The Once & Future Climate?
Between 15 and 20 million years (Myr) ago, Earth's climate took a pause during its long slide into the Pleistocene Ice Age for a period of real global warming. During this relatively brief time glaciers around the world retreated and there are indications that, at least around the edges of the continent, there was significant vegetation on Antarctica. Temperatures may have been as high as 11°C higher than today. Scientists say this global warm spell took place under under CO2 levels in the range of 190–850 ppmv, both significantly higher and lower than today's 390 ppmv. It is hoped that studying conditions during the Miocene warming can provide constraints on the fundamental laws governing the climate system. Why? If the Pleistocene Ice Age is truly coming to an end, as some have said, this may be the climate of the future.
The middle Miocene is an intriguing period of Earth history during which high temperatures reversed the previous global cooling trend. These temperatures caused a substantial retreat of the West Antarctic Ice Sheet and shrinkage of the East Antarctic Ice Sheet to a degree never experienced by modern humans or our ancient ancestors. The generally accepted scientific view is that Antarctica was progressively glaciated after 34 Myr ago and vegetation became restricted to the margins of the continent. However, 15-20 Myr ago a sharp increase in Nothofagidites (southern beech) and Podocarpidites (podocarp conifer) pollen has been linked to resurgent growth of vegetation on Antarctica. This prompted a team of investigators to reexamine previous ice-core samples for pollen and spores. In a letter to Nature Geoscience, “,” Sarah J. Feakins, Sophie Warny and Jung-Eun Lee paint a picture of a much warmer time on our planet. Here is the article's abstract:
From 20 to 15 million years (Myr) ago, a period of global warmth reversed the previous ice growth on Antarctica, leading to the retreat of the West Antarctic Ice Sheet and the contraction of the East Antarctic Ice Sheet. Pollen recovered from the Antarctic shelf indicates the presence of substantial vegetation on the margins of Antarctica 15.7 Myr ago. However, the hydrologic regime that supported this vegetation is unclear. Here we combine leaf-wax hydrogen isotopes and pollen assemblages from Ross Sea sediments with model simulations to reconstruct vegetation, precipitation and temperature in Antarctica during the middle Miocene. Average leaf-wax stable hydrogen isotope (δD) values from 20 to 15.5 Myr ago translate to average δD values of −50‰ for precipitation at the margins of Antarctica, higher than modern values. We find that vegetation persisted from 20 to 15.5 Myr ago, with peak expansions 16.4 and 15.7 Myr ago coinciding with peak global warmth and vegetation growth. Our model experiments are consistent with a local moisture source in the Southern Ocean. Combining proxy measurements with climate simulations, we conclude that summer temperatures were about 11 °C warmer than today, and that there was a substantial increase in moisture delivery to the Antarctic coast.
This Earth held arboreal forests on its southernmost continent, forest that would have had perpetual sunshine during the summers and unending darkness during the long winter's night. It would have been an environment unlike any that exists on our planet today. It was a world warmer than the most fevered dreams of climate change alarmists.
Things were much warmer during the Miocene.
“At the height of the middle Miocene Climatic Optimum, global annual mean surface temperatures were ~ 3 °C higher than present, equivalent to projections for the coming century, with 6 °C warming in mid latitudes and 10 °C warming for high latitudes, based on an evaluation of proxy data and model simulations,” state the authors, no doubt scoring points with warmist reviewers.
The authors gained new insights into ancient climate conditions using hydrogen isotope analysis of plant leaf waxes. Stable isotopes in precipitation act as a tracer of the hydrological cycle, the ratios of isotopes being strongly associated with spatial gradients in temperatures in the middle and high latitudes. Using the varying amount of deuterium present in ice-core samples (δD), variations in temperature were inferred. But Pleistocene ice-core records only extend back about 800,000 years.
“There is, unfortunately, no earlier glacial stratigraphy surviving on Antarctica, although subterranean ice has been reported from the dry valleys,” the paper asserts. “Plant leaf wax is therefore our best proxy for the hydrogen isotopic composition of precipitation for deep time applications.”
