It’s up to you. You can calculate your emissions and arrange for an appropriate number of trees to be planted, or you can simply donate ten trees.

Carbon dioxide, released during electricity generation or when fossil fuels such as gas, oil and coal are burned to create energy, contributes over 80% to man-made global warming. Other important greenhouse gases like methane and nitrous oxide contribute to another 15% of total man-made global warming. Even in the worst case (complete emissions) HFCs would contribute only by 2 % of the total.

Under an agreement with the Revenue, the Society of Motor Manufacturers and Traders (SMMT) will be providing a CO2 enquiry service on the Internet at www.smmt.co.uk for cars first registered from January 1998 to December 2000. Company cars that were first registered before 1 January 1998 will not have an approved CO2 figure, so the percentage used is based on engine size.

The SMMT CO2 emissions enquiry service, available on the Internet, will let you find out the CO2 emissions for particular cars provided they are first registered between January 1998 and December 2000. The website address is www.smmt.co.uk The Vehicle Certification Agency publishes a booklet that tells you about performance of new cars. The figures in this booklet give a very good indication of the approved CO2 emissions figures, although there may be some small variations.

This figure includes domestic emissions (eg. electricity, gas and waste disposal), transport emissions and industrial emissions (less that attributed to goods made for export).

Various factors are taken into consideration when calculating flight emissions and their impact on the environment. The following are the main ones: The type of aeroplane, how much fuel it uses, the number of seats it has and how many are first class (first class seats take up more room than economy seats, and the more there are the fewer passengers the aeroplane carries).

come from car's real fuel consumption i.e. not according to figures provided by UTAC (Union Technique de l'Automobile du Motocycle et du Cycle), which do not take into account cold starting, air-conditioning, acceleration, traffic jams etc. The calculation for motorcycle emissions comes from a study carried out by the Ademe. See Ademe study in PDF format.

The data for CO2 emissions is based on calculations made by the Ademe and the CEREN (Centre d'?tudes et de recherches ?conomiques sur l'?nergie = Research Centre for Economic Studies of Energy) according to size, heating system, age, usage of accommodation.

The packs are calculated on the basis of 9 tonnes of CO2 emissions per person per year. This figure corresponds to France's total emissions of greenhouse gases (CO2, CH4, N20, HFC, PFC, SF6) expressed as CO2 equivalents and divided by number of inhabitants.

This is a hard one, as the National Energy Foundation admit, there are all kinds of variables involved. I used 0.18 kg per mile for a long distance flight, for shorter distances a figure of up to 0.3 kg per mile may apply. Climate Care www.climatecare.org, Future Forests www.futureforests.com , and the National Energy Foundation www.natenergy.org.uk/convert.htm all have excellent calculators!

When looking at CO2 emissions estimates, it is important to look at the units in which they are expressed. The numbers are sometimes expressed as mass of CO2 but are listed in all of our estimates only in terms of the mass of the C (carbon). Because C cycles through the atmosphere, oceans, plants, fuels, etc. and changes the ways in which it is combined with other elements, it is often easier to keep track only of the flows of carbon.

You will need to find our your annual mileage and fuel efficiency in miles per gallon (mpg). If you travel 10,000 miles a year and your car does 30 to the gallon, you will be using 333 gallons, which is 1,514 litres. Emissions are 2.31 kg per litre, which would give a total of 3.5 tonnes of CO2. (Diesel is 2.68 kg per litre.). If this seems complicated, I recommend the calculator at Climate Care www.climatecare.org.

The lower the CO2 emissions, the lower the percentage of the price of the car that will be used to calculate the car benefit charge - subject to a normal minimum charge of 15% . And the higher the CO2 emissions, the higher the percentage that will be used - subject to an absolute maximum of 35%.

The normal minimum charge on 15% of the car 's price will apply to cars that emit CO2 at or below a specified level. The percentage will be increased in 1 percent steps for every additional 5g/km over the specified level - up to a maximum of 35%. The figures calculated in this way will then be increased by 3% for diesel cars (subject to the maximum charge always being 35%) or discounted for certain cars that are particularly environmentally friendly.

Cars without an approved figure of CO2 emissions will be taxed according to engine size as shown on leaflet P523.

The EC takes account of the environmental impacts of the vehicles it uses, including fuel consumption and CO2 emissions, in its fleet management practices. It has already committed itself to: Gradually replace its fleet of service cars with diesel cars equipped with a particle filter (diesel cars emit less CO2 than petrol-powered cars). Equip technical services, for short trips between EC buildings, with small cars emitting less than 140g/km for petrol cars and less than 130g for diesel cars.

It is estimated that the 1% annual reduction in greenhouse gas emissions from transport fuels over their lifecycle required under the revised directive will bring a cumulative saving by 2020 equivalent to around 500 million tonnes of CO2. That is the equivalent of all the greenhouse gas emissions for a year from Spain and Sweden.

CO2 or carbon dioxide is a naturally occurring gas that is generated when fuel and other carbon based material is burnt. CO2 is also released by us breathing and other natural occurring biological and geological processes. Our atmosphere is currently made up of 0.06% of CO2, 20.9% oxygen, 78% Nitrogen and the remaining percentage is made up of various other gases. Back to Top

There are many such "carbon offset" schemes, but the accounting of how much carbon is actually taken up by the trees is very unreliable. In many cases companies are just taking your money and doing what they were going to do anyway -so it doesn't help the climate. Trees take a long time -several decades - to grow to maturity. During this time the CO2 emissions from your flight are still warming the atmosphere, and much of this heat will remain for hundreds of years in the oceans.