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Posted by focalplane on flickr.
While searching for images for my post on climate change this past weekend, I stumbled upon this funny image that shows evidence for “positive proof of global warming.”
(Except that global warming should really be called global climate change!)
I found a similar drawing hanging on a wall in New Zealand at the University of Victoria, Wellington in 2006.
Tags: climate change, global warming, humor, offbeat
Our only home. Image by Aaron Escobar.
Background
In 1998, researchers in eastern Antarctica drilled one of the deepest ice cores that had ever been extracted. It’s called the Vostok ice core (named for where it was drilled, near Russia’s Vostok Antarctic ice station).
Researchers examine an ice core in Antarctica. Photo by Tas van Ommen.
Ice cores are significant in terms of paleoclimatology because scientists noticed that as snow falls year after year, it forms nice little stratified layers that are visible (you can see this in glaciers and such) to the naked eye. Trapped within these layers are small air bubbles that get trapped during heavy snow falls. As more snow accumulates, the pressure eventually fuses these layers of snow together into solid ice and the air bubbles are now permanently trapped in their respective layers.
These air bubbles provide an interesting snapshot of the atmospheric composition at the time they were trapped, in particular the ratio between two oxygen isotopes: O-16 and O-18 as well as the concentration of CO2 (as well as other potential greenhouse gases such as CH4) that are present in the atmosphere. The ratio between O-16 and O-18 is important because it can tell you relative temperatures between two different time periods (more info on how you can tell that is available here). And based on how much CO2 and CH4 is present, you can come up with concentrations in ppm.
The graph shows some interesting results. You’re able to see the relative differences in temperature changes in the past compared to present day, as well as the amount of CO2 in the atmosphere and how both of these things change over time.
Now you’ll also see an interesting correlation (and *this* is what has climatologists and geoscientists the world over worried about climate change). You see a VERY close relationship between the amount of CO2 in the atmosphere and the difference in temperatures. Higher temperatures correlate with a higher concentration of CO2 in the atmosphere, while lower temps correlate with lower concentrations. Hmm! Intriguing!
It’s interesting to note there also appears to be some sort of cyclic process involved as well, as you notice temperature highs and lows seem to have roughly a consistent amount of time between each cycle. It’s hypothesized that this is actually due to something called a Milankovitch cycle, which is the relationship between the Earth’s distance from the sun, orbital eccentricity, tilt of the axis and some other factors. When these all line up in a certain way, they appear to have HUGE effects on Earth’s climate (which might ultimately render the whole global warming debate moot).
Mauna Loa and CO2
In the 1950’s, an intrepid scientist decided to setup a laboratory to record the amount of CO2 present in the atmosphere as an interesting experiment. He setup his lab at 14,000 feet, way up on top of Mauna Loa. This was primarily because Hawaii is smack in the middle of the Pacific and far far away from really major cities that might contaminate or otherwise skew his readings.
This data is still being recorded today. Now comes the part that has everyone worried. His data since the 1950’s is showing an *exponential* increase in the amount of CO2 that is in the atmosphere. Cue graph!
Source: NOAA.
So if you look at that, you notice there is a crazy increase in the amount of CO2 that’s currently in the atmosphere. Some people have tried to explain it away using various arguments (such as volcanic explosions), but with the rapid rate of industrialization going on in the world, how much fossil fuel is being consumed and waste products that are going into the atmosphere, I really think it’s irresponsible to say that humans are not to blame for the increase in CO2 concentrations. Now, notice a distinction.
CO2 vs. Temperature
What we haven’t really seen since the 1950’s is a rapid increase in temperature that corresponds to the increase in CO2 (like we see in the Vostok cores). We HAVE seen an overall increase in temperature (1970’s ice age scares aside), but it’s by no means “as steep” as the CO2 concentration graphs.
This suggests that there may be something else that is responsible for global warming that isn’t obvious to us at the moment (or there is some sort of lag time between CO2 increases and temperature change).
Other Research Related to Climate Change
That said there, I definitely don’t think we should claim ignorance and play dumb until we know for sure what it going on. By then it may be too late. There are some interesting factors we don’t exactly understand though when it comes to controlling CO2 and other greenhouse gases. Among them is carbon sequestration in the ocean.
Though when you also look at CO2 input/output, you have a large amount of CO2 being taken up in plant material (such as rain forests), which then end up being slashed and burned. This has a two-fold effect since now you’re releasing all the trapped CO2 BACK into the atmosphere, as well as diminishing the ability of the forest to take in CO2 by making less forest.
