The Long Road Ahead
With all the predictions of short term climate catastrophes proffered by global warming alarmists it is hard to look forward to a future time on Earth. What does the future hold a thousand, ten thousand, a million years from now? Science has some predictions about that as well, though the news media have not picked up on them. What environmental changes await us on the long road ahead?
The Northern Hemisphere has been hammered by the coldest winter in decades. Chinese provinces prepared to introduce power rationing as electricity supplies lagged behind demand amid harsh winter weather. In the UK things have been so bad that Keith Mitchell, the leader of the Oxfordshire County Council, accused county residents of lacking the “British spirit that defeated Hitler” in the wake of the freezing weather. Just to confuse things, a new report in report in Science says NASA's GISS proclaimed “2009 Hottest Year on Record in Southern Hemisphere.”
In the US, AccuWeather meteorologist Joe Bastardi reports: “The coldest start to an El Niño winter since the '70s, in the wake of the thaw, may have a top 10-15 cold February nationwide.” Outlook India's headline proclaimed “North India Reels Under Cold Wave, 154 Dead.” There were reports of frozen sheep in Scotland, and snow fell Down Under during the Australian summer.
In Europe, the protesters at the Copenhagen Climate Conference were treated to snow and record cold temperatures that some blamed on the Gore Effect. The term “Gore Effect” comes from the observation that unseasonable weather seems to accompany former US Vice President and Nobel Laureate Al Gore whenever he appears at a global warming event or public hearing. Since 2004 these coincidences have occurred with increasing frequency.
President Obama left Copenhagen early in an attempt to avoid the weather, only to arrive back in Washington for a major winter storm that engulfed the entire east coast. Florida experienced the its longest stretch of cold weather in 100 years. In southern Florida frozen iguanas were falling out of the trees. So-called “kamikaze” iguanas are an urban legend among Floridians but became a common sight as temperatures dropped almost to freezing.
All of this wicked weather comes with the often repeated warning that weather is not climate. So what is going on with the climate? It looks like a combination of El Niño and the multi-decadal oscillations in the Pacific and Atlantic are conspiring to cause a temperature downturn world wide. In the near term we are in for the usual multi-decadal variations in hot and cold. Prof Anastasios Tsonis, head of the University of Wisconsin Atmospheric Sciences Group, has recently shown that these MDOs move together in a synchronized way across the globe, abruptly flipping the world’s climate from a ‘warm mode’ to a ‘cold mode’ and back again in 20 to 30-year cycles.
“They amount to massive rearrangements in the dominant patterns of the weather,” Tsonis explained, ‘and their shifts explain all the major changes in world temperatures during the 20th and 21st Centuries. We have such a change now and can therefore expect 20 or 30 years of cooler temperatures.” The bigger question is, does the current cooling trend indicate the start of the next transition from interglacial back to glacial conditions—are we headed back into an ice age?
The Northern Hemisphere has suffered its coldest winter in decades.
So many scientists are predicting continued cooling for 20, 30 even 50 years, though the IPCC insists that global warming will be back with a vengeance. No consensus there. But what about 1,000, 10,000, even 1,000,000 years from now? What follows is speculation, based on science but speculation none the less. These are my projections of what science knows about climate change into the future—just some possible scenarios. Besides, it's not like I'll be around to take the credit or the blame if they do or don't come true.
Earth 3010 AD
The general term “ice age” or, more precisely, “glacial age” denotes a geological period of long-term reduction in Earth's surface and atmospheric temperature, resulting in an expansion of continental ice sheets, polar ice sheets and mountain glaciers. For the past several million years, Earth has been locked in an ice age called the Pleistocene. Glacial periods come and go with remarkable regularity, lasting 100,000 years or so and then transitioning to a much warmer interglacial period for 10,000 to 15,000 years. The last such glacial period finally ended about 11,000 years ago (see “Variations in the Earth's Orbit: Pacemaker of the Ice Ages”).
