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Category: climatology

Street green space can help cool cities, but it will not be enough on its own

A new IIASA-led study finds that expanding street green space can reduce urban heat stress in cities worldwide, but even ambitious greening efforts are unlikely to offset a significant share of the additional heat expected under climate change. Instead, the research shows that street greenery should be part of a broader portfolio of urban adaptation measures.

Cities are on the front line of climate change, with rising temperatures and heat stress posing growing risks to health, productivity, and livability. Street green space, such as trees and vegetation along streets, is often promoted as a practical nature-based solution because it can provide shade, cooling, and other positive benefits, for example, improving the mental health of citizens. Yet, evidence on how much cooling street greenery can deliver, to which extent the amount of vegetation can be increased, and how much cooling can be expected in future climates has remained limited, particularly when taking a global view across very different urban forms and climate zones.

In the new study published in Environmental Research Letters, a team of researchers from IIASA and VITO Belgium combined high-resolution street greenery data with 100-meter urban microclimate model outputs for 133 cities worldwide, providing a neighborhood-scale assessment with global coverage. Rather than relying on satellite-based surface temperature alone, the team assessed how street green space relates to air temperature and wet-bulb globe temperature —a measure that captures heat stress more appropriately than temperature alone because it accounts for humidity, wind, and radiation.

Summer is getting longer, and it’s happening faster than we thought

Summer weather is arriving earlier, lasting longer and packing more heat than it used to—and it’s happening faster than scientists had previously measured. A new study by UBC researchers has found that between 1990 and 2023, the average summer between the tropics and the polar circles grew about six days longer per decade. That’s up from roughly four days per decade found in past research investigations up until the early 2010s.

For many cities, the numbers are even more striking. In Sydney, Australia, summer temperatures now last about 130 days, up from 80 days in 1990, adding 15 days per decade. Toronto summers are expanding by eight days per decade.

The researchers didn’t use the calendar definition of summer (June through August in the Northern Hemisphere and December through February in the Southern Hemisphere). Instead, they defined summer based on the weather: the stretch of days each year when temperatures rise above what was historically typical for a given location during the warmest part of the year—a threshold set using climate data from 1961 to 1990.

Scientists Just Broke the Solar Power Limit Everyone Thought Was Absolute

A new “energy-multiplying” solar breakthrough could push efficiency beyond 100% and transform how we capture sunlight.

Solar energy is widely seen as a key tool in reducing reliance on fossil fuels and slowing climate change. The Sun delivers a vast amount of energy to Earth every second, but today’s solar cells can only capture a small portion of it. This limitation comes from a so-called “physical ceiling” that has long been considered unavoidable.

Breakthrough spin-flip technology boosts solar efficiency.

Earth’s 40,000-year tilt cycle links Antarctic ice growth to subtropical productivity

Cycles in the growth and decay of Antarctica’s ice sheets once shaped marine biological productivity thousands of miles away in the subtropical ocean, according to new research led by scientists at the University of Wisconsin-Madison. The study, published in the Proceedings of the National Academy of Sciences, found that the obliquity cycle—a 40,000-year astronomical cycle tied to changes in Earth’s axial tilt—influenced ocean productivity in subtropical latitudes about 34 million years ago, when the Antarctic ice sheet was first expanding.

The finding surprised researchers because the 40,000-year cycle, while an important factor in the conditions at Earth’s poles, typically has a more limited influence on climate and ocean conditions near the equator.

“We generally expect other astronomical cycles to have a greater influence,” says Stephen Meyers, a professor of geoscience at UW-Madison and one of the study’s lead authors.

Social media feeds: Algorithm redesign could break echo chambers and reduce online polarization

Scroll through social media long enough and a pattern emerges. Pause on a post questioning climate change or taking a hard line on a political issue, and the platform is quick to respond—serving up more of the same viewpoints, delivered with growing confidence and certainty.

That feedback loop is the architecture of an echo chamber: a space where familiar ideas are amplified, dissenting voices fade, and beliefs can harden rather than evolve.

But new research from the University of Rochester has found that echo chambers might not be a fact of online life. Published in IEEE Transactions on Affective Computing, the study argues that they are partly a design choice—one that could be softened with a surprisingly modest change: introducing more randomness into what people see.

Lab study suggests longer waves fracture floating ice sheets at lower stress

When waves are moving across ice-covered seas, they can cause sheets of ice to bend and ultimately break. Understanding the processes underlying these wave-induced ice fractures and predicting when they will occur could help to better forecast how climate change will impact the environment and marine ecosystems on Earth.

Researchers at PMMH Lab, ESPCI, CNRS, PSL University, Sorbonne Université and Université Paris Cité recently performed a new laboratory experiment aimed at shedding new light on this phenomenon. The results of this experiment, published in Physical Review Letters, suggest that the stress at which ice sheets break depends on the length of the underlying waves.

“Since 2021, we wanted to study the propagation of ocean waves in floating ice, with laboratory-scale experiments, and in particular the fracture of a thin sheet by a surface wave,” said Stéphane Perrard, senior author of the paper, told Phys.org. “We were later inspired by the work of E. Dumas Lefevbre and D. Dumont, who monitored the fracture of a real sea ice layer by the wake of an icebreaker. To study a small-scale analog of their experiment, we used the concept of scale invariance: the same physical phenomenon can occur at very different scales, as long as the key ingredients are conserved across scales.”

Methane’s Elaborate Phases and Where to Find Them

A systematic exploration of the phase diagram of methane resolves inconsistencies of earlier studies, with potential ramifications for our understanding of planetary interiors.

As a gas, methane is very simple. But as a liquid and as a solid, it is perplexingly complex. Ambiguity has long plagued our observations and measurements of its structure at different pressure–temperature combinations. Yet, understanding methane’s phase diagram is vital for predicting its behavior deep within our and other planets. In a tour de force contribution Mengnan Wang at the University of Edinburgh in the UK and her colleagues have now charted the turbulent seas of the methane phase diagram [1]. By comprehensively mapping its phases and melting curve, they have resolved the legion of discrepancies of earlier studies.

Methane—one of the simplest of all molecules—is sometimes the subject of flatulence jokes (of which it is odorlessly innocent) but is also a powerful driver of climate change on Earth (of which it is very guilty [2]). The extraction of gaseous methane from Earth drives multibillion-dollar industries, which use the molecule both as a fuel and as a source of hydrogen. Out in the Solar System, methane in planetary atmospheres absorbs red light, which makes Uranus and Neptune shine blue, while icy methane damaged by radiation paints dwarf planets red.

Scientists uncovered the nutrients bees were missing — Colonies surged 15-fold

Scientists have developed a breakthrough “superfood” for honeybees by engineering yeast to produce the essential nutrients normally found in pollen. In controlled trials, colonies fed this specially designed diet produced up to 15 times more young, showing a dramatic boost in reproduction and overall health. As climate change and modern agriculture reduce the availability of natural pollen, this innovation could offer a practical way to support struggling bee populations.

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