Dr. Carlos Umaña, then Co-President of IPPNW, delivering his lecture “Prescription for Hope: Challenges of Civil Society Toward a World Without Nuclear Weapons”
Soka Gakkai International hosted a public lecture by Dr. Carlos Umaña, titled "Prescription for Hope: Challenges of Civil Society Toward a World Without Nuclear Weapons" on 28 September 2025 at the Soka Gakkai Josei Toda International Center in Tokyo. Dr. Umaña was Co-President of International Physicians for the Prevention of Nuclear War (IPPNW) and a member of the International Campaign to Abolish Nuclear Weapons (ICAN) International Steering Group until October 2025. Addressing a diverse audience of 100 people, including junior high and high school students, Dr. Umaña delivered a compelling, evidence-based argument for the global elimination of nuclear weapons.
Dr. Carlos Umaña addressing an audience that included junior high and high school students, along with members of the public
Dr. Umaña asserted that nuclear weapons, alongside the climate crisis, pose the single greatest threat to human existence. The numbers themselves are alarming: he stated that nine nations hold more than 12,000 warheads, with a chilling 2,000 of those maintained on hair-trigger, high alert.
The destructive effects of even a single detonation—the blast, the heat and the ionizing radiation—inflict permanent, intergenerational harm. Critically, the lecture highlighted the grim reality that no meaningful medical response would be possible in the aftermath. Survivors would be condemned to a lifetime of compounding physical, psychological and social suffering.
The threat escalates far beyond local destruction. Dr. Umaña warned that even a limited regional nuclear conflict between India and Pakistan would be enough to trigger a devastating "nuclear winter." This scenario would cause global agricultural collapse and lead to a famine, potentially killing up to two billion people. A full-scale war, he cautioned, would mean the end of civilization itself. Reflecting the severity of this crisis, in 2025 the Doomsday Clock stood at an unprecedented 89 seconds to midnight, driven closer by reckless threats, new technology and the persistent danger of human error. Dr. Umaña offered a stark assessment of our current safety: "If we are alive today, it is because of luck."
Audience members listening during the lecture at the Josei Toda International Center
The continued existence of nuclear weapons, according to Dr. Umaña, isn't a matter of practicality or security; it's fundamentally a political choice. He argues that the system is rooted in a colonial mindset and a gendered hierarchy of power.
The doctrine of nuclear deterrence is presented not as a mechanism for security, but as a symbol for projecting power. This system willfully disregards massive financial expenditures—over $100 billion was spent on nuclear weapons in 2024 alone—along with the certain human suffering and the catastrophic risk of failure.
The clear solution is the universal stigmatization and prohibition of nuclear weapons, following the moral and legal precedent set by the successful banning of chemical weapons and landmines.
The Treaty on the Prohibition of Nuclear Weapons (TPNW), supported by 99 nations at the time of publication, is the essential legal and moral instrument to achieve this. The TPNW categorically prohibits all nuclear weapon activities, effectively stripping them of their perceived value and legitimacy in the international arena.
Dr. Umaña issued a powerful call to action: every individual—from medical professionals to the students—must take responsibility. We must collectively build political will, advocate for the TPNW and make it undeniable that nuclear abolition is the only path compatible with a livable future.
Changing this deeply ingrained norm requires a robust, visible civil society. Dr. Umaña issued a powerful call to action: every individual—from medical professionals to the students—must take responsibility. We must collectively build political will, advocate for the TPNW and make it undeniable that nuclear abolition is the only path compatible with a livable future.
The lecture clearly resonated with the audience and prompted reflection. One participant noted the shocking nature of the destructive power discussed, specifically mentioning the concepts of "nuclear summer" and "nuclear winter," as well as the potential communication breakdown that could result in millions of civilian deaths. Another participant found a particular remark from Dr. Umaña powerful: the idea that "nuclear weapons should someday be regarded as unacceptable, just as slavery is now," left a strong and lasting impression.
