Confusing times

Author: William Tobin

Confusion over the start time of a recent pan-European webinar illustrates one reason why the European Union is considering abolishing the annual seasonal clock change – and why, in an increasingly interconnected world, we should make more use of global time (UTC).

I was lucky. As a first-time participant in a Europe-wide webinar, I decided to switch on my computer 45 minutes beforehand to check that everything was working. The webinar had already begun!

The start time had been announced as 15:00 CET – Central European Time. What should have been specified was 15:00 CEST, Central European Summer Time – one hour ahead of CET. We have already had this spring’s clock change.

Until the last quarter of the 19th century, every town and village kept its own time, based on the moment when the Sun was highest in its daily path across the sky from east to west. 

Noon in London, for example, occurred a little later than in Paris – the time difference between the cities was 10 minutes. For Athens, the difference was 84 minutes the other way.

This cacophony of individual local times became untenable with the widespread deployment of railways and the electric telegraph. Timetable planning was a headache, and telegrams could appear to arrive before they were sent. Railway companies soon instituted a uniform ‘railway time’ for their lines.

The first jurisdiction to legislate a single uniform time for the entire country was New Zealand, in 1868.

Building on an idea from a Canadian railway engineer, Sir Sandford Fleming, the International Prime Meridian Conference in 1884 recommended a worldwide system of 24 one-hour-wide time zones. 

The reference zone was centred around the longitude of Greenwich in the UK. Within it, the reference time was Greenwich Mean Time (GMT), the average time at the Royal Observatory, determined from observations of the Sun.

Over subsequent decades countries slowly adopted the Greenwich Meridian as the basis of their timekeeping.

GMT is now old hat. In 1972 the world’s timekeeping moved from astronomical observations to atomic clocks.

The reference time, derived by averaging atomic clocks in national standards laboratories around the globe, is called Coordinated Universal Time, or Temps universelle coordonné in French, abbreviated to UTC. This abbreviation was carefully chosen so as to correspond to neither the French nor the English names! 

Such is human resistance to change that half a century on, the obsolete term ‘GMT’ is still commonly used, but it is UTC that is the base of our timekeeping.

States and provinces determine what time they keep.

It is fascinating to scrutinize a time-zone map, where cartographers can group most countries into time zones that are roughly 15 degrees wide in longitude, with myriad local variations for practical or political reasons.

The time offsets from UTC are not always a whole number of hours. They can be, for example 5½ hours for India, or 12¾ hours for New Zealand’s Chatham Islands.

Kiribati is a spread-out nation of islands in the western Pacific that spans three time zones. To keep the whole country on the same day of the week, the two easternmost zones are 13 and 14 hours ahead of UTC, rather than 11 and 10 hours behind.

Although China spans the equivalent of five one-hour time zones, the country chooses to keep a single time. Europe does the same, though to a lesser extent. Countries from Spain in the west to Poland in the east, group in the same time zone.

There is an obvious conceptual distinction between a time zone – a geographical area – and the time kept within it. Unfortunately, usage often blurs this distinction.

The armed forces of several countries have adopted a relatively simple system. They name the 24 one-hour time zones with letters, which are usually read out in the NATO phonetic alphabet.

The Z or Zulu Time Zone is the one centred on Greenwich. Zulu Time is the same as UTC. The A or Alpha Time Zone, which includes most of the EU, is the first one to the east. Alpha Time is UTC+1:00.  And so on.

Things are more complicated in the civilian world for two reasons. First, time and time zone naming are more parochial. Second, more than one time scale can be used in a given geographical zone, because of the switch to summer or daylight savings time.

It is primarily the countries in temperate latitudes that make this seasonal change, supposedly to make better use of daylight. Iceland and Singapore, for example, never change their clocks.

Take the Zulu countries UK, Eire, and Portugal. In the winter they keep UTC: the terms GMT (alas!) and Western European Time are also used. 

In the spring their clocks all move forwards one hour to UTC+1:00. In the UK, this is called British Summer Time, BST, whereas in Eire it is called Irish Standard Time, IST, and in Portugal for English speakers it’s Western European Summer Time, WEST.

The Irish name is unfortunate since ‘Standard’ is more usually used to denote the base time in a zone, such as Pacific Standard Time, PST, UTC-8:00, or New Zealand Standard Time, NZST, UTC+12:00.

