observations

Record Low Antarctic Sea Ice | Earth Wise

March 2, 2023 By EarthWise Leave a Comment

Recent satellite observations of the sea ice in the Antarctic found the lowest level of ice cover ever seen in the forty years that these observations have been made. As of February 8th, there were only 849,000 square miles of the Southern Ocean covered with ice. The previous record low was measured last February 24th when the total coverage was 876,000 square miles. Ice melting was likely to continue as the month went on.

This past January had already set a new record for that month’s mean extent of ice coverage at 1.24 million square miles. This rapid decline in sea ice has been going on for the past six years and is very unusual. Average Antarctic ice cover hardly changed at all during the previous thirty-five years.

Antarctic sea ice generally reaches its maximum extent in September or October and its minimum extent in February. At its maximum, the sea ice cover in the Antarctic is generally between 6.9 and 7.7 million square miles. On the other hand, there are some places where the sea ice melts completely during the Southern Hemisphere summer. Sea ice varies much more in the Antarctic than in the Arctic where the ice is much thicker.

Climate warming at the poles is much higher than at lower latitudes. Nonetheless, it is not yet clear whether what we are seeing is the beginning of the end of summer sea ice in the Antarctic, or whether this is just a new phase characterized by low but still stable sea ice cover in the summer.

**********

Web Links

Record low sea ice cover in the Antarctic

Photo, posted January 24, 2012, courtesy of Rob Oo via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Better Marine Protected Areas | Earth Wise

August 17, 2022 By EarthWise Leave a Comment

Marine protected areas are regions of seas, oceans, estuaries, and in the US, the Great Lakes, that are afforded special protections. MPAs restrict human activity for conservation purposes, generally in order to protect natural or possibly cultural resources. MPAs may limit such things as development, fishing practices, fishing seasons, catch limits, moorings, and removal or disruption of marine life.

A new study by the University of Plymouth in the UK looked at the effectiveness of MPAs in increasing the total abundance of reef species. It looked at the MPAs in Lyme Bay, off the south coast of England, where two of them are co-located but governed by different constraints.

The study found that whole-site management of an MPA can increase the total abundance of reef species within its borders by up to 95%. This is in contrast to the MPA where only known features are conserved and human activity is otherwise allowed to continue unchecked. In that place, species abundance increased by only 15%.

The whole-site MPAs were observed to have other benefits as well. They show higher levels of functional redundancy, meaning that when there are species losses, they are compensated by other species. Whole-site MPAs also exhibit higher levels of species diversity.

MPAs are increasingly being recognized as a sustainable way to enhance the marine environment even while supporting coastal communities. The Global Ocean Alliance, a 72-country alliance led by the UK, has set a target of protecting 30% of all marine areas by 2030. The new study shows that even more important than simply establishing marine protected areas, it is essential that they are effectively implemented.

**********

Web Links

Whole-site management of Marine Protected Areas can lead to a 95% increase in reef species

Photo, posted October 28, 2011, courtesy of Benjamin Evans via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Even The Common House Sparrow Is Declining | Earth Wise

March 17, 2021 By EarthWise Leave a Comment

According to the first-ever comprehensive assessment of net bird populations published in 2019, nearly three billion birds have disappeared in the United States and Canada since 1970. The study, by researchers from the Cornell University Lab of Ornithology, found that North American bird populations have lost 2.9 billion breeding adults during that timespan. Forests lost one billion birds, and grassland birds declined 53%.

According to a newer study from Cornell University, it appears that even the common house sparrow is declining. In parts of its native range in Europe, house sparrow numbers are down nearly 60%. Researchers from the Cornell Lab of Ornithology sought to clarify the status of the species in the U.S. and Canada by using 21 years of citizen science data collected through its Project Feederwatch program.

Project FeederWatch is a winter-long survey of birds that visit feeders at backyards, nature centers, community areas, and other locales. For the study, which was recently published in the Wilson Journal of Ornithology, the research team reviewed recorded observations of house sparrows during their non-breeding season. These sightings from nearly 12,500 sites were used and cross-referenced with the National Land Cover database to determine whether the U.S. sightings came from rural or urban locations.

From 1995 to 2016, researchers found that Feederwatch sites reporting house sparrows declined 7.5%, and the mean flock sizes declined 22%. House sparrow populations declined in urban areas, but actually remained stable in rural areas.

The researchers say a lack of green space and nesting sites in urban areas are likely factors in the population declines.

