Fact Check My Feed: Why Are People Taking Discredited Horse Medicine For COVID-19? If you’ve been online at all in the past few weeks, you’ve probably seen discussion about the drug ivermectin. It was originally developed as an antiparasitic treatment for livestock, and in 2015, the Nobel Prize in Medicine went to scientists who found that it helped control parasitic diseases in humans as well. But recently, non-medical groups have been incorrectly promoting the drug as a treatment for COVID-19—even though the coronavirus is a virus, not a parasite. Virologist Angela Rasmussen of the University of Saskatchewan joins Ira to look at the data behind sometimes hyperbolic COVID-19 claims, from the latest on booster shots to the emergence of a new coronavirus variant in South Africa.     What Happens If Atlantic Ocean Currents Cease To Churn? Early last month, the Intergovernmental Panel on Climate Change released its latest report. It was a grim document, concluding that global warming had already set in motion irreversible levels of sea level rise, along with other changes that are threatening lives and health around the globe. The report focused in part on climate tipping points, or phenomena that, if they occur, could lead to a long term re-setting of our global climate and cascades of dangerous changes. Included among tipping points like the loss of the Amazon rainforest and melting of the permafrost, was the potential shutdown of the Atlantic meridional overturning circulation—the AMOC, for short. That circulation, a set of currents that includes the Gulf Stream, ferries cold water from the poles toward the equator, and distributes heat from the equator to northern latitudes. And it’s powered by two things that are both changing as the climate warms: the temperature of ocean water, and the varying concentrations of salt in that water.  Climate models that use data from thousands of years ago can help us predict what might happen if the AMOC shuts down. Because the currents are a huge source of heat redistribution globally, a shutdown could have a complex array of consequences, from rainfall disruptions in the southern hemisphere, to even greater sea level rise on North America’s east coast. And if it shuts down completely, it may not come back on again in any of our lifetimes. Unfortunately, researchers have been finding evidence that the circulation is, in fact weakening, including a study published in the journal Nature Climate Change in early August. Ira talks to Levke Caesar, a researcher at Maynooth University’s ICARUS Climate Research Center. While not affiliated with the latest research, her work has helped map the ongoing pattern of weakening in the AMOC.       A Sourdough Saga, From Starter To Slice What makes sourdough taste sour? Was the first bread invented, or discovered? How did scientists eventually figure out that yeast and bacteria were the true master bakers? Will commercial bread ever be as good as that hand-baked loaf? Ira releases his inner breadmaking nerd in this conversation with Eric Pallant, author of the forthcoming book Sourdough Culture: A History of Breadmaking From Ancient to Modern Bakers.