Larry Grimard (letter, Feb. 15) asks, “Whatever happened to global warming?” and cites data from the National Ocean and Atmospheric Administration indicating that while carbon dioxide concentrations have increased in the last 10 years, temperature has not.

The NOAA reports I have seen, however, show a close correlation between the rise of carbon dioxide and global temperatures.

NOAA also reports that 2012 temperatures were the 10th-highest in the last 100 years and among the 14th warmest in 133 years. NOAA also reported that 2012 bought the highest temperatures (along with drought and forest fires) in recorded history to the lowest 48 states.

To assess temperature changes, annual variations have to be averaged over broad regions and many years. Using simplistic math, Grimard substitutes his understanding for that of climate physicists and questions how a small concentration of greenhouse gases can cause global warming.

He does not appreciate that concentration of carbon dioxide is cumulative and has been going on since the start of the Industrial Revolution.

Richard Muller, head of the Berkeley Earth Sciences Study, states in his final report: “Three years ago I identified problems in previous climate studies that, in my mind, threw doubt on the very existence of global warming.

Last year, following intensive research involving dozens of scientists, I concluded that global warming was real and that prior estimates of the rate of warming were correct.

I’m now going a step further. Humans are almost entirely the cause.”

He further concluded that in the last 250 years global temperature has risen 2.5 degrees with 1.5 degrees of that increase in the last 50 years.

Whatever happened to global warming?

Alas, it is alive and well, threatening our livelihoods , if not our civilization, unless we reverse the emission of greenhouse gases into the atmosphere.

Charles W. Acker

Whitefield