Life on land depends on plants. Every plant balances opening its pores to let in carbon dioxide for photosynthesis; and closing its pores to retain water.
Graham Farquhar’s work has transformed our understanding of the world’s most important biological reaction: photosynthesis.
His models of plant biophysics have been used to understand cells, whole plants, whole forests, and to create new water-efficient wheat varieties. His latest project will determine which trees will grow faster in a high carbon dioxide world.
His work has also revealed a global climate mystery. Evaporation rates and wind speeds are slowing around the world, contrary to the predictions of most climate models. Life under climate change may be wetter than we expected.
Graham is Distinguished Professor of the Australian National University’s (ANU) Research School of Biology and Chief Investigator of the Australian Research Council’s Centre of Excellence for Translational Photosynthesis.
For modelling photosynthesis, the world’s most important biological reaction, Graham Farquhar receives the $250,000 Prime Minister’s Prize for Science.
Graham Farquhar’s citation in full
Graham Farquhar always knew he was going to be a scientist.
“I was a natural fit.” But he also knew his family, farming stock from Tasmania, would expect something more—that his science be practical and preferably contribute to agriculture. And so it has been, in a diverse variety of almost unexpected ways.
When Graham was starting to make decisions about his future in science, it was his father, a CSIRO scientist, who advised him to look at the fledgling area of biophysics. Neither of them really knew what biophysics entailed and where it would lead, says Graham, but his father had just returned from a trip to America convinced that it was going to be the next big thing.
As things turned out, the decision was a masterstroke. And it meant that when he began to study photosynthesis, Graham came at it with a different perspective than that of the traditional biologist.
Photosynthesis is the basis of life on Earth. Through plant production it provides the food we eat. But it also provides the oxygen in our atmosphere as a by-product. And three-quarters of the water returned to the atmosphere from land passes through plants as a consequence of photosynthesis.
Graham’s impact began 35 years ago when he and then-colleagues at ANU published a mathematical representation of the molecular interactions of photosynthesis, the process whereby plants trap light and use it to drive the formation of sugars from water and carbon dioxide (CO2). Their model is still used today by agricultural and environmental scientists all over the world to determine many things, from the yield of crops to the best growing conditions.
The reaction itself is dependent on many factors, including the level and quality of light, availability of water and CO2, temperature, and availability of the right catalysts or enzymes. People working in all these areas tended to view things from their perspective alone.
What Graham and his colleagues did was to integrate these factors, including a new mathematical treatment of the key reaction powered by the enzyme Rubisco. The model could be scaled down or up to look at all facets of photosynthesis, from what happens inside cells to what happens in whole forests.
As part of the whole photosynthesis question, Graham was interested in stomata, the small pores in leaves which can be opened or closed. The leaves are the site of photosynthesis, and the stomata need to be open to allow CO2 to reach the chloroplasts inside, where the reaction happens. But the leaf pays a price for opening up its stomata, because it allows precious water to move out.
Graham and colleagues also discovered a disparity in the way plants handle CO2 molecules containing different forms of carbon during photosynthesis. They calculated the rates at which water and CO2 diffuse into and out of leaves. The two commonly occurring forms or isotopes of carbon differ in weight, and this marginally affects their rate of diffusion, with the heavier carbon diffusing slower.
Plants that are more efficient in using water tend not to open their stomata as widely or for as long. These plants accumulate the rarer, heavier form of carbon, because of the difference in diffusion rates and reaction rates.
Just after he worked this out, Graham was at an outing in a Canberra park and bumped into a friend he had not seen since Year 9 in McKinnon High School in Melbourne. Dr Richard Richards worked on improving crop plants at the CSIRO Division of Plant Industry. He and Graham had plenty to catch up on and talk about, as Richard had some strains that differed in their water-use efficiency. Here was a way to test the theory.
Soon Richard was testing and using the technique, incorporating it into trials and breeding programs. The result was the wheat variety “Drysdale” which provides better yields than usual under dry Australian conditions. Other strains followed. For this work Graham Farquhar and Richard Richards were awarded last year’s Rank Prize for excellence in nutrition.
Graham went on to explore how the two stable oxygen isotopes of CO2 were processed in different ways. He and his co-researchers found that the oxygen isotope ratio found in carbon dioxide reflects the balance between photosynthesis, where carbon is taken up by plants, and respiration, where they burn sugars, giving off carbon. The ratio of light oxygen to heavy oxygen in carbon dioxide in the atmosphere above different areas of land and ocean is now used routinely to assess whether they are carbon sources or carbon sinks.
