Sunday, November 26, 2023

Thursday, July 4, 2013

The foliage on native plants in Australia's arid zones is boosted by CO2

Increased levels of carbon dioxide (CO2) have helped boost green foliage across the world’s arid regions over the past 30 years through a process called CO2 fertilisation, according to CSIRO research.

In findings based on satellite observations, CSIRO, in collaboration with the Australian National University (ANU), found that this CO2 fertilisation correlated with an 11 per cent increase in foliage cover from 1982-2010 across parts of the arid areas studied in Australia, North America, the Middle East and Africa, according to CSIRO research scientist, Dr Randall Donohue.

"In Australia, our native vegetation is superbly adapted to surviving in arid environments and it consequently uses water very efficiently," Dr Donohue said. "Australian vegetation seems quite sensitive to CO2 fertilisation.

The fertilisation effect occurs where elevated CO2 enables a leaf during photosynthesis, the process by which green plants convert sunlight into sugar, to extract more carbon from the air or lose less water to the air, or both.
This, along with the vast extents of arid landscapes, means Australia featured prominently in our results."

"While a CO2 effect on foliage response has long been speculated, until now it has been difficult to demonstrate," according to Dr Donohue.

"Our work was able to tease-out the CO2 fertilisation effect by using mathematical modelling together with satellite data adjusted to take out the observed effects of other influences such as precipitation, air temperature, the amount of light, and land-use changes."

The fertilisation effect occurs where elevated CO2 enables a leaf during photosynthesis, the process by which green plants convert sunlight into sugar, to extract more carbon from the air or lose less water to the air, or both.

If elevated CO2 causes the water use of individual leaves to drop, plants in arid environments will respond by increasing their total numbers of leaves. These changes in leaf cover can be detected by satellite, particularly in deserts and savannas where the cover is less complete than in wet locations, according to Dr Donohue.

"On the face of it, elevated CO2 boosting the foliage in dry country is good news and could assist forestry and agriculture in such areas; however there will be secondary effects that are likely to influence water availability, the carbon cycle, fire regimes and biodiversity, for example," Dr Donohue said.

"Ongoing research is required if we are to fully comprehend the potential extent and severity of such secondary effects."

This study was published in the US Geophysical Research Letters journal and was funded by CSIRO's Sustainable Agriculture Flagship, Water for a Healthy Country Flagship, the Australian Research Council and Land & Water Australia.

Reprinted from CSIRO

Donohue, R. J., M. L. Roderick, T. R. McVicar, G. D. Farquhar. 2013 "Impact of CO2 fertilization on maximum foliage cover across the globe's warm, arid environments. Geophys. Res. Lett. 40, doi:10.1002/grl.50563

Non-deciduous perennials are responding better than deciduous, annual and ephemeral plants

Here is the abstract from a previous paper by Dr Donohue (my paras):

Using Advanced Very High Resolution Radiometer data spanning 1981–2006 and calibrated for long-term analyses of vegetation dynamics, we examine whether vegetation cover has increased across Australia and whether there has been a differential response of vegetation functional types in response to changes in climatic growing conditions. Trends in vegetation cover are interpreted within Budyko's energy – water limitation framework.

Results from an Australia-wide analysis indicate that vegetation cover (as described by the fraction of Photosynthetically Active Radiation absorbed by vegetation; fPAR) has increased, on average, by 0.0007 per year – an increase of ∼8% over the 26 years. The majority of this change is due to a 0.0010 per year increase in persistent fPAR (representing nondeciduous perennial vegetation types; up 21%).

In contrast, recurrent fPAR (representing deciduous, annual and ephemeral vegetation types) decreased, on average, by 0.0003 per year (down 7%), the trends of which are highly seasonal.

Over the same period, Australian average annual precipitation increased by 1.3 mm yr−2 (up 7%).

A site-based analysis using 90 long-term meteorological stations with minimal localized land-cover changes showed that energy-limited sites where total fPAR increased generally experienced decreases in precipitation, and water-limited sites that experienced decreases in cover were almost always associated with decreases in precipitation.

Interestingly, where vegetation cover increased at water-limited sites, precipitation trends were variable indicating that this is not the only factor driving vegetation response. As Australia is a generally highly water-limited environment, these findings indicate that the effective availability of water to plants has increased on average over the study period. Results also show that persistent vegetation types have benefited more than recurrent types from recent changes in growing conditions.

Regardless of what has been driving these changes, the overall response of vegetation over the past 2–3 decades has resulted in an observable greening of the driest inhabited continent on Earth.

