Author: Dr Peter Ridd

Published: August 5, 2022

In 2019, IPA Adjunct Fellow Dr Peter Ridd made a submission to Senate Inquiry questioning the evidence claiming adverse effects of agriculture on the Great Barrier Reef. He also called for a thorough audit to be conducted of the claims by a group of independent scientists not attached to government institutions working on the Great Barrier Reef.

As Dr Ridd points out, the Great Barrier Reef is a long way from the coast and almost totally unaffected by mud and pesticides from farms. Science institutions focus on the effect of agriculture on “Inshore” reefs.  These are the fringing reefs close to shore not the GBR-proper, which is generally 40-100 km from the coast.

The Inshore Reefs are only about 1 or 2% of the coral, a point never made by science institutions claiming agriculture is killing the GBR. Even the Inshore Reefs are only marginally affected by farm runoff.

Here are the salient points Dr Ridd presented:

Sediment from farms

  • Sediment from farm runoff generally does not reach the GBR where about 99% of the coral lives. On very rare occasions, perhaps for a few days in many years, a few of the 3000 reefs of the GBR are affected by very small concentrations of sediment. The risk, if any, is thus restricted to the tiny area of Inshore Reefs.
  • For the Inshore Reefs, the churning of the muddy seabed by waves is the primary exposure of coral to mud. River plumes are a very minor factor. Many of these inshore regions have always been muddy due to mud deposited over millennia.


  • Science institutions almost never bother to measure pesticides on the GBR as they are generally undetectable even with the most sensitive scientific equipment. This is because the GBR water is well flushed by water from the Pacific Ocean.
  • For the Inshore Reefs (1-2% of the coral), most pesticides are not detected. Very occasionally, and only for a few of the inshore coral patches very close to river mouths, do pesticides even occasionally reach concentrations that could cause even a very minor impact.


  • Science organisations claim that fertilizer from farms causes Crown of Thorns Starfish (COTS) plagues. However, the evidence for this is extremely weak and ignores the fact that plagues occur in regions well away from agriculture.
  • The geological evidence indicates that COTS plagues have been around for millennia and there is little good reason to suspect they are worse now than before European settlement.

Reliability of Science Institutions

  • For many disciplines of science, it is regularly found that much of the peer reviewed literature, perhaps half, has serious flaws. This statement is uncontroversial and is accepted by most of the major national academies of science. It is called the “Replication Crisis”. GBR science is not exempt from this general problem.
  • Even Dr Finkel, Australia’s Chief Scientist, accepts there are problems with the general scientific literature.
  • The main system of scientific quality assurance, review by peers, is deficient in many ways not least being that it almost guarantees groupthink, and can often exclude views from dissenting scientist.
  • Major errors in work coming from GBR scientific institutions have been identified and there is a general reluctance of the institutions to rectify problems. They are in denial about their serious deficiency of Quality Assurance protocols. In some cases, they actively cover up problems, and vilify or exclude those who raise concerns.
  • There is thus considerable doubt that our GBR science institutions are providing reliable scientific evidence. This certainly does not imply all their work is wrong, but we cannot conclude that most individual parts of the scientific evidence, or the “consensus” documents, are reliable.

Dr Ridd pointed out that

  • The GBR is too precious to tolerate any significant damage.
  • Every major industry in Northern Queensland, including agriculture, is affected by regulations relating to the GBR

Thus he proposed a full audit of the evidence relating to the potential effect of agriculture be carried out. It is estimated that this could be done for less than $5 million, about 1% of funds presently being spent on the Reef, and take less than 2 years.

Governments would be in a better position to make decisions on a more solid science base.

Download Dr Peter Ridd’s full submission to the Senate Standing Committees on Rural and Regional Affairs and Transport into the ‘Identification of leading practices in ensuring evidence-based regulation of farm practices that impact water quality outcomes in the Great Barrier Reef’ here.

Download Here
- Dr Peter Ridd