The Science of Aerosols

[DrTskoul]

Weak average liquid-cloud-water response to anthropogenic aerosols

Thanks, important article. Lame that they didn't pay for open access though. There's an editorial on it here: https://www.nature.com/articles/d41586-019-02287-z


Last paragraph of the conclusion:

The cancellations between increases and decreases in LWP that we have observed in liquid clouds downwind of different aerosol sources under a wide range of meteorological conditions is in stark contrast to the unidirectional aerosol-induced increases in the LWP simulated by 45 GCMs . Although in multiple GCMs an increase in the LWP enhances the Twomey effect by more than 100%45, our analysis of pollution tracks show that decreases in the LWP in fact offset 23% of the Twomey effect. The compensation between increases and decreases in the LWP in pol- lution tracks agrees with the bidirectional LWP responses found in idealized process-level model simulations15–17 and in global satellite observations of maritime clouds19,20. Now, our analysis of pollution tracks shows with unprecedented confidence that the global average LWP response to anthropogenic aerosols is weak. We expect this con- straint on the LWP response based on observations of pollution tracks to lead to improved aerosol-cloud parameterizations in GCMs and to translate into reduced uncertainty in aerosol forcing calculations and more reliable projections of future climate.

Hope they're on the right track. The number of assumptions and limitations is frightening.

Lame indeed, should have been open access...

[Reginald]

Speaking of Aerosols, but not inside clouds.

Harvard creates advisory panel to oversee solar geoengineering project
https://www.nature.com/articles/d41586-019-02331-y

Nature, July 2019

Scientists will inject particles of calcium carbonate into the atmosphere and study their effects on incoming sunlight.

Plans to test a technique that would cool the planet by blocking sunlight are one step closer to reality. Harvard University in Cambridge, Massachusetts, has created an external advisory panel to examine the potential ethical, environmental and geopolitical impacts of this geoengineering project, which has been developed by the university’s researchers.

Known as the Stratospheric Controlled Perturbation Experiment (SCoPEx), the project would involve the release of calcium carbonate particles from a steerable balloon some 20 kilometres above the southwestern United States.

Louise Bedsworth, executive director of the California Strategic Growth Council, a state agency that promotes sustainability and economic prosperity, will lead the Harvard advisory panel, the university said on 29 July. The other seven members include Earth-science researchers and specialists in environmental and climate law and policy.

[DrTskoul]

And somehow I shudder to the idea...

[TerryM]

And somehow I shudder  to the idea...

While I'm sure that Harvard has been given a thumbs up by all of the worlds various political bodies, I can't but feel the pain this will cause to the installed base of PV and Solar Thermal facilities.


Will the diurnal winds that spin so many turbines be effectively muted in the dim days ahead, and what will become of the marginal northern farms that are limited today not by temperature, but by the seasonal lack of solar radiation. At one time these farms were seen by some as the answer to failing agriculture in more southern climes.


Just because we've made some minor errors - Australian Cane Toads, The Grand Banks Fisheries and  Mono Culture Forestry spring to mind - is no indication that this time won't be, almost uniquely, successful.


Harvard itself has an unblemished reputation - ask any Slav, but even the brightest and the best have been known to err on the side of hubris.
Terry

[jai mitchell]

More on the recent "good news"
https://phys.org/news/2019-08-pollution-wont-global-spike.html

meaning pollution is unlikely to offset more than half of greenhouse gas warming.

our current top of atmosphere energy imbalance as measured by the ocean heat content increases (SEE NODC OHC) is 0.6 Watts per meter squared.  The total forcing from GHGs is about 2.4 Watts per meter squared.  This means that some large portion of the total forcing is being offset by aerosols.  if less than half we still have the 0.6 Watts per meter squared being experienced PLUS the (estimate) 1.0 Watts per meter squared from aerosols.  to reach equilibrium)  Since methane is about 20% of the current forcing and other short lived climate pollutants balancing each other out,

even this 'good news' study indicates that we still have about 1.6 Watts per meter squared of globally averaged annual forcing to be worked through the system before reaching temperature equilibrium.

This does not include the longer term climate warming feedbacks due to carbon cycle emissions as the earth warms from the 1.6 Watts per meter equilibrium warming.

[Oscillidous]

Regarding this recent paper, I don't know of many other papers exploring the idea that reduced droplet formation in clouds is what is responsible for greater cooling, it's the reflective of the particulates themselves, no? Seems to me the equivalent of saying "good news, fire doesn't cause as much frostbite as previously thought" when obviously no one was even considering the possibility.

The paper in Nature recording localized temperature change over North America 3 days after 9/11 is an example of observed warming as a result from absence of some anthropocentric aerosols, which at least to my laymen understanding seems to be a better analogue for what to expect as a result of reduced industrial output.