Tag Archives: rainfall

Climate change is making spring come earlier and earlier in the Northern Hemisphere

The declining number of rainy days in the Northern Hemisphere is making spring arrive earlier and earlier for plants in this half of the globe, new research reports.

Image credits Vinzenz Lorenz.

We have known that warmer average temperatures, a product of climate change, have been causing plants to sprout leaves earlier every year. A new study comes to add details to this picture, reporting that changes in precipitation patterns are also impacting this process.

According to the findings, the decrease in the number of rainy days every year has the second-greatest effect on plants, having quickened the emergence of leaves over the last few decades.

Springing early

“Scientists have looked mainly at how temperature affects when leaves first appear and, if they considered precipitation at all, it was just the total amount,” said Desheng Liu, co-author of the study and professor of geography at The Ohio State University. “But it isn’t the total amount of precipitation that matters the most — it is how often it rains.”

For the study, the team calculated that the decline in the frequency of rainfall in the Northern Hemisphere will cause spring (as defined by plants producing fresh leaves) to arrive sooner. The findings are based on datasets from the United States, Europe, and China, taken in points north of 30 degrees latitude (the northern third of the world). This data included the date each year when observers first note the presence of leaves on wild plants. The team also used satellite images from 1982 to 2018, which recorded when vegetation started to green.

Onset of leafing was then compared to data reporting on the frequency of rainy days each month at the investigated sites.

Overall, the team explains, the (steady) decline in rainy days over the years was associated with earlier onset of leafing in most areas of the Northern Hemisphere. The only exception were grasslands in predominantly semi-arid regions, where a decrease in precipitation (fewer rainy days) slightly delayed spring.

The results were used to create a model that estimates how much sooner spring would arrive in different areas of the Northern Hemisphere through to 2100. Current estimates place this figure at 10 days earlier than the calendaristic onset of spring by 2100. The team calculates that it will arrive one to two days earlier, on average, every decade through to 2100.

As to the link between rainfall and leafing, the team offers two main reasons. The first is that fewer rainy days means fewer overcast days in late winter and early summer. Due to this, plants receive more sunlight during this time, which stimulates the emergence and growth of leaves.

Secondly, more sunlight also means higher average air and soil temperatures during the day. At night, without clouds to reflect heat back down, temperatures will drop more rapidly.

“This contrasting effect earlier in the year makes the plants think it is spring and start leaf onset earlier and earlier,” said study co-author Jian Wang, a doctoral student in geography at Ohio State.

“We need to plan for a future where spring arrives earlier than we expected. Our model gives us information to prepare”.

The paper “Decreasing rainfall frequency contributes to earlier leaf onset in northern ecosystems” has been published in the journal Nature Climate Change.

Credit: Pixabay.

Dry irony: first rain in centuries causes extinction of Atacama Desert microbes

Credit: Pixabay.

Credit: Pixabay.

The Atacama Desert is not only the driest but also the oldest desert on Earth. It’s so dry that in some parts — like its hyper-arid core — there has been no sign of rain recorded for 500 years. You’d think that a bit of rain would be a godsend the few creatures that live there. But for many microbial species that have become adapted to living almost without any water, recent rainfall that penetrated the hyper-core spelled their doom. However, on the upside, we now know a bit more about what hypothetical creatures living on Mars in similar conditions might have experienced during the Red Planet’s rich geological history, according to a new study published in Scientific Reports

When water in the desert is actually a bad thing

The Atacama Desert in northern Chile is a (typically) rainless plateau that covers almost a 600-mile area. It’s 50 times drier than Death Valley and the average rainfall there is just one millimeter per year. In the early 20th century not one single drop of rain reached Atacama’s surface for 173 months. In fact, it’s so dead, barren and alien that NASA regularly conducts tests here simulating conditions on Mars.

