Before we decide to panic, or to enforce destructive public policy, in order to combat Climate change (global warming,) we really should study what the earth was like during a previous warm period.
The obvious candidate would be the Eocene epoch. This was a period from about 55.8 million years ago (MYA) to about 33.9 MYA or a period of about 22 million years. Our
current cycle of ice ages is believed to have started near the end of the Eocene.
The early part of the Eocene is thought to have been the warmest portion
of the Cenozoic era, which is the era in which we live. At times global temperatures may have averaged as much as 27ºC or more. Today’s global mean is someplace less than 20ºC, likely around 16ºC.
In that period, the earth’s land masses were moving towards their current positions but were still in a different configuration than
today. As a result, the major Ocean currents circulated differently. This probably
allowed for part of the extra warmth and distributed the warmth more evenly around the globe. Temperature gradients between the equator and the poles are believed to have been
smaller. That would seem to indicate that temperature cannot get as high today, or that the south polar area in particular, will not warm as much.
Many scientists attribute the beginning of this warm period to an increase in atmospheric CO2 from a major increase in volcanic activity. Perhaps, but haven’t recent volcanic eruptions resulted in global cooling?
Speculation is that some of this CO2may have resulted from lava sheets
heating carbon-rich sediments. Possible, but have any scientists attempted to verify this? There should be some evidence beneath the great lava sheets of the world that exist in Russia, India, the U.S. and elsewhere.
There is also speculation that a warming deep ocean may have released
methane clathrates, but it seems to me the warming would have to occur first, particularly under the higher pressures from a higher sea level.
This could, however, work to reinforce a warming trend. CO2 levels may have been as high as 3000 ppm for relatively short durations during the Eocene.
Whatever the cause of the warm climate, my main topic of discussion is, what was the environment like under those conditions, and what the world will face if they should occur again.Most of the following comes from my imagination with as much scientific support as I could find. Try your own imagination on this.
It is likely that, since the temperature gradient between the poles and the equator was much smaller, there would have been less severe
wind events. More precipitation and higher humidity seems likely over most of the globe. Cloudy skies may have been the norm. The difference between the seasons may have been much less, with only a variation of about 3 or 4 degrees Celsius. Snow would be rare at lower elevations. I wonder about the variations between different elevations, and the difference between the center of large land areas and the
coasts. I assume the differences would be as substantial as they are today.
There was more water and less ice than today, but
what that means for the relationship between land and seas is difficult to reconstruct. It is possible that more area was covered by shallow seas and shorelines were longer but we can only guess.
The landscape was probably dominated by large trees and plants, rainforests and jungle, with less open grasslands.
Fast growth, encouraged by moisture, warm temperatures and high levels of CO2
may have been tempered somewhat by limited sunlight.
Many of the land animals would have seemed somewhat familiar if smaller than what we are accustomed to today. Most of today's mammals
evolved from ancestors of this period. There were larger animals as well, some evolving as the climate cooled towards the end of the Eocene. The dinosaurs were gone but reptiles and amphibians existed,
many very similar to those of today as were fish. Birds and sea life were continuing to evolve and the first whales left the land for permanent residence in the seas.
Life seems to have rebounded
quite well with many new forms after the K-T extinction.
The emergence of the first humans was still a very long time in the future, but had they existed they would probably have had a fairly easy time of
it. Elaborate shelter or clothing would not have been needed. There should have been good hunting and fishing. There would have been
some types of nuts and fruits, but very little grains as grasses were not far along in their evolutionary story.
Is this a time capsule that gives us an idea of what the planet may be
like if current warming continues.
There are some differences. Current warming has proceeded quite rapidly, with what may be unprecedented speed. The placement of land masses is not quite the same, and ocean currents were different.
Some of the end results may be similar. If warming continues some future generations
will probably be facing a warmer, rainier climate with considerably less seasonality in higher or lower latitudes. The earth will probably be a lot greener as a result of warmth and CO2 levels if we don’t pave over too much. Extreme weather events should be less common and less severe with the exception of precipitation events. Changes in precipitation likely will not be consistent.
Sea levels will likely be higher, and in the future, more humans may opt to live in or on the seas.
If the change is too rapid many species may not be able to adapt fast enough and extinctions could occur. However, like in the past, this will leave niches for newer species to evolve into. The progression is the same, with constant change.
Will human beings be able to adapt? It would certainly seem so. Humans have survived
vast changes in the couple of million years of their evolution. And they only seem to have gotten better at it. Instead of simply filling niches as they appear, humans have spread over the entire earth and into all but the most extreme environments. Humans
even live, for short periods, in environments as extreme as space, outside of our atmosphere.
There is no doubt that rising sea levels will make some migrations of population necessary. I doubt if there will be a great hurry, though. Not likely nearly as fast as people will be forced to move from resource-based industry towns, or even nations if their sources of income disappear because of a rapid abandonment of
How quickly could this happen? At the very least it would take 1000 years to approach conditions similar to the Eocene. Probably, it would take much longer. Plenty of time for humans to adapt and prepare, but perhaps a little short for the natural
In much of the world, our biggest concern is still going to be how to stay warm during
our winters. In most cases, this still requires a reliance on fossil fuels.
This morning the temperature outside my door was -28ºC. Wind chill added to make an effective temperature of minus 40, about the same in either Celsius or Fahrenheit. If you are caught unprepared in these temperatures, you can survive only a very short time.
I have experienced temperatures of 40ºC (105ºF.) All I needed was a slight breeze, some shade, and a cool drink to be very comfortable.
What if the opposite to warming occurs, and the earth falls into
a rapid cooling trend with a return to ice age conditions. The maximum glaciation of this ice age (that we are still emerging from) occurred less than 25,000 years ago. This is just the last in a continuing cycle including several glaciations. We could possibly start descending
into a new ice age at any time but it is more likely it will be in 10,000 years or so and take another 70,000 years to reach it’s maximum. It is, however, an almost certain consequence of climate change. It is possible that human-induced warming may delay the onset for a 1,000 years or so.
What would our environment be like? Well, at the height of the last glaciation about 27% of
the earth's land surface was covered with ice, often several kilometers thick. Most areas were much cooler and much drier and there was a lot of dust in the air. Drought was a dominant climatic feature.
Most of Canada, the northern states, northern Europe and large chunks
of Asia were icebound. All the higher elevations carried glaciers. About the only northern areas not glaciated, like Eastern Asia, were bare because there was too little precipitation to build ice. In the southern hemisphere, southern Chile and Argentina carried
ice sheets. Australia was mostly shifting sand dunes. Even some volcanic peaks of Hawaii carried glaciers.
The cold and drought would have made agriculture impossible or severely limited over most of the globe. With those conditions today, most of us would starve, even if we did have a place to live.
Could humans adapt to ice age conditions? To some degree we could,
after all, humans have survived these conditions before, but there is no way the earth could support our current population or, even less so, our expected future population. Luckily, the worst of these conditions are not likely for hundreds of generations.