I think the globalisation of English will have two kinds of effects. First, the language will clearly change as a consequence of its new life as a global language and the increasingly wide range of functions it serves in communities around the world. Second, English will have an impact on other languages and cultures.
As an example of how English will change, I might pick (somewhat at random, because there are so many examples to choose from) the way that electronic communication has created new meeting places for speakers of different languages in cyberspace. This is a slightly different point from the idea that electronic communication has created new ways of using English (such as in e-mail) that seem to break down the distinction between speech and writing. Rather, it suggests that we will be seeing new kinds of fusion between English and other languages. The type of language switching and word borrowing that typically goes on in any multilingual community is now happening on the Internet on a massive scale, and it is difficult to know what long-term impact this might have on the way the international community will use English.
In the second category of change, I think one often overlooked but potentially huge impact on the world is the way that the spread of English is gradually converting all those largely monolingual countries (especially in Europe) into bilingual and multilingual ones. English is spreading from the north of Europe to the south, leaving Ireland and the UK as the least multilingual of all the countries in the European Union. I enjoy the irony that English -- so long thought of as the language of monolingual culture -- is now helping re-establish multilingualism as a societal norm.
In the United States, actually, there's a great deal of anxiety about that -- anxiety that we Americans might lose the ability to communicate with one another if we don't somehow make sure that everyone learns English. And of course there are big advantages to having a language in common. What would you say to people who are opposed to multilingualism?
I don't think multilingualism implies that it isn't important for Americans to understand and speak English. In fact, the whole point about multilingual societies is that you really need to speak more than one language to participate fully. So for me the issue of whether Americans should be able to speak English or not is a non-question. The more interesting question is whether monolingual English-speaking Americans will in future need to learn to speak Spanish in order to participate fully in American society.
The fear of a breakdown in communication perhaps comes from a misunderstanding of how multilingualism works. Around the world, the ability to speak more than one language is a pretty normal state of affairs. In a multilingual society, what people have in common, what binds them and generates a unique cultural identity, is a shared competence in more than one language. I think that communication may even be enhanced where two people know two languages and know also how to switch from one to another.