January historical levels of CO21959 - 315.62
1960 - 316.43
1961 - 316.93
1962 - 317.94
1963 - 318.74
1964 - 319.57
1965 - 319.44
1966 - 320.62
1967 - 322.07
1968 - 322.57
1969 - 324
1970 - 325.03
1971 - 326.17
1972 - 326.77
1973 - 328.54
1974 - 329.35
1975 - 330.68
1976 - 331.66 1977 - 332.69
1978 - 335.1
1979 - 336.21
1980 - 337.8
1981 - 339.36
1982 - 340.92
1983 - 341.64
1984 - 344.05
1985 - 345.25
1986 - 346.54
1987 - 348.38
1988 - 350.38
1989 - 352.89
1990 - 353.79
1991 - 354.87
1992 - 356.17
1993 - 356.86
1994 - 358.22
1995 - 359.87
1996 - 362.04
1997 - 363.04
1998 - 365.18
1999 - 368.12
2000 - 369.25
2001 - 370.52
2002 - 372.45
2003 - 374.87
2004 - 377
2005 - 378.47
2006 - 381.35
2007 - 382.93
2008 - 385.44
2009 - 386.94
2010 - 388.5
2011 - 391.25
2012 - 393.14
2013 - 395.55
Table data source: Dr. Pieter Tans, NOAA/ESRL
Science News
... from universities, journals, and other research organizationsLast Time Carbon Dioxide Levels Were This High: 15 Million Years Ago, Scientists Report
Oct. 9, 2009 — You would have to go back at least 15 million years to find carbon dioxide levels on Earth as high as they are today, a UCLA scientist and colleagues report Oct. 8 in the online edition of the journal Science.
"The last time carbon dioxide levels were apparently as high as they are today — and were sustained at those levels —
global temperatures were 5 to 10 degrees Fahrenheit higher than they are today, the sea level was approximately 75 to 120 feet higher than today, there was no permanent sea ice cap in the Arctic and very little ice on Antarctica and Greenland," said the paper's lead author, Aradhna Tripati, a UCLA assistant professor in the department of Earth and space sciences and the department of atmospheric and oceanic sciences.
"Carbon dioxide is a potent greenhouse gas, and geological observations that we now have for the last 20 million years lend strong support to the idea that carbon dioxide is an important agent for driving climate change throughout Earth's history," she said.
By analyzing the chemistry of bubbles of ancient air trapped in Antarctic ice, scientists have been able to determine the composition of Earth's atmosphere going back as far as 800,000 years, and they have developed a good understanding of how carbon dioxide levels have varied in the atmosphere since that time. But there has been little agreement before this study on how to reconstruct carbon dioxide levels prior to 800,000 years ago.
Tripati, before joining UCLA's faculty, was part of a research team at England’s University of Cambridge that developed a new technique to assess carbon dioxide levels in the much more distant past — by studying the ratio of the chemical element boron to calcium in the shells of ancient single-celled marine algae. Tripati has now used this method to determine the amount of carbon dioxide in Earth's atmosphere as far back as 20 million years ago.
"We are able, for the first time, to accurately reproduce the ice-core record for the last 800,000 years — the record of atmospheric C02 based on measurements of carbon dioxide in gas bubbles in ice," Tripati said. "This suggests that the technique we are using is valid.
"We then applied this technique to study the history of carbon dioxide from 800,000 years ago to 20 million years ago," she said. "We report evidence for a very close coupling between carbon dioxide levels and climate. When there is evidence for the growth of a large ice sheet on Antarctica or on Greenland or the growth of sea ice in the Arctic Ocean, we see evidence for a dramatic change in carbon dioxide levels over the last 20 million years.
"A slightly shocking finding," Tripati said, "is that the only time in the last 20 million years that we find evidence for carbon dioxide levels similar to the modern level of 387 parts per million was 15 to 20 million years ago, when the planet was dramatically different."
Levels of carbon dioxide have varied only between 180 and 300 parts per million over the last 800,000 years — until recent decades, said Tripati, who is also a member of UCLA's Institute of Geophysics and Planetary Physics. It has been known that modern-day levels of carbon dioxide are unprecedented over the last 800,000 years, but the finding that modern levels have not been reached in the last 15 million years is new.
Prior to the Industrial Revolution of the late 19th and early 20th centuries, the carbon dioxide level was about 280 parts per million, Tripati said. That figure had changed very little over the previous 1,000 years. But since the Industrial Revolution, the carbon dioxide level has been rising and is likely to soar unless action is taken to reverse the trend, Tripati said.
"During the Middle Miocene (the time period approximately 14 to 20 million years ago), carbon dioxide levels were sustained at about 400 parts per million, which is about where we are today," Tripati said. "Globally, temperatures were 5 to 10 degrees Fahrenheit warmer, a huge amount."
Tripati's new chemical technique has an average uncertainty rate of only 14 parts per million.
"We can now have confidence in making statements about how carbon dioxide has varied throughout history," Tripati said.
In the last 20 million years, key features of the climate record include the sudden appearance of ice on Antarctica about 14 million years ago and a rise in sea level of approximately 75 to 120 feet.
"We have shown that this dramatic rise in sea level is associated with an increase in carbon dioxide levels of about 100 parts per million, a huge change," Tripati said. "This record is the first evidence that carbon dioxide may be linked with environmental changes, such as changes in the terrestrial ecosystem, distribution of ice, sea level and monsoon intensity."
