CO2 Archives

April 6, 2012December 23, 2015 by Jason Major

1981 Climate Change Predictions Were Eerily Accurate

The disintegrated Wilkins Ice Shelf in April 2009. (Chelys/EOSnap)

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A paper published in the journal Science in August 1981 made several projections regarding future climate change and anthropogenic global warming based on manmade CO2 emissions. As it turns out, the authors’ projections have proven to be rather accurate — and their future is now our present.

The paper, written by a team of atmospheric physicists led by the now-controversial James Hansen at NASA’s Institute for Space Studies at Goddard Space Flight Center, was recently rediscovered by researchers Geert Jan van Oldenborgh and Rein Haarsma from the Royal Netherlands Meteorological Institute (KNMI). Taking a break from research due to illness, the scientists got a chance to look back through some older, overlooked publications.

“It turns out to be a very interesting read,” they noted in their blog on RealClimate.org.

Even though the paper was given 10 pages in Science, it covers a lot of advanced topics related to climate — indicating the level of knowledge known about climate science even at that time.

“The concepts and conclusions have not changed all that much,” van Oldenborgh and Haarsma note. “Hansen et al clearly indicate what was well known (all of which still stands today) and what was uncertain.”

Within the paper, several graphs note the growth of atmospheric carbon dioxide, both naturally occurring and manmade, and projected a future rise based on the continued use of fossil fuels by humans. Van Oldenborgh and Haarsma overlaid data gathered by NASA and KNMI in recent years and found that the projections made by Hansen et al. were pretty much spot-on.

If anything, the 1981 projections were “optimistic”.

Tglobal_giss_verification — Data from the GISS Land-Ocean Temperature Index fit rather closely with the 1981 projection (van Oldenborgh and Haarsma)

Hansen wrote in the original paper:

“The global temperature rose by 0.2ºC between the middle 1960’s and 1980, yielding a warming of 0.4ºC in the past century. This temperature increase is consistent with the calculated greenhouse effect due to measured increases of atmospheric carbon dioxide. Variations of volcanic aerosols and possibly solar luminosity appear to be primary causes of observed fluctuations about the mean rend of increasing temperature. It is shown that the anthropogenic carbon dioxide warming should emerge from the noise level of natural climate variability by the end of the century, and there is a high probability of warming in the 1980’s. Potential effects on climate in the 21st century include the creation of drought-prone regions in North America and central Asia as part of a shifting of climate zones, erosion of the West Antarctic ice sheet with a consequent worldwide rise in sea level, and opening of the fabled Northwest Passage.”

Now here we are in 2012, looking down the barrel of the global warming gun Hansen and team had reported was there 31 years earlier. In fact, we’ve already seen most of the predicted effects take place.

“Drought-prone regions” are receiving less rainfall, the Antarctic ice has begun to crack and crumble and bowhead whales are using the Northwest Passage as a polar short-cut.

Icemelt_Alaska8 — The retreat of Pedersen Glacier in Alaska. Left: summer 1917. Right: summer 2005. Source: The Glacier Photograph Collection, National Snow and Ice Data Center/World Data Center for Glaciology.

And that’s not the only prediction that seems to have uncannily come true.

“In light of historical evidence that it takes several decades to complete a major change in fuel use, this makes large climate change almost inevitable,” Hansen et al wrote in anticipation of the difficulties of a global shift away from dependence on carbon dioxide-emitting fossil fuels.

“CO2 effects on climate may make full exploitation of coal resources undesirable,” the paper concludes. “An appropriate strategy may be to encourage energy conservation and develop alternative energy sources, while using fossil fuels as necessary during the next few decades.”

(Watch a TED talk by James Hansen on “Why I Must Speak Out About Climate Change”)

As the “next few decades” are now, for us, coming to a close, where do we stand on the encouragement of energy conservation and development on alternative energy sources? Sadly the outlook is not as promising as it should be, not given our level of abilities to monitor the intricate complexities of our planet’s climate and to develop new technologies. True advancement will rely on our acceptance that a change is in fact necessary… a hurdle that is proving to be the most difficult one to clear.

Read van Oldenborgh and Haarsma’s blog post here, and see the full 1981 paper “Climate Impact of Increasing Carbon Dioxide” here. And for more news on our changing climate, visit NASA’s Global Climate Change site.

Tip of the anthropogenically-warmer hat to The Register.

April 26, 2011December 24, 2015 by Jason Major

Mars’ Underground Atmosphere

Pitted "swiss cheese" terrain at Mars' south pole hints at sublimation of underground CO2

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Scientists have spotted an underground reservoir near Mars’ south pole the size of Lake Superior… except that this lake is filled with frozen carbon dioxide – a.k.a. “dry ice”!

A recent report by scientists at the Southwest Research Institute in Boulder, CO reveals variations in Mars’ axial tilt can change how much carbon dioxide gets released into the atmosphere, affecting factors from the stability of water on its surface to the power and frequency of dust storms.

The Mars Reconnaissance Orbiter’s ground-penetrating Shallow Radar identified a subsurface deposit of frozen material, confirmed as carbon dioxide ice by its radar signature and visual correlation to the surface pitting seen above. As the polar surface warms during the Martian spring, underground CO2 deposits evaporate (or “sublime”) leaving behind round depressions in the frozen ground. (This has been aptly dubbed “swiss cheese terrain” by researchers on the HiRISE imaging team.)

While scientists were aware of seasonal CO2 ice layers atop the water ice this new discovery brings to light nearly 30 times more frozen CO2 than was previously believed to exist. In fact this particular deposit alone contains 80% the amount of CO2 currently present in the planet’s entire atmosphere.

