The researchers from the Technion and the Weizmann Institute developed a smart map showing the potential climatic benefits of planting trees in different sites
Researchers at the Technion and the Weizmann Institute of Science present in the journal Science A long-term study on the relationship between afforestation and global warming. The findings of the study indicate that although these are vast areas, extensive afforestation of arid areas is not necessarily an effective solution to the mitigation of climate warming.
The research was led by Prof. Yohai Carmel and PhD student Shani Rohtin from the Faculty of Civil and Environmental Engineering at the Technion and Prof. Dan Yakir and Dr. Eil Rotenberg from the Department of Earth and Planetary Sciences at the Weizmann Institute of Science.
"When we started the research, we hypothesized that we would be able to show that extensive planting of forests in arid areas would significantly curb climate warming," says Prof. Carmel. "The study disproved this accepted hypothesis. It is of course disappointing but this is how science works - it discovers the truth and not what we want to discover. Also, there is an important directional reading here: planting forests, no matter how extensive, will not save us from climate change, and instead we should focus on reducing emissions."
The researchers show in their article that if trees are planted in all afforestable places, their carbon absorption will offset only about 1% of all carbon emissions from the burning of fossil fuels by the end of this century. One of the reasons for the low offset is the fact thatIn large areas, afforestation leads to heating rather than cooling Due to the "albedo" effect - the fact that darker areas, such as a forest, absorb more radiation than exposed areas such as deserts and glaciers and therefore increase the heating of the surface in the given area.
The albedo effect was already known in the context of climate change, but the research published inScience Presents for the first time a worldwide mapping of the phenomenon and enables for the first time an intelligent planning of forestry. Furthermore, the study included a simulation of the effects of afforestation for the next 80 years, i.e. until the end of the century.
"The climatic consequences of planting forests depend on many factors, including the local radiation return from the soil, the amount of precipitation and the ability of the trees to fix carbon," says Prof. Yakir. "The positive news of the research lies in the tools we developed, tools that make it possible to predict where afforestation can indeed have a positive effect. We hope that planners will take these findings into account and use them for optimal planting planning."
Shani Rohtin, who built the model, points out that smart afforestation, that is, planting forests only in the climatically correct places based on the current research, is expected to double the absorption rate of carbon from the atmosphere in the new forests.
The main tool developed by the researchers is a digital map of the Earth, which allows the user to focus on the area relevant to him and calculate the potential climatic efficiency of forestry in that area. The researchers hope that in this way planners and decision-makers will be able to promote afforestation in arid areas in a way that will moderate the climatic warming and help reduce the concentration of carbon in the atmosphere.
About 50% of the world's forestry potential is in arid areas, and today large-scale plantings are already underway in China, Saudi Arabia, the Sahel desert near the Sahara, and other areas. These projects are expected to turn about 5 million square kilometers from bare area into forest. The current research shows that without proper planning, these projects may cause undesirable climatic results, therefore it is important to conduct site-focused planning of planting in arid areas.
"Afforestation is a process that has many advantages, including sediment conservation, local cooling, prevention of soil erosion and more," says Prof. Carmel. "However, uncontrolled afforestation may exterminate rare species adapted to life in the open desert and thus damage biological diversity and, as mentioned, also harm the great goal of mitigating climate warming. That's why it's so important to take into account all the considerations before starting the wholesale afforestation of large areas."
The research was supported by the Technion and the Weizmann Institute of Science, the Steven and Nancy Grand Water Research Institute at the Technion, the National Science Foundation, the Minerva Foundation, the Yotam Project and the Sustainability and Energy Initiative at the Weizmann Institute of Science.
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before they restore forests that have been cut down
and then wandered along the edge of the desert which is increasing in many parts of the world at the expense of green space
There is so much goodness in trees