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The scientists of the American Geophysical Union (AGU) warn that greenhouse gas (GHG) emissions must be slashed in half to keep temperatures from rising 3.6 degrees Fahrenheit (2 degrees Celsius)—or else. “Warming greater than 2 degrees Celsius above 19th-century levels is projected to be disruptive, reducing global agricultural productivity, causing widespread loss of biodiversity and—if sustained over centuries—melting much of the Greenland ice sheet with ensuing rise in sea levels of several meters,” the AGU declares in its first statement in four years on “Human Impacts on Climate....

Just as my office would not stay empty for long were I to move out, nature’s real estate changes hands all the time. Potential homes range from holes drilled by woodpeckers to empty shells on the beach. A typical example of what economists call a vacancy chain is the housing market among hermit crabs. To protect its soft abdomen, each crab carries its house around, usually an abandoned gastropod shell. The problem is that the crab grows, whereas its house does not....

When I left home for the first time in 1999 to go to university, I was brimming with hope and optimism. I’d done well in school, expectations for me were high, and I gleefully entered the campus life of lectures and parties. To all appearances, I was a feisty, energetic and capable person with everything to hope for and aspire to. Beneath that veneer, however, I was deeply unhappy, insecure and frightened—frightened of other people, of the future, of failure, of falling short of the punishingly high expectations that I had placed on myself....

The hydrogen bonds that hold together the molecular base pairs of our DNA form in intracellular fluid. Much of our planet’s environmental chemistry occurs in oceans and other bodies of water. Most drugs are synthesized in solvents. Yet chemists generally study the bond-by-bond mechanics of chemical reactions only in the gas phase, where molecules are relatively sparse and easy to track. In a liquid there are more molecules and more collisions among them, so reactions are fast, messy and complicated....

Editor’s note (4/2/2017): This week marks the 100-year anniversary of the U.S. entry into the First World War. Scientific American, founded in 1845, spent the war years covering the monumental innovations that changed the course of history, from the first tanks and aerial combat to the first widespread attacks with chemical weapons. To mark the centennial, we are republishing the article below and many others. For full access to our archival coverage of the Great War sign up for an All Access subscription today....

One of the worst insect pests in the world is coming to the U.S.—and it’s coming in disguise. By almost any measure of pest severity, the Old World bollworm Helicoverpa armigera tops the charts. Annual losses from the pest are estimated at $5 billion. The caterpillars eat more than 180 kinds of plants including cotton, corn, soybeans, citrus fruits and ornamental flowers. A single female can lay thousands of eggs, and adult bollworm moths can ride wind currents up to 2,000 kilometers—about the distance from Mexico City to Albuquerque, N....

India’s interplanetary space program is young but shows no lack of ambition. In 2008 the country launched a spacecraft, Chandrayaan-1, into lunar orbit for the first time. Next came its Mars Orbiter Mission, which arrived in orbit around the Red Planet in 2014. Today, sadly, India apparently fell short of what could have been its greatest milestone yet—an uncrewed landing on the surface of the moon as part of its Chandrayaan-2 mission....

When accidents happen, doctors typically rely on sutures, staples or adhesives to fix the damage. These approaches work, of course, but they tend to cause inflammation in the surrounding tissue and leave scars long after a wound has healed. Researchers at Harvard Medical School and the Massachusetts General Hospital Wellman Center for Photomedicine have recently completed a study they hope will shine some light on this problem—laser light, that is....

Editor’s Note (12/21/21): This article is being showcased in a special collection about equity in health care that was made possible by the support of Takeda Pharmaceuticals. The article was published independently and without sponsorship. Grassroots organizers in Boston, primary care innovators in Chicago and even an academic medical center in Philadelphia responded to the COVID pandemic by bringing mobile vaccine clinics directly to the neighborhoods most impacted by the virus....

It is well known that diabetes wreaks havoc on the vascular system. In fact, vascular complications arising from diabetes are the leading cause of blindness, kidney failure and cardiovascular problems in the U.S. And yet, the physiological mechanisms that link diabetes, which afflicts 26 million Americans, to sickly blood vessels are poorly understood. Researchers have now identified key interactions among two enzymes that may help connect the dots between insulin control and the integrity of blood vessels....

