Forty years after the discovery of HIV, AFP looks at how far we have come in fighting a deadly virus that was once shrouded in fear and shame but is now treated as a manageable chronic condition.

1981: First alert

In June 1981, US epidemiologists report five cases of a rare form of pneumonia in gay men in California.

A glacier in the north of Greenland is melting faster and in a different way than scientists previously thought, and this has troubling implications for the future speed of global sea-level rise.

The new discovery was published in the Proceedings of the National Academy of Sciences Monday. The scientists found that warming ocean water had melted a cavity in the bottom of Petermann Glacier taller than the Washington Monument, as The Associated Press reported. If other glaciers in Greenland and Antarctica behave the same way, it could double predictions for how quickly the burning of fossil fuels will melt ice and raise sea levels.

The Florida legislature passed a bill that could take the state one step closer to using a radioactive waste product from the fertilizer industry in road asphalt, reported NPR on Tuesday.

"HB 1191 would compel the Florida Transportation Department to study using phosphogypsum in paving projects, calling for 'demonstration projects using phosphogypsum in road construction aggregate material to determine its feasibility as a paving material,'" reported Bill Chappell. "If it's approved, phosphogypsum would join pavement aggregates such as crushed stone, gravel and sand. In recent years, the Federal Highway Administration says, industrial byproducts and reclaimed materials have also been used as aggregates. The bill sets a deadline of April 1, 2024, giving the transportation agency less than a year to complete its work and make a recommendation."

When an unexpected rainstorm leaves you soaking wet, it is an annoyance. When a drought leads to fires, crop failures and water shortages, the significance of weather becomes vitally important.

If you could control the weather, would you?

Small amounts of rain can mean the difference between struggle and success. For nearly 80 years, an approach called cloud seeding has, in theory, given people the ability to get more rain and snow from storms and make hailstorms less severe. But only recently have scientists been able to peer into clouds and begin to understand how effective cloud seeding really is.

In this episode of “The Conversation Weekly,” we speak with three researchers about the simple yet murky science of cloud seeding, the economic effects it can have on agriculture, and research that may allow governments to use cloud seeding in more places.

Katja Friedrich, a professor of atmospheric and oceanic sciences at the University of Colorado, Boulder in the U.S., is a leading researcher on cloud seeding. “When we do cloud seeding, we are looking for clouds that have tiny super-cooled liquid droplets,” she explains. Silver iodide is very similar in structure to an ice crystal. When the droplets touch a particle of silver iodide, “they freeze, then they can start merging with other ice crystals, become snowflakes and fall out of the cloud.”

While the process is fairly straightforward, measuring how effective it is in the real world is not, according to Friedrich. “The problem is that once we modify a cloud, it’s really difficult to say what would’ve happened if you hadn’t cloud-seeded.” It’s hard enough to predict weather without messing with it artificially.

Cloud seeding is usually done by planes equipped with devices – like the one attached to the wing of this plane – that spray silver iodide into the atmosphere.

Zuckerle/Wikimedia Commons, CC BY-SA

In 2017, Friedrich’s research group had a breakthrough in measuring the effect of cloud seeding. “We flew some aircraft, released silver iodide and generated these clouds that were like these six exact lines that were downstream of where the aircraft were seeding,” she says. They then had a second aircraft fly through the clouds. “We could actually quantify how much snow we could produce by two hours of cloud seeding.” That effect, according to research on cloud seeding, is an increase in precipitation of somewhere around 5% to 20% or 30%, depending on conditions.

Measuring the effect on precipitation – whether rain or snow – directly may have taken complex science and a bit of luck, but in places that have been using cloud seeding for long periods of time, the economic benefits are shockingly clear.

Dean Bangsund is a researcher at North Dakota State University who studies the economics of agriculture. “We have a high amount of hail damage in North Dakota,” said Bangsund. For decades, the state government has been using cloud seeding to reduce hail damage, as cloud seeding leads to the formation of more pieces of smaller hail compared to fewer pieces of larger hail. “It doesn’t 100% eliminate hail; it’s designed to soften the impact.”