If the current interglacial, optimistically designated the Holocene epoch, follows the previous cycles there could be several thousand years of temperate climate left. But that is just working with average behavior. There have been shorter interglacials and much longer ones as well. Subtle shifts in Earth's orbit around the Sun moderates the amount of energy entering the Earth's climate system. These variations in Earth's orbital and rotational configuration are known to trigger or end glacial periods, but other factors come into play as well.
Variations in solar output occur on much shorter, decadal time-scales than glacial-interglacial climate oscillations. Atmospheric carbon dioxide concentrations also correlate nearly perfectly with Ice Age cycles—but CO2 is thought to be a positive feedback, not the trigger. Other feedback mechanisms—the amount of airborne dust, changes in albedo, shifting ocean currents, etc.—complicate the interplay of environment and solar radiation. When the combination of influences are right Earth's climate undergoes dramatic changes.
There are also longer cycles seen within warm interglacial periods. Perhaps caused by longer term variation in solar output, these cycles can span for centuries. Since people have been around to directly observe them these alternating periods of warm and cold have been given names: The Little Ice Age, the Medieval Warm Period and so on. While Earth has indisputably been in a warming trend for the past 150 years or so, our planet may well enter a new cooling phase that could last for centuries.
Seas rise as the current interglacial continues, 3010 AD.
Most likely, a thousand years from now the climate will have resumed warming. This means that glaciers and the great ice sheets of Greenland and Antarctica will continue to melt, raising sea-levels around the world by several more meters. Many coastal areas will be flooded and humanity will be called on to do what it does best, adapt. My forecast for 3010 AD is for slightly warmer temperatures, moderately higher sea-levels an a slightly more active hydrological cycle (more rain). You may have to move your beachfront cottage, but other than that things will be quite comfortable.
Contrary to the dire warnings that rising sea-levels constitute a climate crisis, rising sea-levels during an interglacial are perfectly natural—an interglacial is one long stretch of glacial melting (see “Ice Core Evidence for Extensive Melting of the Greenland Ice Sheet in the Last Interglacial”). The Eemian interglacial period, the second-to-latest interglacial period of the Pleistocene Ice Age Ice, reached its height around 125,000 years ago. Sea-level at that peak was probably 4-6 m (12-20 ft) higher than today (see “Paleoclimatic Evidence for Future Ice-Sheet Instability and Rapid Sea-Level Rise”). Much of this extra water came from Greenland but some also came from Antarctica. When the glaciers and ice caps stop melting and ice begins to accumulate again it is a sign that Earth is beginning another slow descent into ice age conditions.
Earth 10,010 AD
During each glacial period, the mile-thick ice sheets that cover much of the top of the world also go through cycles lasting a few thousand years: sometimes thickening and extending, other times thinning and receding. In counterpoint to the varying ice the world's oceans rise and fall by as much as 30 m (100 ft), and in doing so make their own contribution to climate change (see “Influence of Bering Strait flow and North Atlantic circulation on glacial sea-level changes”). Cycles within cycles.
Based on geological records available in 1972, the last two interglacials were believed to have lasted about 10,000 years—about the length of the Holocene to date. Assuming that all interglacials were of similar duration, the scientists concluded that “it is likely that the present-day warm epoch will terminate relatively soon if man does not intervene.” Early attempts to predict future climate, based on the cooling trend that started at the peak of the Holocene some 6000 years ago, predicted a cold interval in about 25,000 years and a full glaciation in about 55,000 years.
A new glacial period begins, 10,010 AD.
This implies that, in 10,000 years, Earth could be starting a new glacial period. From paleoclimate records we know that, while the transition from glacial to interglacial takes place quite rapidly, only a matter of a few thousand years, the transition from interglacial to glacial is much slower. By 10,010, the planet may once again be cooling, with glaciers beginning to advance as the climate grows ever colder. Recently, however, some scientists have come to doubt this prediction.
