Category Archives: Nature

Image of the day: Sweden’s fall colors, from space

From NASA’s Earth Observatory, an astronaut’s-eye view of the fall colors of Sweden, with a jet plane’s contrail visible starting from the upper right corner:


From NASA:

Fall in northern Sweden is a brief but spectacular affair. For a few weeks in October, alpine forests in this remote part of Swedish Lapland turn blazing shades of yellow and orange.

The Operational Land Imager (OLI) on the Landsat 8 satellite captured this image of hilly terrain in northern Lapland on October 10, 2016. Birch forests growing along stream valleys are probably the source of most of the color, though other deciduous shrubs and understory plants surely contribute as well. Some of the hills have a dusting of snow. The southern Sun’s low angle above the horizon draws long, dark shadows across the landscape.

In autumn, the leaves on deciduous trees change colors as they lose chlorophyll, the molecule that plants use to synthesize food. Chlorophyll makes plants appear green because it absorbs red and blue sunlight. It is not a stable compound, and plants have to continuously produce it, a process that requires ample sunlight and warm temperatures. When days shorten and temperatures drop, levels of chlorophyll do as well.

As the green fades, other leaf pigments—carotenoids and anthocyanins—show off their colors. Carotenoids absorb blue-green and blue light, appearing yellow and orange. Anthocyanins absorb blue, blue-green, and green light, appearing red.

In fall displays of color in Scandinavia and northern Europe yellows tends to dominate and reds are rare. In fact, northern Europe has just four tree species that turn red, compared with 89 tree species in North America. In East Asia, the number is 150.

In Lapland, the local name for leaf peeping season is ruska, the time of year when Scandinavians head outdoors to savor nature’s display before the long, dark winter descends.

20th Century sea level rise underestimated?

Sea level change resulting from Greenland ice melt, derived from NASA GRACE measurements. Black circles show locations of the best historical water level records, which underestimate global average sea level rise due to Greenland melt by about 25 percent. Credits: University of Hawaii/NASA-JPL/Caltech

Sea level change resulting from Greenland ice melt, derived from NASA GRACE measurements. Black circles show locations of the best historical water level records, which underestimate global average sea level rise due to Greenland melt by about 25 percent. Credits: University of Hawaii/NASA-JPL/Caltech

The world’s coastal regions have been submerging even faster than we thought, according to a new study which finds that the measuring devices used to calculate the rise may be given readings lower than the real rate of sinking.

From NASA:

A new NASA and university study using NASA satellite data finds that tide gauges — the longest and highest-quality records of historical ocean water levels — may have underestimated the amount of global average sea level rise that occurred during the 20th century.

A research team led by Philip Thompson, associate director of the University of Hawaii Sea Level Center in the School of Ocean and Earth Science and Technology, Manoa, evaluated how various processes that cause sea level to change differently in different places may have affected past measurements. The team also included scientists from NASA’s Jet Propulsion Laboratory, Pasadena, California, and Old Dominion University, Norfolk, Virginia.

“It’s not that there’s something wrong with the instruments or the data,” said Thompson, “but for a variety of reasons, sea level does not change at the same pace everywhere at the same time. As it turns out, our best historical sea level records tend to be located where 20th century sea level rise was most likely less than the true global average.”

One of the key processes the researchers looked at is the effect of “ice melt fingerprints,” which are global patterns of sea level change caused by deviations in Earth’s rotation and local gravity that occur when a large ice mass melts. To determine the unique melt fingerprint for glaciers, ice caps and ice sheets, the team used data from NASA’s Gravity Recovery and Climate Experiment (GRACE) satellites on Earth’s changing gravitational field, and a novel modeling tool (developed by study co-author Surendra Adhikari and the JPL team) that simulates how ocean mass is redistributed due to ice melting.

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DroughtWatch: Major relief for California

For the first time in three years, two of California’s counties, Del Norte and Humboldt in the state’s northwestern corner, are officially drought-free, thanks to the storms of the last week.

It’s the first time in ages all of the state hasn’t been one or another of the five stages of drought.

From the United States Drought Monitor:


Maps of the day: It’s getting really, really hot

So hot that 2016 is set to become the hottest year ever recorded since modern meteorologists began collecting data.

First up, a graphic look at the global picture from NASA’s Goddard Institute for Space Studies, showing the relative departures of September temperatures from historical averages:


And a look at conditions in the United States from, again showing the relative departure of temperatures from historical September averages:


Finally, the prognostication from Gavin Schmidt, director of the Goddard Institute for Space Studies, who tweeted “With data now available through September, 2016 annual record (~1.25ºC above late 19th C) seems locked in”:


The universe abruptly grows a lot more populated

That’s because astronomers had been underestimating the number of galazies in the known universe by a factor of ten.

