NEW AIR QUALITY STRATEGY TO START THE CENTURY

The Strategy is part of the government's overall aim to improve the quality of life for people in the UK. It focuses on the most common pollutants in the air which affect our health, our plant life and buildings. The first National Air Quality Strategy was published in March 1997 but since then, reviews of the objectives have led to the publication of the January 2000 Air Quality Strategy. The objectives in this latest Strategy remain the same as in the consultation document (August 1999), see Atmospheric Issues Vol 5, Issue 4.

The new objectives can be summarised as follows:

Compared to the original Air Quality Strategy objectives (1997), the following changes in the new Strategy are highlighted below:

• benzene, 1,3-butadiene, carbon monoxide and lead objectives are to be achieved more quickly;
• there is a tougher new objective to cut the level of lead in air by a further 50% by 2008;
• the existing goal for sulphur dioxide remains but there is a new objective to protect ecosystems from its effects;
• the ozone target is retained;
• the hourly nitrogen dioxide objective is tightened and there is a new objective to protect vegetation from its effects;
• the particulate target is relaxed - the target remains the same but more exceedences are allowed per year, however new objectives for particulates are under review.

The new particles objective is now likely to be widely met in urban areas throughout the UK. The tougher NO₂ objective is now likely to cause the widest concern because it is vastly generated in urban areas from road traffic. It is now NO₂ rather than particles that is likely to lead to Air Quality Management Areas being set up by local authorities in urban areas.

The National Air Quality Strategy is available from The Stationery Office, price £20. It can also be freely downloaded from the DETR website:

http://www.environment.detr.gov.uk/airquality/index.htm

Sources: DETR & FOE Press Releases 19 Jan 2000, Air Quality Management, January 2000.

NEW POWER STATION EMISSION LEVELS ANNOUNCED

The Environment Agency state that they have aimed to create a solution that encourages operators to install and use Flue Gas Desulphurisation (FGD) technology to neutralise acid emissions and therefore protect the environment.

The Agency have come up with two sets of limits; A-Limits (those relating to the emissions of SO₂ from an individual power station that help protect the local environment) and B-Limits (SO₂ emission limits on all power stations owned by a particular generator that help protect the overall environment).

The Agency now requires that by September 2005 the total amount of SO₂ to be released from coal- and oil-fired stations in England and Wales is less than 398,000 tonnes, a reduction of approximately 60 percent over 1996/97 rates Individual operators will also be required to run their FGD-equipped power stations ahead of non-FGD stations.

Further details of the Environment Agency's new emission levels for power stations can be found on their website at:

http://www.environment-agency.gov.uk//modules/MOD44.1553.html

Sources: Environment Agency Press Release 21 Dec 1999, Air Quality Management, January 2000.

CLIMATE CHANGE

CONSENSUS IS THAT GLOBAL WARMING IS REAL

Analysis of temperature records stretching back 150 years, and tree-ring records prior to the instrumental period reveal that in the Northern Hemisphere, the 1990s were the hottest decade during the last 1000 years. In addition the 10 warmest years on record globally have all occurred since 1983, with the 4 warmest being 1998, 1997, 1995 and 1990. In England 1999 was the hottest ever, and the second hottest in the US.

Whilst natural mechanisms affecting the climate (for example changes in output of energy from the Sun) have no doubt influenced the global temperature record, the apparent acceleration in warming towards the end of the 20th century is most readily explained by the rapid increase in greenhouse gas emissions during the post-war period.

Despite better agreement between temperature observations and computer models predicting man-made climate change, it is not yet possible to determine whether the frequency of occurrence of extreme weather events will increase as a result of global warming. The Intergovernmental Panel on Climate Change (IPCC) recognises that whilst recent weather-related catastrophes such as Hurricane Floyd (September, 1999) and the flooding in Venezuela (December, 1999) may reflect shifting climatic patterns, it may simply be that people are being made more aware of their occurrence through improved information coverage.

Sources: Global Environmental Change Report, February 11th 2000.

NORTH ATLANTIC OCEAN CIRCULATION & EL NIÑO

El Niño is an unusually warm surface ocean current that develops every 2 to 7 years in the Tropical Pacific. During El Niño episodes, the warmer water piling up along the equatorial South American west coast produces enhanced levels of rainfall here, thereby reducing rainfall and river runoff into the equatorial Atlantic on the eastern side of the continent, and consequently increasing Atlantic Ocean salinity (saltiness).

The last big El Niño occurred in 1998, resulting in the warmest year globally on record, and extreme weather related events all round the world. Some computer models have projected that global warming could lead to an increased frequency of occurrence of El Niño episodes.

The North Atlantic circulation, in contrast, is a more permanent ocean current. Warm surface water from the equatorial Atlantic in the Gulf of Mexico travels north-westwards (the Gulf Stream), into the North Atlantic, before cooling and sinking. The sinking water, called the North Atlantic Deep Water, maintains the strength of the Gulf Stream, acting as a pulling force or conveyor belt. The presence of the warm Gulf Stream influences the climate of Western Europe, and in particular the UK, keeping winters many degrees Celsius warmer than they would otherwise be.

Some scientists have suggested that global warming may slow or halt the North Atlantic Ocean Circulation. A melting Greenland icecap as a result of global warming could release considerable amounts of fresh water into the North Atlantic, decreasing the ocean's salinity, and therefore density, and slow or halt the deep water sinking. A slowdown in the North Atlantic Deep Water could equally slow or halt the Gulf Stream, and impact upon the regional climate.

By modelling the effects of more frequent El Niños as a result of global warming, Researchers at the Max-Planck Institute in Germany have found the increased salinity in the equatorial Atlantic may actually help to maintain the strength of the North Atlantic Ocean Circulation. According to the model saltier water in the equatorial Atlantic as a result of an El Niño episode would be carried to the North Atlantic with the Gulf Stream and offset higher freshwater inputs as a result of enhanced icecap melting, stabilising the system and preserving the formation of North Atlantic Deep Water.

Source: Global Environmental Change Report, December 24th 1999.

OZONE DEPLETION

RECORD ARCTIC OZONE LOSS?

Ozone holes have been more commonly associated with the Antarctic, where upper atmospheric temperatures are usually lower. At temperatures of less than -78^oC, the presence of polar stratospheric clouds speeds up the destruction of ozone.

This year, temperatures above the Arctic have been consistently low, with polar stratospheric clouds forming since November 1999. There are fears that global warming may enhance the loss of ozone above the Arctic, as trapped radiation in the lower atmosphere (causing surface warming) will lead to further cooling of the stratosphere.

Sources: Global Environmental Change Report, January 28th 2000; New Scientist, no. 2222, 22nd January 2000.

TRANSPORT

PUBLIC PERCEPTION OF PUBLIC TRANSPORT

The report makes clear, however, that many drivers are unaware of the true cost and journey times by public transport, recommending that much more information about transport choices should be made available to the public.

Source: Local Transport Today, 3rd February 2000.