Earth 100,010 AD
That doubt is based on the observation that, over the next 100,000 years, the amplitude of insolation variations will be small, in fact much smaller than during the Eemian. This means that insolation, the energy Earth receives from the Sun, will also vary only slightly. If this proves correct then the Eemian should not be used as a model for the the current interglacial (see “An Exceptionally Long Interglacial Ahead?”).
The small amplitude of future insolation variations is exceptional. In fact, the last time such conditions occurred was more than 400,000 years ago, during the interglacial known as Marine Isotope Stage 11 (see “Oceanic forcing of the Marine Isotope Stage 11”). Then and now, very low eccentricity values coincided with the minima of the 400,000-year eccentricity cycle. Eccentricity will reach almost zero within the next 25,000 years, leading to speculation that the Holocene will last for as long as 28,000 years. Recent results by Peltier and Vettoretti, using the Canadian climate general circulation model, showed that given present-day insolation levels and using preindustrial CO2 levels, no glacial inception is likely.
Some would go even farther, suggesting that human activity will cause an “irreversible greenhouse effect,” short-circuiting the natural cycle of glacials and interglacials. If anthropogenic global warming is taking place at the rate predicted by the IPCC, and if the Greenland and West Antarctic Ice Sheets disappear completely, then today's Holocene may become the transition between the Pleistocene Ice Age and the next geological period.
In 1972, J. Murray Mitchell Jr. already predicted in that “the net impact of human activities on the climate of the future decades and centuries is quite likely to be one of warming and therefore favorable to the perpetuation of the present interglacial.” Would that really be so bad, considering the likely alternative?
New York City buried by resurgent glacial ice, 100,010 AD.
That alternative is a return to full glacial conditions. The 100,000-year cycle only appeared about 800,000 years ago. Prior to that, going back to the very beginning of the Pleistocene Ice Age about 3 million years ago, smaller ice sheets varied at an almost clock-like 41,000-year rhythm. This is the period of changes in orbital tilt. After several million years of shorter cycles, Earth shifted to its current glacial-interglacial timing cycle, the so called “100,000-year world” (see “Glacial Puzzles”).
The defining characteristics of the “100,000-year world” are terminations: rapid and abrupt shifts from extreme glacial to extreme interglacial conditions that are not observed earlier in the Pleistocene. These terminations, which conclude a glacial period, require the buildup of unusually large, presumably unstable ice sheets. The inherent instability of these ice sheets in part explains the extraordinary rapidity of the deglaciation. Some scientists believe that an increase in global temperature, as we are now experiencing, could be a sign of an impending ice age. The warmth causes more precipitation and actually increases the amount of ice on Earth's surface.
What causes the 100,000-year cycle? According to M. E. Raymo, from the MIT Department of Earth, Atmospheric, and Planetary Sciences:
I would answer that it is a pseudoperiodic cycle varying in length from about 80,000 to 120,000 years. It is caused by the periodic buildup of large ice sheets during times of unusually low summer insolation at high latitudes that occur roughly every 100,000 years as dictated by the interaction of precession with eccentricity and, to a lesser degree, obliquity. A cycle ends abruptly, with a termination, when insolation increases above a threshold value that causes the ice sheet to become unstable and melt rapidly.
What this all means is that the glaciers will probably return, once again burying the Northern Hemisphere under a thick blanket of ice. In North America during glacials past, the ice reached the present day location of the Ohio and Missouri Rivers, although the last advance (called the Wisconsin) did not reach as far south as some of the previous advances. Still, expect New York City and a host of other modern metropolises to vanish under miles of frozen H2O, while land that has not been above the surface of the ocean in millennia reappears. The forecast for 100,010 is cold and snowy with cool summers and falling sea-levels. If people still exist on this planet they might think a little global warming would be a good idea.