Today, the Arctic Ocean is covered with frozen ice all year long, an ice cap that has been there for about 14 million years.
"Prior to that, there was no permanent sea ice cap in the Arctic," Tripati said.
Some projections show carbon dioxide levels rising as high as 600 or even 900 parts per million in the next century if no action is taken to reduce carbon dioxide, Tripati said. Such levels may have been reached on Earth 50 million years ago or earlier, said Tripati, who is working to push her data back much farther than 20 million years and to study the last 20 million years in detail.
More than 50 million years ago, there were no ice sheets on Earth, and there were expanded deserts in the subtropics, Tripati noted. The planet was radically different.
Co-authors on the Science paper are Christopher Roberts, a Ph.D. student in the department of Earth sciences at the University of Cambridge, and Robert Eagle, a postdoctoral scholar in the division of geological and planetary sciences at the California Institute of Technology.
The research was funded by UCLA's Division of Physical Sciences and the United Kingdom's National Environmental Research Council.
Tripati's research focuses on the development and application of chemical tools to study climate change throughout history. She studies the evolution of climate and seawater chemistry through time.
"I'm interested in understanding how the carbon cycle and climate have been coupled, and why they have been coupled, over a range of time-scales, from hundreds of years to tens of millions of years," Tripati said.
In addition to being published on the Science Express website, the paper will be published in the print edition of Science at a later date.
And you may remember this one Garthie...since you keep repeating yourself......I may as well keep repeating the facts....not that it will sink in for you....
Environment| News
Climate myths: Higher CO2 levels will boost plant growth and food production 17:00 16 May 2007 by David Chandler and Michael Le Page
For similar stories, visit the Climate Change Topic Guide
According to some accounts, the rise in carbon dioxide will usher in a new golden age where food production will be higher than ever before and most plants and animals will thrive as never before. If it sounds too good to be true, that's because it is.
CO2 is the source of the carbon that plants turn into organic compounds, and it is well established that higher CO2 levels can have a fertilising effect on many plants, boosting growth by as much as a third.
However, some plants already have mechanisms for concentrating CO2 in their tissues, known as C4 photosynthesis, so higher CO2 will not boost the growth of C4 plants.
Where water is a limiting factor, all plants could benefit. Plants lose water through the pores in leaves that let CO2 enter. Higher CO2 levels mean they do not need to open these pores as much, reducing water loss.
However, it is extremely difficult to generalise about the overall impact of the fertilisation effect on plant growth. Numerous groups around the world have been conducting experiments in which plots of land are supplied with enhanced CO2, while comparable nearby plots remain at normal levels.
These experiments suggest that higher CO2 levels could boost the yields of non-C4 crops by around 13 per cent.
Limiting factors
However, while experiments on natural ecosystems have also found initial elevations in the rate of plant growth, these have tended to level off within a few years. In most cases this has been found to be the result of some other limiting factor, such as the availability of nitrogen or water.
The regional climate changes that higher CO2 will bring, and their effect on these limiting factors on plant growth, such as water, also have to be taken into account. These indirect effects are likely to have a much larger impact than CO2 fertilisation.
For instance, while higher temperatures will boost plant growth in cooler regions, in the tropics they may actually impede growth. A two-decade study of rainforest plots in Panama and Malaysia recently concluded that local temperature rises of more than 1ºC have reduced tree growth by 50 per cent (see Don't count on the trees).
Another complicating factor is ground level ozone due to air pollution, which damages plants. This is expected to rise in many regions over the coming decades and could reduce or even negate the beneficial effects of higher CO2 (see Climate change warning over food production).
In the oceans, increased CO2 is causing acidification of water. Recent research has shown that the expected doubling of CO2 concentrations could inhibit the development of some calcium-shelled organisms, including phytoplankton, which are at the base of a large and complex marine ecosystem (see Ocean acidification: the other CO2 problem). That may also result in significant loss of biodiversity, possibly including important food species.
Levelling off
Some have suggested that the increase in plant growth due to CO2 will be so great that it soaks up much of the extra CO2 from the burning of fossil fuels, significantly slowing climate change. But higher plant growth will only lock away CO2 if there is an accumulation of organic matter.
Studies of past climate changes suggest the land and oceans start releasing more CO2 than they absorb as the planet warms. The latest IPCC report concludes that the terrestrial biosphere will become a source rather than a sink of carbon before the end of the century.
What's more, even if plant growth does rise overall, the direct and indirect effects of higher CO2 levels will be disastrous for biodiversity. Between 20 to 30% of plant and animal species face extinction by the end of the century, according to the IPCC report.
As for food crops, the factors are more complex. The crops most widely used in the world for food in many cases depend on particular combinations of soil type, climate, moisture, weather patterns and the infrastructure of equipment, experience and distribution systems. If the climate warms so much that crops no longer thrive in their traditional settings, farming of some crops may be able to shift to adjacent areas, but others may not. Rich farmers and countries will be able to adapt more easily than poorer ones.
Predicting the world's overall changes in food production in response to elevated CO2 is virtually impossible. Global production is expected to rise until the increase in local average temperatures exceeds 3°C, but then start to fall. In tropical and dry regions increases of just 1 to 2°C are expected to lead to falls in production. In marginal lands where water is the greatest constraint, which includes much of the developing world but also regions such as the western US, the losses may greatly exceed the gains.