SIGN CHANGE: Not a sign of the times

A recent letter (Feb. 2) points out that Glacier National Park changed 3 signs which had stated that some glaciers would melt by 2020. The presumed point of that letter was to cast doubt on global climate change.

The GNP sign change has become a big sound bite of deniers. But what are the details behind the story?

In 2003, a climate model predicted that the warming would melt the glaciers by 2030. In 2010, field measurements of the glaciers indicated they were melting faster than predicted, with an estimation that if the trend continued the glaciers would be gone by 2020. New signs at the glaciers were placed in 2010 to inform the public of this trend. So obviously those predictions were overly pessimistic.

More studies show that the last pieces of glaciers are typically higher in elevation and more shaded, so they don’t completely melt as fast as simple models indicate. Plus, maybe some local weather caused the shrinkage to temporarily slow down.

Does that mean that global climate warming isn’t happening? Of course not. Summer heat records continue to be set around the world.

Even though there are short-term zigs and zags in the temperature readings, the last five years are the warmest on record for at least the last 1,000 years.

JAMES FILLMORE

Coeur d’Alene