There are some interesting experiments that have been done though. Some have argued that increased concentrations of CO2 will actually lead to healthier forests. An experiment trying to determine this was carried out by Duke University and it appears they have concluded it does… up to a point. Researchers in Texas concluded the same thing.
“We found that many of the plants’ physiological processes responded fairly linearly to increases in carbon dioxide, and plant production went up,” said Jackson. “However, production and soil carbon storage basically saturated above 400 parts per million, a CO2 concentration very close to the current one.
“For me, this was the most interesting part of the study, because it indicates that we are now right at a threshold where the benefits of extra CO2 may not be all that great.” Particularly important, said Jackson, were the measures of soil nitrogen availability. Soil bacteria metabolize organic matter, mobilizing nitrogen as ammonia and nitrate, which serves as the plants’ nitrogen nutrient source
Intergovernmental Panel on Climate Change - Fourth Assesment Report (Jan. 2007)
Though there is a definite swing in public opinion and research that is showing more and more that you actually can trace some aspects of climate change in the past 100 years to human activity. Look no further than the Fourth Assessment report (published in January of this year) put out by the Intergovermental Panel of Climate Change.
Based on all the latest research they’ve been able to review and synthesize, they believe with 90% confidence that current climate change can be attributed to humans and is the result of increased concentrations of greenhouse gases (such as CO2) present in the atmosphere.
Global atmospheric concentrations of carbon dioxide, methane and nitrous oxide have increased markedly as a result of human activities since 1750 and now far exceed re-industrial values determined from ice cores spanning many thousands of years. The global increases in carbon dioxide concentration are due primarily to fossil fuel use and land-use change, while those of methane and nitrous oxide are primarily due to agriculture.
And a few more tidbits from the report.
Warming of the climate system is unequivocal, as is now evident from observations of increases in global average air and ocean temperatures, widespread melting of snow and ice, and rising global average sea level.
Most of the observed increase in globally averaged temperatures since the mid-20th century is very likely due to the observed increase in anthropogenic greenhouse gas concentrations. This is an advance since the TAR’s conclusion that “most of the observed warming over the last 50 years is likely to have been due to the increase in greenhouse gas concentrations”. Discernible human influences now extend to other aspects of climate, including ocean warming, continental-average temperatures, temperature extremes and wind patterns
Unfortunately, the paper concludes that it may be too late to alter or prevent significant climate change due to the amount of CO2 currently in the atmosphere, but we may be able to mitigate it by enacting certain measures.
You can download a summary (PDF file) of the report from here.
Conclusions
I think it’s a bit foolish for people to still completely ignore human activity as a potential source of climate change. Sure, there are natural factors that can (and are) attributed to global warming, but the Vostok Ice Cores, data from Mauna Loa, foraminefera data from all over the ocean plus many other sources of data provide pretty compelling evidence that something is beginning to happen that may not completely be in sync with natural cycles.
Anyway, whether we are ultimately responsible for global warming or not, I definitely think something should be done about the rapid rise in CO2 concentrations and such. Besides, what do many people have against breathing clean air? ;)
Tags: carbon, climate, climate change, global warming, greenhouse, ice cores, oceans
A new study released by University of Colorado at Boulder’s Institute of Arctic and Alpine Research says that overall sea level rise from climate change may be lower than originally predicted. Many researchers believe that sea levels could increase 20 to 30 feet by the end of the century. The team at Boulder modeled various scenarios relating to melting glaciers and ice caps, as well as thermal expansion of water, and believe the most plausible scenario shows a rise of only 3 to 6 feet by the end of the century.
The team began the study by postulating future sea level rise at about 2 meters by 2100 produced only by Greenland, said Pfeffer. Since rapid, unstable ice discharge into the ocean is restricted to Greenland glacier beds based below sea level, they identified and mapped all of the so-called outlet glacier “gates” on Greenland’s perimeter — bedrock bottlenecks most tightly constraining ice and water discharge.
“For Greenland alone to raise sea level by two meters by 2100, all of the outlet glaciers involved would need to move more than three times faster than the fastest outlet glaciers ever observed, or more than 70 times faster than they presently move,” said Pfeffer. “And they would have to start moving that fast today, not 10 years from now. It is a simple argument with no fancy physics.”
[...]
Considering all major sources of sea level rise, including Greenland, Antarctica, smaller glaciers and ice caps and the thermal expansion of water, the team’s most likely estimate of roughly 3 to 6 feet by 2100 is still potentially devastating to huge areas of the world in low-lying coastal areas, said Pfeffer.
