oceans capture barely half of what we and nature spew skyward. CO2 flows in twice as fast as drained. It's filling our atmospheric bathtub. It's not been this high for over 800,000 years.

Terrifyingly, we're unsure how much the tub can handle before the critical overflow point is reached. Best estimates say that at the currently projected rate of greenhouse gas production, that point will arrive by 2050.

To dodge this point of no return, researchers say we must cut pollutant emissions by 80 percent. To do less will keep the bathtub filling faster than the detrimental gas can be absorbed.

The size of this reduction will require a massive shift from fossil fuels to clean, renewable energy sources. Can we?

Mark Jacobson at USC and UC Davis' Mark Delucchi investigated. In short, they found that it is technologically possible to get to zero greenhouse gas emissions (yes, zero) ... and do it a full 20 years before the scientific community says an 80 percent reduction is required.

I'm excited that it's technologically feasible, but fearful because energy transformation rests with politicians. That's because nations must have the will through regulatory rules and incentives to push the enormous conversion.

The investigators examined eliminating fossil fuels and biomass combustion generating sources and replacing with wind, solar, geothermal, tidal and hydroelectric supplies. The team limited their calculations to technologies that work today or are immediately available. They ignored hoped-for breakthroughs.

Further, they looked only at means that would produce near-zero emissions throughout their lifecycles and present no significant waste disposal or terrorist risks.

After assuring that the technologies exist, meet their criteria and allow for full implementation within two decades, the question turned to how great the need. That is, what is the optimum distribution of wind turbines, water machines and solar installations?

The numbers are large, but achieving the needed scale for conversion is doable, based on similar massive transformations. They cite, for example, the conversion of auto factories to aircraft production in World War II and construction of Eisenhower's 47,000 miles of interstate highways.

And the cost is dramatically lower than staying with the old technologies. They found that conversion to wind, water and solar power will, first, spectacularly lower energy needs.

For instance, the United States will witness a full 38 percent reduction in energy demand. That's largely because usable energy produced from petroleum and coal is only 20 percent efficient. That's put to shame by electricity's 75 percent efficiency.

The prediction is that by 2050 the annual global demand for energy will be 16.9 TW (terrawatts), up from today's 12.5 TW. To attain the 16.9 TW demand level if we remain wedded to dirty sources will require new fossil fuel generation plants and refineries at a cost of $10 trillion.

Compare that to replacement clean energy facilities (wind, water and solar) for $3 trillion. And the globe's clean energy supply potential far exceeds the projected human demand. Wind, for instance, can reasonably produce over 40 TW and solar 580 TW worldwide annually.

As witnessed in current health care reform efforts, though, entrenched special interest groups (i.e., fossil fuel combines) will oppose these changes. We'll need solid political leadership to overcome their aggressive lobbyists and tactics.

If leaders fail to look ahead, humankind will keep trying variations on outdated polluting technologies until it's too late. Human survival requires technologies that meet clean and renewable energy goals.

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Gary Knox is a retired Yuma area school superintendent and guest columnist for the Yuma Sun.