Wednesday, May 29, 2013

The Heat is On....Stop Procrastinating, People

Don't take comfort from the Bayesians or other low estimates of climate sensitivity - this study says it's going to get bad, and worse if we don't act now...

Uncertainty no excuse for procrastinating on climate change

By Roger Bodman, Victoria University and David Karoly, University of Melbourne

Today we released research which reduces the range of uncertainty in future global warming. It does not alter the fact we will never be certain about how, exactly, the climate will change.

We always have to make decisions when there are uncertainties about the future: whether to take an umbrella when we go outside, how much to spend on insurance. International action on climate change is just one more decision that has to be made in an environment of uncertainty.

The most recent assessment of climate change made by the Intergovernmental Panel on Climate Change in 2007 looked at what is known with high confidence about climate change, as well as uncertainties. It included projections of future global warming to the end of this century based on simulations from a group of complex climate models.

These models included a range of uncertainties, coming from natural variability of the climate and the representation of important processes in the models. But the models did not consider uncertainty from interactions with the carbon cycle – the way carbon is absorbed and released by oceans, plant life and soil. In order to allow for these uncertainties, the likely range of temperature change was expanded.
Our recent study has re-visited these results and tested an approach to reduce the range of uncertainty for future global warming. We wanted to calibrate the key climate and carbon cycle parameters in a simple climate model using historical data as a basis for future projections. We used observations of atmospheric carbon dioxide concentrations for the last 50 years to constrain the representation of the carbon cycle in the model. We also took the more common approach of using global atmospheric and ocean temperature variations to constrain the response of the climate system.

This led to a narrower range of projected temperature changes for a given set of greenhouse gas emissions. As a consequence, we have higher confidence in the projections. In other words, using both climate and carbon dioxide observations reduces the uncertainties in projections of global warming. (Click the chart to enlarge it.)

Figure 1. Global-mean temperature change for a business-as-usual emission scenario, relative to pre-industrial. Black line: median, shaded regions 67% (dark), 90% (medium) and 95% (light) confidence intervals. The sidebars are uncertainty ranges based on the IPCC likely range and best estimate (grey column) for 2090-2099 and our corresponding results (purple column) from the simple climate model (MAGICC); the black bars are the respective best estimates (modified from Nature Climate Change paper). Bodman & Karoly

We found that uncertainties in the carbon cycle are the second-largest contributor to the overall range of uncertainty in future global warming. The main contributor is climate sensitivity, a measure of how the climate responds to increases in greenhouse-gas concentrations.

Climate sensitivity has been discussed recently on The Conversation. A recent study by Alexander Otto of Oxford University and colleagues, published in the journal Nature Geoscience, also considered future global warming in the context of observations of global mean temperature change over the last decade.
Unlike that study, our results do not show lower climate sensitivity or lower mean projected global warming. Our study uses the same observed global atmospheric and ocean temperature data. But we also used observed carbon dioxide data and represented important additional processes in our simplified climate model, particularly the carbon cycle on the land and in the ocean and uncertainties in the climate forcing due to aerosols.

In our study, the reductions in uncertainty came from using the observations, the relationships between them and how these affect the parameters in the simple climate model. We found 63% of the uncertainty in projected warming was due to single sources, such as climate sensitivity, the carbon cycle components and the cooling effect of aerosols, while 37% of uncertainty came from the combination of these sources.
Once we reduced the uncertainty we found there is an increased risk of exceeding a lower temperature change threshold, but a reduced chance of exceeding a high threshold. That is, for business-as-usual emissions of greenhouse gases, exceeding 6°C global warming by 2100 is now unlikely, while exceeding 2°C is virtually certain.

These results reconfirm the need for urgent and substantial reductions in greenhouse gas emissions if the world is to avoid exceeding the global warming target of 2°C. Keeping warming below 2°C is necessary to minimise dangerous climate change.

It is unlikely that uncertainties in projected warming will be reduced substantially. Indeed, if you allow for population growth, levels of economic activity, growth in demand for energy and the means of producing that energy, overall uncertainty increases. We just have to accept that we will have to manage the risks of global warming with the knowledge we have. We may not know exactly how much and by when average temperatures change, but we know they will. This is an experiment we probably don’t want to make with the only planet we have to live on.

Roger Bodman received funding from the Australian Research Council while completing his PhD.
David Karoly receives funding from the Australian Research Council and the Australian Antarctic Division. He is a Chief Investigator in the ARC Centre of Excellence for Climate System Science, a member of the Climate Change Authority and a member of the Science Advisory Panel to the Climate Commission.

The Conversation
This article was originally published at The Conversation. Read the original article.