These contributions to measuring changes in land-use and forestry led to Graham’s interest in measuring global change generally and then to him becoming an Australian delegate to the conference that developed the Kyoto Protocol in 1997. As a member of the Inter-governmental Panel on Climate Change (IPCC) he was one of the recipients of the Nobel Peace Prize in 2007. And he is still at it, still picking away at the details of what the changes in our atmosphere are doing to our climate and forests.
The Bureau of Meteorology in Australia and other similar organisations elsewhere have for many decades—at least 50 years in some cases—maintained specific metal pans to measure changes in the rate of evaporation over time. As the average global temperature rises, most people assume the air will become hotter and drier, and that evaporation will increase. Graham and his colleague Michael Roderick at ANU have found the reverse, the level of evaporation over the past 50 years has tended to decrease.
Initially, they thought this was to do with increasing cloud cover and polluting aerosols in the atmosphere, a phenomenon dubbed global dimming. And in some industrialised areas of the world, there is good evidence that this is what has happened. But not in New Zealand, and parts of Australia, where the air is as clean as anywhere in the world, and the level of evaporation has still decreased.
That’s when Graham and Michael found something even stranger. The reduction in evaporation in those places was associated with a reduction in wind speed – global stilling.
“None of the climate models show such a decrease in wind speed. It’s a paradox, which shows we haven’t thought about climate change and its impact enough yet,” says Graham. He thinks it’s possible we could end up with a warmer, wetter world, while still subject to the droughts and floods we have experienced for centuries.
Graham is also now leading a multi-million dollar project entitled Forests for the Future: making the most of a high CO2 world, financed by the Science and Industry Endowment Fund and partnering ANU, CSIRO and the University of Western Sydney. The project will use Graham’s techniques to help identify trees that will grow faster in response to high CO2 levels. The project will he hopes lead to improved forestry production and a boost to carbon capture through forestry.
|PhD (Environmental Biology), Australian National University (ANU)
|Bachelor of Science (Honours in Biophysics), University of Queensland
|Bachelor of Science, ANU
|Australian Academy of Science (AAS) Macfarlane Burnet Medal and Lecture
|Life Member, Australian Society of Plant Scientists
|Carnegie Centenary Professor, Universities of Scotland
|Rank Prize for Human and Animal Nutrition and Crop Husbandry, UK
|2013 – ongoing
|Member, Singapore National Research Foundation Competitive Research Program Panel
|Honorary Doctorate, Wageningen University, Netherlands
|Officer of the Order of Australia, General Division
|Honorary Professor, Centre for Agricultural Resources Research, Shijiazhuang, Chinese Academy of Sciences
|Einstein Professor, Chinese Academy of Sciences
|Foreign Associate, National Academy of Sciences, USA
|Alexander von Humboldt Research Award
|Peter Baume Award, ANU
|2010 – ongoing
|ANU Research Misconduct Assessor for Science
|Senior Research Fellow, Land & Water Australia
|2007 – 2011
|Vice President and Secretary (Biological) and member of Executive Committee and Council, AAS
|Nobel Prize (shared): Inter-governmental Panel on Climate Change
|Honorary Doctorate, University of Antwerp, Belgium
|R.M. Johnston Memorial Medal, the Royal Society of Tasmania
|2005 – 2008
|Associate Director, Research School of Biology, ANU
|JG Wood Lecturer, Australian Society of Plant Scientists
|Gary Comer Climate Change Mentor Award
|2004 – ongoing
|Distinguished Professor, Research School of Biology, ANU
|2003 – 2004
|Chair, Board of Institute of Advanced Studies, ANU
|Centenary Medal, Commonwealth of Australia
|CSIRO Medal for Research Achievement
|Thomson Reuters Leading Australian Citation Laureate
|Science adviser and Australian delegate, Framework Convention on Climate Change, Conference of Parties, Kyoto, Japan
|Fellow, Royal Society, London
|1994 – 1998
|Chairman, National Greenhouse Gases Inventory Working Group on Carbon Dioxide from the Biosphere
|1994 – 1996
|Chairman, Australian Committee, International Geosphere-Biosphere Programme
|Corresponding Member, American Society of Plant Physiologists
|CSIRO Medal for Research Achievement
|Scholarship, Ministry of Higher Education and Research, France
|Royal Society Exchange Award
|British Council Academic Links and Interchange Scheme Award
|Gottschalk Medal, AAS
|Australian American Educational Foundation (FULBRIGHT) Senior Scientist Fellowship for Research, Carnegie Institution of Washington, Stanford, USA
|Senior Scientist Award, Japan/Australia Science and Technology Agreement for Collaborative Research, RIKEN, Japan
|Goldacre Award, Australian Society of Plant Physiologists