Earth 1,000,010 AD
Today, only 11,000 years have passed since the last glacial and scientists can not be certain that we are living in a post-glacial Holocene epoch instead of just another in the long sequence of Pleistocene interglacials. Geologic history shows that ice ages eventually come to a complete end and do not occur again for many millions of years. We know that the Milankovitch Cycles control the timing of glacials and interglacials, but what controls the longer term climate pattern?
There are a number of theories that link cosmic rays and the solar system's position within the Milky Way Galaxy to long term climate trends. These include Cosmoclimatology, espoused by Svensmark and Shaviv, et al., and the Galactic Geologic Interval Theory, proposed by MOShaver and others. Given the time scales these theories work on, and our only approximate knowledge of the distant past, it is not surprising that they have not been widely accepted. They do, however, propose a mechanism for the beginning and ending of earthly icehouse conditions.
Most simply put, our galaxy's spiral arms are filled with dust and young, hot, short-lived stars that frequently explode. When the solar system is in one of the arms Earth receives high levels of galactic cosmic rays. These cosmic rays interact with Earth's atmosphere to increase cloud cover and create conditions favorable to climate cooling. Conversely, during the long transits of the inter-arm gaps the climate warms and ice ages do not occur. Arm transits have also been blamed for mass extinction events, but that is outside the purpose of this article.
The solar system's place in the galaxy. NASA.
The solar system, including our Earth, is orbiting around the center Milky Way Galaxy every 225 million years, in an orbit that is 52,000 light years long. At our radial distance from the Galaxy core—about 26,000 light years—six spiral arms intersect with our orbit. Our current position is close to the inner rim of the Orion Arm, a spur of one of the arms. The orbital speed of the Solar System is approximately 220 km/s. At this speed, it takes around 1,400 years for the Solar System to travel a distance of 1 light-year, or 8 days to travel 1 AU (astronomical unit, the mean distance between Earth and the Sun, approximately 150 million km or 93 million miles). In a million years one might guess that the solar system would be 700 light-years farther across the Orion Arm and headed for the open space separating it from the next arm out, but things are not so simple.
The spiral arms, which are thought to be compression waves, not moving bands of stars, are themselves moving (for a detailed discussion of cosmic rays and spiral arms see The Resilient Earth, Chapter 11). The Relative velocity of our solar system to the Orion Arm is 26 km/s into the Solar Apex point, the star Vega in the constellation Sagittarius. Assuming the next Major Geological Galactic Period is within maximum deviation limits recorded, statistically, it is certain to occur within the next 8 million years.
The Pleistocene Ice Age ends, 1,000,010 AD.
Given the information above, my forecast for 1,000,010 AD is more like a long range weather forecast—the Ice Age could be clearing as early as 1,000,000 years from now, but it could take millions of years longer. Eventually the solar system will pass out of the Orion Arm and the Pleistocene Ice Age will truly come to an end. Estimates of how long it takes to cross an average inter-arm gap of 4,500 light-years range from 50±5 to 70±14 million years. The distance between the local arm and the next arm out, the Perseus Arm, is about 6,500 light-years. This means that, if the cosmoclimatology theory is correct, once we pass into the inter-arm gap we should be done with ice ages for quite a while.
Earth 1,000,000,010 AD
In the far future, a billion years from now, the climate is going to change in ways never before seen on Earth. Our star has been slowly growing brighter over the ages, a trend that will continue right up until the Sun becomes a red giant. Estimates vary, but it is thought that Earth will become too hot to support life a billion years from now. The nurturing Sun, the source of all life energy on Earth will eventually bake us to a crisp.
In 1982, Lovelock and Whitfield suggested that, as the luminosity of the Sun increases over its lifespan, biologically enhanced silicate weathering may be able to reduce the concentration of atmospheric CO2 so that Earth's surface temperature is maintained within an inhabitable range. Unfortunately, in about 900,000,000 years all of Earth's atmospheric CO2 will have been absorbed and that will have some rather drastic consequences for all living things (see “Too Little CO2 To End Life On Earth”).