Some scientists have theorized that continuing warming trends in Greenland and Antarctica could warm the Earth by 4 degrees F over the present by 2100. The last time that happened, roughly 125,000 years ago during the last interglacial period, glacier changes raised sea level by 12 to 20 feet or more. But the time scale is poorly constrained and may have required millennia, Pfeffer said.
“In my opinion, some of the research out there calling for 20 or 30 feet of sea rise by the end of the century is not backed up by solid glaciological evidence,” said Pfeffer.
[Via Eurekalert]
Sphere: Related ContentTags: climate change, glaciers, global warming, Greenland, ice caps, oceans, sea levels
I’m going to summarize two global warming and climate change studies that were published today.
Ice cores reveal fluctuations in the Earth’s greenhouse gases
A core drilled through 3 kilometers of ice in the middle of Antarctica has returned CO2 (carbon dioxide), CH4 (methane) and O2 (oxygen) stretching back 800,000 years. Temperature curves (implied based on the ratio of O2 isotopes) mostly show a close correlation between the amount of CO2 in the atmosphere and the relative temperature.
“The temperature curve over the past 800,000 years matches the CO2 curve beautifully – during glacial periods in which the climate is cold, there is less CO2 in the atmosphere,” says Professor Thomas Blunier from the Centre for Ice and Climate at the Niels Bohr Institute, University of Copenhagen. He explains that when it is cold there is less plant growth, and so there are fewer plants to absorb the CO2 from the air, while more CO2 is absorbed in the oceans, so the final calculation is a low CO2 content in the atmosphere during glacial periods. This produces a lower greenhouse effect, and leads to an even colder climate.
However, the new results show that during the glacial period that occurred between 650,000 and 750,000 years ago, the CO2 level was extremely low – lower than any previous measurements have indicated. It happened twice in this period, while the temperature was not lower than during other glacial periods.
Warming climate is changing life on global scale
A NASA study suggests that human induced climate change is impacting ecosystems and habitats at a large scale. The study looked at physical and biological impacts going back to 1970 and compared them to rising temperatures over that time frame.
Sphere: Related ContentObserved impacts included changes to physical systems, such as glaciers shrinking, permafrost melting, and lakes and rivers warming. Biological systems also were impacted in a variety of ways, such as leaves unfolding and flowers blooming earlier in the spring, birds arriving earlier during migration periods, and plant and animal species moving toward Earth’s poles and higher in elevation. In aquatic environments such as oceans, lakes, and rivers, plankton and fish are shifting from cold-adapted to warm-adapted communities.
The team conducted a “joint attribution” study. They showed that at the global scale, about 90 percent of observed changes in diverse physical and biological systems are consistent with warming. Other driving forces, such as land use change from forest to agriculture, were ruled out as having significant influence on the observed impacts.
Tags: Antarctica, climate change, CO2, drilling, global warming, ice cores, temperature
A new study released by the A.M. Obukhov Institute of Atmospheric Physics RAS, in Moscow, Russia claims that human generated emissions of greenhouse gases (such as CO2) are irrelevant to climate change.
The press release is rather light on details, however a PDF of the report can be found here.
The link between the carbon cycle, and human effects caused by emissions, energy use and agriculture, may only be relevant for the next ’several centuries,’ suggest Igor Mokhov and Alexey Eliseev from the A.M. Obukhov Institute of Atmospheric Physics RAS, in Moscow, Russia. The authors used a climate model known as IAP RAS CM to study how feedback between our climate and the carbon cycle changes over time. In their simulations, the authors assumed that fossil fuel emissions would grow exponentially with a characteristic timescale from 50 to 250years.
In their models, Mokhov and Eliseev found that although climate–carbon cycle feedback grows initially, it then peaks and eventually decreases to a point where the feedback ceases. If we succeed in slowing down the rate of emissions, the peak would be reached much later. However, a steep increase in emissions would bring the peak in coupling between climate and carbon emissions even closer.
The authors suggest that we are heading inexorably towards the saturation peak, irrespective of how quickly we get there: “Even weak but continuing emissions lead to eventual saturation of the climate–carbon cycle feedback,” Mokhov and Eliseev explain.
This one study goes counter to about 20 years worth of peer-reviewed research on the topic, so take it with a grain of salt. Of course, this is all that’s needed for opponents of alternative energies to rally behind.
[Via Eurekalert]
Sphere: Related ContentTags: climate change, CO2, emissions, greenhouse gases