The present is on the right in this image. If you look at the height and width of the interglacial warm periods, you will notice that we are nearing the end of the present warm period.
Does a marvelous job of showing our place in the scheme of things. From the very long ice age cycle perspective, down to the present-day rate of CO2 emission and the irrelevancy of it.
It would be a great introductory paper to give to anyone just starting out on a journey of discovery about the Global Warming Scare and a nice read that pulls together a lot of disjoint bits for those of us who have been looking at things for a while.
For example, in one minor place it mentions the 206 year solar cycle. There is a link to a PDF file. No fanfare, no big deal about it. But the paper is about how the Maya had problems from droughts that happened on a roughly 206 year period … and postulates that a major drought driven by cycles of the sun may have been the cause of the collapse of their civilization. That’s one of the minor links…
More importantly, the research shows, the droughts — one of which is thought to have contributed to the collapse of the Maya civilization — appear to have been caused by a cyclical brightening of the sun. “It looks like changes in the sun’s energy output are having a direct effect on the climate of the Yucatan and causing the recurrence of drought, which is in turn influencing the Maya evolution,” said David Hodell, a UF professor of geology and the paper’s lead author.
I’ve not yet explored the other links to see what treasures they might provide. In the body of the paper, there are wonderful graphs of the ice age cycles and great renditions of the temperature peak of the Medieval Warm Period with the Little Ice Age for perspective, with references.
There is a wonderful little map of the world during the last ice age showing both the extent of the ice, and equally important, the much larger area of desert that comes with the cold. Cold is dry. Warm is wet. Warm and wet is very much better for humanity AND all the other life on the planet than cold and dry. Comparing that map to the one of the present makes it very clear just how precious is this moment in time, this interglacial.
The case is made, and rightly so, that the only ‘tipping point’ is to the downside, back into a glacial period. The only looming catastrophe is death by ice. And there is bugger-all we can do to stop it. (Though the good part is that we probably have a couple of more thousand years of the present regime before things get bad, so plenty of time to contemplate it.)
I would also point out that the historic warming in past interglacial periods has been higher than our present temperatures, but not by much. There is something that slaps us back down whenever the planet tries to warm up above this point. My guess would be the fact that IR radiation will increase with the 4th power of temperature, and trying to beat a 4th power function is a very hard hand to play. (Google the Stefan–Boltzmann law for thermodynamics details…)
For what it’s worth, with the theoretical impact of CO2 being a log function (so decreasing impact with each added unit) and with the Stefan–Boltzmann law putting a 4th power lid to the upside, the conclusion I draw is that the best thing we could do for the planet is to raise the CO2 levels. We can’t make it hotter, but we might be able to dampen some of the downside cooling.