statistics

The American butterfly census

April 15, 2025 By EarthWise Leave a Comment

There has been a great deal of interest in the plight of monarch butterflies in this country. Monarchs’ population and migratory habits are closely watched, and many people have been planting milkweed in their gardens to help their caterpillars. But other butterfly species have received much less attention despite the fact that many butterfly populations are in decline.

A groundbreaking new study has provided comprehensive answers about the status of butterflies in America. Over the past 20 years, the contiguous US has lost 22 percent of its butterflies.

The study is based on over 12 million individual butteries counted in 77,000 surveys across 35 monitoring programs from 2000 to 2020. Three hundred forty-two butterfly species in total were analyzed. Thirty three percent showed statistically significant declines while less than 3% displayed statistically significant increases. Overall, 13 times as many species decreased as increased.

Why are butterfly populations crashing? Experts point to a combination of factors: habitat loss as land in converted for agriculture or development, climate change, and pesticide use. It is not clear which factor is most important and may well vary by location. Pesticide use – especially neonicotinoids – has been shown to play a particularly lethal role in studies.

Insects including butterflies play a huge role in supporting life on earth. They pollinate plants, feed birds and many other creatures in the food web. Nature collapses without them. And butterflies are clearly in trouble.

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See How Butterflies Are Surviving, or Not, Near You

Photo, posted August 9, 2016, courtesy of Rachel Larue/Arlington National Cemetery via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Predicting major earthquakes

October 10, 2024 By EarthWise Leave a Comment

Natural disasters continue to be major threats for people, just as they always have been. But modern technology has greatly improved our ability to prepare for and, in many cases, escape from the worst effects of these events. A good example is hurricane forecasting. Nowadays, there is plenty of warning when a major hurricane is headed toward a populous area. It is still up to people to get away from the danger zone, but at least there is the opportunity to do so.

Major earthquakes are a different story. There is generally little or no warning when one will strike. But scientists at the University of Alaska Fairbanks and the Ludwig Maximilian University in Munich, Germany have developed a technique that may provide days or even months of warning about an impending major earthquake.

The detection method is based on machine learning and is described in a paper in the journal Nature Communications. The researchers wrote a computer algorithm that looks for abnormal seismic activity. Advanced statistical techniques found that approximately three months of abnormal low-magnitude regional seismicity occurred in the regions where two major earthquakes took place. One was the magnitude 7.1 Anchorage earthquake in 2018 and the other was a similar-sized quake in Ridgecrest, California in 2019.

Considerably more testing – particularly in real-time rather than looking at historical data – is needed. But accurate earthquake forecasting has the potential to save lives and reduce economic losses. However, there are ethical and practical questions to answer. False alarms could lead to unnecessary panic, economic disruption, and loss of public trust. On the other hand, missed predictions can have catastrophic consequences.

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UAF scientist’s method could give months’ warning of major earthquakes

Photo, posted January 22, 2012, courtesy of the Climate and Ecosystems Change Adaptation Research University Network via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Expanding solar and wind in the U.S.

August 20, 2024 By EarthWise Leave a Comment

According to new data from the Federal Energy Regulatory Commission, solar and wind now make up more than 20% of the total US electrical generating capacity. Adding up all renewable energy sources – which also include biomass, geothermal, and hydropower – renewable energy is now nearly 30% of the total electrical generating capacity in this country.

During the first five months of 2024, 10.669 gigawatts of solar and 2.095 gigawatts of wind power came online. There were also 212 megawatts of hydropower and 3 megawatts of biomass added to generating capacity. All told, renewables constituted 89.91% of new generating capacity added this year. This does not include 1.1 gigawatts of nuclear power added at the Vogtle-4 reactor in Georgia.

Solar power is booming. The amount added this year was more than double the amount added over the same period last year. Solar has been the largest source of new generating capacity for nine months straight. Wind was the second largest.

About one-third of US solar capacity is in the form of small-scale – that is, rooftop – solar. The statistics quoted in this report do not take that into account. If it was included, solar plus wind would be closer to 25% of the US total.

Predictions are that over the next three years, nearly 90 gigawatts of additional solar power will be added to the grid as well as 23 gigawatts of wind power. Over that period, coal, natural gas, and oil are projected to shrink by more than 20 gigawatts.