**********

Web Links

Study finds even the common house sparrow is declining

Nearly 3 Billion Birds Gone

Photo, posted May 14, 2014, courtesy of Jacob Spinks via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Global Warming And Sea Turtle Births | Earth Wise

January 11, 2021 By EarthWise Leave a Comment

Climate change is a serious threat to species whose sex is determined by temperature. Among these are sea turtles. Whether marine turtles are born male or female turns out to depend on the temperature of their nest during incubation.

Sea turtle nests need to be around 84.6 degrees Fahrenheit on average to produce a 50:50 sex ratio for embryos developing in eggs. If temperatures are higher, embryos predominantly become female. There is a transitional range of temperatures over which both males and females are produced. Below that range, only males are produced; above that range, only females are produced.

According to recent research published in the journal Conservation Science and Practice, sand temperatures along the Red Sea exceeded the 84.6-degree threshold in all but one of the sites studied. Some sites measured nearly 96 degrees. The Red Sea region is home to five of the world’s seven species of sea turtles, including endangered green turtles and critically endangered hawksbill turtles.

Skewing the sex distribution of a species is a serious threat to the future survival of the population.

The Red Sea findings are similar to observations around the world. In Florida, sea turtle hatchlings were born 100% female in seven out the past 10 years, and in the other three years, males only made up 10-20% of the brood. In Australia’s Raine Island, the largest green turtle nesting ground in the Pacific Ocean, the ratio of female to male turtle hatchlings in 2018 was 116:1.

Marine turtles have been around since the late Triassic period and have adapted to previous climate shifts. But the rapid pace of human-driven climate change is threatening the future survival of these creatures.

**********

Web Links

Rising Temperatures Driving a Shift to All-Female Sea Turtle Populations

Photo, posted in October, 2005, courtesy of Frank_am_Main via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

A Camera For Insects | Earth Wise

August 26, 2020 By EarthWise Leave a Comment

Electronic devices get smaller and smaller all the time. We are used to carrying around phones in our pockets that incorporate a whole host of sophisticated devices. But we can still be amazed by miniaturization. Recently, scientists at the University of Washington announced the development of a tiny, wireless camera small enough to be worn by insects. The work was published in the journal Science Robotics.

The device weighs only 250 milligrams, which is less than one hundredth of an ounce. The camera streams high-resolution video to a smartphone at up to 5 frames per second, which allows scientists to record video of what insects see in real time.

The device has a mechanical arm that allows the camera to pivot 60 degrees, which can allow it to create panoramic shots. It is controlled by a smartphone app and can be operated up to 120 meters away from the insect.

The new camera system enables scientists to better understand insect behavior and explore novel environments. Having a first-person view from the back of a beetle while it is walking around allows researchers to explore how it responds to different stimuli that it sees in its environment.

Of more general interest, the technology can be used to help develop the next generation of small robots. Insects can traverse rocky environments, which is really challenging for small robots to do. The device will allow engineers to study how insects can move around in such environments. It will also be useful for observing and collecting samples from hard-to-navigate spaces.

It is remarkable how sophisticated technology keeps getting smaller and smaller.

*********

Web Links

Scientists Develop Tiny Camera Backpack for Insects

Photo courtesy of Mark Stone/University of Washington.

Earth Wise is a production of WAMC Northeast Public Radio.

The Arctic As A Carbon Source

December 16, 2019 By EarthWise Leave a Comment

According to a new NASA-funded study, the Arctic may now be a source for carbon in the atmosphere rather than being the sink for it that is has been for tens of thousands of years.

The study, published in Nature Climate Change, warns that carbon dioxide loss from the world’s permafrost regions could increase by more than 40% over the next century if human-caused greenhouse gas emissions continue at their current pace. Worse yet, carbon emitted from thawing permafrost has not even been included in most climate models.

Permafrost is the carbon-rich frozen soil and organic matter that covers nearly a quarter of Northern Hemisphere land area, mostly in Alaska, Canada, Siberia, and Greenland. Permafrost holds more carbon than has ever been released by humans from fossil fuel burning, but it has been safely locked away by ice for tens of thousands of years.

As global temperatures rise, the permafrost is starting to thaw and release greenhouse gases into the atmosphere.

The recent findings indicate that the loss of carbon dioxide during the winter in the Arctic may already be offsetting carbon uptake during the growing season. The researchers compiled on-the-ground observations of carbon dioxide emissions across many sites and combined these with remote sensing data and modeling. They estimate that the permafrost region is now losing 1.7 billion metric tons of carbon during the winter season but taking up only 1 billion during the growing season.

The major concern is that as the Arctic continues to warm, more carbon will be released into the atmosphere from the permafrost region, which will further the warming. Climate modeling teams across the globe are trying to incorporate these findings into their projections.