Just nine months after its launch, NASA’s Transiting Exoplanet Survey Satellite (TESS) has found at least eight planets, with more than 300 planetary candidates waiting in the wings. A bizarre planet at least 23 times the mass of Earth, unveiled on 7 January, is among the confirmed planets—some of which have been reported before. The newly described planet whizzes around its star on a stretched-out orbit once every 36 days, says Xu Chelsea Huang, a TESS scientist at the Massachusetts Institute of Technology (MIT) in Cambridge....

Recently, billionaires Richard Branson and Jeff Bezos used their wealth to loft their bodies upward by a tiny percentage of the Earth’s radius. This is not much to be proud of, since space is vast. The observable universe extends out to 1019 Earth radii, and the only way to respect our cosmic insignificance is not to show off, but rather to stay modest. It was presumptuous of us to send the “Golden Record” on the Voyager mission....

In the early months of the COVID-19 pandemic, some U.S. leaders and pundits pointed to hard-hit cities such as New York, Milan and Wuhan as proof that population density was to blame for coronavirus hotspots. But simple density has not adequately predicted the disease’s course in the U.S., where the new coronavirus has spread well beyond urban areas to ravage rural communities and suburbs during the country’s long summer. Many public health and urban planning researchers agree that the concentration of people within a certain area does not tell the whole story....

The researchers coated conventional paper with nanoparticles of two chemicals: Prussian blue, the pigment that gives blueprints their characteristic color, and titanium dioxide, a substance used in sunscreens. A blast of ultraviolet light makes the titanium dioxide nanoparticles donate electrons to their Prussian blue neighbors. That jolts the pigment into shifting its color from midnight blue to milky white. By shining that UV light through a transparent screen marked with black text, the researchers “printed” blue text on a white background....

Imagine a beach crowded with vacationers enjoying the hot summer sun. As children paddle about in the shallows, foraging for shells and other treasures, dead and dying animals begin to wash ashore. First, a few struggling fish, then smelly masses of decaying crabs, clams, mussels and fish. Alerted by the kids’ shocked cries, anxious parents rush to the water to pull their children away. Meanwhile, out on the horizon, frustrated commercial fishermen head for port on boats with empty nets and holds....

By Reuters Staff WASHINGTON (Reuters) - The U.S. Senate voted overwhelmingly on Wednesday to confirm Dr. Robert Califf as head of the Food and Drug Administration, an agency that regulates everything from food and drugs to tobacco, cosmetics and dietary supplements. Califf, 64, a well-regarded cardiologist and researcher, takes the helm at the FDA when lawmakers are pressuring the agency to speed the approval process for drugs and medical devices and finalize a proposed rule giving it authority to regulate e-cigarettes....

You can accuse fusion power advocates of being overly optimistic but never of thinking small. Fusion occurs when two elements combine, or “fuse,” together to form a new, third element, converting matter to energy. It is the process that powers the sun, and the fusion world’s marquee projects are accordingly grand. Consider the International Thermonuclear Experimental Reactor (ITER), which a consortium of seven nations is building in France. This $21-billion tokomak reactor will use superconducting magnets to create plasma hot and dense enough to achieve fusion....

As the coronavirus outbreak continues to spread worldwide and more people become critically ill, scientists are racing to find a treatment that will help turn the tide. Dozens of medicines are in clinical trials in China—and now in the U.S.—to treat the disease, officially named COVID-19. Some are antiviral drugs that are already used to narrowly target other viruses. Experts say these medications are unlikely to do much against the novel coronavirus....

Editor’s Note (12/21/21): This article is being showcased in a special collection about equity in health care that was made possible by the support of Takeda Pharmaceuticals. The article was published independently and without sponsorship. As the Delta variant causes COVID-19 cases to swell, resurrects mask mandates and forces hospitals back to surge capacity, a familiar pattern is emerging. Like its less transmissible predecessors, this dangerous SARS-CoV-2 variant is especially affecting vulnerable populations in minority and rural communities, where vaccinations have lagged because of a perfect storm of reduced access to care, vaccine hesitancy, targeted misinformation campaigns and historically rooted mistrust....

Henry Markram has become famous as the creator of the world’s most expensive brain simulation, but neuroscientists know him best for his pioneering experiments on synapses. Markram was one of the first to investigate the sequential version of Hebb’s rule in a systematic way, by varying the time delay between the spiking of the two neurons when inducing synaptic plasticity. (Changes in the synapses, the connection points between cells. One scientist reduced Hebb’s rule to: “Cells that fire together, wire together....