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Solar and wind now make up more than 20% of US electrical generating capacity

Photo, posted October 28, 2016, courtesy of Daxis via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Tree Diversity | Earth Wise

March 4, 2022 By EarthWise Leave a Comment

Scientists have estimated that there are more than 8 million species of plants and animals in existence. Amazingly, only about 1.2 million of them have been identified and described so far and most of those are actually insects. Millions of other organisms have yet to be discovered.

One would imagine that most of these unknown species are tiny things that are hard to spot or encounter. But our ignorance of species even applies to trees, which are pretty easy to spot if you encounter them.

A new study involving more than 100 scientists across the globe has produced an estimate of the number of tree species on the Earth. The new global estimate is that there are 73,000 tree species, which is about 14% more than previously thought. Based on a combination of data from two global datasets, the study yielded a total of 64,100 documented tree species worldwide. The researchers then used novel statistical methods to estimate the total number of unique tree species at biome, continental, and global scales, which includes species yet to be discovered and described by scientists. Therefore, the estimate predicts that there are likely to be over 9,000 tree species still to be found.

Roughly 40% of the undiscovered tree species are likely to be in South America, which is the continent with the highest number of rare tree species and the highest number of continentally endemic tree species – meaning those found only on that continent. Hot spots of undiscovered tree species are likely the tropical and subtropical moist forests of the Amazon basin and the Andes-Amazon interface.

Extensive knowledge of tree richness and diversity is key to preserving the stability and functioning of ecosystems.

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Number of Earth’s tree species estimated to be 14% higher than currently known, with some 9,200 species yet to be discovered

Photo, posted November 5, 2017, courtesy of Deensel via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Coral Reef Status Report | Earth Wise

December 23, 2021 By EarthWise Leave a Comment

In October, the Global Coral Reef Monitoring Network released the first-ever report collecting global statistics on the world’s corals. It documents the status of reefs across 12,000 sites in 73 countries over 40 years. Overall, the news is not good, but there were some bright spots.

From 2009 to 2018, the world has lost 14% of its corals, corresponding to about 4,500 square miles of coral. Global warming has led to prolonged marine heatwaves that trigger coral bleaching. Local pollution has also damaged reefs. The International Panel on Climate Change has reported that 2 degrees Celsius of global warming would wipe out 99% of the world’s corals.

The report does show that corals can recover globally if given a decade of cooler waters. Some places in the world – particularly the Coral Triangle in Asia, which contains nearly a third of the world’s coral – have actually seen coral growth over the past decade.

The Global Coral Reef Monitoring network started collecting data in 1978. Coral health was fairly steady until 1998 when the first mass bleaching event occurred, triggered by a powerful El Niño event. For the next 12 years, corals recovered nicely, but then bleaching events in 2010 and 2015-17 took their toll.

The Pacific, Australia, and the Caribbean have all seen major decreases in coral. The Coral Triangle is a major exception which is thought to be a result of genetic diversity among the region’s corals.

Coral conservationists globally are working to protect corals and to actively restore them. The situation is fairly dire, but there continue to be reasons for hope.

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Finding Bright Spots in the Global Coral Reef Catastrophe

Photo, posted October 13, 2015, courtesy of Albert Straub via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Balloons And Seabirds

March 19, 2019 By EarthWise Leave a Comment

It’s no secret that there is a ton of plastic in the ocean – millions of tons, in fact. Scientists estimate that there is more 165 million tons of plastics swirling about in our oceans today, with an additional 8.8 million tons flowing in every year. As the oceans swell with plastic debris, many marine species wind up ingesting the stuff – often with dire consequences.

All this plastic trash winds up affecting more than just aquatic species, too. According to researchers from the University of Tasmania, a seabird that ingested a single piece of plastic has a 20% chance of mortality. This statistic jumps to 50% if the seabird consumes nine pieces of plastic.

The study, which was recently published in the journal Scientific Reports, also found that while hard plastics account for the majority of plastic debris ingested, it’s far less likely to prove fatal than soft plastics, such as balloons.

In fact, the researchers found that balloons or balloon fragments were the number one marine debris risk of mortality for seabirds, killing almost one in five of the seabirds that ingested them.

The leading cause of death among the seabirds studied was blockage of the gastrointestinal tract. While soft plastics only accounted for 5% of the ingested plastics, they were responsible for more than 40% of seabird mortality. But the researchers make clear that hard plastics were still responsible for more than half of the study’s seabird deaths.

If we want to reduce the number of marine species dying from plastic ingestion, we need to reduce the volume of plastic going into the ocean and do what we can to remove what’s already there.

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