Snow_Miser

How is acknowledging the obvious fact that human aerosol emissions have caused very large negative forcing and cooling "extreme" or "alarmist?"

 

Do you deny that a significant fraction of the sun's SW radiation does not even reach the surface of the earth anymore because of these aerosols, a phenomenon known as "global dimming" which has gone so far as to even slow the growth of plant life on earth?

 

You cannot simply wish these facts away. It is yet another nail in the coffin of denialism. The earth would have warmed far more if we were not literally blocking out the sun with aerosols. 

I'm not saying that human induced aerosols are not important, but saying that the contribution of Greenhouse Gases to recent warming trends is over 100% because aerosols are masking some of that warming is most certainly alarmist. In addition, aerosol forcing isn't understood all that well, and is probably one of the largest uncertainties in Climate Science. Aerosols have an impact, but my stance is that anthropogenic aerosols are likely not as significant as you assert.

For example, the average lifespan of an anthropogenic aerosol is quite a bit less than the average lifespan of a molecule of CO2, and thus the effects from aerosols are likely to be much more local than the effects from CO2. Most of the anthropogenic aerosols are found in the Northern Hemisphere as a result of this local effect.

Yet, the Northern Hemisphere has actually warmed faster than the Southern Hemisphere according to both satellite measurements and surface temperature measurements. While this doesn't disprove an effect from aerosols, it suggests that the forcing from aerosols may lean more towards 0 in the IPCC's aerosol error range.

Also, do you deny that a significant increase in SW radiation has been absorbed at the Earth's surface over the last 30 or so years? This would seem to suggest that anthropogenic aerosols have not masked much warming during the late-20th Century warm period.

http://www.atmos-chem-phys.net/13/8505/2013/acp-13-8505-2013.html

From the paper:

"The 340 nm LER is highly correlated with cloud and aerosol cover because of the low surface reflectivity of the land and oceans (typically 2 to 6 RU, reflectivity units, where 1 RU = 0.01 = 1.0%) relative to the much higher reflectivity of clouds plus nonabsorbing aerosols (typically 10 to 90 RU). Because of the nearly constant seasonal and long-term 340 nm surface reflectivity in areas without snow and ice, the 340 nm LER can be used to estimate changes in cloud plus aerosol amount associated with seasonal and interannual variability and decadal climate change. The annual motion of the Intertropical Convergence Zone (ITCZ), episodic El Niño Southern Oscillation (ENSO), and latitude-dependent seasonal cycles are apparent in the LER time series. LER trend estimates from 5° zonal average and from 2° × 5° , latitude × longitude, time series show that there has been a global net decrease in 340 nm cloud plus aerosol reflectivity. The decrease in cos²(latitude) weighted average LER from 60° S to 60° N is 0.79 ± 0.03 RU over 33 yr, corresponding to a 3.6 ± 0.2% decrease in LER. Applying a 3.6% cloud reflectivity perturbation to the shortwave energy balance partitioning given by Trenberth et al. (2009) corresponds to an increase of 2.7 W m⁻² of solar energy reaching the Earth's surface and an increase of 1.4% or 2.3 W m⁻² absorbed by the surface, which is partially offset by increased longwave cooling to space."

This doesn't make any sense...if the aerosols are anthropogenic

I was on my phone typing that, so the grammar was likely not great.

What I am saying is that the extreme alarmist makes a claim that more warming has occurred than observed. This is because anthropogenic aerosols have masked some of the warming. Because anthropogenic aerosols have masked warming, this means that more warming should have occurred without the presence of anthropogenic aerosols, and thus, climate sensitivity is higher.  

I have a different categorization and think you can create more groups.

Extreme alarmist: 100% human induced

Alarmist: > 75% human induced, < 25% natural

Denier: 100% Natural

Skeptic: > 75% natural, < 25% human induced

Middle of the road can be broken down IMO.

High end Middle of the roader: 25-50% naturally induced, 50-75% human induced

Central Middle of roader: Around a 50/50 split for natural and human factors

Low end Middle of roader: 25-50% human induced, 50-75% naturally induced

So 7 categories total.

The extreme alarmist claims that there is actually more warming than observed that is due to humans, but some of that additional warming is being masked by anthropogenic aerosols.

I'm a 4 on Tacoman's list. I don't deny warming, and I don't deny a human component to that warming. However, the more important questions are,

• How much of the warming is due to the Anthropogenic Forcing?
• What implications might this have for climate sensitivity?
• How much warmer will we get?
• To what degree can we attribute climate change to extreme weather?
• Why do GCMs overestimate temperature changes over the last 20 years?
• Why can't GCMs accurately simulate the early-20th Century warming trend?

A lot of these are open questions that have not been resolved. The "pause" in the warming has shown how poor our understanding of the climate system is. To claim that the science is setlled and we know all, is ignorant and arrogant.

Blaming the 2012 drought on CC isn't ignorant at all. It's probably correct. CC is supposed to cause summer drying over much of the U.S. and especially the western U.S. CC has probably made droughts like last year more likely. 

Just like the Colorado Floods are also due to CC, right?

I think you are trying to over-simplify things. Do you really think that just because someone likes cold/snow they are just going to believe whatever they want about climate change? I mean, I'm sure those people are out there, but if anything, cold/snow lovers should be more worried than the average person right? (Assuming they live in a region that is likely to see less cold/snow with further warming).

If anything, because I like snow, I should be biased towards more warming, since there's some speculative research that decreased Sea Ice results in more high latitude blocking, and thus, colder and snowier mid latitude winters.

I don't think the methane burst from the Arctic that Vergent was concerned about in 2011 had any detectable impact on the Global Temperature at all.

I think it was in 2010 when we had a pretty large Heat Wave take shape in the middle to later part of August. That was pretty brutal stuff.