The importance of this finding is how the carbon dioxide ultimately affects the global Martian climate as it freezes and thaws. When the CO2 is frozen and locked away in subsurface deposits like this, it’s not free to enter the atmosphere and do what CO2 does best: warm the planet… as well as increase atmospheric pressure. This means that liquid water cannot last as readily on the surface since it will either freeze or boil away. Also with less air pressure the strength of wind is decreased, so dust storms are less frequent and less severe.

When factored in with the axial tilt difference – and thus variations in the amount of sunlight hitting the poles – researchers’ models show that Mars’ average atmospheric pressure may at times be 75% higher than it is today.

These shifts in the orientation of the Red Planet’s axis occur on 100,000-year intervals… long by human standards but geologically very frequent. Mars may have had liquid water existing on its surface fairly recently!

Mars' south polar ice cap, seen in April 2000 by Mars Odyssey. NASA/JPL/MSSS

Although this may sound that Mars has had its own share of global warming due to CO2 emissions in its history, it must be remembered that Mars and Earth have very different atmospheric compositions. Earth’s atmosphere is much thicker and denser than Mars’, so even when doubling its CO2 content Mars’ atmosphere is still too thin and dry to create a strong greenhouse effect… especially considering that the polar caps on Mars increase cooling more than additional CO2 in the atmosphere raises global temperature. Without oceans and atmosphere to collect and distribute heat, the effect of any warming quickly radiates out into space…and eventually the planet swings back into a freeze-dried state.

“Unlike Earth, which has a thick, moist atmosphere that produces a strong greenhouse effect, Mars’ atmosphere is too thin and dry to produce as strong a greenhouse effect as Earth’s, even when you double its carbon-dioxide content.”

– Robert Haberle, planetary scientist at NASA’s Ames Research Center

Read the full news release on the NASA Missions site.

Image credit: NASA / JPL / University of Arizona

June 18, 2009December 24, 2015 by Nancy Atkinson

More Atmospheric CO2 Today Than in the Past 2.1 Millions Years

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Researchers have been able to determine the atmospheric carbon dioxide levels over the past 2.1 million years in the sharpest detail yet by analyzing the shells of single–celled plankton. Their findings shed new light on CO2’s role in the earth’s cycles of cooling and warming, confirming many researchers’ suspicions that higher carbon dioxide levels coincided with warmer intervals during the study period. But it also rules out a drop in CO2 as the cause for earth’s ice ages growing longer and more intense some 850,000 years ago.

The study, published in the June 19 issue of the journal Science shows that peak CO2 levels over the last 2.1 million years averaged only 280 parts per million; but today, CO2 is at 385 parts per million, or 38% higher. This finding means that researchers will need to look back further in time for an analog to modern day climate change.

Bärbel Hönisch diving for plankton in an early phase of the study. Credit: Steve Doo

In the study, Bärbel Hönisch, a geochemist at Lamont-Doherty Earth Observatory, and her colleagues reconstructed CO2 levels by analyzing the shells of single-celled plankton buried under the Atlantic Ocean, off the coast of Africa. By dating the shells and measuring their ratio of boron isotopes, they were able to estimate how much CO2 was in the air when the plankton were alive. This method allowed them to see further back than the precision records preserved in cores of polar ice, which go back only 800,000 years.

Around 850,000 years ago, the climate cycles on Earth switched from being dominated by 40,000 year cycles, to the stronger 100,000 year cycles of the more recent times. The time period from 800 – 1,000 kyr ago is called the mid-Pleistocene transition, and since the rhythms of the Earth’s orbit didn’t change, some scientists have attributed that shift to falling CO2 levels. But the study found that CO2 was flat during this transition and unlikely to have triggered the change.

“Previous studies indicated that CO2 did not change much over the past 20 million years, but the resolution wasn’t high enough to be definitive,” said Hönisch. “This study tells us that CO2 was not the main trigger, though our data continues to suggest that greenhouse gases and global climate are intimately linked.”

The timing of the ice ages is believed to be controlled mainly by the earth’s orbit and tilt, which determines how much sunlight falls on each hemisphere. Two million years ago, the earth underwent an ice age every 41,000 years. But some time around 850,000 years ago, the cycle grew to 100,000 years, and ice sheets reached greater extents than they had in several million years—a change too great to be explained by orbital variation alone.

Barbel Honisch with a mass spectrometer used to measure boron isotopes to reconstruct past CO2. Credit: Lamont-Doherty Earth Observatory

A global drawdown in CO2 is just one theory proposed for the transition. A second theory suggests that advancing glaciers in North America stripped away soil in Canada, causing thicker, longer lasting ice to build up on the remaining bedrock. A third theory challenges how the cycles are counted, and questions whether a transition happened at all.

The low carbon dioxide levels outlined by the study through the last 2.1 million years make modern day levels, caused by industrialization, seem even more anomalous, says Richard Alley, a glaciologist at Pennsylvania State University, who was not involved in the research.

“We know from looking at much older climate records that large and rapid increase in C02 in the past, (about 55 million years ago) caused large extinction in bottom-dwelling ocean creatures, and dissolved a lot of shells as the ocean became acidic,” he said. “We’re heading in that direction now.”

The idea to approximate past carbon dioxide levels using boron, an element released by erupting volcanoes and used in household soap, was pioneered over the last decade by the paper’s coauthor Gary Hemming, a researcher at Lamont-Doherty and Queens College. The study’s other authors are Jerry McManus, also at Lamont; David Archer at the University of Chicago; and Mark Siddall, at the University of Bristol, UK.

Source: EurekAlert