View Single Post
Old 11-07-2013, 11:44 PM   #18
Isaac Clarke
Junior Member
 
Isaac Clarke's Avatar
 
Join Date: Jul 2009
Posts: 261
Quote:
Originally Posted by Tommycat View Post
Actually it IS an ad-hom to call the paper names. If you claim the paper does not have the science right, that's fine. But calling them the Daily Fail is an ad hom.
Ad hominems only apply when the only argument presented is an attack. Calling the paper a name because they didn't understand the science behind climate change is not an ad hominem, because I presented the argument that they did not understand it, and backed it up with valid reasoning.

Quote:
Originally Posted by Tommycat View Post
I don't agree that much needs to be done. Global climate change occurred before man, and in much greater frequency than current trends.
Irrelevant. The global climate changes according to whichever force is dominant; and right now, that force is anthropogenic CO2 emissions.

Quote:
Originally Posted by Tommycat View Post
We've been blessed with a rather long period of stability.
No, we have not been "blessed".

Quote:
Originally Posted by Tommycat View Post
And with Mars temps rising at similar rates as Earth, it seems a bit early to say it's settled.
I presume you are referring to the study Fenton 2007, which compared the 1977 Viking composite to the 1999 MGS composite, and found a 22 year warming trend of 0.65C?

Now, there are many things wrong with that study; not the least of which is a centuries-old statistics mistake of connecting just two data points, and trying to draw a conclusion. Now, you and I both know, I'm sure, that this is folly; you can derive inaccurate solutions (no warming since 1998?) So, why did he notice a warming trend between these two years? I can tell you this: it's not global warming.

No, rather it is global dust storms, that shift the sands of Mars, covering the range in brighter dust. This increases Mars' albedo. Eventually, as the dust settles once again, the dust goes back to its original, dark state.

The Viking composite, as it turns out, was taken right after one of those dust storms in southern latitudes, increasing the planet's albedo. The 1999 MGS composite, however, was taken when the dust on Mars had returned to its usual, dark state. This accounts for the "global warming" reported by Fenton.

(One thing to note: the source also shows that the dust was brighter in the southern hemisphere after a global dust storm in 2001 than it was in 1977.)

Quote:
Originally Posted by Tommycat View Post
I'm not claiming that man doesn't contribute to warming. Just that it's too early to claim anything is settled, and quite a few seem to be doing exactly that.
And for a good reason, too. Let me give you a breakdown of science.

Science doesn't work with absolute certainties. Those are reserved for mathematics. Science, rather, works with uncertainties. When dealing with the physical world, we can't know anything with 100% certainty. The best we can get is a very high certainty. Which, by the way, is the state of anthropogenic global warming, with a confidence of 95%, according to the IPCC AR5 report.

However, we do know with a high certainty that humans are contributing enormously to the CO2 content in the atmosphere. First, we look at international energy statistics, from places like the CDIAC (which has some very good data, by the way.) This is all well and good, but we only have one data set to work with! So instead of living with that huge uncertainty, climate scientists double-check their data with measurements of carbon isotopes in the atmosphere. Now we have a lesser uncertainty, but it is still there, and it is still rather substantial -- so they check it again, this time with data of falling oxygen levels, likely due to burning of fossil fuels. If this isn't enough, there are many other lines of empirical evidence used to confirm with a high certainty that yes, humans are contributing CO2 to the atmosphere, and yes, it is substantial.

Quote:
Originally Posted by Tommycat View Post
Do keep in mind that we are still emerging from the "Little Ice Age" and have not returned to the temperatures from before that.
You're making some assumptions here. These are:

1) The climate oscillates around a certain condition which it must return to after a period of warming or cooling.
2) The forcing responsible for the "Little Ice Age" is reversing and causing warming, back to or even above the equilibrium described in the previous assumption.

But this is just plain folly.

Climate change is caused by a response to a change in Earth's energy balance, called 'radiative forcing'. If the incoming solar thermal radiation is equal to the outgoing long-wave infrared radiation, then the planet is in equilibrium and its temperature will not increase significantly.

The temperature can still be affected slightly in this equilibrium by natural processes such as the Pacific decadal oscillation. However, as implied by the name, this process is an oscillation, which means it shifts between a "positive" and "negative" state, and so does not affect the temperature on average. These oscillations also do not create or remove heat; rather, they move it around. This means that if the surface were to warm, then the ocean would have to cool, which is not what we observe. No, both the surface and the ocean are warming.

Many things could explain this phenomenon, such as solar activity, concentration of greenhouse gases in the atmosphere, volcanic activity, albedo, and Milankovitch cycles. These are all forcings that change Earth's energy balance. The Earth will not just "reverse phase" from a previous trend. It needs an unbalancing force.

What caused the Little Ice Age, though? Climate scientists think they have it down to three major factors. These are:

1) Decreased solar activity. The Little Ice Age was a period of cool climate from around the 16th to 19th century. However, during this period, there were three different periods of decreased solar activity, the Spörer Minimum (1460-1550), the Maunder Minimum (1645-1715), and the Dalton Minimum (1790-1830). Solar activity has increased since then (but is not the cause of current global warming, as solar activity has not increased on average since the mid-20th century.)

2) Increased volcanic activity. Throughout the Little Ice Age, there was a period of heightened volcanic activity. Volcanic eruptions release aerosols into the atmosphere (airborne solid or liquid particles), that block sunlight. From 1400-1850, the volcanic contribution to the climate is around 50%. However, volcanic activity still does not account for current global warming, since volcanic activity has had a net cooling effect on the climate since 1950.

3) Decline in human population. The Little Ice Age happened around the time of the Black Death in Asia and Europe, which meant a decline in the human population and in agriculture. A similar effect is observed in the conquest of North America by European colonists in the 16th century. Because of the decreased human agricultural activity, reforestation is a likely cause of uptake of CO2 from the atmosphere to the biosphere, having a cooling effect. Ruddiman concludes,

Quote:
Originally Posted by Ruddiman
If the 10-ppm CO2 decreases are caused by plague-induced reforestation events, they would cool northern hemisphere temperatures by ∼0.17°C, assuming a 2 × CO2 sensitivity of 2.5°C.
Unbalancing forces do not reverse because it gets "too cold" or "too hot". They change because of certain causes, like changes in forestation, burning of fossil fuels, uptake of carbon dioxide, change in solar activity, etc.




The Earth is warming, and we're the cause. I can't believe there is even any doubt about that.

Last edited by Isaac Clarke; 11-08-2013 at 10:56 AM.
Isaac Clarke is offline   you may: quote & reply,