Plants absorb more CO2 than we thought, but …

Plants doing the photosynthesis thing

A new study shows plants may absorb more carbon than we thought. Jason Samfield/Flickr, CC BY-NC-SA

By Pep Canadell, CSIRO

Through burning fossil fuels, humans are rapidly driving up levels of carbon dioxide in the atmosphere, which in turn is raising global temperatures.

But not all the CO2 released from burning coal, oil and gas stays in the air. Currently, about 25% of the carbon emissions produced by human activity are absorbed by plants, and another similar amount ends up in the ocean.

To know how much more fossils fuels we can burn while avoiding dangerous levels of climate change, we need to know how these “carbon sinks” might change in the future. A new study led by Dr. Sun and colleagues published today in PNAS shows the land could take up slightly more carbon than we thought.

But it doesn’t change in any significant way how quickly we must decrease carbon emissions to avoid dangerous climate change.

Models overestimate CO2

The new study estimates that over the past 110 years some climate models over-predicted the amount of CO2 that remains in the atmosphere, by about 16%.

Models are not designed to tell us what the atmosphere is doing: that’s what observations are for, and they tell us that CO2 concentrations in the atmosphere are currently over 396 parts per million, or about 118 parts per million over pre-industrial times. These atmospheric observations are in fact the most accurate measurements of the carbon cycle.

But models, which are used to understand the causes of change and explore the future, often don’t match perfectly the observations. In this new study, the authors may have come up with a reason that explains why some models overestimate CO2 in the atmosphere.

Looking to the leaves

Plants absorb carbon dioxide from the air, combine it with water and light, and make carbohydrates — the process known as photosynthesis.

It is well established that as CO2 in the atmosphere increases, the rate of photosynthesis increases. This is known as the CO2 fertilisation effect.

But the new study shows that models may not have quite right the way they simulate photosynthesis. The reasons comes down to how CO2 moves around inside a plant’s leaf.

Models use the CO2 concentration inside a plant’s leaf cells, in the so called sub-stomatal cavity, to drive the sensitivity of photosynthesis to increasing amounts of CO2. But this isn’t quite correct.

The new study shows that CO2 concentrations are actually lower inside a plant’s chloroplasts — the tiny chambers of a plant cell where photosynthesis actually happens. This is because the CO2 has to go through an extra series of membranes to get into the chloroplasts.

This means that photosynthesis takes place at lower CO2 than models assume. But counterintuitively, because photosynthesis is more responsive to increasing levels of CO2 at lower concentrations, plants are removing more CO2 in response to increasing emissions than models show.

Photosynthesis increases as CO2 concentrations increase but only up until a point. At some point more CO2 has no effect on photosynthesis, which stays the same. It becomes saturated.

But if concentrations inside a leaf are lower, this saturation point is delayed, and growth in photosynthesis is higher, which means more CO2 is absorbed by the plant.

The new study shows that when accounting for the issue of CO2 diffusivity in the leaf, the 16% difference between modelled CO2 in the atmosphere and the real observations disappear.

It is a great, neat piece of science, which connects the intricacies of leaf level structure to the functioning of the Earth system. We will need to reexamen they way we model photosynthesis in climate models and whether a better way exists in light of the new findings.

Does this change how much CO2 the land absorbs?

This study suggests that some climate models models under-simulate how much carbon is stored by plants, and in consequence over-simulate how much carbon goes into the atmosphere. The land sink might be a little bigger — although we don’t know yet how much bigger.

If the land sink does a better job, it means that for a given climate stabilisation, we would have to do a little bit less carbon mitigation.

But photosynthesis is a long, long way before a true carbon sink is created, one that actually stores carbon for a long time.

About 50% of all CO2 taken in by photosynthesis goes back to the atmosphere soon after through plant respiration.

Of what remains, more than 90% also returns back to the atmosphere through microbial decomposition in the soils and disturbances such as fire over the following months to years — what stays, is the land sink.

Good news, but not time for complacency

The study is a rare and welcome piece of possible good news, but it needs to be placed in context.

The land sink has very large uncertainties, they have been well quantified, and the reasons are multiple.

Some models suggest that the land will continue to absorb more carbon all throughout this century, some predict it will absorb more carbon up to a point, and some predict that the land will start releasing carbon — becoming a source, not a sink.

The reasons are multiple and include limited information on how the thawing of permafrost will effect large carbon reservoirs, how the lack of nutrients could limit the further expansion of the land sink, and how fire regimes might change under a warmer world.

