CharlesW

David

Here is a brief summary for you on determining CO2 levels in the past

"Variation in the past

CO2 concentrations over the last 400,000 yearsThe most direct method for measuring atmospheric carbon dioxide concentrations for periods before direct sampling is to measure bubbles of air (fluid or gas inclusions) trapped in the Antarctic or Greenland ice caps. The most widely accepted of such studies come from a variety of Antarctic cores and indicate that atmospheric CO2 levels were about 260–280µL/L immediately before industrial emissions began and did not vary much from this level during the preceding 10,000 years.

The longest ice core record comes from East Antarctica, where ice has been sampled to an age of 800,000 years before the present.[10] During this time, the atmospheric carbon dioxide concentration has varied between 180–210 µL/L during ice ages, increasing to 280–300 µL/L during warmer interglacials.[11] The data can be accessed at here.

Some studies have disputed the claim of stable CO2 levels during the present interglacial (the last 10 kyr). Based on an analysis of fossil leaves, Wagner et al.[12] argued that CO2 levels during the period 7–10 kyr ago were significantly higher (~300 µL/L) and contained substantial variations that may be correlated to climate variations. Others have disputed such claims, suggesting they are more likely to reflect calibration problems than actual changes in CO2.[13] Relevant to this dispute is the observation that Greenland ice cores often report higher and more variable CO2 values than similar measurements in Antarctica. However, the groups responsible for such measurements (e.g., Smith et al.[14]) believe the variations in Greenland cores result from in situ decomposition of calcium carbonate dust found in the ice. When dust levels in Greenland cores are low, as they nearly always are in Antarctic cores, the researchers report good agreement between Antarctic and Greenland CO2 measurements.


Changes in carbon dioxide during the Phanerozoic (the last 542 million years). The recent period is located on the left-hand side of the plot, and it appears that much of the last 550 million years has experienced carbon dioxide concentrations significantly higher than the present day.On longer timescales, various proxy measurements have been used to attempt to determine atmospheric carbon dioxide levels millions of years in the past. These include boron and carbon isotope ratios in certain types of marine sediments, and the number of stomata observed on fossil plant leaves. While these measurements give much less precise estimates of carbon dioxide concentration than ice cores, there is evidence for very high CO2 concentrations (>3,000 µL/L) between 600 and 400 Myr BP and between 200 and 150 Myr BP.[15] On long timescales, atmospheric CO2 content is determined by the balance among geochemical processes including organic carbon burial in sediments, silicate rock weathering, and vulcanism. The net effect of slight imbalances in the carbon cycle over tens to hundreds of millions of years has been to reduce atmospheric CO2. The rates of these processes are extremely slow; hence they are of limited relevance to the atmospheric CO2 response to emissions over the next hundred years. In more recent times, atmospheric CO2 concentration continued to fall after about 60 Myr BP, and there is geochemical evidence that concentrations were <300 µL/L by about 20 Myr BP. Low CO2 concentrations may have been the stimulus that favored the evolution of C4 plants, which increased greatly in abundance between 7 and 5 Myr BP. Although contemporary CO2 concentrations were exceeded during earlier geological epochs, present carbon dioxide levels are likely higher now than at any time during the past 20 million years[16] and at the same time lower than at any time in history if we look at time scales longer than 50 million years. NOAA research estimates that 97% of atmospheric CO2 created each year is from natural sources and approximately 3% is from human activities.[17]"

David Lock

Thank you very much indeed Charles. I guessed that much would be interpreted from ice core samples and your additional information is most helpful. I take it NOAA is the USA agency National Oceanic & Atmospheric Administration.

It seems your last line is the most significant in the current debate saying that only 3% of CO2 is from human sources. So this must be disputed by the huge majority of environmental scientists?

I am trying to find the links to the atmospheric data taken over the USA after 9/11 when there were no planes for a few days as I think this threw up some quite interesting statistics. Thanks again. dl

Jay m A

iTrader: (2)

Yes, one aspect was to do with vapour trails (or lack of) contributing to warmer days in that period, evidence to back global dimming theory

CharlesW

Here's another article that touches on CO2 and climate in the past, specifically the Carboniferous in what is today West Virginia.

Climate during the Carboniferous Period

An interesting point is made by the author.

"Today, at 380 ppm our atmosphere is CO2-impoverished, although environmentalists, certain political groups, and the news media would have us believe otherwise."

CharlesW

David

This paper gives a more detailed approach to modelling CO2 levels through Phanerozoic time.

http://www.geocraft.com/WVFossils/Re...III-Berner.pdf

David Lock

OK. I personally don't buy the argument that says "it's just the government conning us so they can get more taxes". It can't be popular for any political party in any country to impose restrictions on emissions so why are they all doing it? Simple question surely? dl

PS. I have more sympathy with the arguments that particulate emissions might well make a difference to climate rather than minor gaseous changes.

scunnered

iTrader: (1)

Global warming/cooling of our climate is caused by something that's been happening since the creation of our planet. The earth's orbit is not linear, it wobbles in three axis, eccentricity, axial tilt, and precession. Global temperature variations were mapped out for 600,000 years back in the 1800's by a Serbian astrophysicist called Mulatin Milankovitch.


ECCENTRICITY; This is the shape of the earth's orbit around the sun. One full cycle takes approx 100,000 years. Today a difference of only about 3 percent occurs between aphelion (farthest point) and perihelion (closest point). This 3 percent difference in distance means that Earth experiences a 6 percent increase in received solar energy in January than in July. This 6 percent range of variability is not always the case, however. When the Earth's orbit is most elliptical the amount of solar energy received at the perihelion would be in the range of 20 to 30 percent more than at aphelion. Most certainly these continually altering amounts of received solar energy around the globe result in prominent changes in the Earth's climate and glacial regimes. At present the orbital eccentricity is nearly at the minimum of its cycle.

