The development of English as a global language is one of the most remarkable phenomena of the late 20th and early 21st centuries.
For the first time in the history of human society, a single language has become sufficiently universal that it can be used as a global lingua franca for communication between speakers of many languages.
The history of English has traditionally been divided into three main phases: Old English (450-1100 AD), Middle English (1100-circa 1600 AD) and Modern English (since 1600). But it seems that Global English represents a new and fourth phase in which its main use around the world is between non-native speakers - a phase of its history which has only just begun and in which both the status and linguistic form of the language are rapidly developing.
In the next 10-15 years we may witness a situation that has been much discussed since the nineteenth century, in which the majority of the world's population can speak English.
Although Global English is largely a product of economic globalisation and very recent developments in communications technology (and indeed has helped accelerate both), the wider roots of English as a world language lie much further in the past.
Some point to the first English colonies in Wales and Ireland in the 12th century, or to the late 17th century when English-speaking settlements were established in North America and the slave trade brought cheap labour from Africa. But it was largely the British colonial expansion in the 19th century which helped establish the large communities in which English now serves as a second language - in West and East Africa, South and South-East Asia.
New varieties of English - often referred to as New Englishes - quickly emerged from contact with local languages. Indeed, by the end of the nineteenth century there was concern that these New Englishes were diverging so much from native-speaker varieties that English would become a group of mutually unintelligible languages - in the same way as Spanish, French and Italian evolved from Latin.
In other words, World English might have been no more than a celebration of diversity, like World Music, rather than the global lingua franca which it has also become.
The Linguistic Nature of Global English
Describing Global English as a lingua franca - a means of communication between speakers of different mother tongues - does not necessarily imply that it has become a new standard language, like the old standard languages of nation states but now on a global level.
The use of English continues to diverge in many new, largely uncharted, ways. One major domain of Global English lies within the many dispersed specialist communities -- from air traffic control to microbiology to international finance.
But each of these communities has its own specialist terminology and language registers which may be understood well amongst colleagues but not by outsiders.
English is also now used by ever more culturally hybrid communities where it has been adapted to meet the needs of the complex identities created by globalisation.
And improved communications are encouraging new forms of social networking which allow individuals to stay in touch simultaneously with friends, family and work colleagues with different language backgrounds.
The evidence points to a growing tolerance of multiple standards in English and growing flexibility and fluidity in the use of English by global citizens.
In this context, what are the mechanisms for maintaining the effectiveness of English as an international language?
First, there is a principle of mutual intelligibility. It turns out that native-speaker varieties (including both American and British) are not actually as intelligible as some second language varieties worldwide. Furthermore, strict adherence to a particular standard of usage may not be the most important means of achieving mutual comprehension.
Speakers of Global English can happily carry over linguistic features from their first languages provided they do not endanger intelligibility.
At the same time, native-speaker features which cause problems for learners and which are not essential for international intelligibility can be safely disregarded. In other words, it is not necessary to sound like a native speaker in order to be understood around the world, and speakers of Global English do not have give up their existing identities.
For example, research has shown that a ‘correct’ articulation of 'th' may be of the mark of a native speaker, but is unimportant in Global English. On the other hand, the distinction between short and long vowels (eg the difference between 'sit' and 'seat') remains crucial to intelligibility.
Second, there are pragmatic strategies used by any skilled cross-cultural communicator which need to be adopted even by native speakers if they wish to be understood in lingua franca contexts.
For example, using highly idiomatic language should be avoided, as should appeals to very specific cultural knowledge. Many native speakers, unfortunately, tend to speak more colloquially and informally when they want to make things clearer.
However, in lingua franca contexts more formal language may actually be more comprehensible. For instance, loan words in English derived from Latin form a common, recognisable vocabulary across much of Europe, whereas 'simple', short Anglo-Saxon words may be the most opaque to speakers of other languages.
The Wave of Global English to Come
Governments across the world, from Chile to China, from Malta to Malaysia, have in the last few years embarked on ambitious educational reforms which will integrate English more deeply into the curriculum.
English will cease to be a foreign language for many, perhaps most, of the world's citizens as it becomes repositioned as a 'basic skill', to be learned by primary school children alongside other 21st century skills in Information Technology.
There are now about 5.8 billion people who do not speak English as either their first or second language. However, we have entered a period in world history, unprecedented and probably unrepeatable, when children throughout formal education - from early primary school to college and university - are all learning beginner or intermediate level English.
Already, there are almost 180 million learners of English in the formal education system in China, and that number continues to rise. In addition, a large, but unknown, number of adults are learning English in the workplace or in their free time.
A 'wave of English' is now building up. Within a decade nearly a third of the world population will all be trying to learn English at the same time.
But looking further ahead, the wave of learners may subside almost as quickly as it came. If the project to make English a second language for the world's primary school children is successful, a new generation of English-knowing children will grow up who will not need English lessons in the future.
As this generation of children move through the education system, secondary school children will be expected to start learning curriculum subjects such as maths and science through the medium of English. Indeed, this is already happening in many countries.
The Politics of Global English
The spread of English around the world was historically a colonial process. Does the emergence of Global English represent a form of neo-imperialism, serving the economic and cultural interests of the English-speaking countries - especially the United States of America?
Undoubtedly, there has been an economic advantage for English speakers during recent decades. Individual native speakers have found themselves with a skill much in demand overseas.
Multinationals based in English-speaking countries have found it easier to outsource manufacturing and services to parts of the world with cheap labour. But Global English has not arisen because of a conspiracy between English-speaking governments or multinationals.
Learning English is now seen as being of economic benefit to individuals and national economies in every part of the world.
In fact, the continuing spread of English may no longer be in the economic and political interests of English-speaking countries. Universities across the world are now able to attract international students who might otherwise have gone to English-speaking countries by teaching their courses through the medium of English.
And in future, monolingual English-speaking graduates will find it difficult to compete, even in their own countries, with job applicants from other countries who speak several languages - including English - fluently, who are more internationally mobile and more experienced in intercultural communication.
For many centuries, Latin served as a lingua franca between educated elites in Europe. Global English may be the new global Latin but just as the use of Latin gradually faded away, so Global English may not prove to be a permanent phenomenon.
It took centuries for Global English to develop and, like Latin, it may take centuries for its influence to decline. The global linguistic future is already looking more complex. Language learners in some parts of the world are already queuing for classes in Chinese, Spanish and Arabic.