November 22, 2023: A massive build-up of America's nuclear arsenal is underway, record-setting drought in the Amazon and the science our editors are most thankful for. —Andrea Gawrylewski, Chief Newsletter Editor | | | In 2021 Congress authorized the first investments in an updated nationwide intercontinental ballistic missile system called Sentinel. An estimated $100 billion will go to that project which represents only the first step of what is anticipated to be a $1.5-trillion investment in the U.S. nuclear weapons system. Already underway is the production of new plutonium pits (discussed last week). The broader initiative will also involve modernizing and restaffing nuclear silo sites, updating nuclear waste management facilities, and constructing the first new warhead since the cold war–called the W87-1, which will be affixed to the tip of the new Sentinel missiles. Why this matters: The decades-long effort to control global nuclear weapons seems to be at an end. Russia has suspended its participation in a 2011 treaty with the U.S. to reduce nuclear armament. And it's believed that China is increasing the size of its arsenal. Global powers treat nuclear weapons as bargaining chips, writes journalist Abe Streep in our exclusive look into America's atomic arsenal. "History shows that one country's escalation follows its rivals'. The worst-case scenario is apocalyptic," he says.
What the experts say: "The old cold war never really ended institutionally," says Zia Mian, co-director of Princeton University's Program on Science and Global Security, of the U.S. nuclear program. "The core structures remain exactly the same." | | | An unprecedented drought is gripping the Amazon rainforest this year. Climate change is involved, yes. But researchers say other factors have collided to make things worse, which has cut river communities off from supplies including food, and has forced Indigenous residents to use dirty, contaminated water, resulting in gastrointestinal and other illnesses. What's behind this: Three major factors are at play: Deforestation: About 20 percent of the Amazon rainforest is deforested, and 40 percent is degraded, drastically making it a hotter, less resilient place. El Niño: During this phenomenon, winds that usually blow east to west along the Equator weaken or reverse. Changing rain patterns in South America cause dry air in the north, where the rainforest lies, and damp air in the south. Warming of the Atlantic Ocean: The intertropical convergence zone is a region near the Equator that affects cloud formation and rainfall. The warming of these waters has shifted the zone, taking the storms with it, away from northern Brazil.
What the experts say: As the climate continues to warm, "the tendency is that we have stronger and more frequent episodes," says Karina Lima, a geographer at the Federal University of Rio Grande do Sul in Porto Alegre. This could be catastrophic for the Amazon rainforest, already battered by deforestation and a warming and drying climate. "The forest's tipping point is coming closer—and it's coming quick." |  | Aerial view of a small boat (known locally as "rabetas"), which are the only crafts that can pass certain points of the drought-hit rivers, on a small branch of the Amazon River that connects with the Negro River on October 04, 2023 in Manaus, Brazil. Credit: Bruno Zanardo/Getty Images | | | • Our climate is hurtling toward 1.5 degrees Celsius of heating over preindustrial levels, and likely will hit that milestone by the end of the decade. Scientists have declared that level of warming a "catastrophic threshold" for life on Earth, and we should keep fighting with all our might to curb our emissions-producing behaviors, writes Amy Martin, founder and executive producer of Threshold, a Peabody Award–winning documentary podcast that explores human relationships with the natural world. "Working relentlessly to limit global temperature rise to 1.5 degrees C—even if we temporarily surpass it—is choosing to reduce suffering for people and life on the planet as a whole," she says. | 11 min read | | | • Unplanned pregnancies for people over 40 is surprisingly common. | The Atlantic | | | • Lumping 60 percent of the world's population into one "Asian" category obscures a myriad of health disparities. | STAT | | | If you're so inclined, let me know what you're thankful for this year, I'd love to read about it. And send any other suggestions or feedback to: newsletters@sciam.com. Today in Science will return on Monday! | —Andrea Gawrylewski, Chief Newsletter Editor | | Subscribe to this and all of our newsletters . | | | | Scientific American
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