text: Aspects of the carbonate-silicate cycle have changed through Earth history as a result of biological evolution and tectonic changes. Generally, the formation of carbonates has outpaced that of silicates, effectively removing carbon dioxide from the atmosphere. The advent of carbonate biomineralization near the Precambrian-Cambrian boundary would have allowed more efficient removal of weathering products from the ocean. Biological processes in soils can significantly increase weathering rates. Plants produce organic acids that increase weathering. These acids are secreted by root and mycorrhizal fungi, as well as microbial plant decay. Root respiration and oxidation of organic soil matter also produce carbon dioxide, which is converted to carbonic acid, which increases weathering.
  Tectonics can induce changes in the carbonate-silicate cycle. For example, the uplift of major mountain ranges, such as Himalayas and the Andes, is thought to have initiated the Late Cenozoic Ice Age due to increased rates of silicate weathering and draw down of carbon dioxide. 
  Seafloor weather is linked both to solar luminosity and carbon dioxide concentration. However, it presented a challenge to modelers who have tried to relate the rate of outgassing and subduction to the related rates of seafloor change. Proper, uncomplicated proxy data is difficult to attain for such questions. For example, sediment cores, from which scientists can deduce past sea levels, are not ideal because sea levels change as a result of more than just seafloor adjustment. Recent modeling studies have investigated the role of seafloor weathering on the early evolution of life, showing that relatively fast seafloor creation rates worked to draw down carbon dioxide levels to a moderate extent.
  Observations of so-called deep time indicate that Earth has a relatively insensitive rock weathering feedback, allowing for large temperature swings. With about twice as much carbon dioxide in the atmosphere, paleoclimate records show that global temperatures reached up to 5 to 6 °C higher than current temperatures. However, other factors such as changes in orbital/solar forcing contribute to global temperature change in the paleo-record.
  Human emissions of CO have been steadily increasing, and the consequent concentration of CO in the Earth system has reached unprecedented levels in a very short amount of time. Excess carbon in the atmosphere that is dissolved in seawater can alter the rates of carbonate-silicate cycle. Dissolved CO may react with water to form bicarbonate ions, HCO, and hydrogen ions, H. These hydrogen ions quickly react with carbonate, CO to produce more bicarbonate ions and reduce the available carbonate ions, which presents an obstacle to the carbon carbonate precipitation process. Put differently, 30% of excess carbon emitted into the atmosphere is absorbed by the oceans. Higher concentrations of carbon dioxide in the oceans work to push the carbonate precipitation process in the opposite direction (to the left), producing less CaCO. This process, which harms shell-building organisms, is called ocean acidification.