Mercury released by permafrost thaw puts Yukon River fish at risk: study

By Yereth Rosen

ANCHORAGE (Reuters) – If carbon emissions continue at current rates, so much mercury will leach from thawing permafrost that fish in the Yukon River could become dangerous to eat within a few decades, according to a study published Wednesday in the journal Nature Communications.

Current emissions rates threaten to trigger enough thaw release to drive mercury levels in Yukon River fish above federal safety guidelines by 2050, according to the study.

Mercury concentration in the Yukon is expected to double by the end of the century if carbon emissions continue at present rates, according to the study.

But if emissions are reduced in line with the 2015 Paris Agreement, mercury concentrations will increase by only 14% by the end of the century, keeping levels in fish at or below safety guidelines, according to the study.

“A lot will depend on what we do in terms of response to climate change,” said Kevin Schaefer of the Colorado-based National Snow and Ice Data Center, the study’s lead author.

The study has implications beyond the indigenous communities in Alaska and Canada that depend on Yukon River fish for their income, diets and culture, Schaefer said.

The nearly 2,000-mile river is “a bellwether or a canary-in-the-coal mine kind of thing, an indicator of what might happen over the whole Arctic,” he said. Thaw-released mercury will work its way from the land to the river and ultimately, into the oceans, and thaw-released mercury in gaseous form will encircle the world, he said.

“What happens in the Yukon is going to affect the entire globe, not just the people who live on or around the Yukon River,” he said.

A 2018 study co-authored by Schaefer, in collaboration with partners from the U.S. Geological Survey and other institutions, estimated that Northern Hemisphere’s permafrost soils hold nearly twice as much stored mercury as is in all the rest of the world’s soils, the oceans and the atmosphere combined.

(Reporting by Yereth Rosen; Editing by Bill Tarrant and Christopher Cushing)

Mercury poised for rare ‘transit’ across sun’s face on Monday

The planet Mercury is seen in silhouette lower left as it transits across the face of the sun

By Irene Klotz

CAPE CANAVERAL, Fla. (Reuters) – Stargazers will have a rare opportunity on Monday to witness Mercury fly directly across the face of the sun, a sight that unfolds once every 10 years or so, as Earth and its smaller neighboring planet come into perfect alignment.

The best vantage points to observe the celestial event, known to astronomers as a transit, are eastern North America, South America, Western Europe and Africa, assuming clouds are not obscuring the sun. In those regions, the entire transit will occur during daylight hours, according to Sky and Telescope magazine.

But Mercury is too small to see without high-powered binoculars or a telescope, and looking directly at the sun, even with sunglasses, could cause permanent eye damage.

Fortunately NASA and astronomy organizations are providing virtual ringside seats for the show by live-streaming images of the transit in its entirety and providing expert commentary.

The tiny planet, slightly larger than Earth’s moon, will start off as a small black dot on the edge of the sun at 7:12 a.m. Eastern (1112 GMT). Traveling 30 miles (48 km) a second, Mercury will take 7.5 hours to cross the face of the sun, which is about 864,300 miles (1.39 million km) in diameter, or about 109 times larger than Earth.

“Unlike sunspots, which have irregular shapes and grayish borders, Mercury’s silhouette will be black and precisely round,” Sky and Telescope said in a press release.

The event will come into view in the western United States after dawn, with the transit already in progress. The show will end at sunset in parts of Europe, Africa and most of Asia.

NASA Television, available on the Internet, will broadcast live video and images from the orbiting Solar Dynamics Observatory and other telescopes. The show includes informal discussions with NASA scientists, who will answer questions submitted via Twitter using the hashtag #AskNASA.

Other options for armchair astronomers include:

– SkyandTelescope.com plans a live webcast with expert commentary, beginning at 7 a.m. EDT/1100 GMT.

– Slooh.com, which offers live telescope viewing via the Internet, will host a show on its website featuring images of Mercury taken by observatories around the globe.

– Europe’s Virtual Telescope, another robotic telescope network, will webcast the transit at www.virtualtelescope.eu

Scientists will take advantage of Mercury’s transit for a variety of science projects, including refining techniques to look for planets beyond the solar system.

“When a planet crosses in front of the sun, it causes the sun’s brightness to dim. Scientists can measure similar brightness dips from other stars to find planets orbiting them,” NASA said.

Mercury’s last transit was in 2006 and the planet will pass between the sun and Earth again in 2019. After that, the next opportunity to witness the event will not come until 2032.

(Editing by Frank McGurty and James Dalgleish)

Five planets visible in pre-dawn sky for first time in 11 years

Early-morning stargazers will have the rare opportunity to observe five planets at the same time during the next few weeks, according to a recent post on astronomy website EarthSky.org.

EarthSky says it’s the first time in more than 11 years that the five brightest planets — Mercury, Venus, Mars, Jupiter and Saturn — will simultaneously appear in the sky above Earth.

People had their first chance to catch the five planets before sunrise this morning, according to EarthSky, and the rare sight can be witnessed just before dawn every day through February 20.

The planets can be seen without a telescope or binoculars from anywhere on Earth, the EarthSky post says. Unclear skies could prevent some people from observing the spectacle on certain days.