By William C.  Shelton

(The opinions and views expressed in the commentaries of The Somerville News belong solely to the authors of those commentaries and do not reflect the views or opinions of The Somerville News, its staff or publishers.)

Would you like to play Russian roulette?  Is the idea attractive to you?  In a real sense, our nation‚Äôs leaders are playing Russian roulette with the planet‚Äôs capacity to support human life.

As Tip O‚ÄôNeil famously said, all politics are local.  The fact that climate change will be globally catastrophic does not diminish how devastating it will be locally. And given the federal government‚Äôs dereliction of responsibility to ‚Äúprovide for the common defense,‚Äù I think that it‚Äôs worthwhile to have a conversation about it here in Somerville.

You may think my suggestion that climate change poses a national security threat is sensationalist.  The Pentagon doesn‚Äôt think so.  In 2003, it published a report entitled, ‚ÄúAn Abrupt Climate Change Scenario and Its Implications for United States National Security.‚Äù  You can find it by Googling its title. It argues that ‚Äúadverse weather conditions could develop relatively abruptly‚Äù producing ‚Äúa significant drop in [Earth‚Äôs] human carrying capacity‚Äù that ‚Äúcould potentially de-stabilize the geo-political environment, leading to skirmishes, battles, and war.‚Äù

This year the Intergovernmental Panel on Climate Change (IPCC) said evidence is ‚Äúunequivocal‚Äù that the planet is heating up, and ‚Äúwe are in deep trouble.‚Äù  What kind of trouble? Only immediate and massive action, the IPCC says, will avert devastation of grain-growing regions, raging wildfires, scores of Katrinas, epidemics, destruction of forests, and rising sea levels deluging lands that are now home to millions. 

As a people, we expect plot resolutions in one-hour dramas and ever improving quarterly corporate earnings.  So it‚Äôs hard to grasp that changes already taking place in the atmosphere and oceans will drastically alter our lives thirty years from now.  But the atmospheric and oceanographic studies I‚Äôve been reading make the IPCC‚Äôs forecast seem conservative.

Science, by its nature, is conservative, insisting on the slow accumulation of evidence that can be universally reproduced and tested by doubters before a consensus is established.  And getting leading scientists from 120 nations to agree on one statement ensures that the statement will be moderate in its conclusions.

For example, the IPCC estimates that the earth‚Äôs mean temperature will increase up to 11.5 degrees by the year 2100, melting glaciers, thinning polar ice, and raising sea levels 21 inches.  These projections come from conservative computer models. According to them, Greenland‚Äôs ice will take 1,000 years to melt.

But a chaotic system is difficult to model.  Recent satellite measurements indicate that Arctic ice is melting so rapidly that the region could be ice-free by 2030.  A 5-degree increase in global temperatures 3 million years ago produced an 80-foot rise in sea levels.

The IPCC report forecasts a gradual, but inexorable, change.  It makes little mention of positive feedback loops that can abruptly and catastrophically change global climate.  A positive feedback loop occurs in a system when certain conditions produce effects that, in turn, increase those conditions and effects, resulting in exponential growth of the effects, eventually destroying the system.

Here is one example.  ‚ÄúGas hydrates‚Äù are gas molecules like carbon dioxide (CO2) and methane (CH4) surrounded and trapped by ice crystals, under great pressure.  There is as much carbon dioxide thus trapped in polar seabeds and permafrost as exists in all the earth‚Äôs fossil fuels.  And CH4 is twenty-one times as potent a greenhouse gas as CO2.

250 million years ago, earth hosted a rich ecosystem.  On land, the food chain went from plants, to insects and invertebrates, to lizard-like creatures.

In what is now Siberia, magma seeped up through fissures, emitting greenhouse gases. Temperatures increased only a little, but this killed off many plants, and the food chain that depended on them.  Continuing emissions created vicious acid rains.  Trees and larger plants died.

Global temperatures increased a few more degrees and the tundra began to thaw out.  Released carbon dioxide and methane expanded a hundred fold.  This positive feedback loop produced a violent heat pulse and lowered atmospheric oxygen.

Rivers washed rotting plant and animal material into the sea, creating a slime that choked seabed life. Released CO2 killed plankton, the planet‚Äôs largest oxygen producer.  Decay drew more oxygen out of the atmosphere. Best estimates are that 90% of marine species, and 70% of land vertebrates became extinct.  Most probably suffocated before they could starve.

Suppose there is a relatively small probability that this could happen. How many chambers must the revolver have for you to feel comfortable with Russian roulette being continuously played with you head?

Thousands of pages of White House documents obtained through the Freedom of Information Act lay out a policy formulated by the Vice President and implemented by the White House Council on Environmental Quality. That policy uses industry-connected White House appointees to systematically distort federal climate scientists‚Äô findings and downplay the extent of climate change. 

Do you think that assessing real-world conditions and discussing their implications is worth a conversation?