These uncertainties put together are many times bigger than the possible effect of the leaf CO2 diffusion. The bottom line is that humans continue to be in full control of what’s happening to the climate system over the coming centuries, and what we do with greenhouse emissions will largely determine its trajectory.

The Conversation

Pep Canadell receives funding from the Australian Climate Change Science Program.

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


Taking a measured approach to CSG

CSIRO through the Gas Industry Social and Environmental Research Alliance (GISERA) is undertaking a comprehensive study of methane seeps in the Surat basin.

By Tsuey Cham

Our scientists are taking to the sky above the Surat basin in south-west Queensland to answer a big question – is coal seam gas (CSG) green?

Not literally green, of course: CSG is invisible to the naked eye. What we’re actually looking to determine is the CSG industry’s greenhouse gas footprint. The industry is set to increase production in Australia in coming years, so it’s important to be able to adequately monitor current and future CSG developments and provide information that will help limit any potential environmental impact.

One way to determine the CSG industry’s greenhouse gas footprint is by measuring methane seeps. Methane seeps occur naturally from underground, as well as in soils, swamps and rivers. Another key component is measuring fugitive methane – methane that leaks from CSG well heads, pipes and other infrastructure.  Initial findings show that fugitive methane emissions are lower in Australia than the US.

In south-west Queensland, the Surat basin is where CSG activities are in full swing, with its network of production wells, pipelines, access tracks and warning signs. With CSG development in the basin increasing over the next few years, we are trying to establish the amount – and source – of methane emissions now,  so that in the future we can determine what is attributable to natural sources, and what is attributable to CSG activity.

Taking CSG measurements.

A four wheel drive-mounted methane detector, with onlookers.

To do this, our scientist are using airborne sensors aboard helicopters to measure natural methane emissions. With this data in hand, they then calibrate and validate it with land-based sensors to identify how much methane naturally occurs from the ground.

Findings from this research will provide a methane emissions data set that can be used to compare against changes in methane emission as CSG production increases; and will add to the bigger picture of assessing the industry’s whole-of-life-cycle greenhouse gas footprint.

For more information, visit GISERA or our website.


Voting in swarms is all the buzz

By Emily Lehmann

There’s been a buzz around town about our bee research this year, and for good reason.

In a world first, we’ve been microchipping thousands of bees with tiny sensors in Australia and South America to monitor their activity and the way they interact with the environment.

Bee with backpack/

A bee. With a backpack. What of it?

We’ve called this ‘swarm sensing’ and it could help gather the information we need to find a solution to the mysterious and devastating decline of bees around the world.

While we’ve been buzzily strapping these tiny sensors on bees in the Amazon in collaboration with Vale Institute of Technology, there has been a swarm of attention around our work back home.

Swarm sensing hit the polls earlier this week, as one of five finalists in The Australian Innovation Challenge’s category for Environment, Agriculture and Food. And, it’s up to the people – that means you – to decide which one of these innovations deserves to win $5000.

Bee hive

These guys are an important link in the global food chain – and they need our help!

Now, if cute honey bees wearing mini, colour-coordinated ‘backpacks’, isn’t enough to sway your vote, then we’ve gathered a few hot facts about why this work is so critical to get you over the line:

  1. Around one third of the food we eat relies on bees for pollination. If bees are in danger, so is our global food supply.
  1. By aiding agriculture, honey bees earn an estimated $4-6 billion for Australia every year.
  1. Wild honey bee populations are dropping drastically or vanishing all together around the world. There are two major problems causing their decline: the varroa mite and the little understood Colony Collapse Disorder
  1. While there is a real risk, bees in Australia have not been affected by the Varroa mite or Colony Collapse Disorder.
  1. Parasites, pollution and pesticides are potential factors in the decline of honey bee populations.

To vote CSIRO, visit The Australian Innovation Challenge article and select ‘swarm sensing’ in the poll at the bottom of the page. Go on, #voteCSIRO and do it for the bees!


The other CO₂ problem

By Eamonn Bermingham 

Where would we be without the ocean? Swimming, surfing, snorkelling would be tough, not to mention all the yummy food we’d miss. But it has also played a more important role in all of our lives; fulfilling the noblest of causes.

For many years the ocean has been on the front line in the fight to slow down climate change, absorbing around a quarter of the carbon dioxide we produce. The problem is that the scars of this attack are beginning to show.

Ocean acidification is often referred to as the “other CO₂ problem”, and is a chemical response to the dissolving of carbon dioxide into seawater.

The equation is simple: as CO₂ in the atmosphere goes up (and there was a record-breaking increase in 2013), the pH of the ocean falls, with negative impacts on marine biodiversity, ecosystems and society.

