Axios' new science editor Andrew Freedman writes: Human activities are encroaching on the lands we've set aside to protect vulnerable species, according to new research.

Key findings: About 33% — or roughly 2.3 million square miles — of protected land worldwide is under "intense human pressure" from development, such as roads, growing urban areas and agriculture, per the study, published Thursday in Science. Only 42% of protected land is free of any "measurable human pressure."

What they did: The authors devised a metric for the human footprint on our planet that includes proximity to built environments, pasture lands, intensive agriculture, nighttime lights and human population density, among other variables.

• On a positive note, the average human footprint within protected areas was almost 50% lower than the global mean for all types of land areas.
• But just 4,334 protected areas, or 10% of analyzed protected areas, "are completely free of intense human pressure," they wrote.
• Such areas tend to occur in remote areas of the globe, such as parts of Russia and Canada, rather than the tropics, which are both rich in biodiversity and have human populations encroaching upon them.

Go deeper: Read the story here.

• Water woes: The first map of freshwater availability changes around the world illustrates profound implications for agriculture and security, per Andrew.
• Vaping: More adults may be trying e-cigarettes, but fewer people are making it a habit, Eileen Drage O'Reilly reports.
• Now: April was the 400th straight warmer-than-average month on Earth, Andrew reports. "The last month with below average temperatures for the globe was December 1984, when Ronald Reagan was president."
• Coming... There will be 5.6 billion air conditioners in the world by 2050, according to the International Energy Agency — making it harder to cut carbon emissions enough to prevent catastrophic warming levels, per Axios' Ben Geman.
• Full circle: Astronomers directly measured light from a galaxy 13.8 billion light-years from Earth and speculate many stars could have been forming there just 250 million years after the Big Bang.

The World Health Organization this week issued a list of must-have diagnostic tools for nations to adopt, Eileen Drage O'Reilly reports. They expect the first round of the Essential Diagnostics List (EDL) will encourage manufacturers to boost production of the tests.

Why it matters: Diagnostic tools are the first key step in ensuring a patient receives the correct treatment and in assisting countries in containing and responding to disease outbreaks, but many developing countries do not have access to them.

"Diagnostics are going to be key ... to be able to triage and respond and manage patients when an outbreak happens."

The context: Creating a global pandemic response system, which would include rapid diagnostic tests, is increasingly being recognized as a major health and security priority. "The world needs to prepare for pandemics the way it prepares for war," Bill Gates said recently.

Go deeper: Read the rest of Eileen's story.

• Unknown source: Emissions of banned chemical CFC-11 — which depletes the ozone layer — have risen 25% globally since 2012, per The Washington Post's Chris Mooney. Who is producing it where — and why — is unclear.
• Buzz: Blue orchard bees could help to alleviate the devastation of colony collapse disorder, but beekeepers and researchers are struggling to produce enough of them, Anna Katrina Hunter writes in Inside Science.
• Memories: UCLA researchers report using RNA to move memories from one snail to another. That, they say, suggests memories are stored in the nucleus of neurons rather than the connections between them. Usha Lee McFarling at STAT talked to the skeptics.
• Ancient Rome: The economic activity of Romans between 1100 B.C. and 800 A.D. has been pieced together using measurements of lead emissions — a proxy for the production of coins — in the Greenland Ice Sheet, Robinson Meyer reports for The Atlantic.

Etched by wind and water, the sandstone bridges and arches of southern Utah seem to be stoics of the desert. But as rock features go, they are quite sensitive.

What's new: University of Utah professor Jeff Moore and graduate student Paul Geimer borrowed techniques from civil engineering to study 15 arches across southern Utah, including continuously monitoring Aqueduct Arch.

"[It's] a magnificent smooth form that is probably on its last legs as an arch. I have a soft spot for it," says Geimer.

• The vibrations they measured there and elsewhere varied 3%–5% over the course of a day, according to research they presented this week at the annual meeting of the Seismological Society of America.
• That's "actually very similar to changes that have been measured in man-made bridges and buildings, despite the lack of engineered design or materials," Geimer says.
• Over a year, the vibrations in the rock changed more than 25%. The arches recover, but Geimer suspects the vibrations could weaken them over time.

The goal: They want to use the measured frequencies and 3D models of the arches to estimate their thickness and strength, and to try to track trends. From that, they hope to create a framework for monitoring sensitive sites or one day predicting imminent collapse in seemingly stable structures.