Climate Change (4.4)
Greenhouse Gases
Greenhouse gases are those gases which trap long wave radiation from the earths atmosphere during the Greenhouse Effect. The two most significant greenhouse gases are:
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Others include: Nitrogen oxides and methane gas. These however have less of an impact on the Greenhouse Effect. Both nitrogen oxides and methane are in very small amounts in the atmosphere. However, they both do trap heat, so the more there are the greater the amount of heat trapped.
The most abundant gas in the earth's atmosphere is nitrogen, which is NOT a greenhouse gas!
The most abundant gas in the earth's atmosphere is nitrogen, which is NOT a greenhouse gas!
The Greenhouse Effect
The greenhouse effect is what keeps our earth warm. Solar radiation from the sun penetrates the atmosphere and is absorbed by the earth and clouds. Some of this is radiated back into the atmosphere as long wave radiation. This long wave radiation is absorbed by greenhouse gases (H20, CO2, CH3, N3O, etc). Some of the radiation is released into space the rest is emitted back to earth to repeat the cycle. Without the greenhouse effect our earth would remain a cool -18 degrees Celsius.
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Climate Change Overview
Climate Change is the term given for the changing climate. Often lumped together with global warming. Generally no scientist is arguing that the climate is not currently changing/ warming up. The ultimate question lies with whether humans have caused a permanent change (a tipping point) in the natural cycles and therefore an irreversible effect on the ecosystem, for this, the debate is still heated (pun intended).
Climate Change Data Sites |
Effects on Coral Reefs
Summary: Warmer ocean water dissolves more CO2. Increased CO2 concentrations, combine with water and carbonate ions to produce an carbonic acid. The CO2 means a decrease in the availability of calcium carbonate used for skeleton and shell creation of many sea creatures.
How the Climate affects coral reefs- NOAA Coral Reefs What is ocean acidification?- NOAA PAMEL Program Acidification slows growth |
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Global Climate Patterns
Current Carbon Dioxide Patterns
For the 60+ years we have been tracking global CO2 levels (which began in the late 1800s, but modern tracking systems began in 1950s), the CO2 levels have been increasing (see graph to the left of data from the Hawaii Mauna Loa Observatory).
Unfortuntely, this is not that much data in terms of the long term effects of CO2 on the globe. While the data is very much concerning, remember that climate has long term, global outlooks. As a result, in the timescales of climate and the earth, this is not nearly enough data to make conclusions from, other than to say in recent history CO2 levels have been rising. |
Ancient Carbon Dioxide Patterns
In order to go back in time to look at CO2 patterns on a global scale, scientists use Ice Core data. This is data obtained from drilling into the arctic or antarctic ice core caps and then measuring the gasses trapped inside the layers of ice from different ages. A few comments about this:
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This graph is from the British Antarctic Survey site. It shows the changes between CO2 and deuterium (D), which is used as a measurement of temperature in ice core data. As you can see the numbers do have some correlation. A summary of their findings are quoted below:
"Ice cores provide direct information about how greenhouse gas concentrations have changed in the past, and they also provide direct evidence that the climate can change abruptly under some circumstances. However, they provide no direct analogue for the future because the ice core era contains no periods with concentrations of CO2 comparable to those of the next century." |
Carbon Dioxide and Temperature
There are correlations between global temperatures and carbon dioxide concentrations. It is also fact that our CO2 levels are rising higher than pre-industrialization levels. The question then becomes does temperature correlate with CO2. If CO2 is the cause of rising temperatures then we should be able to see that CO2 rises before temperature rises in the past. The following graph is of the Vostok Ice Core Data for the last 400,000 years. You can definately see how CO2 and Temperature appear to be following eachother. The question then becomes, does one cause the other? See one scientists response below.
According to Dr. Roy Spencer, a climate scientist:
"So, where does CO2 fit into all of this? ....Hansen’s theory does require that temperature drives CO2…at least to begin with. Hansen claims the Milankovitch cycle in Earth-sun geometry caused a small temperature change, which then led to a CO2 change, and then the CO2 took over as the forcing. Or, maybe you could say the CO2 provided a strong positive feedback mechanism on temperature. But it has often been noted that the Vostok CO2 record lags the temperature record by an average of 800 years, which is somewhat of a problem for Hansen’s theory. After all, if CO2 “took over” as the main driver of temperature, why do the CO2 changes tend to come after the temperature changes? But then there have also been uncertainties in dating the CO2 record due to assumptions that have to be made about how far and how fast the CO2 migrates through the ice core, giving the appearance of a different age for the CO2. So the lead-lag relationship still has some uncertainty associated with it. But even if the CO2 and the temperature record lined up perfectly, would that mean Hansen is correct? No. It all hinges on the assumption that there was no forcing other than CO2 that caused the temperature changes. Hansen’s theory still requires that the temperature variations cause the CO2 changes to begin with, which begs the question: What started the temperature change?... If Hansen is correct, and CO2 is the main forcing in the Vostok record, then it takes only about 10 ppm increase in CO2 to cause 1 degree C temperature change. The full range of CO2 forcing in the Vostok record amounts to 1.6 to 2 Watts per sq. meter, and if that caused the full range of temperature variations, then today we still have as much as 10 deg. C of warming “in the pipeline” from the CO2 we have put in the atmosphere from fossil fuel burning. That’s because 1.6 Watts per sq. meter is about the same amount of manmade forcing that supposedly exists in today’s atmosphere."
"So, where does CO2 fit into all of this? ....Hansen’s theory does require that temperature drives CO2…at least to begin with. Hansen claims the Milankovitch cycle in Earth-sun geometry caused a small temperature change, which then led to a CO2 change, and then the CO2 took over as the forcing. Or, maybe you could say the CO2 provided a strong positive feedback mechanism on temperature. But it has often been noted that the Vostok CO2 record lags the temperature record by an average of 800 years, which is somewhat of a problem for Hansen’s theory. After all, if CO2 “took over” as the main driver of temperature, why do the CO2 changes tend to come after the temperature changes? But then there have also been uncertainties in dating the CO2 record due to assumptions that have to be made about how far and how fast the CO2 migrates through the ice core, giving the appearance of a different age for the CO2. So the lead-lag relationship still has some uncertainty associated with it. But even if the CO2 and the temperature record lined up perfectly, would that mean Hansen is correct? No. It all hinges on the assumption that there was no forcing other than CO2 that caused the temperature changes. Hansen’s theory still requires that the temperature variations cause the CO2 changes to begin with, which begs the question: What started the temperature change?... If Hansen is correct, and CO2 is the main forcing in the Vostok record, then it takes only about 10 ppm increase in CO2 to cause 1 degree C temperature change. The full range of CO2 forcing in the Vostok record amounts to 1.6 to 2 Watts per sq. meter, and if that caused the full range of temperature variations, then today we still have as much as 10 deg. C of warming “in the pipeline” from the CO2 we have put in the atmosphere from fossil fuel burning. That’s because 1.6 Watts per sq. meter is about the same amount of manmade forcing that supposedly exists in today’s atmosphere."
Evaluating Claims of Human Caused Climate Change
Pro
Is Climate Change real?- evidence for Climate Change "Why the skeptics are wrong" - NY Times article CO2 lags temperature- Skeptical Science |
Con
An Obnoxious Fabrication of Global Warming- interesting counterargument Sunspots and Climate- possible alternative explanation A literature review of An Inconvenient Truth movie My Global Warming Skepticism, for Dummies by Dr. Roy Spencer |
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