Thursday, December 13, 2012

Coming soon...

I've cleaned this blog out again.  I'm going to be writing some more serious articles here about science and environment with a particular focus on Australia.  That's a job for the first quarter in 2013.

I now have a sister blog,, which I started as a way of letting off steam about the appalling treatment I got from the operators and moderators at a large Australian share trading discussion board.  I plan to develop that blog with articles about a variety of topics, including sexism and bullying, but with an emphasis on climate science denial - what motivates people to lie and deceive and discussing tactics of deniers etc.

Meanwhile, I wish you all a very happy Christmas, Hanukkah or whatever you celebrate over the holiday season, and a healthy, happy and prosperous 2013.

Tuesday, January 31, 2012

Cattle Banned! Finally some protection for Victoria's High Plains

Victoria's high country is safe from cattle grazing in the national park. The Victorian Government says it is not ruling out a High Court challenge, but lets hope they don't waste their money. It's enough that they've reneged on other environmentally important issues, like restricting wind farms.

After the cattle were kicked out last time around, the plants grew profusely. I've been visiting the high plains for forty years and, until a couple of years after the cattle had left, I had never in my life seen such a density of growth with so many different plants growing together.

Here is the media release from Tony Burke MP, the Federal Minister for Sustainability, Environment, Water, Population and Communities:
A proposal by the Victorian Government to reintroduce cattle to the National Heritage listed Alpine National Park in Victoria has been determined to be clearly unacceptable under national environmental law and will not proceed.

Environment Minister Tony Burke said after careful consideration he had accepted the advice of the Environment Department that the proposal to reintroduce cattle to the Alpine National Park would have a clearly unacceptable impact on the national heritage values of the Australian Alps National Parks and Reserves National Heritage Place.

In December, the Victorian Department of Sustainability and Environment submitted a proposal to the Federal Government for assessment under the Environment Protection and Biodiversity Conservation (EPBC) Act 1999 to reintroduce up to 400 cattle to graze in the state's Alpine National Park for up to five months a year for five years, as a research trial.

Nine out of the 10 sites selected by the Victorian Government are partly or entirely located within the Australian Alps National Parks and Reserves which was included on the National Heritage List in 2008. The area contains a number of important ecological environments.

Last year, the Federal Government made regulatory changes that formally recognise the significant impact of livestock grazing on the Australian Alps National Parks and Reserves National Heritage place under the EPBC Act.

The regulation specifies that grazing of domestic stock including cattle could have a significant impact on the heritage values of the Australian Alps Heritage Area and that any future new grazing activities proposed in the Australian Alps Heritage Area, including the Alpine National Park, need to be assessed under the EPBC Act.

"My decision is based on a thorough and rigorous assessment of the proposal, taking into account the advice of my department," Mr Burke said.

"I have accepted the advice of my department that the proposed action of reintroducing up to 400 cattle would have a clearly unacceptable impact on the listed national heritage values of the Australian Alps National Parks and Reserves National Heritage Place.

"The assessment has shown there is irrefutable evidence that cattle grazing would damage the sensitive natural environment, disturb the remote and wild character of the area, detract from aesthetic values, and erode its heritage values.

"While my personal views on this matter are known, in determining this decision I have considered only whether or not the proposed action would be in breach of the EPBC Act.

The Alpine National Park forms part of the Australian Alps National Parks and Reserves national heritage place that was listed on the National Heritage List to identify and protect the wide range of nationally significant natural and cultural values found within it. The parks and reserves extend over the Victorian, New South Wales and Australian Capital Territory borders and in total cover over 1.6 million hectares.

Wednesday, January 18, 2012

Scientists say the Draft Murray-Darling Basin Plan should be scrapped

The Wentworth Group of Concerned Scientists have called for the Draft Murray Darling Basin Plan, released last month, to be scrapped

They say the plan should be started afresh. Not throwing out all the work they've done - but they need to completely re-think what the plan is meant to be a plan of (water management, irrigation, environmental flows and so forth). It's not a plan yet and it won't do the job.

This is the next episode in the ongoing sad saga of planning for the Murray Darling Basin.

Previously - Mike Taylor quit as Chair of the Murray Darling Basin Authority, saying the government set impossible expectations that could not be delivered and were not in accordance with the Water Act. He had just released the Guide to the proposed Basin Plan, flagging "a long-term average increase of 7,600 GL/y (would mean) the environmental targets are all met and all catchments improve from their existing status to good flow levels".

The Minister then appointed former NSW Labor MP Craig Knowles as Chair. Shortly afterwards, Wentworth Group of Scientists who were consulting on the plan quit. They said the process itself was flawed and that a decision had already been made that the minimum flows required (4,000 GL/year) would not be met.

