It was an inspiring speech, and amusingly delivered - but the most awful and cynical part came when he admitted that "our" (I'm including me + those older than me in there) generation has totally, utterly, abjectly failed in moral fortitude and courage. We have abdicated the consequences to a host of issues, ranging from health care reform to our dependence on oil. Our penchant has been to prevaricate - and is characterized by a persistent refusal to recognize inevitable resource depletion...and to outsource pollution and all sorts of debts to the next generation. He didn't put it that way exactly, but still, his was a blunt statement.
"While stratospheric ozone shields us from ultraviolet radiation, in the troposphere this irritating, reactive molecule damages forests and crops; destroys nylon, rubber, and other materials; and injures or destroys living tissue. It is a particular threat to people who exercise outdoors or who already have respiratory problems.
Ozone affects plants in several ways. High concentrations of ozone cause plants to close their stomata. These are the cells on the underside of the plant that allow carbon dioxide and water to diffuse into the plant tissue. This slows down photosynthesis and plant growth. Ozone may also enter the plants through the stomata and directly damage internal cells."
In its first major climate report to the United Nations in four years, the United States reported Tuesday that its projected climate-warming greenhouse gases will grow by four per cent through 2020.
The first such report submitted under the Obama administration includes a 1.5 per cent rise in carbon dioxide emissions, the main gas from fossil fuel burning blamed for global warming.
But it's the culpability of hydrofluorocarbons, or HFCs — promoted worldwide to replace chemicals that harm the globe's ozone layer — that gets a starring role.
Though HFCs account for only about two per cent of the globe's climate-warming gases, their share is expected to grow by up to a third of all greenhouse gases by mid-century.
That is mainly because of their promotion under the Montreal Protocol, the 1987 accord aimed at fixing the huge, seasonal hole in the stratospheric ozone layer over Antarctica.
U.S. says HFC increase has hurt environment (CBC)
'A large portion of emissions growth is driven by HFCs, which are projected to more than double between 2005 and 2020, as they are more extensively used as a substitute for ozone-depleting substances,' the report submitted to the United Nations by the U.S. State Department says."
"What are the main causes of Tropospheric Air Pollution?
While there are many natural causes, the principal man-made contributors are:
1. Oxides of sulphur (SOx)
2. Oxides of nitrogen (NOx)
3. Carbon monoxide (CO)
4. Ammonia (NH3)
7. Volatile organic compounds (VOCs)
Oxides of nitrogen (NOx) and sulphur (SOx – principally SO2) both contribute to the formation of acid rain which can result in damage to aquatic life, crops, trees and erosion of buildings. International controls are already in place limiting emissions of SO2 and NOx.
Carbon monoxide arises mainly from the incomplete combustion of fuel (largely road transport) and is now controlled increasingly through the compulsory fitting of catalytic converters to road vehicles.
VOCs contribute to creation of excess ozone in the troposphere.
Given sunlight, NOx and VOCs in the right proportions and calm air conditions, ozone can build up to form ozone ‘episodes’. These are like ‘clouds’ of ozone which may last for 2 or 3 days and travel considerable distances. In some sunny and heavily polluted environments, such as Athens and Los Angeles, ozone smog can be very persistent and significantly exceed maximum recommended levels.
High levels of ground level ozone can damage plant life, crops and buildings, Ozone can also have short term effects on humans, especially those with breathing difficulties such as asthmatics, the old or people taking strenuous exercise.
At the moment there is no globally accepted definition of a VOC. The United Nations definition is organic compounds of anthropogenic nature, other than methane, that are capable of producing photochemical oxidants by reactions with nitrogen oxides in the presence of sunlight.
More than 200 VOCs have been identified which can contribute to ozone formation. Some VOCs contribute more to the formation of ozone and so are described as being more reactive or having greater POCP (photochemical creation potential).
The reactivity is very important when considering industry’s contribution to ozone formation. While the use of aerosols accounts for about 3% of all man-made VOC emissions in the UK, the VOCs are low POCP types and so their contribution to ozone formation is proportionately less.
Leaving aside methane, it is estimated that man-made emissions of VOCs in the UK account for two-thirds of ozone production, the balance being due to methane, carbon monoxide and natural emissions such as those from trees.
While aerosol products make a small contribution to tropospheric ozone formation, their impact is at a very low level and equivalent to that of many other similar products."