In response to a question on my Mail Brane blog of Feb. 28, I replied that if global warming is accelerating - meaning much higher CO2 concentrations added each year- there'd higher solar insolation (by about 2 W/m^2 per year) and the date of the first year of no seasons could arrive as early as 2025, if not sooner. Now a new report appears to validate that, and indeed the global temperatures are hotter now than they've been in 4,000 years.
This research team just published their results in the journal Science, assembling a record of global temperatures going back to the end of the last ice age — about 11,000 years ago — when mammoths and saber-tooth cats roamed the planet. The study confirms that what we're seeing now is unprecedented and we may well be past the time to do anything effective.
The Science researchers effectively peered into the past. They analyzed ice cores from polar regions that show what temperatures were like over hundreds of thousands of years. However, those only reveal changes only in specific regions; cores aren't so good at depicting what happened to the whole planet. Tree rings give a more global record of temperatures, but only back about 2,000 years.
According to Shaun Marcott, a geologist at Oregon State University:
"Global temperatures are warmer than about 75 percent of anything we've seen over the last 11,000 years or so."
He adds that the other (optimistic) way to look at is that 25 percent of the time (since the last ice age), it's been warmer than now.
Given such a relatively lower proportion of higher temperatures since the previous Ice Age, many people might ask, 'Why worry?' After all, it's been colder for 75% of the time! But Marcott dismisses this given the record shows the alarming rate is unusual and we ought to be worried at this recent trend. As he puts it:
"It's really the rates of change here that's amazing and atypical. Essentially, it's warming up superfast."
And in fact, my answer in the Mail Brane tried to draw emphasis to the RATE of warming. Indeed, in earlier blogs I also noted that this was critical since a threshold for the runaway Greenhouse Effect could be reached much sooner. This would mean maximum entropy globally, not a favorable prospect. According to statistical mechanics, the entropy (σ ) is defined according to:
σ = log g
where g denotes the number of accessible states. As that number g increases, so does log g and hence the entropy. When g is maximized for a given system one will say it is in an equilibrium condition and has no further states which can be accessed. Such is the case with a planet (e.g. Venus) uniformly at 450 C across its surface ....no climate to speak of, no 'cool nights', no variation in temperatures of any significance. The first year of no seasons for Earth would mark our strong trend toward that unsavory end.
Of course, the world will become unbearable long before that. The full horrors incepted, of which the loss of seasons is merely the most distinguishing, will include lack of sufficient water, lack of food - because of the inhospitable conditions to grow crops, and other hostile factors (catastrophic storms with hundreds of F5 tornadoes a year, monster hurricanes, rising sea levels inundating 30% of coastal lands in the U.S. alone).
Back to the Science journal paper, we can ask: What happened after the end of the ice age? What does the 11,000 year record disclose? Well, the planet got warmer, then, 5,000 years ago, it started to get cooler — but slowly. In all, it cooled 1.3 degrees Fahrenheit, up until the last century or so. Then it flipped again — global average temperature shot up. This coincides almost exactly with the kicking in of CO2 atmospheric absorption from the Industrial Revolution. This is verified by a previous 2000-year record of C14:C12 deviations compiled by P.E. Damon ('The Solar Output and Its Variation', The University of Colorado Press, Boulder, 1977)
As John Eddy observes concerning this output (Eddy, The New Solar Physics. p. 17):
“The gradual fall from left to right (increasing C14/C12 ratio) is…probably not a solar effect but the result of the known, slow decrease in the strength of the Earth’s magnetic moment exposing the Earth to ever-increased cosmic ray fluxes and increased radiocarbon production.The sharp upward spike at the modern end of the curve, representing a marked drop in relative radiocarbon, is generally attributed to anthropogenic causes—the mark of increased population and the Industrial Age. "
Not surprisingly, the Science authors report:
"Temperatures now have gone from that cold period to the warm period in just 100 years,"
Hence, it's taken just 100 years for the average temperature to change by 1.3 degrees, when it took 5,000 years to do that before.
The Science research team tracked temperature by studying chemicals in the shells of tiny, fossilized sea creatures called foraminifera. Their temperature record matches other techniques that look back 2,000 years, which supports the validity of their much longer record.
Climate scientists predict that the current warming will continue, given the amount of greenhouse gases going up into the atmosphere. According to Gavin Schmidt, a climate reseachers at NASA's Goddard Institute for Space Studies:
"The climate changes to come are going to be larger than anything that human civilization and agriculture has seen in its entire existenc. And that is quite a sobering thought."
"Sobering" is perhaps an understatement to describe what's in store for us!