Knowles released the draft Basin Plan last month, which only provides for environmental flows of 2,750 GL/year.

The prospects for the Murray Darling have fallen a lot, as shown by:

2010 - Desirable 7600 GL/year
2010 - Probably target 4000 GL/year
2011 - 2750 GL/year - less 2600 GL/year removed from groundwater.

From the Wentworth Group of Scientists:

The draft Plan released for public comment by the Murray-Darling Basin Authority on the 28 November 2011 does not provide the most basic information required to allow anybody to make an informed decision on the future management of the water resources of the Basin.
The absence of this information makes it impossible for the community, science or Parliament to understand the implications or have confidence the Plan has any prospect of delivering a healthy working river:
  1. The Plan specifies a volume of water but it does not identify the volume of water required to deliver a healthy working river, as required by the Commonwealth Water Act;
  2. The Plan cites river management infrastructure as the limiting factor however there is no assessment of the feasibility or cost of redesigning river management infrastructure (such as periodically flooding paddocks or raising the height of a bridge) so that a healthy working river can be delivered;
  3. The Plan does not incorporate in the modelling the impact that increasing groundwater extractions by over 2,600GL will have on surface water flows, many of the groundwater systems in the Basin are linked to river systems;
  4. The Plan sets long term diversion limits on the assumption that there is no risk to river health from climate change; and
  5. There is no information presented on the effectiveness of the Plan to cope with long dry periods such as that experienced throughout the Basin during most of the last decade, or deliver the volumes of water required keep the Murray mouth open as a functioning (Ramsar listed) estuary and export the 2,000,000 tonnes of salt accumulating in the river system each year.

Details of their statement can be found here.

We'll probably be into the next drought within the next year or two. What will happen then? I do hope it is not too late for the Coorong and the red gum plains along the Murray.

Sunday, September 11, 2011

Will USA wake up soon that climate change is already here?

On the fires in Texas - like the 2009 fires in Victoria - more precautionary burning wouldn't have made much difference. And it would probably have been dangerous to attempt it any time in the past 12 months - too dry. From Jeff Masters:
As I reported in yesterday's post, there has never been a Texas summer hotter than the summer of 2011. The summer of 2011 now holds every major heat record for the city of Austin, including most 100° days (67 so far), hottest month in recorded history (August, breaking the previous record by a remarkable 2.1°), hottest summer (by 1.1°), and hottest day in history (112°F, tied with Sep, 5, 2000.)

As wunderground's weather historian Christopher C. Burt documents in his latest blog post, the situation is similar across the rest of the state. Seventeen major cities in Texas recorded their hottest summer on record in 2011. Most of these stations had records extending back more than 100 years, and several of the records were smashed by an amazing 3.4°F--at Lubbock and at Wichita Falls.

Neighboring states also experienced unprecedented heat, withOklahoma recording America's hottest month by any state in recorded history during July, and Shreveport, Louisiana breaking its record for hottest month by 3°F in August. Mr. Burt commented to me: " I do not believe I have ever seen a site with a long period of record, like Shreveport, where records go back to 1874, break its warmest single month on record by an astonishing 3°. This is unheard of. Usually when a site breaks its single month temperature record, we are talking about tenths of a degree, rarely a whole degree, let alone 3 degrees! Hard to believe, frankly."

Texas has also had its worst fire season on record, with over 3.5 million acres burned this year, and it's driest 1-year period in recorded history.

While people are trying to control the Texas fires, rain is pelting down elsewhere. More from Jeff Masters:
An extreme rainfall event unprecedented in recorded history has hit the Binghamton, New York area, where 7.49" fell yesterday. This is the second year in a row Binghamton has recorded a 1-in-100 year rain event; their previous all-time record was set last September, when 4.68" fell on Sep 30 - Oct. 1, 2010. Records go back to 1890 in the city.

The skies have now cleared in Binghamton, with this morning's rain bringing the city's total rainfall for the 40-hour event to 9.02". However, another large region of rain lies just to the south in Pennsylvania, and all of the rivers in the surrounding region are in major or record flood.

The Susquehanna River at Binghamton is at 25.18', its highest level since records began in 1847, and is expected to overtop the flood walls protecting the city this afternoon. In Hershey, Pennsylvania, Swatara Creek is 18' over flood stage, and more than 8' above its record flood crest. Widespread flash flooding is occurring across the entire area, and over 125,000 people have been evacuated from their homes.

And read the comments here on ClimateProgress for more about what rainfall records are being broken around the world.