Let’s move eastwards into the military’s Alpha time zone. In winter, the time kept there is Central European Time, CET, and is one hour in advance on UTC, i.e. UTC+1:00. 

After setting the clocks forward in the spring, the time kept becomes UTC+2:00, which is known as Central European Summer Time, CEST. The next zone eastwards is the Eastern European time zone, with Eastern European Time, EET, UTC+2:00 in winter and Eastern European Summer Time, EEST, UTC+3:00, in summer. 

Visit for a full list of time and time zone names and abbreviations in English as well as offsets from UTC.

Names and abbreviations are of course different in other languages. 

Central European Time is l’heure normale d’Europe centrale, HNEC, in French, while CEST is l’heure avancée d’Europe centrale, HAEC, or informally l’heure d’été d’Europe centrale. In German we have Mitteleuropäische Zeit, MET, and Mitteleuropäische Sommerzeit, MESZ.

Head spinning? I don’t blame you! And this is without considering subtleties such as leap seconds which occasionally give us minutes with 61 seconds.    

I suspect my webinar organisers announced the wrong time because they confused the time with the time zone. CET and CEST are separate, differing by 1 hour.

It seems excessively pedantic to make any distinction between the Central European Time Zone and the Central European Summer Time Zone, since in geographical extent they are identical, but the times kept within them are not.

In 2001 the EU obliged all member states to make the summer-winter time changes in unison to reduce time-difference confusion, which was seen as a hindrance to the internal market.

To reduce confusion further, Finland and Germany are among EU countries militating to dispense with seasonal time changes entirely.

A public consultation held by the European Commission in 2018 received an unprecedented 4.6 million responses, 84% of which were in favour of abolishing the clock change. In March 2019, the European Parliament expressed support for a Directive in this sense.

The matter is now with the European Council, where I suspect it has stalled.

According to a recent report by the House of Lords, the British Government has expressed opposition to the change, though it has said it will reconsider if the measure is adopted by the EU.

Clock changes are not a reserved matter in Northern Ireland, so if the EU proposal is enacted it is possible that Stormont will have to choose between an annual half-year ‘time border’ within the island of Ireland or with the rest of the UK. 

Varying time differences between Britain and the EU (or within the UK) would certainly be a further complication of Brexit and promote confusions such as affected my webinar organisers.

But are we over-fixated by time zones and local times? They ensure that the Sun is highest in the sky at noon, roughly, and give an indication of when most people are likely to be up and about rather than in their beds.

Beyond that, however, there are large cultural differences about how the day is divided up such that local times are not that informative for international relations.

Madrid and Warsaw share the same time, but that gives little indication as to whether a business associate will be away at lunch when you telephone.

Time zones complicate working out how many more hours until the end of that tedious intercontinental flight. 

In international affairs, would it not be better to pay more attention to Sir Sanford Fleming’s ultimate goal, which was "every city and district on the surface of the globe … brought to the one common time-reckoning"?

UTC is this common time-reckoning and underlines technical aspects of numerous activities, such as navigation, telecommunications and international electricity interconnections.

On a more prosaic level, international broadcasters like Deutsche Welle already provide their schedules in terms of UTC (or GMT for the BBC’s World Service). Some credit-card clearance agencies produce receipts with the transaction time in UTC, particularly for on-line purchases.

Is this the way of the future for us all?

Let me end with my recommendations for avoiding scheduling errors for international webinars and the like.

First, know how your local time relates to UTC (or GMT, if you must), since UTC is the universal. A Google query “UTC now?” will help you.

Announce your schedule in UTC and your local time, if it’s not UTC, being sure to indicate which time is local for you (BST, CET, CEST...).

Then give local times in zones where you expect large proportions of participants.

If you’re not sure about what time is currently being kept in a zone, a Google query “Time zone for XXX?” appears to give reliable answers for location XXX, despite the question being marred by the aforementioned conceptual contraction between time and time zones. Remember, if it’s summer, expect to find ‘Summer’ or ‘Daylight’ in the answer (except for Ireland). 

Another option is to use timeanddate’s international meeting planner (click on the chosen meeting time to get the time/time zone names).

Best wishes for all of this. I hope to be able to participate in future pan-European webinars through good planning, not good luck!

William Tobin

About the Author

William Tobin

William Tobin is a British-New Zealand astronomer retired in France.  


View all articles
William Tobin

About the Author

William Tobin

William Tobin is a British-New Zealand astronomer retired in France.  


View all articles

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