HOT TIME ON THE OLD PLANET
We’re on our way. Yes, we are. We’ve got a one-way ticket to the PETM. Don’t know what that acronym stands for? Your grandchildren will know what it means, most certainly, by the time they reach old age on the eve of the 22nd century.
Fifty-five million years ago, at the close of the Paleocene epoch, when horses were no larger than Springer spaniels and flightless terror birds of South America were the size of cars, crocodiles thrived on Baffin Island, Canada, at latitudes similar to northern Greenland today. Then, global mean temperatures were far above what they are in 2016. Paleoclimatologists (now that’s a mouthful) call that period in the deep past the Paleocene-Eocene Thermal Maximum, the PETM.
At that time--at mid-continent in Asia, Australia, Africa, and North America--temperatures were thought to be so intense as to render millions of square miles uninhabitable to most living things. Of course, hominids would not evolve for 50 million years, so the PETM had no impact on our ancestors whatsoever, except to register as a curiosity to us today.
But there is a parallel between the Paleocene-Eocene Thermal Maximum and the climate unrest evolving today. Right now the level of carbon dioxide in the atmosphere has surpassed 400 parts per million and is climbing steadily. At no time since the demise of the dinosaurs 65 million year ago have CO2 levels approached 400 parts per million, except during the PETM. Then, unusually intense volcanism over thousands of years accounted for the heavy burden of the greenhouse gas in the atmosphere.
We humans have been burning fossil fuels, and therefore pumping long-buried carbon into the atmosphere in ever increasing quantities, since the late 1700s. We have become, in short order, our very own chain of nonstop erupting volcanoes. Our civilization has thrown a nice warming blanket over our home planet and we’re adding layers of blankets at light speed, if one thinks in terms of geological time rather than daylight savings time.
Since we’ve been disgorging carbon into our atmosphere at such a rapid rate, it is no longer surprising that the heat that has been building up in the oceans and air masses is beginning to assert itself in very unpleasant ways. Just this past week, the super floods in Louisiana, Texas, Mississippi and Arkansas were fueled by massive volumes of moisture upwelling from record warm waters in the Gulf of Mexico. Last year, severe drought across western Canada, the United States, and in Siberia created a powder keg in Northern Hemisphere forestlands. Millions of acres of woodlands burned, filling northern latitude cities on three continents with smoke and haze. Two years ago, record snowfalls were recorded in the East, the snow totals pumped up by huge plumes of moisture riding the Gulf Stream north into the path of polar vortex cold streaming relentlessly down across Canada from the Arctic.
While 500-year floods and hyper-typhons are showing up with alarming regularity now, they are likely to pale in comparison to the storms of the future, when CO2 levels are still higher and the greenhouse gas is joined in concert with a far more effective and dangerous heat-trapping gas: methane.
Locked in permafrost in tens of millions of acres of arctic lands that ring the polar ocean is long dead, frozen vegetation. Permafrost is a massive carbon sink. As long as the ground remains frozen, the carbon is stable. But thaw the permafrost and microbes begin to break down the dead vegetation, releasing methane.
In Siberia, reports have surfaced over the past decade of huge blow holes appearing in the tundra. In photographs, they appear as if they are meteor craters in the land. These deep, steep-walled depressions are the result of explosions caused by the high pressure buildup of methane under the frozen surface strata. All are recent, very recent.
The immense methane motherload lurking in permafrost is dwarfed by another ungodly source of the potent gas, an ice known as methane hydrate that has accumulated for tens of millions of years on the deep seabed off the continental shelves all over the world. Under intense pressure and in near freezing temperatures in the deep, methane hydrate ice is stable and of no threat. But it is very temperature sensitive. Warm the deep ocean only a few degrees and the ice would turn from a solid directly into a gaseous state and bubble up to the surface. There is some evidence accumulating now indicating the presence of great methane plumes collecting above the world’s oceans.
The methane specter is the monster in the climate closet than prevents researchers from sleeping through the night. Methane is more than twenty times more effective at trapping and holding heat than carbon dioxide. Should our current increasingly unstable climate cross a threshold wherein the vast global stores of methane are released rapidly, we will enter uncharted realms on our way to an extreme climate regime, possibly something like what prevailed during the Paleocene-Eocene Thermal Maximum.
At the end of the Paleocene, the climate changed slowly over many thousand years, apparently slowly enough for the majority of life’s creatures and plants to adapt to the changing conditions. What could happen in the near future should the methane genie be freed from its entrapment and partner with our record CO2 levels is an abrupt switch from a climate that permitted our species to flourish over the last 10,000 years to a climate that is suddenly hostile to human civilization, not to mention most life forms.
Not convinced? We do know climate can change dramatically in an eye blink. Here’s an example. In 1815, a single large volcano named Tambora disintegrated in a spectacular explosion off the coast of Sumatra and deposited millions of tons of volcanic aerosols in the stratosphere. The aerosols blocked some fraction of incoming sunlight from reaching the earth’s surface. The following summer was so cold that snow fell at Concord, New Hampshire each month of the year and skim ice on ponds and lakes was reported in August. Famine stalked the land in Europe, Asia, and parts of North America.
While US oligarchs pay off politicians to deny global warming, each one of us has only to walk outside to see the effects of climate change underway. Growing seasons are longer in the north. Ticks that were once a rarity in states hugging the Canadian border are fully entrenched now. Typically arid regions of the world are experiencing more prolonged droughts. The glaciers in Glacier National Park are disappearing so quickly that it is thought the park will be ice free in summer in a generation.
On a personal level, climate change has been a blessing to me and my family, at least so far. We like to garden here in northern New England. Forty-five years ago, we could count on 90 to 100 frost-free days in the garden each year. Today, we regularly experience 125 frost-free days a year and 150 days is not unusual. That pronounced shift in frost-free days in half a lifetime is, I think, astonishing.
Just as astonishing was watching presidential candidate Marco Rubio -- who two days before had met with the mayors of Florida’s largest cities who urged him to take climate change seriously – state before a national Republican debate audience that “climate is always changing” and there is “nothing we should be doing about it.” The very same week, highly regarded climate scientist and former NASA chief James Hanson opined that, according to climate data pouring in from all over the world over the past decade, climate change is accelerating, fast outpacing even the most dire computer climate models.
Last week, too, for the first time in recorded history, the mean global temperature reached the two degree Celsius mark above pre-industrial revolution levels. At every international climate summit since the ‘90s, the two degree mark was seen as a threshold that should not be crossed. Too late now. We are there. And temperatures are going to swing higher. That prediction is “baked into the cake,” because CO2 levels will remain elevated for at least a millennium even if we stop driving our cars and running our power plants this very minute. It will take that long for natural systems to sequester the excess carbon in the atmosphere.
The heat is on. I won’t live to see the worst effects of it, as I’m a member of the check-out generation now. But my granddaughter will surely experience some of the brooding climate anomalies of the future, when city planners in Boston, New York, Baltimore, D.C., and Miami hustle for federal dollars to pay for the construction of scores of miles of sea wall to keep out rapidly rising Atlantic Ocean waters. When Albany and Springfield and Hartford are choking on smoke-filled haze from immense forest fires burning along the Canadian border. When grain producers in Texas, Oklahoma, and southern Kansas give up their wheat crops because summer temperatures on the Plains are simply too hot to support growth. When Las Vegas runs out of water.
When the Paleocene-Eocene Thermal Maximum is relabeled to reflect the looming crisis: the Present Thermal Maximum.
