At the time of my arrival, significant currents of change in science in the developing world were surfacing at a serene and largely uneventful pace. No one could have predicted that science in the South – and indeed the entire world – was about to embark on an era of profound transformation.

I remember my first TWAS general conference held in Brazil in 1997, just a few weeks after I had arrived. The presentations were first rate. Yet much of the discussion focused on aspirations, not accomplishments.

Now fast forward to the TWAS general conference in Brazil in 2006. The presentations were again exceptional. But, this time, so too was the level of confidence. Aspirations were matched by a broad range of accomplishments, proudly stated, as well as a prevailing sense that the future would be even brighter. Here is what I wrote at the conclusion of the TWAS conference in Brazil in 2006:

"Science and technology have clearly experienced much progress since TWAS last met in Brazil. The nation may be on the verge of joining a select but growing group of nations where science-based sustainable development is the norm and where the strength of scientific institutions does not depend on individual benefactors but is woven into the fabric of government and society."

***

The same sense of rapid progress and buoyant optimism was echoed in 2003 in China, where TWAS held the general conference marking the Academy's 20th anniversary.

Before a packed audience in the Great Hall of the People, which included a large contingent of schoolage children, President Hu Jintao opened the meeting with an announcement that China's first astronaut had returned safely to the Earth.

It was all part of a larger effort to showcase the historic advances that were taking place in science-based development in China and, more generally, in the developing world. The atmosphere was festive, the rhetoric was purposeful, and the vision was clear and compelling.

Compare this to the memorable description that TWAS's former executive director Mohamed H.A. Hassan provided in an article he wrote for Nature magazine recalling his initial view of China on the eve of the Academy's general conference in 1987:

"When I landed at Beijing's international airport, I could hardly believe my eyes. The airport, consisting of a few poorly maintained structures, was no larger than the airport in Trieste, a city with some 220,000 people that was home to the TWAS secretariat.

"TWAS's founding president Abdus Salam", Hassan went on to say, "had told me on more than one occasion that TWAS could make a real difference in the developing world. With his elegant English accent and penetrating deep brown eyes, he had an uncanny ability to make you believe what he believed.

"Yet Beijing's international airport, marked by peeling paint and dim lighting, a lack of signs and service, and an endless and anxious wait for luggage and the few taxis that were available suggested that it was going to take a lot of work to realize Salam's dream – even (and perhaps especially) in the world's most populous nation. I could not help but think that the Academy might be just a tad too small to do the job."

***

Now let's move several years ahead to the first decade of the 21st century.

When TWAS held a general conference in Delhi in 2002, there was no denying that science-based development was charging ahead in India at an unprecedented pace and that a new dawn in science was rising.

Yet there was also a sense that these positive forces, however welcomed, had gained a strong foothold in only a few select scientific fields – most notably, information and communication technologies and, to a lesser extent, pharmaceuticals.

While there was much to praise, there was also a prevailing sense that the advances were fragile and could stall or even be reversed at a moment's notice – and that if such a reversal occurred, it would be difficult to get back on the right track.

Yet here's the more positive sentiment that I noticed upon the return of TWAS to India in 2010: "The country's shimmering future was on full display, most notably in the ceaseless construction and buoyant optimism that is evident everywhere you look. India's science- and technology-based growth is not confined to a few isolated areas but is now a nationwide phenomenon."

***

What has been true of Brazil, China and India has become increasingly true in a growing number of countries across the developing world. Today global science is indeed a global phenomenon that is no longer confined to the developed world.

Yet the rapid changes in science in the developing world pose challenges as well as opportunities.

First, there is the issue of the countries left behind.

As several surveys conducted by TWAS have shown, some 80 developing countries, mostly located in sub-Saharan Africa and countries with predominantly Muslim populations, continue to lag far behind in scientific capacity.

