Earth Gets Greener as Globe Gets Hotter
Carbon dioxide emissions are fueling more verdant landscapes around the globe, but the potentially temporary greening doesn't mean global warming is good. Continue reading →
The excess carbon dioxide in the atmosphere has created a greener planet, a new NASA study shows.
Around the world, areas that were once icebound, barren or sandy are now covered in green foliage. All told, carbon emissions have fueled greening in an area about twice the size of the continental United States between 1982 and 2009, according to the study.
While lush forests and verdant fields may sound like a good thing, the landscape transformation could have long-term, unforeseen consequences, the researchers say.
The radical greening "has the ability to fundamentally change the cycling of water and carbon in the climate system," lead author Zaichun Zhu, a researcher from Peking University in Beijing, said in a statement. [Video: See Global Warming Make Earth Greener]
Fuel for plants
Green leafy flora make up 32 percent of Earth's surface area. All of those plants use carbon dioxide and sunlight to make sugars to grow - a process called photosynthesis. Past studies have shown that carbon dioxide increases plant growth by increasing the rate of photosynthesis.
Other research has shown that plants are one of the main absorbers of atmospheric carbon dioxide. Human activities, such as driving cars and burning coal for energy, account for about 10 billion tons of carbon dioxide emissions per year, and half of this CO2 is stored in plants.
"While our study did not address the connection between greening and carbon storage in plants, other studies have reported an increasing carbon sink on land since the 1980s, which is entirely consistent with the idea of a greening Earth," said study co-author Shilong Piao, of the College of Urban and Environmental Sciences at Peking University.
However, it wasn't clear whether the greening seen in satellite data over recent years could be explained by the sky-high CO2 concentrations in the atmosphere (the highest the planet has seen in 500,000 years). After all, rainfall, sunlight, nitrogen in the soil and land-use changes also affect how well plants grow.
To isolate the causes of planetary greening, researchers from around the world analyzed satellite data collected by NASA's Moderate Resolution Imaging Spectrometer and the National Oceanic and Atmospheric Administration's Advanced Very High Resolution Radiometer instruments. They then created mathematical models and computer simulations to isolate how each of these variables would be predicted to influence greening. By comparing the models and the satellite data, the team concluded that about 70 percent of the greening could be attributed to atmospheric carbon dioxide concentrations, the researchers reported Monday (April 25) in the journal Nature Climate Change.
"The second most important driver is nitrogen, at 9 percent. So we see what an outsized role CO2 plays in this process," said study co-author Ranga Myneni, an earth and environmental scientist at Boston University.
Warming still worrisome
Excess CO2 emissions also bring a host of more worrisome consequences, such as global warming, melting glaciers, rising sea levels and more dangerous weather, according to accumulating research.
What's more, the greening may be a temporary change.
"Studies have shown that plants acclimatize, or adjust, to rising carbon dioxide concentration and the fertilization effect diminishes over time," said Philippe Ciais, associate director of the Laboratory of Climate and Environmental Sciences in Gif-sur-Yvette, France.
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The surface area of the Earth covered by leafy green vegetation has increased dramatically over the last several decades, thanks to excess carbon emissions. But the greening isn't necessarily a good thing; they are harbingers of more worrisome impacts of climate change, like sea level rise and glacier met.
You've heard a lot about how human-driven climate change will lead to hotter temperatures, cause sea levels to rise and make storms more intense. But it's projected to have plenty of other unpleasant and even disastrous effects as well. Here are 10 of them. Scientists believe that rising temperatures will lead to increased evaporation of the Great Lakes' water, and precipitation won't make up the difference. That means we're likely to see declines in water levels over the next century, and one study predicts they may drop as much as 8 feet.
Thanks to climate change, jumbo-sized ragweed plants will spew out more pollen for a longer, more miserable allergy season.
By altering the wild environment, climate change makes it easier for newly mutated microbes to jump between species, and it's likely that as a result, diseases will emerge and spread across the globe even more rapidly.
A recent Nature article reported that male Australian central bearded dragons have been growing female genitalia because of rising temperatures, a phenomenon that had not previously been observed in that species.
Rising sea levels are wiping out beaches all over the world already. Importing fresh sand and building them up again is only a temporary solution. To make matters worse, there's currently a sand shortage, due to demand from fracking, glass and cement making.
Bark beetles are eating old growth forests, because the winters aren't cold enough to kill them off. So more trees like this American Elm will die.
Warmer temperatures mean there will be more water vapor trapped in the atmosphere, leading to more lightning. A University of California-Berkeley study predicts that lightning strikes will increase by about 12 percent for every degree Celsius gained.
Wine grape harvests are being hurt. Regions that have historically supplied the world’s best wine will no longer be hospitable climates to grow wine grapes, according to research by the Environmental Defense Fund and others.
Coffee flavor depends upon really narrow conditions of temperature and moisture, and climate change is going to wreak havoc with that. Worse yet, as coffee growing regions become warmer, pests that couldn't survive in the past will ravage the crops. This is already being seen in Costa Rica, India and Ethiopia, which have experienced sharp declines in crop yields.
Scientists say that as ice sheets and glaciers melt, the weight that's removed from the Earth's crust changes the stresses upon volcanoes. That unloading effect can trigger eruptions.