During the middle of the Miocene the isotope data, along with microfossil analyses of associated sediments, indicate ice-free conditions in the Ross Sea in two brief pulses. As shown in the figure below, spikes at 16.4 and 15.7 Myr ago correspond to pulses of global warmth each <30,000 yr in duration. What this basically means is that during the general period of global warming there were at least two identifiable bouts of rapid warming.
Miocene climate records.
What is most interesting here is that these warm spikes were very rapid and very pronounced. One of the arguments used to make anthropogenic global warming seem scarier is that it is “rapid” and unlike anything found in nature. Here are two examples of climate change happening rapidly (on a scale of millions of years saying that the spikes lasted less than 30,000 years is at the limit of data resolution—things could have happened very rapidly indeed). These are just the latest examples of sudden climatic shifts. Others include the sudden cooling and recovery of the Younger Dryas (10,800 to 9,500 BC) and the radical warming of the Paleocene–Eocene Thermal Maximum (PETM: 55.0 million years ago).
“These exceptional reversals of past ice-house conditions may offer valuable insights into hydrological processes under future warming scenarios,” Feakins et al. offer blandly, again with veiled reference to climate change orthodoxy. Still, they may have inadvertently uncovered a larger truth. When talking about climate change most people ask the wrong question—it is not if the climate will change but when, for hotter or colder and by how much are more intelligent queries.
The middle Miocene Climate Optimum is just another example of the unpredictable variation displayed by Earth's climate. For reasons unknown to science, a 50 million year descent into an ice age was put on hold for a couple of million years of balmy weather. Atmospheric CO2 levels went from notably lower that modern levels, quadrupling by the peak of the warming. But note that the warming caused the rise in CO2 levels, not the other way around. And then, despite levels more than twice current readings, the climate resumed global cooling. Atmospheric CO2 levels are a side effect of climactic change, not a driving cause. Human emissions will not cause a return to an ice free Arctic or a forested Antarctica—both natural and certainly not unprecedented conditions. The climate will change and we, like all of Earth's creatures will simply have to deal with it.
Antarctica could look this way again.
The sad fact of climate science at the beginning of the 21st Century is that a few alarmists have managed to convince the majority of humanity that people are making the world heat up. This implies that the main product of human advancement is inevitable ecological retribution by a tortured ecosystem. That such a myth has been eagerly sized upon by diverse groups of individuals is unsurprising—global warming provides frightening and effective cover for all manner of schemes, scams and flimflams.
“The oceans are rising! it's because of global warming, therefor it is because of the rich industrial nations!” yell the leaders of the third world (and quit a few “advocates” they never asked for). “ We demand reparations, send money!”
“Yes, truly this requires coordination on an international scale,” agree the UN bureaucrats. “We must build a framework controlled by, well, the UN and all nations must cede their sovereign rights to us! You must start by sending us more money.”
“Not so fast,” say the international brotherhood of climate prognosticators. “We do not know the true extent of the looming catastrophe! We must continue to study it, plumb it depths, consume ever larger piles of grant money. Yes, that's the right path, we need more funding.”
We have a drought, it's global warming; we have torrential rain and flooding, it's global warming; we have an outbreak of tornadoes, it's global warming; we just had a week of really hot weather, it's global warming; we just suffered the worst hurricane ever, it's global warming; we no longer have to look for a cause for anything bad, it's always global warming. Whether you believe AGW is the result of a plot by evil multinational corporations or the righteous wrath of the Earth Mother paying humanity back for ravaging the ecosystem we must surely be doomed. Does any of this sound like science?
Of course it doesn't sound like science. Science is supposed to be rational and based on empirical evidence, what most people would call facts. When it comes to global warming the facts are few and far between and what science there is consists of conjecture and hand waving. But as a boogie man global warming is just too useful to the scoundrels and parasites of the world. But even the best scams eventually wear out, people go from frightened and alarmed to bored and disinterested. So it has become for global warming. The true believers continue to try inflaming public opinion, but more and more their warnings are falling on deaf ears. This is how bad science dies—not through reasoned debate or the weight of countervailing evidence, but from terminal boredom.
Be safe, enjoy the interglacial and stay skeptical.