The peer-reviewed study in Science Advances from The Nature Conservancy and 21 institutional partners found that nature’s contribution could equal 21% of the nation’s current net annual emissions, by adjusting 21 natural management practices to increase carbon storage and avoid greenhouse emissions. The study is the first to include the climate benefits of coastal wetlands and grasslands in a comprehensive mix along with forests and agriculture.

In October the Intergovernmental Panel on Climate Change special report called for global action immediately to limit warming to 1.5?Centigrade (approximately 3? Fahrenheit) to avoid the most damaging climate change impacts. This new study highlights how, and which, natural solutions in the United States offer the most promise to help limit temperatures below that 3? Fahrenheit goal.

Joe Fargione, Director of Science for The Nature Conservancy, was the study’s lead author: “One of America’s greatest assets is its land. Through changes in management, along with protecting and restoring natural lands, we demonstrated we could reduce carbon pollution and filter water, enhance fish and wildlife habitat, and have better soil health to grow our food — all at the same time. Nature offers us a simple, cost-effective way to help fight global warming. In combination with transitioning to zero carbon energy production, natural climate solutions can help protect our climate for future generations.”

Lynn Scarlett, Chief External Affairs Officer for The Nature Conservancy and former Deputy Secretary of the Department of the Interior, spoke to practical elements of the study’s findings: “An ounce of prevention is worth a pound of cure, so we should reduce carbon pollution where we can. But we also need to put natural solutions to work as a tool to insulate ourselves from global warming. This study provides good news that making investments in nature will make a big difference, while offering the potential for new revenue to farmers, ranchers, foresters, and coastal communities at the same time.”

Of the 21 natural solutions analyzed, increased reforestation (the planting of trees) emerged as the largest means to achieve greater carbon storage, equivalent to eliminating the emissions of 65 million passenger cars. Other high-performing forest solutions include allowing longer periods between timber harvest to increase carbon storage; increasing controlled burns and strategic thinning in forests to reduce the risk of megafire; and avoided loss of forests from urban sprawl.

The study identified a maximum of 156 million acres that could be reforested, 304 million acres where forest harvest rotations could be extended, and at least 42 million additional acres of forests that would benefit from fire risk reduction treatments. In addition, almost a million acres of forest are being converted to non-forest habitat a year, largely due to suburban and exurban expansion, which could be addressed through better land use planning. The study also finds that urban reforestation can add important carbon storage benefits.

“Planting trees and improving the health of existing forests will be a deciding factor in whether we are able to get ahead of the climate curve,” said Jad Daley, CEO of American Forests. “This breakthrough analysis clarifies the highest impact actions for keeping our forests as a growing and resilient carbon sink and the potential scale of climate benefit.”

Grasslands are underappreciated for their carbon storage opportunity. Grassland is being lost at a rate of over one million acres per year. When grassland is converted to cropland, about 28% of the carbon in the top meter of soil is released to the atmosphere. This trend could be reversed by re-enrolling 13 million acres of marginal cropland in conservation programs and restoring them to provide habitat and storage of carbon in the soil.

Existing croplands have an important role to play. Farmers can optimize their nutrient application, saving money and avoiding emissions of nitrous oxide, a potent greenhouse gas. Farmers can also plant cover crops, which suck carbon out the atmosphere and return it to the soil during times of the year when fields would normally be bare.

“Farmers are some of our best land stewards, and Danone North America is partnering with farms across the country to find climate solutions through our soil health initiative. Improved nutrient management, cover crops, and crop rotations are examples of practices that can help reduce GHG emissions and over time improve a farm’s bottom-line. Farmers and the food industry depend on a predictable climate, so it’s important to work together to reduce the risks of climate change.” said Chris Adamo, Vice President Federal & Industry Affairs at Danone North America.

Natural solutions can be found under water as well. An estimated 27% of tidal wetlands have been disconnected from the ocean, increasing the release of methane. Reconnecting tidal wetlands to the ocean virtually eliminates those methane emissions, and also restores fish habitat important for coastal communities.

“Shellfish growers make a living on the water and have witnessed salt marshes losing productivity due to freshwater inundation. Not only does this damage important waters and increase emissions, but it also harms their ability to make a living growing oysters, clams, mussels and other species that support many coastal communities and other important stakeholders. By restoring salt marshes, we can help shellfish farmers, wholesalers, retailers and restaurants and the climate all at the same time,” said Davis Herron, Director, Retail & Restaurant Division, Lobster Place, spokesman for the Shellfish Growers Climate Coalition.

