Elements of Climate Change- Part Three

Ocean heat and storms, ozone, and particulate matter.

Written by Neil McCabe


Ocean heat and storms

The oceans are giant water storage tanks for water of different temperatures. Carbon and other gases left in the atmosphere can stay there for decades and centuries. These gases and water vapour trap the heat below them in the atmosphere and the heat affects the surface temperature of the oceans. Due to their very high thermal mass, oceans actually absorb more than 90% of the excess energy produced by greenhouse gases in the last 50 years. This heat causes the sea level to rise. Higher temperatures from ocean water surfaces mixed with the excess heat and gases in the atmosphere directly result in more powerful storms surges. In other words- more heat = more storms. 

Ozone at ground level and high in the sky

Ozone (O3) is a very strong oxidising agent and a significant greenhouse gas. Ozone is not actually released into the air directly by humans as a pollutant, but rather it occurs as a chemical reaction between various gases in the atmosphere. These gases are called “precursor emissions” and are made up mainly from carbon monoxide (CO), volatile organic compounds (VOCs) and nitrogen oxides (NOX). Chemically, carbon dioxide (CO2) and the precursor gases mix in the presence of solar radiation and form ozone. 

Regrettably, it is human actions that create the precursors that cause ground level ozone or, “tropospheric ozone” to form. This results from the release of chlorofluorocarbons (CFCs) and VOCs. These CFCs and VOCs are produced from exhaust gases in transportation, the burning of fuel for energy in power plants, the production of consumables and, surprisingly, vegetation. 

Trees and vegetation emit VOCs usually as part of the pollination process when the tree wards off insects and animals. However, trees actually give off VOCs at times of stress as well. Isoprene is a natural VOC released from trees and vegetation at these times. Growing in excess heat, taking in too much fertiliser, not enough water, soil acidification and being surrounded by traffic congestion and its pollution qualities are root causes of Isoprene release. Ozone is a photochemical that only forms during the day in certain conditions. A hot sunny dry day in a large city during a traffic jam would produce higher concentrations of ozone as compared with the rural environment. 

The ozone layer

Ozone in the atmosphere is named “stratospheric ozone” better known as the “ozone layer” and consists of 90% ozone. This ozone absorbs the harmful ultraviolet rays travelling from the sun and stabilises the earth’s temperature and literally protects life on earth. Damage to the ozone layer is responsible for climate change and many of its attributed problems. Ozone depletes the earth’s atmosphere over time. 

The hole in the Ozone layer was first discovered in 1985. By 1987, 130 Countries had signed the “Montreal Protocol.” They acknowledged and agreed that CFCs were the main source of ozone depletion in the stratosphere causing the famous “hole”. The international response was to agree to phase out the offending CFCs by banning their use and to introduce new HydroChloroFlouroCarbons (HCFCs). 

HCFCs effects are less offensive and cause less damage than CFCs because they break down naturally and faster in the atmosphere than CFCs. CFCs and HCFCs are greenhouse gases and cause a lot more damage than CO2. Scientists have found four man made ozone depleting substances (ODSs) that were previously unknown. It is not yet known what causes these new substances or how they were created. These new ODSs are: CFC – 112, CFC – 112a, CFC 113a and HCFC – 133a. These substances did not exist before the 1960s. Monitoring between 1960 and 2012 has yielded staggering results. 

Two of the ODSs have increased in volume by 48% but they are actually exempt from the Montreal Protocol because they are used in the pre-production (intermediate stage) of substances such as pesticides, before they are fully produced as new other substances. If the ODS growth rate figures are anything to go by this needs urgent redress at top level internationally. Luckily scientists also say that there is only 74,000 tonnes of ODS in the atmosphere at present. 

Particulate matter

Particulate matter (PM) is a form of pollution sometimes called particle pollution. It comes from a combination of different sized solid and liquid particles suspended in the air. PM is usually thought of as dust and organic components, while actually mostly a mixture of liquid droplets and small particles made from nitrates and sulphates, organic chemicals, metals, smoke, soot and soil or dust particles. These fine particles can be found coming from roadways and gases created in industry and energy plants worldwide. 

We inhale PM into our respiratory system and it is absorbed into our bloodstream. PM also travels in the atmosphere over long distances and is proven to have long term effects on our health. The scale and seriousness of this pollution is not generally understood but needs to be. PM is not just something to be associated with transport, it’s everywhere and mostly caused by human activity especially heating our homes. Shifting to diesel fuel vehicles over petrol fuel cars is proven to produce less carbon emissions. In large cities and areas of congestion this is especially effective. Air quality tracking and monitoring probes have been able to demonstrate this. But diesel vehicles still poor out sulphur dioxide and nitrous oxide and these are the same PM that are causing the poor air quality.