The Sun that nurtures us will eventually incinerate the Earth.
According to an article in PNAS, Earth's entire biota are threatened by the eventual loss of atmospheric carbon dioxide. You see CO2 is plant food and without it there are no plants. Without plants there are no animals, and that includes human beings (assuming we manage to survive until then). The eventual death of the planetary biosphere due to lack of carbon dioxide tells us some things about the current CO2 induced global warming hysteria. As S. Franck, C. Bounama, and W. von Bloh put it in “Causes and timing of future biosphere extinction” in Biogeosciences Discussions:
Procaryotes, eucaryotes, and complex multicellular life forms will extinct in reverse sequence of their appearance. This is a quantitative manifestation of the qualitative predictions of Ward and Brownlee (2002). We have shown that nonlinear interactions in the biosphere-geosphere system cause bistability during the Neo- and Mesoproterozoic era. For realistic values of the biotic enhancement of weathering there is no bistability in the future solutions for complex life. Therefore, complex organisms will not extinct by an implosion (in comparison to the Cambrian explosion). Eucaryotes and complex life extinct because of too high surface temperatures in the future. The ultimate life span of the biosphere is defined by the extinction of procaryotes in about 1.6 Gyr because of CO2 starvation. Only in a small fraction (1.3 Gyr) of its habitability time (6.2 Gyr) our home planet can harbour advanced life forms.
Though carbon dioxide levels have varied widely over the 4.5 billion years of Earth's existence the trend is irrefutably downward. When taken as part of the grand sweep of Earth's history the current rise of atmospheric CO2 levels is not even noteworthy. The PNAS article cited above states “As this process continues, however, between 100 and 900 million years (Ma) from now the CO2 concentration will reach levels too low for C3 and C4 photosynthesis, signaling the end of the solar-powered biosphere.” Life will die and the ever hotter Sun will provide a suitable funeral pyre. The forecast for 1,000,000,010 is hellishly hot with 100% chance of total extinction.
Earth 10,000,000,010 AD
Our Sun, like all stars, will die. The fate of a star when it leaves the main-sequence, after exhausting its supply of hydrogen fuel, depends partly on its mass. Once a star's hydrogen is spent, it will start burning helium in a nuclear reaction that forms carbon and oxygen. A side effect of this change in nuclear fuel is swelling and cooling of a star's outer layers. When this happens, the star becomes a red giant.
At the end of their lives, stars rapidly burn through helium and progressively heaver elements, but it is a loosing proposition. When a star the size of the Sun runs totally out of fuel it collapses, and the sudden contraction causes one or more explosions. These explosions blow off the outer layers of the star, forming a planetary nebula. Over time, the matter in the nebula will disperse, leaving behind a white dwarf—the cooling remains of the burned-out star.
This is where we came from and where our atoms will return to some day.
In the long run we are all going to end up scattered atoms that may well become part of a new planet circling a new star. A few of your atoms or mine might even end up is some sentient creature, perhaps a creature that is worried about its species and the future of its planet's environment. In the future Earth's climate is going to change with or without mankind's puny contributions to global warming. We try to predict the future, but the road ahead will undoubtedly contain twists and turns we can not even imagine.
So here is my long term 10 billion year forecast: Continued warm with occasional periods of glaciation, eventually followed by a permanent thaw and slowly rising temperatures, finished off by the Sun shedding its out layers and scattering our ashes into space. But don't be depressed: this bleak end lies further in the future than twice the Earth's total lifespan to date. No form of complex multicellular life, no species alive today has survived even a tenth that long. In the short term, I am going to follow Jimmy Buffett's advice: “we'll survive this global warming if we chill the rosé.”
Be safe, enjoy the interglacial and stay skeptical.
“We'll survive this global warming if we chill the rosé.” lyrics by Jimmy Buffett from Turn up the Heat and Chill the Rosé.