The Australian has retreated from its claim that rising sea levels are “not linked to warming” faster than a melting glacier — but it’s still not telling the full story on a recently released scientific paper.
Yesterday, as hundreds of IPCC scientists met in Hobart, The Australian‘s environment editor Graham Lloyd claimed “the latest science on sea level rises has found no link to global warming”. The story cited a paper which ran in the Journal of Climate last year, co-authored by the CSIRO’s Dr John Church.
Church said that was inaccurate, and IPCC chief Rajendra Pachauri said “sane and rational voices must respond to … this scepticism”.
The Australian‘s outright climate scepticism on this paper didn’t last long after Crikey published Church and Pachauri’s comments. The heading on The Oz online has switched from “Sea rise ‘not linked to warming’, says report” to “Sea level rise ‘linked to climate change’” (AAP copy).
Today, the national broadsheet has written three stories relating to the Journal of Climate paper — a news story, a feature and an editorial — seeking to portray its original story as the product of a dispute between the authors of the paper and criticising the ABC for using a technique favoured by The Oz itself: quoting non-scientists on climate (remember 80-year-old Wollongong local Kevin Court’s prominent views on sea level rise in 2009?). Today’s stories also delve deeper into the research paper’s contents.
Perhaps not deep enough. The stories paint the research paper as casting doubt on whether human-induced climate change is causing sea levels to rise. Here’s what is actually in the paper — and what you won’t read in The Australian.
The paper — Twentieth-century global-mean sea-level rise: is the whole greater than the sum of the parts? (lead author is JM Gregory) — is based on the observation that sea levels rose by more than might be expected in the 20th century, and that rise was linear (that is, the rate did not accelerate markedly as humans emitted more greenhouse gases).
The researchers found sea levels were rising largely due to glaciers melting and thermal expansion of the oceans (as water warms, it takes up more space and therefore sea levels rise). It is difficult to reconcile this conclusion with the one reached by Lloyd yesterday.
Sea level rise due to thermal expansion “shows a tendency for increasing rate as the magnitude of anthropogenic global climate change increases”, the paper said. It concluded the sea level rise was linear partly because of a difference in the number of volcanic eruptions between the early 20th century and the late 20th century, which had a greater impact on sea levels earlier on. This may have balanced out the increasing impact of human-induced warming, so that the overall rate was upwards and linear.
The paper found a key factor in sea level rise last century was glaciers melting, “consistent with a warming climate worldwide”. It suggested glacier melt may have contributed more to sea level rise in the early 20th century because low-altitude glaciers are the first to melt, and they contain more mass.
In any event, the paper found the linear trend in sea level rise has changed: “In the last two decades, the rate of [sea level rise] has been larger than the 20th-century time-mean, due to increased rates of thermal expansion, glacier mass loss, and ice discharge …”
The authors also explicitly state the paper is not aimed at “the detection and attribution of climate change”; it did not aim to attribute changes in the climate system to “the agents which forced those changes to occur (such as anthropogenic greenhouse gases …)”. Instead, it aimed at attributing sea level rises to oceans, land ice and water storage. So it was more about the mechanics of where the extra water is coming from, not why.
The Journal of Climate paper is one of many hundreds of scientific papers on climate change published each year. A common theme in recent years is that the impacts of climate change may be more severe, and happening more quickly, than previously predicted. Such papers do not tend to run prominently in The Australian.