The next 10 are:

16. The ozone hole: In the early 1980s, scientists discovered that, each spring, a hole was opening in the ozone layer over the Antarctic due to destructive interactions between human-made chlorofluorocarbons and ozone in the stratosphere. The ozone layer is essential because it blocks a portion of the UV-B light that comes from the sun, protecting people, animals, and plants from potentially damaging exposure to too much UV-B radiation. In 2019, NASA found that the ozone hole is the smallest ever recorded. When growing in the spring, the hole is as large as 8 million square miles, but this year, it reached a maximum size of 6.3 million square miles and then shrank down to less than 3.9 million square miles.
17. CO2 fertilization: NASA also reports that, “From a quarter to half of Earth’s vegetated lands has shown significant greening over the last 35 years largely due to rising levels of atmospheric carbon dioxide.” Furthermore, the greening of the planet is benefitting developing nations the most. The research, a collaborative effort among 32 authors and 24 institutions in eight countries, found a 14% increase in green, leafy biomass, or plants, over the past three decades. They estimated that 70% of the increase is due to increased levels of CO2 in the atmosphere.
18. Genetic library: To speed up responses to pathogens — pests and diseases — in agricultural crops, a genetic “library” has been created by researchers at the John Innes Centre in the U.K., with help from researchers in the U.S. and Australia. Together, they have developed a technique called AgRenSeq that uses genetic material from wild plants known to be resistant to a variety of pests and diseases. Researchers can insert the disease-resistant genes into domestic relatives and then speedily clone crops that have a defense against many pathogens the crops might encounter.
19. Cosmic crisp apple: After being designed and bred for more than two decades, the ‘Cosmic Crisp’ apple is now being sold commercially. The apple has been in development since 1997, with generation after generation carefully selected to grow in all of Washington state’s microclimates. Even more impressive is the fact that, once picked, it can last up to a year in the refrigerator. So far, the new variety has been very popular; four million individual trees were planted in 2019.
20. Pesticides: While they are often vilified, pesticides have been used for decades to protect crops and significantly increase yields in both industrial and smaller and organic farming. When used properly, these pesticides can help reduce losses of fruits and vegetables by between 50 and 90%. That means more food is produced on fewer acres of land. Additionally, new technologies allow farmers to reduce overall pesticide use, while still maintaining productivity.
21. Geospatial technology: This technology allows for more accurate pest detection and more effective and targeted use of pesticides. Additionally, as noted above, genetically engineered crops now have built-in protection against pests and diseases. Both technologies help protect crops from predation, saving around $60 billion in the U.S. from 2002 to 2008.
22. Genetic engineering to fight crop diseases: The enset, a banana-like staple food crop that grows in a wide variety of conditions, is being genetically engineered by the International Institute of Tropical Agriculture and Ethiopian researchers to resist bacterial wilt. Scientists are sequencing the DNA of hundreds of varieties of enset to determine how best to spread the use of this beneficial crop to other areas of the world that need it the most.
23. GMOs in aquaculture: In eastern Indiana, AquaBounty Technologies is growing the first genetically modified salmon, “creating sustainable fishing and getting fresh seafood closer to consumers.” The company edited genes in Atlantic salmon so the fish grow to market size almost twice as fast as wild varieties. By isolating their operations in an inland setting, they can also reduce disease spread and address concerns about these fish influencing wild populations.
24. Polar bears are thriving: Contrary to claims that accompanied a heart-wrenching 2017 video of a starving polar bear, the species is not being driven to extinction by climate change. In fact, according to The State of the Polar Report 2018, the wild population has increased from about 5,000 in the 1950s to the current “global mid-point estimate above 30,000.”
25. Halting extinctions: Scientists are working to halt the impending extinction of the northern white rhinoceros. The last remaining male of the species died of old age in 2018. But scientists preserved sperm from that individual and have harvested ten eggs from the remaining two females. A joint effort, involving the Ol Pejeta Conservancy, the Leibniz Institute for Zoo & Wildlife Research, Dvůr Králové Zoo in the Czech Republic, and the Kenya Wildlife Service, is using IVF to breed offspring. This extraordinary attempt may save the near-extinct species, and provide a ray of hope for other threatened and endangered species.

We’ve covered a lot of ground so far, but we’re still only halfway through our list of 50! Be sure to check out the first two 50th Anniversary of Earth Day posts here and here. Then check back soon for points 26 through 35.

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