3.4 Harmful algal blooms
Some CDR methods also have risks. One is rapid escape of stored CO2 into the atmosphere, reducing its effectiveness.
Iron fertilisation may harm marine ecosystems: for example, by creating ‘red tides’ of harmful algae (Figure 7). Such a red tide in 2013 was reported to have killed 276 manatees in Florida (Brown, 2013). Red tides also pose a risk to human health through eating contaminated shellfish.