Hundreds of doom-laden studies about the effects of climate change on the Earth’s oceans may be flawed and unreliable, a major review has found.
For years, scientists have warned that rising levels of carbon dioxide are marking our seas more acidic – and that this spells disaster for marine life. But a review of hundreds of studies into the effects of acidity on sea creatures suggest the vast majority may be unreliable or not fit for purpose.
The review – by two experts in Australia – said only 27 of more than 400 studies into the issue were appropriately carried out.
It is the latest research to highlight difficulties with many of the doom-mongering predictions about climate change. Last month, experts from University College London highlighted how the ice-cap in the Arctic actually regrew by 40 per cent in 2013 – surprising scientists. It showed how much care needs to be taken when assessing claims about the Earth’s climate.
When it comes to the oceans, the UN has warned that the effects of increasing acidity could cost the world economy $1trillion (£644billion) by the end of the century. Again, rising levels of carbon dioxide are said to be to blame. Carbon dioxide causes global warming when it ends up in the air – trapping heat. But when it is absorbed by the sea it makes the water more acidic.
Forecasters warn this so-called ‘acidification’ will have numerous effects, including wiping out valuable fisheries and killing off coral reefs. The Earth’s seas are not yet acidic – but the opposite – slightly alkaline. But forecasters believe they are edging towards an acidic level and could rise above the neutral midpoint of ph7 by 2100.
However, a review of 465 studies into the effects of acidification on sealife said only 27 used an ‘appropriate experimental design’. And 278 studies were ‘clearly inappropriate’ which means a huge amount of research is not fit for purpose. Some of the research, if ‘reanalysed’, might yield useful data, but not in its current form, say the authors.
Christopher Cornwall, who studies ocean acidification at the University of Western Australia, and ecologist Catriona Hurd of the University of Tasmania, wrote in their paper in the ICES Journal of Marine Science: ‘This analysis identified that most laboratory manipulation experiments in ocean acidification research used either an inappropriate experimental design and/or data analysis, or did not report these details effectively.’ To test the effect on ocean creatures – whether lobsters, plankton, mussels, or fish – is a complex business. It requires using big tanks of seawater containing sealife to slosh around on moving tables that simulate the effect of the tides for days on end. Seawater is made more acidic by adding chemicals.
Errors made in the studies include increasing acidity without increasing temperature, not looking at other effects such as an increase of chemicals called carbonates and failing to eliminate the risk of observer bias.
The authors, commenting in Nature, say the ‘overwhelming evidence’ of ocean acidifiation still stands. But they say it is hard to assess the impact of ocean life from most of the experiments that have been carried out.