These countries are home to 1.6 billion people, nearly 20% of the world's population. Their scientists, however, produce less than 1% of the publications published in peer-review international scientific journals. Not surprisingly, these scientifically lagging countries are also among the world's poorest countries.

Second, there are existential issues posed by the pressures that have been placed on the Earth's resources and ecology. According to the United Nations, global population reached 7 billion people on 31 October 2011. That is one billion people more than in 2000.

The population of the world passed 1 billion in 1800. So, thresholds that took hundreds of thousands of years to cross, now take little more than a decade. If current trends continue, global population could reach 10 billion by 2050.

The world's endlessly growing population, combined with the increasing wealth and dramatic life-style changes occurring in a growing number of developing countries, have placed unprecedented pressure on the world's resources. According to some studies, on an annual basis the world now consumes 30% to 50% more resources than it can replenish. This trend is unsustainable.

And, third, there is the issue of scientific collaboration in a world separated by nation states that are engaged in intense competition for wealth and power.

How will developed countries react to their declining status in global finance and science? These countries are unlikely to fall far (if at all), but they will have to share the stage with others.

Will developed countries graciously welcome the emerging economic and scientific powers, or will they be suspicious and resentful of the newcomers? How will the attitude of the established powers in science affect the future of global science, which will inevitably be characterized by a shift in strength and focus from the North to the South?

Conversely, how will emerging economies deal with their rapidly rising influence?

Will scientists in developing countries choose to draw on their growing scientific capabilities to ally largely with colleagues in developed countries in ways that deepen conventional pathways to cutting-edge science. Or, will they ally largely with scientists in developing countries to create new pathways of global scientific exchange marked by South-South cooperation?

Better yet, are there ways to simultaneously pursue South-North and South-South cooperation to strengthen both frontier science and science for development? If so, what might a successful paradigm for global science in the 21st century look like, and what should be the responsibilities of scientifically advanced and scientifically lagging countries in the new 'ecumenical' union of global science?

None of these issues were readily discussed when I began my tenure at TWAS. But today they are at the forefront of the dialogue on science in rich and poor countries alike.

On the one hand, these discussions show how successful efforts to promote scientific capacity building have been in a growing number of emerging economies and developing countries. On the other hand, they show just how far we still have to go to ensure that all countries have the ability to embrace science to propel their economies forward.

The good news is that the ledger sheets on science are rapidly changing as an increasing number of developing countries move from the column marked 'in need of assistance' to the column marked 'able to give assistance'. Undoubtedly this change is here to stay, creating both new opportunities and new challenges that I will leave to my successor to observe and record on behalf of TWAS.

***

For me, it has indeed been a privilege to witness and explore such historic changes. I owe a deep measure of gratitude to many individuals who have made my tenure at TWAS so interesting and rewarding. Most notably, I would like to extend a warm thank you to Mohamed H.A. Hassan, who led the Academy during most of my time here, and to Romain Murenzi, who assumed the reins of the Academy last April. I also owe a great deal of thanks to the TWAS public information office staff. Gisela Isten has been with the Academy since nearly its inception, and her 'institutional memory' continues to play a key role in the public information office. Thanks also to Peter McGrath and Brian Smith, who have moved on to other positions (Peter is now the Academy's programme officer and Brian is with UNESCO in Paris), as well as to Tasia Asakawa and Cristina Serra, who arrived later in my tenure and who are part of the editorial team for my final TWAS Newsletter issue. And then there are people outside of TWAS to whom I owe a great deal, most notably Rado Jagodic and Sandra Zorzetti, who have been responsible for the newsletter's design and graphics, and Linda Nordling, who has been a contributing writer. And, finally, I would like to extend a warm thanks to the TWAS members, eminent scientists largely from developing countries whose research, dedication and enthusiasm have inspired my – our – efforts from the very beginning.

I sincerely thank you all. I wish you a fond farewell and I hope that our paths cross again sometime soon.

Daniel Schaffer, TWAS Public Information Officer