For millions of years, regions of the Atacama Desert have remained hyperarid. But even in such inhospitable conditions, some surface soil microbial species have adapted to survive with meager amounts of liquid water. However, researchers from the Center for Astrobiology (CAB) at the Universidad Autónoma de Chile found that recent unexpected rainfall caused many microbial species to quickly perish from the osmotic shock caused by the sudden abundance of water.

According to the researchers, the extinction range reaches 85%, wiping out all archaea and eukaryotes. Only a handful of bacteria, such as a newly identified species of Halomonas, remain metabolically active and are able to reproduce in the lagoons. The rains have been attributed to changing climate over the Pacific Ocean.

“Our group has discovered that, contrary to what could be expected intuitively, the never-before-seen rainfall has not triggered a flowering of life in Atacama, but instead, the rains have caused enormous devastation in the microbial species that inhabited the region before the heavy precipitations,” Dr. Alberto G. Fairén, lead author of the new study, said in a statement.

The findings are important in the context of the astrobiological exploration of Mars, a hyperarid planet that experienced catastrophic floodings in ancient times. During the Red Planet’s early days, in a period called the Noachian (4.5-3.5 billion years ago), its surface used to to be richly covered in water, not at all that different from Earth. This is an undisputed fact among researchers, judging from hydrogeological evidence present on the Martian surface such as hydrated minerals, and geological formations such as dried rivers, lakes, deltas, and a huge basin that looks like an ocean in the northern plains.

An artist’s impression of what ancient Mars may have looked like, based on geological data. Image by Ittiz.

After this ‘wet’ period, which looks like it could have easily supported life, Mars lost its atmosphere and hydrosphere.

“But at times during the Hesperian period (from 3.5 to 3 billion years ago), large volumes of water carved its surface in the form of outflow channels, the largest channels in the solar system. If there were still microbial communities withstanding the process of extreme drying, they would have been subjected to processes of osmotic stress similar to those we have studied in Atacama,” Fairén said.

When liquid water resurfaced on Mars, it might have actually killed any pockets of life that may have survived submerged deep under the soil, these new findings seem to suggest.


It Is Possible Jupiter Could Support Life, Scientists Say

Jupiter and its shrunken Great Red Spot. Credit: Wikimedia Commons.

Jupiter and its shrunken Great Red Spot. Credit: Wikimedia Commons.

A new factor has been added to the debate on whether or not living organisms could exist on Jupiter. You probably know Jupiter is a Jovian planet, a giant formed primarily out of gases. So how could alien life be able to exist in an environment where most of the phases of matter are absent? The answer is simply found in the element of water.

Within the rotating, turbulent Great Red Spot, perhaps Jupiter’s most distinguishable characteristic, are water clouds. Many of the other clouds in this enormous perpetual storm are comprised of ammonia and/or sulfur. Life theoretically cannot be sustained in water vapor alone; it thrives in liquid water. But according to some researchers, the fact alone that water exists in any form on the planet is a good first step.

The Great Red Spot is still a planetary feature which stumps much of the scientific community today. As it has been observed for the past century and a half, the Great Red Spot has been noticeably shrinking. The discovery of water clouds may lead to a deeper understanding of the planet’s past, including whether or not it might have sustained life, as well as weather-related information.

Some scientists have pondered the possibility that, due to the hydrogen and helium content in its atmosphere, Jupiter could be a diamond-producing “factory.” They have further speculated that these diamonds could enter into a liquid state and a rainfall of liquid diamonds would be in the Jovian’s weather forecast.

Likewise, the presence of water clouds means that water rain (a liquid) is not entirely impossible. Máté Ádámkovics, an astrophysicist at Clemson University in South Carolina, had this to say on the matter:

“…where there’s the potential for liquid water, the possibility of life cannot be completely ruled out. So, though it appears very unlikely, life on Jupiter is not beyond the range of our imaginations.”

Scientists are acting accordingly, researching the part which water plays in the atmosphere and other natural systems on Jupiter. They remain skeptical but eager to follow up on the new discovery. They shall also strive to find out just how much water the planet really holds.