You might be unaware of the fact that you live your life in an ice age. To be more precise, you live in a warm period of our present ice age. As far as we know this ice age is the fifth ice age Earth has experienced. Its name is “Quaternary” and it began about 2.58 Million years ago. Nobody knows when it’s going to end.
By our standards, Earth is old, around 4.5 billion years old. Climate on earth has changed constantly, sometimes fast, sometimes slowly.
However, it’s unusual for Earth to be in an ice age. Earth has had a warm and wet climate without polar ice caps and ice glaciers for most of its existence.
What exactly is an ice age? It is an era in which the surface and atmosphere of the Earth becomes so cold to result in continental ice sheets, polar ice sheets and alpine glaciers. An ice age consists of periods of glaciations (more ice on earth) and interglacials (less ice on earth).
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To our knowledge there have been five ice ages during the history of our planet: our own (2.58 million to present), Karoo (360 to 260 million years ago), Andean-Sharan (450 to 420 million years ago), Cyrogenian (800 to 635 years ago) and Huronian (2400 to 2100 million years ago). The first four ice ages were between 30 and 300 million years long. This might suggest that our own has just begun – or it might not. The length of earlier ice ages does not necessarily mean that our current one will turn out to be of similar length. Nobody knows.
All five ice ages taken together lasted roughly 600 million years. The Earth is about 4550 million years old and therefore during less than 20% of its existence the Earth’s poles have been covered in ice. Almost 4000 million years of its existence the Earth was iceless.
What do we know about the carbon dioxide content of the first four ice ages? If it were true that an atmospheric increase of C02 leads to an increase in temperature then we would expect to see low C02 levels during the glaciation periods of the last ice ages.
But we don’t. In fact, although there is considerable uncertainty concerning the exact C02 levels during the preceding ice ages various proxy measurements conclude that carbon dioxide levels were much higher than they are today. A clear correlation between C02 and temperature over geological time scales, i.e. millions of years, does not exist:
“Various proxy measurements have been used to attempt to determine atmospheric carbon dioxide levels millions of years in the past…. While these measurements give much less precise estimates of carbon dioxide concentration than ice cores, there is evidence for very high CO2 volume concentrations between 200 and 150 Ma of over 3,000 ppm and between 600 and 400 Ma of over 6,000 ppm.” (http://en.wikipedia.org/wiki/Carbon_dioxide_in_Earth’s_atmosphere)
Compare those levels with our current C02 level of 391 ppmv (parts per million).
Geochemical processes like super volcanism and the breaking up of continents released enormous amounts of C02 into the atmosphere millions of years ago. The levels of C02 were between 10 and 20 times higher than today but the temperatures were nonetheless much lower. This fact alone invalidates any attempts to portray C02 as the determining factor of driving Earth’s climate.
It is correct that there is a correlation between CO2 and temperatures for the last 600,000 years or so. However, correlation is not the same as causation. If the data is studied at sufficient resolution increases in CO2 are seen to lag behind increases in temperature by about 700 to 1000 years. In other words, an increase in temperature – independent of what the cause of this increase might be – seems to be followed by an increase in C02 with a lag of several hundred years. How does that happen? Earth’s oceans contain a tremendous amount of dissolved C02. Interestingly, the colder the water the more dissolved C02 it can contain. Therefore, if the oceans’ surface water warms due to an increase in the temperature of the air some of the water’s C02 is released into the atmosphere.
Climate is the result of many factors most of which are still poorly understood. We are not sure, for example, what exactly triggered the beginning of the various ice ages nor do we understand what caused them to end. The mind-boggling complexity of climate makes it very difficult to analyze. There is no lack of suggestions what might have caused Earth to undergo its ice ages: variations in solar energy, orbital variations, increased rotation of Earth, changes in ocean circulation, super volcanism, variations in cloud cover etc. The only certainty is that we do not know for sure.
Perhaps precisely this lack of certainties helped to make climate change such an easy target to be used by politicians and climate scientists for their own purposes. The brazenness with which frivolous answers are assigned to complex scientific questions is remarkable. And the readiness of the media to accept and promote such answers is noteworthy too. But it’s all topped off by the eagerness of the Obama Administration to base its entire energy policy on such shaky grounds.
Al Gore is convinced that “right now we are facing a planetary emergency, and it is time for action.” (“An Inconvenient Truth”, p. 287, published in 2006) According to this modern doomsday racketeer there is no time left to think. It is easy to see why that must be so: thinking will lead to very different answers than those hoped for by those who have built their careers around human caused climate change.
Part 2 “Global Warming in the Eemian of the Quaternary” will follow soon.