Blog 82. Temperature doesn’t forecast climate

Regarding climate change, the political arguments focus on whether the temperature is increasing.  It is, but that’s not a firm indicator.  It’s like a car is speeding toward a brick wall while the driver listens for sounds.  You’ve gotta look ahead.

Here’s the simple picture.  Graphs show the continuing huge increase of carbon dioxide (CO2) and other “greenhouse gases” in the atmosphere.  And why is that more important than temperature data?  As you can feel, sunshine  warms the surface of the earth.  Over time, the earth sends that energy back into space via infrared radiation.  CO2 inhibits the infrared, thus keeping the earth warmer.  Earth’s surface is a massive thing; it takes time to warm up.  But it will.  That’s how a greenhouse works, except in the greenhouse it is the glass that retains the infrared instead of CO2.  Like the atmosphere, the glass lets the visible sunshine in, but inhibits loss of heat.

Temperature measurements, though indicative, offer a small numbers that encourage misleading political arguments.  It’s popular to show graphs of temperature for the last few years, or last few decades, all of which indicate a small rise in global temperature starting with the industrial revolution and the burning of fossil fuels—and the dumping of carbon dioxide into the atmosphere.  It’s not necessarily meaningful to compare this year’s average temperature against last year’s.  Small changes, up or down, do not predict the future.  The CO2 data do.

Global climate is a complex system—that is, it is composed of many separate elements (actors), each changing based on the influence of the other elements.  Temperature affects moisture that affects clouds that affect snow and vegetation and oceans, all of which affect each other and temperature.  How much the global temperature will rise on earth’s surface depends on the loss of arctic ice, the changes in cloudiness, the changes in the oceans, the changes in vegetation and the many factors that make climate a complex system.  Details will vary, but adding CO2 to the atmosphere is like wrapping a blanket around an electric heater.  The temperature must go up.

Extensive calculations predict a temperature rise of 5 to 10 degrees F during this century.  Enough to change life as we know it.  The United Nations recognized the threat in 1988, but people in the U.S. still argue about temperature measurements.  The energy picture—the retention of heat by the CO2—presents a simple picture.  Driver, there’s a brick wall ahead, whether or not you hear it yet.

My own prediction is this: It’s the social upheavals that will hurt first as water supplies, food, and population movements generate disruption and terror.  When events seem beyond control, people will seek repression as a counter-action, maintaining denial of the facts.  We can choose a better outcome, but not by denying the simple fact of accumulating heat.