Stephen Sheppard was a founder of the Urban Forestry department, U of British Columbia, where Lorien Nesbitt is now an assistant professor. David Price retired after a career in forestry modeling for Canada's Natural Resources department. We discuss with several Pugwashites the health challenges of urban trees and the value of planting them as a means of cooling the cities, mainly through their transpiration, "exhaling" of water vapor. The foresters all agree that the health and comfort of living in cities would be improved if most of the lawns are replaced with trees, and possibly whole local blocks can be devoted to small urban neighborhood forests. For the video, audio podcast, transcript and public comments: https://tosavetheworld.ca/episode-538-our-urban-trees.

Darryl Stellmach is an anthropologist who teaches emergency management at the University of Tasmania in Australia. This is a new career for him, after some 20 years of work coordinating responses to emergency crises around the world, initially with Doctors Without Borders. He became increasingly aware that interventions provided by humanitarian workers often are not implemented as expected because the local communities have alternative views that clash with the aid. Because humanitarian workers shift from one setting to another rapidly, they may not develop cultural insights to transcend the problem, whereas anthropologists working in the same area may have a deeper rapport with the affected populace. For the video, audio podcast, transcript and comments: https://tosavetheworld.ca/episode-537-complex-emergencies.

Frank von Hippel, Emeritus Professor of International Affairs, Princeton University, had a big influence with Gorbachev in ending the Cold War and promoting nuclear disarmament. Erika Simpson is an Associate Professor of International Affairs, Western University. Gordon Edwards is president of the Canadian Coalition for Nuclear Responsibility. They point out that the recent publicity about a breakthrough in nuclear fusion is meant to deceive the public into considering it as a great day for sustainable energy, whereas the real research was done by nuclear weapons scientists for the sake of the continued development of nuclear weapons. For the video, audio podcast, transcript and comments: https://tosavetheworld.ca/episode-536-fake-fusion-story.

Gregory Dipple studies mine tailings, Peter Van Straaten is an agro-geologist who studies the application of minerals as fertilizers. Thomas Vanacore owns rock quarries and studies the application of rock dust. Here they discuss the present state of scientific knowledge about the benefits and potential risks of the dual-purpose application of rock dust and mine tailings to farmland. Dipple believes that the most serious gap in knowledge concerns the possible addition of greenhouse gas because of the otherwise appropriate application of such soil amendments. They consider ways of encouraging the government to support progress faster because of the urgency of the climate threat. For the video, audio podcast, transcript, and comments: https://tosavetheworld.ca/episode-535-rocks-mine-tailings-climate.

Peter Jones is a professor of international relations at the University of Ottawa and director of the Ottawa Dialogues, an organization that develops "backchannel" communications between nations that are in conflict. Often the two sides take the public position that they will "never negotiate" with each other, while in fact they are conducting unofficial meetings – or at least authorizing citizens to carry out such meetings. This is "track two diplomacy." The term also can apply to the kind of contacts that civil society organizations conduct without authorization, or even against the wishes of their governments, because they wish to lower the acrimony between the two sides and create conditions that in the future may allow negotiations to take place. For the video, audio podcast, transcript and comments: https://tosavetheworld,ca/episode-524-track-two-diplomacy.

Adeyemi Adesina, John Orr, and Ryan Zizzo are all experts on concrete. They advise construction companies and architects on how to use materials efficiently and with minimal emission of carbon dioxide during construction and afterward, throughout the structure's lifetime. John Orr particularly emphasizes the value of reducing the amount of concrete used in construction, for it is one of the leading sources of greenhouse gas and global warming. It is possible in most cases to design buildings that meet al the standards but use much less concrete. Another source of reductions is the use of more concrete that does not require such a long period of curing. For the video, audio podcast, transcript and comments: https://tosavetheworld.ca/episode-532-use-less-concrete.

Lonnie King has been the chief Veterinary officer of the United States. He also created a department in the Center for Disease Control addressing zoonotic diseases -- ones that originate in animals and spread to people. His new publication emphasizes the recent trend (over about 25 years) for new diseases to emerge and spread widely, and suggests ways of bringing researchers together in teams to find the ecological conditions that create disease "hot spots." Much of the solution will come, he thinks, from allocating funding more through national and regional organizations. For the video, audio podcast, transcript, and comments: https://tosavetheworld.ca/episode-531-global-health-tomorrow.

Hans Kristensen works with the Federation of American Scientists studying nuclear weapons all around the world. Pavel Podvig is also a nuclear weapons analyst, but he specializes in the Russian bombs. We discuss the trends on thinking among the strategists who control all the nuclear nations' arsenals: Is the risk increasing or decreasing, over all? Kristensen says the recent developments have contradictory effects, both motivating those who would like to acquire more such bombs as a means of security, while also convincing others that the bombs are more dangerous than they are helpful. Podvig takes the same view and believes in the persuasive efforts of the states parties to the Treaty on the Prohibition of Nuclear Weapons. For the video, audio podcast, transcript and comments: https://tosavetheworld.ca/episode/530-nuclear-weapons-today.

The Pugwash inquiry is concerned here with a proposal to brighten clouds over Hudson Bay, retaining some ice year round. The experts here are Alan Gadian, Stephen Salter, Michael Diamond, Paul Beckwith, Peter Wadhams. The consider the challenging problem of estimating the effectiveness of this intervention. Much of the complexity results from the dynamics of the multiple factors -- the way the clouds of different altitudes react differently, the impact of water vapor, altitude, temperature, the changing amount of light in different seasons, etc. Although the mathematical modeling gives a specific prediction, it may be necessary to check it with a real-life experiment, and we have to decide whether Hudson Bay is the best place to carry out such an experiment. For the video, audio podcast, transcript, and comments: https://tosavetheworld.ca/episode-529-clouds-and-climate.

Paul Werbos is discouraged about the failure of COP27, but was excited about a zoom meeting in China where the Chinese seem eager to set up an internet-regulating system; he would like to combine that with the Guterres and Biden desire for an office to manage all existential threats. Opinions in the group were divided as to whether a ceasefire in the Ukraine war would allow Putin to recollect his forces for another round in the war or whether he would go for a real peace settlement. For the video, audio podcast, transcript and comments: https://tosavetheworld.ca/episode-527-global-town-hall-nov-2022.