Your assertion that grasslands can replace forests as carbon sinks is False. Your assertion that grasslands and savannahs are far superior to forests as carbon sinks is ridiculous and laughable.
Forests are the largest and highest intensity carbon sinks on land.
Forests and other land vegetation currently remove up to 30 percent of human carbon dioxide emissions from the atmosphere during photosynthesis, but thanks to this latest study, experts now know that we have tropical forests to thank for a great deal of this work - absorbing a whopping 1.4 billion metric tons of CO2 out of a total total global absorption of 2.5 billion metric tons. That's more than what is absorbed by most boreal forests types (as found in Canada, Siberia, and other northern regions) combined!
linkHu says the implications are that grasslands can be carbon sinks -- at least for the short term. The magnitude of carbon sequestration in such a grassland is yet to be determined, he notes.
Soil microbes appear to play a critical role in the process, Hu explains. The increased atmospheric carbon dioxide stimulates the grassland plants to grow more quickly, drawing nitrogen from the soil in the process. That results in less nitrogen available for use by the microbes in the soil, reducing the microbes’ ability to decompose dead plant material. With less plant material decomposed, less carbon is released into the air as carbon dioxide. Additionally, the research indicated that under elevated carbon dioxide levels, fungi become a more dominant part of the microbial community, which is also conducive to protecting soil carbon from decomposition.
At the same time, the research indicates that the extent of carbon buildup in the grassland soil may be limited, because the lower rate of plant decomposition reduces the supply of nitrogen for additional plant growth.
"Forests are of greater potential as a long-term carbon sink than annual grasslands because trees can sequester carbon in above-ground biomass and their roots can exploit nutrients in deeper soils," he said.
linkForests are far more that just carbon sinks, they serve irreplaceable roles in the global climate and the habitability of the planet.
Clearing trees not only releases carbon into the atmosphere, adding to the greenhouse gas effect, but also alters rain patterns and increases temperatures worldwide. This distorts Earth's normal wind and water systems and puts future agricultural productivity at risk.
"Tropical deforestation delivers a double whammy to the climate - and to farmers," lead study author Deborah Lawrence said in a statement. "Most people know that climate change is a dangerous global problem, and that it's caused by pumping carbon into the atmosphere. But it turns out that removing forests alters moisture and air flow, leading to changes - from fluctuating rainfall patterns to rises in temperatures - that are just as hazardous, and happen right away."
More Heat, Less Rain
Most people might think that this only impacts tropical places like South America, which is home to the expansive Amazon rainforest. However, researchers say that these findings even apply to the United Kingdom and Hawaii, which could see an increase in rainfall, while less rain would fall in the US Midwest and Southern France.
Overall, there would be 10-15 percent reduced rainfall in the region surrounding where the tree clearing took place. Thailand has already seen less rainfall at the start of its dry season, and the Amazon's annual rainfall schedule has started to shift as well.
In addition, deforestation in South America, Southeast Asia and Africa may alter growing conditions in agricultural areas in the tropics and as far away as the US Midwest, Europe and China, which is bad news for farmers.
Complete tropical deforestation could lead to a rise in global temperature of 0.7 degrees Celsius (33.3 Fahrenheit), which is on top of the projected impact from greenhouse gases such as carbon dioxide.
According to the report, described in the journal Nature Climate Change, temperature increases are guaranteed with deforestation.
"This does not change, no matter what you do - no matter what kind of model you use, temperature increases occur - whether it's half a degree, a full degree or two degrees," Lawrence explained.
"That's a very big deal," she added. "In the last few centuries, the average global temperature has never varied by more than about one degree. Once we go above one degree - to 1.5 degrees or more - we're talking about conditions that are very different from anything humanity has ever experienced."
The "Lungs of the Earth"
Tropical forests move more water than any other ecosystem on land and are central to the Earth's ability to generate moisture, helping to keep the planet cool. But removing large swaths of forests disturbs this natural cycle. What's more, as more deforestation occurs, the greater its impact worldwide will be.
"While complete deforestation is unlikely to occur, over the course of history, deforestation has continued as countries develop," Lawrence said. "Further, this study fills gaps in our understanding of deforestation tipping points - and what could happen if we continue down this path."
According to the research, if 30-50 percent of the Amazon rainforest is cut down, it would put deforestation at the tipping point, meaning any more forest clearing than that would lead to rainfall reductions that could significantly change ecosystems, as well as raise the risk of forest fires.
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