Every 10 years, the state of North Dakota does an analysis on the economic impacts of the cloud seeding program, measuring both reduction in hail damage and benefits from increased rain. Bangsund led the last report and says that for every dollar spent on the cloud seeding program, “we are looking at something that is anywhere from $8 or $9 in benefit on the really lowest scale, up to probably $20 of impact per acre.” With millions of acres of agricultural fields in the cloud seeding area, that is a massive economic benefit.

Both Freidrich and Bangsund emphasized that cloud seeding, while effective in some cases, cannot be used everywhere. There is also a lot of uncertainty in how much of an effect it has. One way to improve the effectiveness and applicability of cloud seeding is by improving the seed. Linda Zou is a professor of civil infrastructure and environmental engineering at Khalifa University in the United Arab Emirates.

Her work has focused on developing a replacement for silver iodide, and her lab has developed what she calls a nanopowder. “I start with table salt, which is sodium chloride,” says Zou. “This desirable-sized crystal is then coated with a thin nanomaterial layer of titanium dioxide.” When salt gets wet, it melts and forms a droplet that can efficiently merge with other droplets and fall from a cloud. Titanium dioxide attracts water. Put the two together and you get a very effective cloud-seeding material.

From indoor experiments, Zou found that “with the nanopowders, there are 2.9 times the formation of larger-size water droplets.” These nanopowders can also form ice crystals at warmer temperatures and less humidity than silver iodide.

As Zou says, “if the material you are releasing is more reactive and can work in a much wider range of conditions, that means no matter when you decide to use it, the chance of success will be greater.”

Most diamonds are formed deep inside Earth and brought close to the surface in small yet powerful volcanic eruptions of a kind of rock called “kimberlite”.

Our supercomputer modeling, published in Nature Geoscience, shows these eruptions are fueled by giant “pillars of heat” rooted 2,900 kilometres below ground, just above our planet’s core.

A glacier in the north of Greenland is melting faster and in a different way than scientists previously thought, and this has troubling implications for the future speed of global sea-level rise.

The new discovery was published in the Proceedings of the National Academy of Sciences Monday. The scientists found that warming ocean water had melted a cavity in the bottom of Petermann Glacier taller than the Washington Monument, as The Associated Press reported. If other glaciers in Greenland and Antarctica behave the same way, it could double predictions for how quickly the burning of fossil fuels will melt ice and raise sea levels.

A newly published assessment from the U.S. Environmental Protection Agency warns that three of the most commonly used neonicotinoid insecticides threaten the continued existence of more than 200 endangered plant and animal species.

"The EPA's analysis shows we've got a five-alarm fire on our hands, and there's now no question that neonicotinoids play an outsized role in our heartbreaking extinction crisis," Lori Ann Burd, environmental health director at the Center for Biological Diversity (CBD), said Friday in a statement.

Mercury is the closest planet to the Sun, whipping around our star every 88 days compared to Earth’s 365.25 days. Mercury will also be the first planet destroyed when the Sun expands on its way to becoming a red giant in about 5 billion years.

So it seems a bit rough that we blame Mercury for all our problems three to four times a year when it’s in retrograde. But what does it mean when we say Mercury is “in retrograde”?

Advances in genetic engineering have given rise to an era of foods – including genetically modified organisms (GMOs) and gene-edited foods – that promise to revolutionize the way we eat.

Critics argue these foods could pose risks to human health and the environment. Proponents point to their potential for enhancing yields, reducing food waste, and even combating climate change.

People are finding huge, scaleless fish with sharp fangs and bulging eyes on the beaches of Oregon — and it's not clear why it's happening, according to the Associated Press.

"Within the last few weeks, several lancetfish have appeared on beaches from Nehalem, in northern Oregon, to Bandon, which is about 100 miles (161 kilometers) from the California border, Oregon State Parks said on Facebook," reported Becky Bohrer and Beatrice Dupuy. "The agency asked beachgoers who see the fish to take photos and post them online, tagging the agency and the NOAA Fisheries West Coast region."