AXIAL TILT: This is the inclination of the Earth's axis in relation to its planetary orbit around the Sun. This tilt ranges from 21.5 degrees to 24.5 degrees and takes around 41,000 years for a complete cycle.
Today the Earth's axial tilt is about 23.5 degrees, which largely accounts for our seasons. Because of the periodic variations of this angle the severity of the Earth's seasons changes. With less axial tilt the Sun's solar radiation is more evenly distributed between winter and summer. However, less tilt also increases the difference in radiation receipts between the equatorial and polar regions. One hypothesis for Earth's reaction to a smaller degree of axial tilt is that it would promote the growth of ice sheets. This response would be due to a warmer winter, in which warmer air would be able to hold more moisture, and subsequently produce a greater amount of snowfall. In addition, summer temperatures would be cooler, resulting in less melting of the winter's accumulation. At present, axial tilt is in the middle of its range.

PRECESSION: This is the earth's slow wobble as it spins on its axis (Like a top wobbling as it slows down). A precession cycle takes approx 23,000 years. It goes from pointing at Polaris as the north star to pointing at Vega. Due to this wobble a climatically significant alteration must take place. When the axis is tilted towards Vega the positions of the Northern Hemisphere winter and summer solstices will coincide with the aphelion and perihelion, respectively. This means that the Northern Hemisphere will experience winter when the Earth is furthest from the Sun and summer when the Earth is closest to the Sun. This coincidence will result in greater seasonal contrasts. At present, the Earth is at perihelion very close to the winter solstice.
At present, only precession is in the glacial mode, with tilt and eccentricity not favourable to glaciation.

So in conclusion, if we can stop the wobbling of the earth in its orbit, we can stop global warming.

David Lock

So why are so many presumably respected, scientists jumping on the man-made-CO2-is-the-problem unpopular bandwagon? I can't see any mileage in this for them. dl

Jay m A

iTrader: (2)

Perhaps its to do with the groups that pay their wages? Equally those that debunk the idea too?

How many reports are truely independant?

CharlesW

Most of these scientists are academics. They are employed by universities. so in effect they are employed/funded by governments. If they produce research that backs the government's line, they are more likely to get funding.
That's why they are jumping on the "global warming" band wagon.

However by doing this, they do run the risk of losing their reputation, if the whole thing is debunked in the future. It's a risk they are willing to take. They have bills to pay and mouths to feed like the rest of us.

David Lock

Hmmm...

But there is an equally strong argument that says an opposition party would earn considerable brownie points by saying "Hey - vote for us - we're not going to tax you on emissions and make you buy an electric milk float".

I do accept the point about scientists not wishing to bite the hands that feed them but surely this can't be true for the overwhelming majority of them?? Just asking

CharlesW

How many MPs have a science background? I don't know, but I suspect precious few. Political parties are influenced by their own supporters and pressure groups such as Greenpeace, who are not known for sticking to the facts.

As to how many scientists work in academia and how many work in industry; again i don't know. But I do know that those who work in industry follow research pertaining to their employers' business. Only those in academia are able to follow just any line of research they fancy. However they are more likely to get funding if they follow lines of research that attract funding from governments or possibly pressure groups.

Scientists in the US have on the whole been more sceptical about the influence of man made emissions on climate change than those in Europe. This might be because on the whole US universities are less dependent on government funding.

David Lock

No

You don't need a science background to understand this sentence (from your post)

"NOAA research estimates that 97% of atmospheric CO2 created each year is from natural sources and approximately 3% is from human activities."

Prescott aside that is.

If that statement is true then it's game over? dl

CharlesW

With regards to alternative energy sources, our government again driven by Greenpeace seem to obsessed by wind power. This a complete waste of money as Denmark and Germany have discovered to their cost. They turbines are expensive to construct and they only supply power for less than 30% of the time. And that is in the windiest part of the British Isles!

MIT which produces a lot of good, independent and original science has recently completed a study on alternatives sources of energy.

MIT-led panel backs 'heat mining' as key U.S. energy source - MIT News Office

They reckon geothermal energy is the way to go. The US is already the largest producer of geothermal energy, but that is high grade geothermal energy from volcanic areas. What they recommend is low grade geothermal energy. This would supply the whole of the US's the energy needs. We already have the technology. It's call an drilling rig!

As anyone working in the oil business already knows, if you drill a hole in the ground down to 10000 ft for example, and then circulate water down the drill pipe and back to the surface, it comes out at high temperature. If not hot enough to provide steam for power generation, it is hot enough to provide an awful lot of heating.

A couple of years ago I worked on a well drilled in Copenhagen. It was a pilot for just such a scheme. The hot water would provide heating for an area of Copenhagen. If it was a success, they planned to drill many such wells.

http://www.ita.doc.gov/exportamerica...e/gnl_1202.pdf

The Copenhagen Post

GEUS Bulletin 4, Review of Survey activities 2003, pp 17-20

Geothermal energy results from volcanic activity and more generally from the decay of radioactive elements in earth's crust and mantle. In other words it is everlasting.

David Lock

Let's get drilling then!

I might add solar power to this as I have a feeling that in the next 20 years the price of panel production will decrease significantly. So, for example, towns in hot places by the sea could have drinking water from desal' plants and some energy in Africa for water wells and communication. After all sunshine is about all Africa has going for it at the moment. dl

I hope no one from the Isle of Lewis was reading your post dl

CharlesW

I hope they do read it on the Isle of Lewis.

Solar power is a way to go too. After all fossil fuel is derived in a round about way from solar power. Coal was produced via photosynthesis during the Carboniferous and other periods since then. The route from solar radiation to oil is a little more complex.