The Kenyan academic passed away in the US at the age of 64, drawing emotional responses in Kenya and the world.

Prominent Kenyan academic Calestous Juma has died in the United States at the age of 64, prompting an outpouring of grief and tributes on social media.

“Intellectual giant”, “innovator”, “tireless champion of the world’s poorest” – these are just some of the words used to describe the Harvard University professor after news of his death broke out on Friday.

Juma, whose research and writing focused on science and the environment, was a passionate advocate of the role of technological innovation in transforming African countries.

Earlier this year, he was named among the 100 Most Reputable People on Earth by Reputation Poll, a South African consulting company. Juma was also repeatedly included in the annual list of the 100 Most Influential Africans by the New African magazine.

His lawyer, Peter Wanyama, told Kenyan newspaper Daily Nation that Juma was “unwell for two years” and was undergoing treatment in the US city of Boston when he passed away. Wanyama did not specify the cause of Juma’s death.

Kenya’s President Uhuru Kenyatta offered condolences on Twitter, saying he was dismayed by the news of the professor’s passing.

“We have lost one of our most distinguished scholars and patriots,” Kenyatta wrote.

https://twitter.com/UKenyatta/status/941713455693869056?ref_src=twsrc^tfw

Paul Kagame, Rwanda’s president, said the world has “lost a brilliant mind who was dedicated to innovation, education and Africa’s prosperity”.

Saddened to hear of the passing of Prof Calestous Juma. We have lost a brilliant mind who was dedicated to innovation, education and Africa's prosperity. Condolences to his family and friends. May he rest in peace. — Paul Kagame (@PaulKagame) December 15, 2017

Amina Mohamed, Kenya’s foreign minister, described Juma as a “friend, compatriot and a role model”.

“The best of the best”, wrote fellow Kenyan academic Makau Mutua. Juma was a “towering scholar and a great human being”, he added.

Shocked and deeply saddened to hear of the passing of Prof Calestous Juma, an African intellectual giant. He was a towering scholar and a great human being. The best of the best. Unbelievable. — Prof Makau Mutua (@makaumutua) December 15, 2017

A former student, Farai Gundan, said Juma was a “great mentor” whose office was “a haven for discussions on [Africa] and its development”.

Heart💔broken over the passing of one of my favorite @Harvard professors, Dr. @Calestous Juma. His office was a haven for discussions on the continent and its development. He was truly a champion & advocate for #Africa. Rest well sir! You were a great mentor! pic.twitter.com/nG12ND3ZUT — Farai Gundan (@FaraiToday) December 15, 2017

The Bill and Melinda Gates Foundation, which has funded some of Juma’s work, said he was “a tireless champion for economic and social development in Africa”.

.@Calestous was a tireless champion for economic and social development in Africa. His legacy will live on through the fruits of his many years of work as an impassioned scholar, fearless advocate and mentor to students and policymakers around the world. https://t.co/YEHMa4iXTJ — Gates Foundation (@gatesfoundation) December 15, 2017

A prolific author, Juma published more than a dozen books on sustainable development and won several international awards for his work on the subject, Harvard said.

His latest book, Innovation and its Enemies: Why People Resist New Technologies, draws on nearly 600 years of economic history to explain how new technologies emerge and take root.

His writings have also appeared in Al Jazeera, as well as The New York Times and The Guardian.

Juma served on the jury of the Queen Elizabeth Prize for Engineering, among others, and was elected to several scientific academies, including the Royal Society of London and the US National Academy of Sciences.

Tributes also flowed in from politicians, journalists, celebrities and academics.

Here’s a sample of some of them:

Dear #Africa,

Let us honour our great teacher @calestous by working towards & achieving African integration. Let us transform agriculture & see a food secure & thriving continent.

Let us invest in #Science #Innovation for sustainable solutions to our challenges.#RIPCalestous 🌍 pic.twitter.com/x3Ih14zE58 — Julie Gichuru (@JulieGichuru) December 15, 2017

When heroes who leave marks and footprints wherever they step on pass on, they are never forgotten. Your efforts will never go unrecognized #RIPCalestous pic.twitter.com/IBi2hxb7hq — Janet Machuka (@janetmachuka_) December 15, 2017

The world lost yet another intellectual giant, Professor @Calestous Juma. Not only was he a great patriot of our great continent but was also a passionate advocate for all things #ForAfrica & #ByAfricans. My thoughts and prayers are with his family. #RIPCalestous 🙏🏼 https://t.co/CiulLVPYb6 — Mohammed Dewji MO (@moodewji) December 15, 2017

Shocked and saddened to learn of the passing of Havard Professor @calestous Juma. His support for our innovation community was empowering #RIPCalestous — UNESCO Botswana 👉🏾 follow for updates on the #UN (@UNESCO_BW) December 15, 2017

It is with deep sadness that I received the news of the passing of the distinguished Kenyan scholar Prof. Calestous Juma, who helped build the country’s profile across the globe. We pray for and mourn with his family, students and the entire Harvard University fraternity. pic.twitter.com/eflxnR9OOr — Raila Odinga (@RailaOdinga) December 15, 2017

Not unexpected, but still desperately sad. RIP Calestous Juma – you taught us much and we are grateful for it. Your constant good humour and intellectual honesty will be missed by all. https://t.co/l3WudXLdgv https://t.co/gEIUX33O2h — Mark Lynas (@mark_lynas) December 15, 2017

Really shocked and saddened this morning to hear that Kenyan Professor @calestous has passed away. I’ll miss our exchanges about Africa, and his lively mind. Rest In Peace my friend. 🙁 — Karen Attiah (@KarenAttiah) December 15, 2017