Many species of fish - and the ecosystems that support them - could be threatened by ocean acidification.

Many species of fish – and the ecosystems that support them – could be threatened by ocean acidification. Image: flickr.com/psykedelic61/

But how bad is it?

For the past two years we’ve been working as part of an international team brought together by the United Nations to investigate the impacts of ocean acidification, and our findings have been released today.

The rate of acidification since pre-industrial times and its projected continuation are unparalleled in the last 300 million years, and are likely to have a severe impact on marine species and ecosystems, with flow-on effects to various industries, communities and food security.

We’ve estimated that the loss of tropical coral reef alone – such as the Great Barrier Reef – could end up costing a trillion US dollars a year.

A groundswell of scientific studies are providing us with more information than ever about the effects of ocean acidification.

A groundswell of scientific studies on the effects of ocean acidification are developing our understanding of the issue.

What does the future hold?

Ten years ago, only a handful of researchers were investigating the biological impacts of ocean acidification. Around a thousand published studies later, our understanding of ocean acidification and its consequences has increased tremendously.

Experimental studies show the variability of organisms’ responses to simulated future conditions: some are impacted negatively, some positively, and others are apparently unaffected.

If we are to truly understand the future impacts of ocean acidification, more research is needed to reduce the uncertainties, reduce emissions, and reduce the problem.

Read the full report: “An updated synthesis of the impacts of ocean acidification on marine biodiversity” 

The report was compiled by the UN’s Convention on Biological Diversity, an international team of 30 scientists.


Explainer: how ‘biocontrol’ fights invasive species

A picture of rabbits.

Rabbit numbers have been considerably reduced by the introduction of two viruses – Rabbit calicivirus and myxoma

By Louise Morin, CSIRO; Andy Sheppard, CSIRO; Tanja Strive, CSIRO.

Australia’s “ferals” — invasive alien plants, pests and diseases — are the largest bioeconomic threats to Australian agriculture. They also harm our natural ecosystems and biodiversity. Some, such as mosquitoes, also act as carriers of human diseases.

These invasive species cost Australian agriculture more than A$10 billion a year — more or less what states and territories spend on roads every year.

One method of controlling invasive plants and pests — known as biological control, or “biocontrol”— is to use their own enemies against them. These “biocontrol agents” can be bacteria, fungi, viruses, or parasitic or predatory organisms, such as insects.

To find biocontrol agents, we travel to the native home of invasive species and search for suitable natural enemies. After extensive safety testing, they are introduced into Australia.

But do they work?

Learning from the cane toad catastrophe

Cane toads, which were introduced in 1935 to control cane beetles in Queensland’s sugar cane crops, are probably the most infamous example of biocontrol going wrong in Australia.

But Australia’s borders were more open back then. To protect against such harmful mistakes, Australia now has world-leading biosecurity import regulations and an effective quarantine system.

To be allowed entry into Australia, a candidate biocontrol agent must be assessed using internationally-recognised protocols. This demonstrates that it will not pose unacceptable risks to domestic, agricultural, and native species.

A cost-effective solution

Other control methods, such as the use of poisons and mechanical removal, require continued reapplication. Many biocontrol agents of plants and insects, once established, are self-sustaining and don’t have to be reapplied.

Prickly pear is a perfect success story of biocontrol. The plant was introduced into Australia in the late 1770s and grown in a few areas of NSW and Queensland until it became invasive after rapidly spreading following the flood of 1893. Biocontrol was initiated in the early 1900s and the prickly pear moth, Cactoblastis cactorum, was introduced in 1926 from the pear’s native home in the Americas. Cactoblastis has been keeping prickly pear under control almost by itself to this day.

Cactoblastis moth larvae eating prickly pear

Cactoblastis moth larvae eating prickly pear

Since then, many more biocontrol agents have been introduced to control invasive plants. These include mimosa in our top end, bridal creeper in southern Australia, parthenium in Queensland and ragwort in Tasmania.

A series of cost-benefit analyses in 2006 revealed that for every dollar spent on biocontrol of invasive plants, agricultural industries and society benefited by A$23. This was due to increases in production, multi-billion dollar savings in control costs and benefits to human health.

Biocontrol has also proven to be the only effective way to significantly reduce European rabbits across Australia. Myxoma virus was released in 1950, followed by rabbit calicivirus in 1995, causing regular disease outbreaks in wild rabbits. Together, they have kept rabbit numbers well below the devastating pre-1950s levels.

It’s estimated that the benefit of rabbit biocontrol to agriculture is worth more than A$70 billion. This is the only example of a successful large-scale biocontrol program against a vertebrate pest anywhere in the world.

