Ironically, if the world burns significantly less coal, that would lessen CO2 emissions but also
reduce aerosols in the atmosphere that block the sun (such as sulfate particulates), so we would have to limit CO2 to below roughly 405 ppm.
Not exact matches
Researchers sought to learn more about the impact of a process
in which volcanoes give off
aerosol particles that reflect sunlight, cooling the
atmosphere and leading to
reduced rainfall.
Black carbon
aerosols — particles of carbon that rise into the
atmosphere when biomass, agricultural waste, and fossil fuels are burned
in an incomplete way — are important for understanding climate change, as they absorb sunlight, leading to higher atmospheric temperatures, and can also coat Arctic snow with a darker layer,
reducing its reflectivity and leading to increased melting.
Indeed, conventional wisdom held that higher levels of
aerosol pollution
in the
atmosphere should cool the earth's climate because
aerosols can increase cloudiness; they not only
reduce precipitation, which raises the water content
in clouds, but they also increase the size of the individual water droplets, which
in turn causes more warming sunlight to be reflected back into space.
It hardly takes imagination to posit that while initial
aerosol dimming might depress temperatures, the
aerosols and
atmosphere might react
in ways that change heat balance
in other directions as they disperse, through stratospheric chemistry, and the fact that, unsurprisingly, there is a difference
in aerosol behaviour depending on day vs night (you can't
reduce the sunlight that reaches the south pole on June 23rd....).
It is likely that at least some of this change, particularly over Europe, is due to decreases
in pollution; most governments have done more to
reduce aerosols released into the
atmosphere that help global dimming instead of
reducing CO2 emissions.
Nations collectively to begin to
reduce sharply global atmospheric emissions of greenhouse gases and absorbing
aerosols, with the goal of urgently halting their accumulation
in the
atmosphere and holding atmospheric levels at their lowest practicable value;
7.4.5 Impact of Cosmic Rays on
Aerosols and Clouds 43 44 High solar acti0vity leads to variations
in the strength and three - dimensional structure of the heliosphere, 45 which
reduces the flux of galactic cosmic rays (GCR) impinging upon the Earth's
atmosphere by increasing 46 the deflection of low energy GCR.
Furthermore, it is suggested that
aerosols with high absorptivity such as black carbon absorb solar radiation
in the lower
atmosphere, cool the surface, stabilise the
atmosphere and
reduce precipitation (Ramanathan et al., 2001).
The control knob for climate change is the amount of dimming sulfur dioxide
aerosol emissions
in the
atmosphere — the fewer there are, the warmer it gets — and we are
reducing them as fast as we can, thanks to the EPA.
Aerosols in the lower
atmosphere have
reduced global warming and the frequency of intense hurricanes by reflecting a small fraction of sunlight back to space.
I was at an international conference on
aerosol in September and I made a comment that we're getting to the stage with CLOUD where we will understand the processes extremely well, but we still won't be able to
reduce the errors because we don't have good enough atmospheric observations of what the concentrations of these vapors are
in the
atmosphere versus altitude.
Results of this measurement campaign indicate that alcohol fuels (E85, E100) significantly
reduce both primary particulate emissions as well as subsequent secondary
aerosol formation
in the
atmosphere when compared emissions of gasoline fuels.
The failure to actually
reduce global emissions has meant that all possibilities are now on the table, including some that sound like premises from a science - fiction novel: Humans could sequester carbon dioxide by removing it from the air through technologies that mimic trees, or we could spray water droplets
in the lower
atmosphere to reflect light and heat back to space, or we could seed sulfur
aerosols in the stratosphere to do the same.