**********

Web Links

Arctic Shifts to a Carbon Source due to Winter Soil Emissions

Photo, posted July 27, 2015, courtesy of Gary Bembridge via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Climate Change Is Not Natural

July 5, 2019 By EarthWise Leave a Comment

It has been the overwhelming consensus of the scientific community for a long time that human activity and other external factors are responsible for the continuing rise in global temperature. Despite this widespread agreement, there have been those who argue that natural ocean cycles might be influencing global warming over the course of multiple decades.

A new study, published in the Journal of Climate, provides an answer to the question of how much influence natural cycles might have, and that answer is very little to none.

The study looked at observed ocean and land temperature data since 1850 and, apart from human-induced factors such as greenhouse gas concentrations, took into account other occurrences such as volcanic eruptions, solar activity, and air pollution peaks. The findings demonstrated that slow-acting ocean cycles do not explain the long-term changes in global temperatures.

Based on the study, the researchers can state with confidence that human factors like greenhouse gas emissions and particulate pollution, along with year-to-year changes caused by natural phenomena like volcanic eruptions or El Niño, are sufficient to explain virtually all the long-term changes in temperature. The idea that the oceans could have been driving the climate either in a colder or warmer direction for multiple decades in the past and therefore will do so in the future is unlikely to be correct.

A number of previous studies have compared flawed observations with flawed modeling results to claim that naturally-occurring ocean cycles have played a large role in global temperatures. The new study shows that such cycles have little influence on the climate. Reducing greenhouse gas emissions is really what we need to do.

**********

Web Links

Global temperature change attributable to external factors, confirms new study

Photo, posted November 13, 2007, courtesy of Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Thoreau And Climate Change

March 27, 2019 By EarthWise Leave a Comment

Henry David Thoreau was a 19th-century American naturalist, philosopher, poet, essayist, and social reformer. He is best known for “Civil Disobedience,” an essay advocating for the rebellion against an unjust government, and for “Walden,” a book about his experiences living simply in nature. Now, Thoreau’s observations from “Walden” are the foundation of a new study exploring the effects of climate change on tree leaf-out and the emergence of spring wildflowers.

This research, which was recently published in the journal Ecology Letters, relies on Thoreau’s scientific observations gathered during the 1850s when he spent 26 months living in isolation at Walden Pond in Concord, Massachusetts. These observations from Thoreau were combined with current research to measure tree and wildflower leaf-out dates for 37 different years between 1852 and 2018. “Leaf out” refers to the time in spring when plants and trees begin producing leaves. An alteration in this timing can have a domino effect throughout an ecosystem.

Over the past century, temperatures in Concord, Massachusetts have warmed five degrees Fahrenheit. As a result, leaf-out dates have changed significantly. According to researchers, wildflowers are leafing out about one week earlier, while trees are leafing out about two weeks earlier than they did 160 years ago.

Ground-dwelling plants like wildflowers have a narrow window to accomplish growth, photosynthesis, and reproduction, before the canopy trees leaf out and block the sunlight. Temperature-driven shifts in the timing of tree leaf-out between Thoreau’s time and now are likely already hindering wildflower abundance and flowering.

As the climate continues to warm, the already small window of time between wildflower emergence and tree leaf-out will likely shorten further.

**********

Web Links

Using Thoreau, scientists measure the impact of climate change on wildflowers

Photo, posted August 13, 2008, courtesy of Adam Pieniazek via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Are Big Cats In Big Trouble?

January 16, 2018 By EarthWise Leave a Comment

According to researchers with the National Geographic Society’s Big Cats Initiative, cheetahs are much closer to extinction than previously thought. The research team has released a study, which was recently published in the journal PeerJ, that updates the cheetah population numbers in southern Africa, the largest of its remaining habitat.

The Effects Of One Degree

October 9, 2017 By EarthWise Leave a Comment

In discussions of global warming, we often hear about the effects of a 2-degree rise in temperature or a 1-degree rise in temperature. For most of us, such changes seem pretty insignificant. Of course, in our daily lives, a one-degree temperature change is not particularly noticeable. But in the context of climate change, we are talking about a change in average temperature over time, not the temperature on a particular day or at a particular time.

The Great American Eclipse

August 18, 2017 By EarthWise

On Monday, August 21, there will be a total solar eclipse visible in a band across the entire contiguous United States. The last time that happened was in June of 1918. In fact, the last time a total solar eclipse was visible anywhere at all in the continental U.S. was in 1979. So, this is a big deal for American eclipse watchers and millions of us will be heading for some part of the 65-mile-wide band of totality that wends its way from Oregon to South Carolina.