Not only do natural climate solutions have strong benefits for personal enjoyment, healthier water, air, wildlife, and soil, many are quite affordable. As states and the federal government evaluate rules and markets for greenhouse gas emissions, these low-cost reductions from natural solutions offer the United States a powerful tool to address a warming planet.

The crater measures more than 31 km in diameter, corresponding to an area bigger than Paris, and placing it among the 25 largest impact craters on Earth. The crater formed when a kilometre-wide iron meteorite smashed into northern Greenland, but has since been hidden under nearly a kilometre of ice.

“The crater is exceptionally well-preserved, and that is surprising, because glacier ice is an incredibly efficient erosive agent that would have quickly removed traces of the impact. But that means the crater must be rather young from a geological perspective. So far, it has not been possible to date the crater directly, but its condition strongly suggests that it formed after ice began to cover Greenland, so younger than 3 million years old and possibly as recently as 12,000 years ago — toward the end of the last ice age” says Professor Kurt H. Kjær from the Center for GeoGenetics at the Natural History Museum of Denmark.

Giant circular depression

The crater was first discovered in July 2015 as the researchers inspected a new map of the topography beneath Greenland’s ice-sheet. They noticed an enormous, but previously undetected circular depression under Hiawatha Glacier, sitting at the very edge of the ice sheet in northern Greenland.

“We immediately knew this was something special but at the same time it became clear that it would be difficult to confirm the origin of the depression,” says Professor Kjær.

In the courtyard at the Geological Museum in Copenhagen just outside the windows of the Center for GeoGenetics sits a 20-tonne iron meteorite found in North Greenland not far from the Hiawatha Glacier.

“It was therefore not such a leap to infer that the depression could be a previously undescribed meterorite crater, but initially we lacked the evidence,” reflects Associate Professor Nicolaj K. Larsen from Aarhus University.

The crucial evidence

Their suspicion that the giant depression was a meteorite crater was reinforced when the team sent a German research plane from the Alfred Wegener Institute to fly over the Hiawatha Glacier and map the crater and the overlying ice with a new powerful ice radar. Joseph MacGregor, a glaciologist at NASA, who participated in the study and is an expert in ice radar measurements adds:

“Previous radar measurements of Hiawatha Glacier were part of a long-term NASA effort to map Greenland’s changing ice cover. What we really needed to test our hypothesis was a dense and focused radar survey there. Our colleagues at the Alfred Wegener Institute and University of Kansas did exactly that with a next-generation radar system that exceeded all expectations and imaged the depression in stunning detail. A distinctly circular rim, central uplift, disturbed and undisturbed ice layering, and basal debris. It’s all there.”

In the summers of 2016 and 2017, the research team returned to the site to map tectonic structures in the rock near the foot of the glacier and collect samples of sediments washed out from the depression through a meltwater channel.

“Some of the quartz sand washed from the crater had planar deformation features indicative of a violent impact, and this is conclusive evidence that the depression beneath the Hiawatha Glacier is a meteorite crater, ” says Professor Larsen.

The consequences of the impact on the Earth’s climate and life

Earlier studies have shown that large impacts can profoundly affect Earth’s climate, with major consequences for life on Earth at the time. It is therefore very resonable to ask when and how and this meteorite impact at the Hiawatha Glacier affected the planet.

“The next step in the investigation will be to confidently date the impact. This will be a challenge, because it will probably require recovering material that melted during the impact from the bottom of the structure, but this is crucial if we are to understand how the Hiawatha impact affected life on Earth,” concludes Professor Kjær.

Apes, or hominoids, are a group of primates from Africa and Southeast Asia that includes the gibbons and the great apes: chimps, orangutans, gorillas, and humans. Ancient ape remains from Miocene deposits in the Siwaliks of India and Pakistan have been key for understanding the evolution of great apes and humans. In this study, the researchers examined an ape jaw fragment excavated from the Kutch basin, in the Gujarat state of western India, about 1000 km south of the Siwaliks deposits.

X-ray computed-tomography revealed details of the preserved canine and cheek teeth, such as the tooth enamel and root structure. The ape mandible belonged to an adult individual of the Sivapithecus genus, but the species could not be identified. The authors dated the specimen to the basal Late Miocene, around 11 to 10 million years ago based on previous mammalian fossil findings in the site. The new finding is the first Miocene ape fossil to be discovered so far south in the Indian peninsula, and extends the southern range of ancient apes in the subcontinent by about 1000 km.

The authors add: “This is a landmark discovery of 11 million-year-old human ancestors in Kutch, Gujarat.”

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