Hasn't the Earth been warming since the last ice age?

Question

Ice core samples taken from greenland show CO2 in the air in very high concentrations thousands of years ago. Scientists please respond, not the spoon-fed media politico response. I am interested in real science!

Answer 1

1 - CO2 LEVELS

One of the best ways to measure historical atmospheric concentrations of CO2 is by analysis of ice cores. The ice core record now extends back nearly 750,000 years and during this period CO2 levels have fluctuated between 180 and 290 ppmv*.

Coinciding with the start of the Industrial Revolution in the 19th century there has been a marked rise in CO2 levels and they now stand at 384ppmv.

Using a technique known as Geochemical Modelling* we can extend the CO2 record back through the Phanerozoic Eon* and this gives us a little over half a billion years data to go at.

Analysis of this data shows that millions of years ago, long before the advent of the homo genus (humans), atmospheric CO2 levels were many times higher than they presently are. The modelling methods aren't precise so it's impossible to say just how much higher but it's likely to have peaked some 500 million years ago at 10 to 20 times current levels.

* PPMV = Parts Per Million by Volume, a measure of atmospheric gas concentrations

* Geochemical Modelling - Estimation of past levels of CO2 using stomatal density in fossilised flora, ratios of carbon isotopes in fossilsed soils or the shells of phytoplankton (timy marine plants).

* Phanarezoic Eon = The current eon, representing the period of complex life forms on the planet, covers the last 542 million years

2 - WARMING OF EARTH

Often when people refer to the last ice age they're referring to the most recent period of extended glaciation, this is the 'ice age' that began receding some 18,000 years ago. The last ice age per se was some 150 million years ago and even then, it wasn't much of an ice age*; the last true ice age was approx 300 million years ago.

In the last 18,000 years Earth's temperature has been rising. For the first 7,500 years of this period temperatures rose by 7 degrees Celsius and this brought about a large scale galcial retreat. Prior to this, extensive parts of the continents of Asia, Europe and North America were covered in ice. In the subsedquent 10,000 years temperatures rose by a further one degree.

Earth and the Sun both go through a complicated series of cycles* and the interaction causes warming or cooling of the planet, it's done this since the formation of our planet a little over 4.5 billion years ago.

The long term (glacial / intergalcial) trend sees temperatures of our planet vary by about 20 degrees C over typically 50 million years, within these long trends are much shorter trends. Whilst the short term trend is one of warming we're also in a much longer cooling trend which has been ongoing for a little over 50 million years.

The current cause for concern is due to the fact that temperatures are now rising much faster than can be attributed to natural cuases. Warming has accelerated to 156 times the rate over the 10,000 years prior to the Industrial revolution and 17 times the rate during the glacial retreat of 10,500 to 18,000 years ago.

* The position of land masses on Earth's surface at that time prevented formation of large ice sheets.

* For mole about the Earth's cycles search for 'Milankovitch Cycles', for more about the Sun search for 'Solar Variation'.

Answer 2

Yes, it has been increasing for a very long time. The concern seems to be it is increasing at a faster rate than in previous cycles (based on analyzing ice core samples and estimating what it was hundreds and thousands of years ago), and CO2 levels seem to be higher than in past cycles. Many scientists have theorized from this that man has added to much CO2 and that due to that, the world is heating up faster and will reach a higher temperature than it would have naturally.

I think this is a valid theory and one logical conclusion. It may or may not prove to be right. After all, we are comparing measurements taken today with estimates made from analysis of ice core samples from thousands of years ago. There is probably room for some error there. We may find the earth is just going to get hotter anyway and there is nothing we can do.

What do we have to lose by going ahead and trying to reduce our use of fossil fuels? We know it pollutes and we need to get off our dependency of foreign oil.

Answer 3

You won't get real science from the "chicken little" crowd. All you can expect is the political agenda. They'll all bring up things like the UN report on climate change... but they'll fail to mention that MANY of the people credited on that report aren't scientists, they're politicians. They'll also fail to mention that MANY of the actual scientists credited on that report disagree with it; some so much that they've sued to have their names removed from it.

