Letters to the Editor

Viewpoint: 350 ppm must be our target

The world is watching as delegates from nearly every nation on Earth meet in Copenhagen in an effort to draft an international treaty on climate change.

The evidence that most of the warming measured this century can be linked to human activity is now very solid. The Intergovernmental Panel on Climate Change report published two years ago indicates a confidence level of 95 percent that the 1.1 degree Fahrenheit increase we have measured over the last century is human caused. If there is a “climategate” issue (which claims that data on warming has been purposefully manipulated to look worse than it actually is), then apparently the Arctic didn’t get that memo. The melting of Greenland and the Arctic sea ice is accelerating at a pace far beyond what any scientist could have imagined even two years ago.

Many among us wonder how such a small increase could be such a big deal. The truth is that 1.1 degrees of warming over 100 years is tolerable. What is intolerable is the expected warming of between 2.6 and 10.4 Fahrenheit in this coming century. Global warming, you see, increases at an accelerating rate. Continued warming causes more warming at a faster and faster pace. Put another way, the warmer it gets, the faster it gets warmer. At some point it is very likely that global warming will hit a “tipping point” — the point beyond which warming will continue much faster. The reasons have to do with positive feedback, commonly known as the “snowball effect.” For example, as the highly reflective ice at the North Pole melts, it exposes water below. That water, being darker, absorbs more energy from the sun, thereby warming the air and water more, causing even more ice to melt. This exposes more dark water and the vicious cycle continues.

The effects of a world warmed by 6 or 8 or 10 degrees Fahrenheit are extreme. They include the commonly known rise of global sea levels and more powerful weather events the world over, but also include the loss of a steady supply of fresh water from melted glaciers, the spread of tropical diseases as insects move into areas formerly too cold for them, expansion of the world’s deserts and the loss of the world’s forests as climate becomes warmer and drier.

On a local level, the fallout from climate change, if not corrected, is expected to be severe as well. The Climate Action Team, formed at the request of Gov. Arnold Schwarzenegger and headed by Daniel Cayan of the Scripps Institute of Oceanography, has recently completed a comprehensive report outlining the likely effects of global warming on California’s economy and ecosystems. The news is almost entirely negative and includes a deep decrease in snowpack in the Sierra, increased risk of wildfire in southern California and in the Sierra, loss of coastal development to rising sea levels along with the pollution of coastal aquifers from saltwater intrusion, a loss of oak woodland ecosystems from central California as the climate becomes too dry for them and an increase in utility rates as hydropower production falls.

It is hard to find good news when a civilization founded on and entirely dependent on a stable and predictable climate faces changes of several degrees in less than a century.

The Earth’s atmosphere currently holds 388 parts of carbon dioxide for every million molecules of other gases (388 ppm). Many scientists agree that the tipping point for uncontrollable climate change was back in 1989 when carbon dioxide concentrations passed 350 ppm. They argue that to avoid the enormous, wrenching changes that very likely await us, we must act boldly and very swiftly to bring concentration of carbon dioxide back to 350 as soon as possible. Some economists argue that this is impossible and that the best we can do is shoot for 450 or even 550 ppm.

How can humanity do anything but make 350 the target for negotiations in Copenhagen? It is not a matter of whether or not we can achieve 350. The point is that it is our moral duty and our human responsibility to do all in our ability to get back to 350. We owe the future no less.

The silver lining of climate change, if there is one, is that this issue is so serious that it may be the thing that brings humanity together in a common purpose — for it will take all of us working together to achieve this goal.

350 parts per million. Copenhagen owes us that.

Mark DiMaggio teaches earth and environmental sciences at Paso Robles High School.