Sunday, January 03, 2010
…climate is process.
Media focus on "Global Warming" and climate change centers on two measures of climate: global average temperature and global average atmospheric CO2 concentration. The basic assumption underlying the headlines is that human produced CO2 above an undefined "pre-industrial" level is causing the global average temperature to rise, thus creating "global warming."
This focus on contemporary patterns of data variation masks the underlying reality of climate change, viewed through the long lens of geologic time.
In short, climate is not data, climate is process.
The simplistic assumption that CO2 rise equals warmer temperatures ignores the complex interplay of meteorological and geophysical factors that combined together through time result in a variable global climate. Sea floor spreading, plate tectonics, aridity, humidity, ocean currents, atmospheric aerosols, relative cloud cover, variations in solar irradiation, dust, CO2, ozone fluctuations, all combine in a chaotic dance to produce what we perceive of as climate.
Despite the overwhelming presence of climate in the long view, humans respond most immediately to weather. As we continue to consider the long-term implications of climate change, our headlines are dominated by cold temperature records and blizzards blanketing the countryside, saying, "What's up with this, then?" Once again, weather clouds our understanding of climate.
Rather than human produced CO2 causing global warming, what is actually happening is that our planet is engaged in a long term dance of climate variation. For the past 500,000 years the earth has been in a climate cycle characterized by periodic glacial advances and retreats in approximately 100,000 year cycles. Interglacial periods have been from 10,000 to 12,000 years in duration, during which glacial ice retreated and climate conditions stabilized at temperatures about 2 C lower than today.
Our most recent interglacial has been in effect for 10,000 to 12,000 years. We are now climbing up the steep slope to higher temperatures, increased CO2 concentration that marks the end of interglacial and the beginning of the next ice advance. Over the next 1,000 to 2,000 years, we will see temperature and CO2 concentration begin to decline, glacier melt declining and glaciers advancing throughout the world.
This is all a natural process of such magnitude and universality that it completely overwhelms any human contributions by way of atmospheric CO2 production. Consequently, there is nothing that human society can do about it, other than accommodate to the changing climate. Reducing anthropogenic CO2 will not change the outcome. The cycle will continue as it has for the past 500,000 years, until plate tectonics changes ocean current circulation sufficiently to bring about another global climate cycle.
Don't toss out your long johns and snow shovels just yet, the Ice Age is returning!