The results have been sobering.<\/p>\n
\u201cThese Papua New Guinea reefs are telling us that with every bit of increase in CO\u2082, we will see fewer corals and more fleshy algae,\u201d said Dr. Sam Noonan, AIMS researcher and lead author of the study. \u201cCritically, we also found far fewer baby corals. Without new recruits, reefs can\u2019t grow or recover quickly \u2013 and that affects all the species that depend on them, including people.\u201d<\/p>\n
Today\u2019s oceans remain slightly alkaline, with a pH of about 8.0, but acidity has already increased by roughly 30% since the industrial era. If emissions continue to rise, global ocean pH could fall to around 7.8 by 2100 \u2013 bringing it close to the values observed at the Milne Bay seep sites.<\/p>\n
By surveying 37 reef sites along a 500-metre CO\u2082 gradient, the researchers documented a steady ecological transformation.<\/p>\n
\u201cThere was no sudden tipping point,\u201d Fabricius noted. \u201cAs CO\u2082 increased, fleshy algae gradually took over, smothering corals and other calcifying species.\u201d<\/p>\n
The implications of the study extend far beyond Papua New Guinea. Early signs of CO\u2082-driven change are already emerging on parts of the Great Barrier Reef. These seep sites \u2013 the latest to be analysed \u2013 show what may lie ahead.<\/p>\n
\u201cOcean acidification is a massive global problem and one that has been understudied and underreported,\u201d Fabricius continued. \u201cThis research offers the first field-based glimpse of how whole reef communities may transform under rising CO\u2082.<\/p>\n
\u201cThe more carbon we emit, the greater the changes will be for reefs, for marine biodiversity, and for coastal communities that rely on them.\u201d<\/p>\n