Saturday, August 13, 2016
New Paper Shows Antarctic Ozone Hole Receding
False color images of the Antarctic ozone hole left (in September, 2000) and right (in September 2014. According to a recent paper the hole area has shrunk by 4.5 million square kilometers. (Blue tones indicate areas of extremely low O3 concentrations)
One of the events that got me interested in solar research occurred when a massive solar flare shredded the ozone layer in the early 1970s. The then Skylab orbital observatory reported up to 80 percent of the ozone layer "eroded" by one single super flare (class 4B optical, and X 9 x-ray). The event also aroused my curiosity regarding the ozone layer and its importance for Earth - or rather the organisms that inhabit the Earth.
By now most people know that ozone O3 - is a form of oxygen - and fond 20-30 km above Earth's surface or at the lower edge of the stratosphere. It basically is critical in protecting life forms from the effects of the Sun's ultraviolet (UV) radiation. Take that layer away and you will behold sunburns the likes of which would rival 20 hours straight in a tanning bed, not to mention an explosion of skin cancers. Minus the ozone layer, in other words, life as we know it would not exist.
So, it is important what happens to that layer.
What disturbed many space and atmospheric scientists is that the ozone layer over the Antarctic appeared to be especially susceptible to erosion, but not from solar flares. We became aware of this via tracking of ozone concentrations by NASA satellites since the 1970s. This paved the way for a study that tapped into that database thereby discovering the adverse role of chlorfluorocarbons or CFCs.
This ground breaking research by Susan Solomon and her team discovered that these chemicals - often released via hair sprays, spray deodorants etc. - reduced stratospheric ozone concentrations all over the world. At that time (1986) industries also used CFCs in refrigeration and dry cleaning. The reduction was observed to be especially bad over Antarctica hence the term "ozone hole".
One by product of the work was to explicate the processes underlying ozone hole formation. It was known, for example, that CFCs destroyed Antarctic ozone every spring. But only later was it revealed that the process begins even before winter. It commences, in fact, at the summer solstice or shortly thereafter when the Sun rises causing light to strike the ambient CFCs, breaking its chemical dons and freeing chlorine (e.g. CCl3F → CCl2F. + Cl. )
The freed chlorine atoms (at the end of the right side of the above equation) then strip the oxygen (O2) from the ozone (O3) to form other chemicals destroying the ozone itself. This leads to the emergence of an "ozone hole" which generally reaches peak area in October.
The latest research by Solomon et al, published on June 30th, e.g.
shows the extent to which changes in atmospheric chemistry and human activity are inextricably linked. Specifically, the authors show how public policy efforts i.e. (to ban CFCs) over decades have paid off by shrinking the Antarctic ozone by more than 4 million square miles (a 16 percent decrease) since 2000.
The obvious question is whether the success of activated public policy as it pertained to CFCs - to significantly reduce the ozone hole -could also have relevance to global warming and cutting CO2 emissions. We know that every 2 ppm increase in CO2 concentration in the atmosphere increases the effective solar insolation value by 2.0 w/ m2 .
This means the impact of CO2 on greenhouse heating is analogous to the impact of CCl3F on ozone depletion. It makes sense then that dramatically reducing the source, CO2, can make for an improved situation with anthropogenic global warming. The problem, of course, is that carbon - which gives rise to CO2- is a far more contentious substance with vast economic import. This is because it is part and parcel of the fossil fuels which when converted in factories or automobile engines, spawns CO2. Resistance to cutting CO2 emissions really signals opposition to altering, lowering economic growth.
Hence, naturally then there will be far more opposition to limiting fossil fuels (and by association carbon deposition) than eliminating CFCs for refrigeration or hair sprays - since alternatives can easily be found for the latter/
Never mind! A way must be found to sanely balance energy demands and needs with the worst effects of the CO2 that issues from carbon burning.