The real science is that the planet has always had changing climate; include rapid increases and decreases in temperature (see the medieval warm period and little ice age).

The real science is that there is no proof that CO2 causes global warming, in fact exactly the opposite. The data shows an increase in temperature BEFORE the increase in CO2 levels (AKA temperature causes an increase in CO2).

They'll make claims about increase in temperature since human industrialization, but fail to mention that since the planet has been heavily industrialized we've experienced MORE years of cooling than warming ( bringing about the global cooling claims a few decades ago ). In fact during the years of most rapid industrialization the planet was cooling off.

Answer 4

The temperature of the earth is constantly fluctuating; we in fact are just emerging from a major "global cooling." Look up the little ice age. In the early 70s, Time released an article very similar to this notioning how global cooling will kill us all. The issue just happens to be attracting an obscene amount of left wing attention this time.
Kaze, the issue is that it is entirely normal to have substantial fluctuation in temperature within these gradual climate shifts, which can last thousands-millions of years.
Next edit: CO2 actually has a relatively insignificant greenhouse effect.
The issue isn't even CO2, it just happens to be drawing the most attention because emissions are reducible. The U.N.s #1 gas causing the greenhouse effect is methane(20 times higher effect than CO2 at retaining temperature). Nearly all methane on earth is emitted by livestock....cow flatulation is FAR more substantial in contributing to warming than cars. Look it up for yourself, it's on any gov't site. Whole thing is a messy political issue, can imagine scientists wouldn't be paying much attention to it otherwise.

Answer 5

Science doesn't get any realer than this.

First,10 peer reviewed studies of the last 1000 years, with references and some links to the original scientific articles. The graph stops in 2004. If it went to 2006, it would be even more impressive.

http://www.globalwarmingart.com/wiki/Image:1000_Year_Temperature_Comparison_png

The last time Earth was warmer, the sea level was tens of feet higher. If that happens again it will cost us a lot of money. In poor countries enough agricultural land will be flooded to cause many deaths by starvation.

Next, eight peer reviewed studies (and the references) on temperatures for the last 12,000 years. Note the arrow for 2004, 2005 and 2006 are higher.

http://www.globalwarmingart.com/wiki/Image:Holocene_Temperature_Variations_Rev_png

If you think these summaries are somehow political, go to the library and read the references.

Answer 6

Ice core samples show a change in atmosphere over thousands of years it's true. However, these changes were all gradual and natural. The concentrations of greenhouse gases in our atmosphere have changed drastically due to human intervention. The temperature of the planet has also risen over the last tens of thousands of years. But again, the amount that it has risen in the last 50 years is way more than the natural increase in temperature. The fact that thousands of scientists from all different fields agree that the atmosphere and our planetary temperature have changed dramatically, and in no sort of natural way, should be a sign that the stuff you hear about global warming is not just some sort of political ploy.

Answer 7

Yes! You hit the nail on the head. When the earth warms, it melts the polar ice caps. Because the ice is white, it reflects sunlight. With less ice, the earth will absorb heat, causing the earth to get even warmer. The warmth will eventually result in evaporation, resulting in more cloud cover. This cloud cover will block sunlight, cooling the planet and re-freezing the ice caps (or, we will have another asteriod hit that throws up millions of tons of dust that will also block the sun). But, don't wait around for this .. the cycle takes tens of thousands of years.

Answer 8

the difficulty isn't that we are inflicting worldwide warming, as much as we've prevented nature from entering what might desire to be yet another cooling cycle. Nature will certainly preserve herself. because of the fact the greenhouse gases build in the ambience, they initially hold the warmth because of the fact the glass does in a greenhouse. yet because of the fact the gases proceed to thicken, they start to act as a shield, and the photograph voltaic rays would be pondered removed from the planet, subsequently transforming into an ice age to end existence as all of us comprehend it. Oh, happy day

Answer 9

CO2 hasn't been as high as they are today for atleast 650.000 years. They have varied between 180 ppm during cold glacial times and as high as 300 ppm during warm interglacials. It is presently at 379 ppm.

Answer 10

http://en.wikipedia.org/wiki/Global_warming