And that means a radical increase of the number of solar systems with planets capable to supporting life.

From the Space Telescope Science Institute in Baltimore:

The universe suddenly looks a lot more crowded, thanks to a deep-sky census assembled from surveys taken by NASA’s Hubble Space Telescope and other observatories.

Astronomers came to the surprising conclusion that there are at least 10 times more galaxies in the observable universe than previously thought.

The results have clear implications for galaxy formation, and also helps shed light on an ancient astronomical paradox — why is the sky dark at night?

In analyzing the data, a team led by Christopher Conselice of the University of Nottingham, U.K., found that 10 times as many galaxies were packed into a given volume of space in the early universe than found today. Most of these galaxies were relatively small and faint, with masses similar to those of the satellite galaxies surrounding the Milky Way. As they merged to form larger galaxies the population density of galaxies in space dwindled. This means that galaxies are not evenly distributed throughout the universe’s history, the research team reports in a paper to be published in The Astrophysical Journal.

“These results are powerful evidence that a significant galaxy evolution has taken place throughout the universe’s history, which dramatically reduced the number of galaxies through mergers between them — thus reducing their total number. This gives us a verification of the so-called top-down formation of structure in the universe,” explained Conselice.

One of the most fundamental questions in astronomy is that of just how many galaxies the universe contains. The landmark Hubble Deep Field, taken in the mid-1990s, gave the first real insight into the universe’s galaxy population. Subsequent sensitive observations such as Hubble’s Ultra Deep Field revealed a myriad of faint galaxies. This led to an estimate that the observable universe contained about 200 billion galaxies. The new research shows that this estimate is at least 10 times too low.

Conselice and his team reached this conclusion using deep-space images from Hubble and the already published data from other teams. They painstakingly converted the images into 3-D, in order to make accurate measurements of the number of galaxies at different epochs in the universe’s history. In addition, they used new mathematical models, which allowed them to infer the existence of galaxies that the current generation of telescopes cannot observe. This led to the surprising conclusion that in order for the numbers of galaxies we now see and their masses to add up, there must be a further 90 percent of galaxies in the observable universe that are too faint and too far away to be seen with present-day telescopes. These myriad small faint galaxies from the early universe merged over time into the larger galaxies we can now observe.

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DroughtWatch: Another week. still no changes

All of California remains in one level or another of drought conditions, with no change in levels for the last three months.

From the United States Drought Monitor:


Map of the day: Spread of a deer-killing disease

A lethal plague is spreading the deer population of North America, a disease threatening to annihilate a critical species in already endangered ecosystem.

Dubbed Chronic Wasting Disease [CWD], the ailment is similar to the human affliction Creutzfeldt-Jakob disease [mad cow disease], and like the human ailment, it attacks the brain and nervous system, resulting in erratic behavior and a wasting away of bodily tissues.

Both diseases appear to be caused by prions, particles smaller than viruses.

From the U.S. Geological Survey:

Chronic wasting disease may have long-term negative effects on white-tailed deer, a highly visible and economically valuable keystone species, according to a new study from the USGS and published in Ecology [$38 to read].

CWD is an always-fatal, neurological disease of the deer family, scientifically referred to as cervids that include white-tailed deer, mule deer, elk and moose. The disease is an internationally-significant wildlife management issue for free-ranging and captive white-tailed deer. Originally described in captive mule deer about 35 years ago in Colorado, CWD has now been discovered in 24 states, two Canadian provinces, the Republic of Korea and Norway.

“Despite the health threat of CWD to deer populations, little is known about the rates of infection and mortality caused by this disease,” said Dr. Michael D. Samuel, USGS wildlife biologist and lead author on the report.

Researchers used mathematical models to estimate infection and mortality for white-tailed deer in Wisconsin and Illinois outbreaks. They found that adult male deer have three times the risk of CWD infection than female deer and males also have higher disease mortality than females.

“Additional research is needed to more fully understand how CWD is transmitted to healthy deer and the potential long-term impact of the disease on North American deer populations,” said Samuel. USGS scientists found that CWD-associated deaths can cause substantial reductions in deer populations in areas where CWD is not addressed.

Scientific understanding of the ecology and transmission of CWD in free-ranging wildlife is limited, but this information is critical for making management decisions and helping to better understand the ecology of CWD in free-ranging populations.

The paper, “Chronic wasting disease in white-tailed deer: infection, mortality, and implications for heterogeneous transmission,” was published in Ecology and authored by Michael D. Samuel, USGS, Wisconsin Cooperative Wildlife Research Unit, University of Wisconsin; Daniel Storm, Department of Forest and Wildlife Ecology, University of Wisconsin, and currently with the Wisconsin Department of Natural Resources.