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Scientists have known for years that silicate minerals react with CO2 water to remove CO2 From the atmosphere, it acts as a thermostat that has broadly stabilized the Earth’s climate over billions of years. But how sensitive is that thermostat? To figure it out, scientists will have to scale up their lab measurements to the real world, but they’re going to have to use lab work in soils and rivers. It was impossible to match the real-world measurements made in
This gap in our understanding has hampered efforts to model the Earth’s long-term carbon cycle and climate, and it is difficult to pinpoint how effective silicate weathering, both natural and man-made, is in removing CO2. making it difficult to predict2 from our atmosphere.
In a paper published in Science, Pennsylvania State University Professor Susan Brantley and her team show that temperature is consistent across all scales, from laboratory measurements and real-world measurements in landscapes to the entire world. We have discovered a method to quantify the weathering response of silicates. In doing so, we identified the types of landscapes that have the most impact on the Earth’s thermostat.
Jeremy Caves Rugenstein, a professor at Colorado State University who was not involved in the study, said, “This is an ambitious undertaking … to bring different studies across different spatial and temporal scales into one unifying framework. It’s about integrating,” he said.
approach from scratch
“It always bugged me. We were creating these global models and I just couldn’t get out of Flask. [in the lab] To backyard dirt,” Brantley told Ars.
It is impossible to replicate in the laboratory the myriad effects of minerals breaking down from bedrock, dissolving and interacting with plants, microbes and groundwater before finally flowing into the ocean. “There are so many processes all combined that you end up with a different temperature sensitivity than in the lab,” says Brantley.
As a result, scientists disagree about how sensitive climate change is to global temperature changes.
Brantley’s team tackled the problem by collecting the vast number of observations that Brantley and her students have collected over the years, pulling together data from more than 200 published papers. To make sense of her data, Brantley looked at the most important drivers and tracers of weathering responses at different scales. “I really think that intersecting spatial and temporal scales like this forces you to think about what is important,” said Brantley.
While others have tried to use rock types to magnify the weathering response, Brantley’s team instead focused on feldspar, the most abundant silicate mineral in those rocks.
Feldspar governs chemical reactions involved in the removal of CO2 From the air; these reactions also produce most of the dissolved sodium in river water (which makes seawater salty). Brantley’s team used sodium as a proxy to calculate the amount of silicate weathering occurring in river catchments around the world. This setup allowed researchers to avoid problems with other cations (mainly potassium, calcium, and magnesium) produced by silicate weathering. These cations are complicated by other processes that use these elements.
They examined the degree of weathering of dozens of soils across a range of average annual temperatures and precipitation on Earth. The team also used previous research on how long these soils were weathered. The study relied on beryllium-10, an isotope produced when minerals are exposed to cosmic rays at the surface of the earth. Soils with a lot of beryllium-10 on the surface are stable for a long time, so fresh silicate minerals do not react with CO.2.
In parallel, the team examined sodium produced by weathering in different river basins in different climatic zones. When this data was combined with the soil data, they finally understood the discrepancies between the laboratory, various locations in the real world, and the entire planet.Temperature (Arrhenius equation).
“What surprises me is that we can match across these different spatial scales. It takes a lot of thinking to do that,” Brantley said.
