Bill, I'm a scientist

Translation of my blog on the global -climat website: https://global-climat.com/2023/10/15/bill-je-suis-une-scientifique-et-toi/

Bill Gates recently made a particularly ill-considered statement: “I don’t use unproven methods such as trees, are we the science people or are the we idiots? ? (interview video, min 18, one comment). This is perhaps the worst sentence he has uttered in his entire life. Bill, as far as I'm concerned, I'm a scientist. I would like to explain two or three points to you.

Global temperatures reached a new record in September, the previous maximum value was exceeded by 0.5°C (JL). If this rate of warming continued, the Earth would be 5°C warmer in thirty years, and many parts of Europe 10°C warmer, so we hope that this jump remains an exception, and the weather has good of course an intrinsic variability. El Nino will likely cause additional warming in spring 2024, it typically peaks at this time of year. The coming decades could well bring higher temperatures and more severe disasters. In addition, warming causes ocean acidification and deoxygenation. Warmer water, depleted in oxygen, will not allow the survival of many fish, their possible habitats would be reduced and it would maintain this temperature for a long time. Even a temporary warming of 2°C would affect ocean life for hundreds of years (CSIRO-Météofrance). Tropical forests could also succumb to a particularly torrid year, and other feedback loops would further destabilize living conditions on Earth. It is therefore necessary to keep the earth's temperature as low as possible.

To do this, we must limit atmospheric CO2 as quickly as possible. Current promises from States are insufficient even to achieve the objectives of COP21. We need to extract from the atmosphere one to three additional gigatons of carbon dioxide equivalents (PNNL).

Trees are the most reliable way to reduce atmospheric carbon. It becomes wood, because trees are about half carbon. Trees also enrich the soil with falling leaves and roots. They nourish an ecosystem of bacteria and animals, also made of ca 50% of carbon. In addition, vegetation retains and protects the soil, moderates the local climate, and promotes the formation of normal-sized clouds. Our biosphere has functioned this way for more than 300 million years, well before the appearance of humans, and we are adapted to it. Numerous scientific studies recommend this type of solutions, and there are several complementary ways to increase the number of trees on the Planet.

New scientific studies on CO2 capture by vegetation:

A recent study proposes three ways to reduce the greenhouse effect: on the one hand the reduction of different gases, on the other hand an increase in carbon capture, and finally the reduction of deforestation (PNNL). Control of fluorinated gases can be done by requiring better fridges or recycling old ones, nitrous oxide and methane are emitted by agricultural processes, and could be reduced. A tax on agricultural emissions may be necessary to achieve this and acceptable to the public (Mattauch & Tenkhoff). However, the most obvious solutions are carbon capture and halting deforestation (PNNL). Vegetation seems to be the best technology available today on a large scale.

Boreal and temperate forests are now the planet's main carbon sinks (INRAE). On a global scale, carbon stocks in terrestrial biomass increased between 2010 and 2019 by around 500 million tonnes of carbon per year, particularly in temperate and boreal regions, where climatic conditions favored vegetation in the last decades. However, we can look around us and see that there is still room for many trees or shrubs. Tropical jungles, older and degraded by deforestation, fires and drought, are today almost carbon neutral. They even emitted some lately. However, if the forested area increased in these regions, if new trees grew back on the cleared land, they would capture carbon. This year, new Brazilian President Lula has already reduced Amazon deforestation by two-thirds. This is great, we should also let the trees grow back in deforested areas.

Abandoned lands:

On the other hand, many fields have been abandoned on the Planet since 2003. The reasons are diverse: land degradation, institutional and socio-economic changes, disasters, armed conflicts and urbanization.

Better management of these abandoned fields would be an excellent solution for the climate. They could produce more food or capture carbon. If they were grown for food production, pressure to clear forests would reduce, protecting existing forests. If abandoned croplands were reforested, the young trees could help remove global warming carbon dioxide from the atmosphere and help mitigate climate change.

By analyzing geo-spatial data, researchers found that of the 101 million hectares of abandoned cropland worldwide, 61 million hectares were suitable for cultivation. The yield of this land was calculated based on that of the surrounding fields. They would produce enough food to feed between 292 and 476 million people a year, and, with the help of agricultural improvements such as irrigation, they would feed up to a billion people.

In addition, researchers also established that 83 million hectares of uncultivated fields worldwide are suitable for reforestation. If trees grew there, they could absorb up to 1,066 million tonnes of carbon dioxide per year. The gigatonne of carbon dioxide that we must eliminate could therefore be absorbed by trees planted on unused land. This would be enough to achieve the Paris promises.

If land use is optimized, with the most fertile land reserved for agriculture, afforestation would still capture around 750 Mt of CO2 (Nature Com). Some agricultural lands could also be covered with walnut trees, chestnut trees, almond trees and moringa which would feed the populations. Areas particularly suitable for reforestation should be devoted to it immediately.

Oxalogenic trees:

Several scientists emphasize that it is better to avoid monocultures, favor varied forests or, even better, natural regrowth. Each region should probably be examined separately, and a suitable solution chosen. Artificial reforestation should only be practiced where trees do not take root spontaneously.

Another problem is albedo, caused by the color of the surface. A light sandy desert or yellowed grass reflect more sunlight than trees; this must be taken into account when considering plantings, hence the choice of eucalyptus in certain places. On the other hand, plants enrich the soil with carbon and stabilize it.

Other solutions, such as the integration of trees into cultivated areas and conservation agriculture, also allow increased carbon capture. Agro-forestry can allow agriculture to withstand the heat and irrigation could be developed and benefit from technological innovations.

Another article presents oxalogenic trees. These secrete a molecule into the soil that specific bacteria transform into calcium carbonate deposits. Through photosynthesis, the tree produces oxalic acid in its tissues: leaves, bark, roots. This is the case for all trees, but the production of some is more abundant. Oxalic acid is transformed into calcium carbonate. A recent study suggests planting such trees on arid lands by adding specific bacteria to the soil that cause the formation of calcium carbonate (TIPS). They could capture even more carbon in a stable form. An optimal combination of soil, tree type and bacteria could improve the soil and lock in carbon. If it works well, it would be deposited in the ground for a long time, and otherwise the trees themselves will accumulate it in their trunks, branches and roots. These plantations would use desert areas or areas in the process of desertification. They could thrive on the northern slopes of the hills, which are a little more humid and contribute less to the albedo.

Nature-based solutions could allow us to reach and even exceed the Paris promises. I am not at all asking to replace solar panels with trees. I believe that timing is essential, and that we must do it faster to ensure the security of Humanity. While continuing to replace fossil fuels with renewable energies, we must increase natural carbon capture solutions next year. Climeworks recommended by Bill Gates may eliminate enough in thirty years, but that day our cities could resemble Libya devastated by the recent flood, where entire buildings were swept away by the water. A warming of one degree has already brought more than a meter of rain in places, and a temperature of 49.8°C in Canada or 60°C in Bahrain. These values are clearly at the limit of what is bearable for humans, and this will be crossed more and more often. In Australia, waters submerged a town to a height of 17 meters. We will see more serious disasters anyway. increasing floods are predicted by the IPCC. Let's plant today the trees? that will capture carbon and protect us from the vagaries of the climate in ten years. It would even be better to use plants that will absorb a lot of carbon in a few years already. Numerous initiatives in this direction have already started (led for example by Prof. Tom Crowther), but they could change in scale. Agroforestry could make it possible to plant more. The question of the use of wood in forty or fifty years is secondary to climate control over the coming decades. Not all forests will survive climate change, fires, droughts and new diseases. We could well lose half of it, so we must plan for more, a sufficient quantity to save the Planet.