Claim: Australia drying caused by greenhouse gases

But the paper ignores land use and land cover change

From NOAA Headquarters and the “its the evil gases wot dun it and nothing else” department, comes more modeling madness via another poorly written press release by Monica Allen monica.allen@noaa.gov that doesn’t mention the name and/or DOI of the paper, making me hunt for it, but worries about useless details like telling me the image below is “embargoed until 1 p.m. ET, July 13, 2014 “. – as it that matters when the press release today included it anyway. To add insult to the injury, this paper funded by the taxpayers of the United States is paywalled.

New NOAA climate model zeroes in on regional climate trends

NOAA scientists have developed a new high-resolution climate model that shows southwestern Australia’s long-term decline in fall and winter rainfall is caused by increases in manmade greenhouse gas emissions and ozone depletion, according to research published today in Nature Geoscience.

“This new high-resolution climate model is able to simulate regional-scale precipitation with considerably improved accuracy compared to previous generation models,” said Tom Delworth, a research scientist at NOAA’s Geophysical Fluid Dynamics Laboratory in Princeton, N.J., who helped develop the new model and is co-author of the paper. “This model is a major step forward in our effort to improve the prediction of regional climate change, particularly involving water resources.”

NOAA researchers conducted several climate simulations using this global climate model to study long-term changes in rainfall in various regions across the globe. One of the most striking signals of change emerged over Australia, where a long-term decline in fall and winter rainfall has been observed over parts of southern Australia. Simulating natural and manmade climate drivers, scientists showed that the decline in rainfall is primarily a response to manmade increases in greenhouse gases as well as a thinning of the ozone caused by manmade aerosol emissions. Several natural causes were tested with the model, including volcano eruptions and changes in the sun’s radiation. But none of these natural climate drivers reproduced the long-term observed drying, indicating this trend is due to human activity.

Southern Australia’s decline in rainfall began around 1970 and has increased over the last four decades. The model projects a continued decline in winter rainfall throughout the rest of the 21st century, with significant implications for regional water resources. The drying is most severe over southwest Australia where the model forecasts a 40 percent decline in average rainfall by the late 21st century.

“Predicting potential future changes in water resources, including drought, are an immense societal challenge,” said Delworth. “This new climate model will help us more accurately and quickly provide resource planners with environmental intelligence at the regional level. The study of Australian drought helps to validate this new model, and thus builds confidence in this model for ongoing studies of North American drought.”

###

================================================================

Here is the paper I chased down:

Regional rainfall decline in Australia attributed to anthropogenic greenhouse gases and ozone levels

Thomas L. Delworth & Fanrong Zeng Nature Geoscience (2014) doi:10.1038/ngeo2201

Precipitation in austral autumn and winter has declined over parts of southern and especially southwestern Australia in the past few decades^{1, 2, 3, 4}. According to observations and climate models, at least part of this decline is associated with changes in large-scale atmospheric circulation^{1, 2, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14}, including a poleward movement of the westerly winds and increasing atmospheric surface pressure over parts of southern Australia. Here we use a high-resolution global climate model to analyse the causes of this rainfall decline. In our simulations, many aspects of the observed regional rainfall decline over southern and southwest Australia are reproduced in response to anthropogenic changes in levels of greenhouse gases and ozone in the atmosphere, whereas anthropogenic aerosols do not contribute to the simulated precipitation decline. Simulations of future climate with this model suggest amplified winter drying over most parts of southern Australia in the coming decades in response to a high-end scenario of changes in radiative forcing. The drying is most pronounced over southwest Australia, with total reductions in austral autumn and winter precipitation of approximately 40% by the late twenty-first century.

Paywalled here at the expense of the public:  http://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo2201.html

This paywalling of publicly funded science, combined with the recent developments surrounding the failure of peer review, which seems to be little more than pal review in some cases, is why we need a sea-change in science review and publication.

Now while I can’t properly criticize what I can’t read, it seems to me that land use and land cover change might play a big role, if not bigger than GHG’s. But land use and land cover change isn’t mentioned in the abstract and press release, and so it seems to me that the paper is myopic in scope.

This paper (which isn’t paywalled) was discussed at Jo Nova’s forum last year:

The effect of land clearing on rainfall and fresh water resources in Western

Australia: A multi-functional sustainability analysis

Mark A. Andrich & Jörg Imberger DOI: 10.1080/13504509.2013.850752

Abstract (excerpt)

It is widely recognized that southwest Western Australia has experienced approximately a

30% decline in rainfall, in areas inland from the coastal margin, over the last forty years or

more. It is generally thought that this decline was due to changes induced by global warming, but recently evidence has emerged suggesting that a substantial part of the decline may be attributed to changes in land use. These changes involved extensive logging close to the coast and the clearing of native vegetation for wheat planting on the higher ground. We present a methodology that compares coastal and inland rainfall to show that 50 – 80% of the observed decline in rainfall is the result of land clearing.

Read it here: Andrich_and_Imberger_(2012a)