Bridal creeper.

The invasive plant bridal creeper affected by its rust fungus

The initial costs of biocontrol programs are generally high. That’s because we have to find suitable candidate agents overseas, test them for safety in quarantine, and comply with regulations around release.

But once biocontrol agents are released and affect the invasive species across its range, follow up control costs are greatly reduced.

Biocontrol is not a ‘silver bullet’

Biocontrol will not solve all problems to do with invasive species.

Weather and climate can affect biocontrol agents, like all living organisms. These two factors can slow and even stop the agents building-up to sufficient levels to control the invasive species.

In the case of the two rabbit viruses, virus-host co-evolution has led to a decline in effectiveness of the viruses over time as they lost virulence and rabbits developed resistance to them. This is similar to how bacteria can develop resistance to antibiotics. As a result, we must continue to search for ways to counteract these effects.

Like a multi-drug cocktail, biocontrol agents must often be used together to knock out an invasive species. And while biocontrol rarely completely eradicates an invasive species on its own, it may control it enough to be able to use other methods at a lower cost.

Picture of Crofton weed.

Crofton weed has overtaken hillsides of Lord Howe Island, but a new fungal disease will help control it.

And just because we use biocontrol, it doesn’t mean we don’t need good farm practices and land management, such as bush restoration, to ensure the recovery of ecosystems affected by invasive species.

Biocontrol is unlikely to be the solution where invasive species are very closely related to species that we value — cats, for instance. Feral cats have recently been in the media as the greatest threat to Australia’s mammals. But because they are the same species as the cherished family moggy, a biocontrol program would be highly controversial.

New biocontrol programs

The historic successes of biocontrol in Australia justify continued investment. For widespread invasive species, there are no alternatives as cost-effective that work across the vast landscapes where feral species roam.

For example, the European carp pest makes up 90% of the fish biomass in the Murray Darling river system. The most promising option being developed for large-scale control is the carp-specific koi-herpes virus that is in the final stages of testing (to make sure the virus only targets carp). Its proposed release in Australia will soon be open for public debate.

A picture of Carp fish

CSIRO has been testing in quarantine a new virus to control invasive carp.

Another case is the recent release of a rust fungus from Mexico for the biocontrol of crofton weed in eastern Australia. This invasive plant smothers grazing systems and natural ecosystems, including on the hillsides of Lord Howe Island, a World Heritage Area. The expectation is that this new highly-specific rust fungus will significantly contribute to control of this plant, the way other rust fungi have successfully done in the past against other invasive plants.

After 100 years of history in Australia, biocontrol should continue to have a bright future given it is the only approach that is environmentally-friendly, cheap and effective.

This article was originally published on The Conversation.


Holy sunbeams batman: Five places you never thought you’d see a solar panel

Garden gnome

Gnome-on-a-log… of course.

As the price of producing solar panels starts to fall and people are finding smarter, thinner and more flexible materials to create them, it seems like no place is safe from these sun sucking devices. Even the humble garden gnome is getting in on the act. To celebrate the arrival of spring and the advent of slightly warmer weather, we thought we’d share some of the more unusual places we’ve seen solar panels popping up.

Batmobile lawn mowers
If your dream is to own a batmobile, but you can’t afford it, then this might be the next best thing – a solar powered mower by Husqvarna. But at around $2k it might be cheaper to buy a goat.

Bikinis
If checking Facebook at the beach is that important to you a US-based designer is intricately stitching panels together in the form of a bikini so you can charge your iPhone on the beach.

Sun-powered cinema
In the UK, The Sol Cinema is a unique mobile cinema powered by the sun. It accommodates eight people and features a library of short videos, many with environment themes.

Catwalks
Last year the Chanel runway show at Paris Fashion Week featured a catwalk that looked like it was made from solar panels. Unfortunately it was more power dressing that power generating as the panels were fake, but it looked fancy.

 Magazine ads
Nivea broke new ground for advertisers last year when they launched a concept video featuring a solar panel in a magazine which you could use to charge your phone.

CSIRO is also working on new applications for solar panels and recently launched a printer that can print cells the size of an A3 sheet of paper. Read about some of the potential applications of this technology on the ABC news website.

 


The future of biodiversity is in our hands

Australia’s Biodiversity series – Part 12: Conclusions

When talking about the fate of biodiversity it’s easy to get bogged down in doom and gloom—we know that it’s in decline, that human populations and demand for resources continue to grow, and therefore the pressure we’re putting on other species is increasing, and that big gaps remain in our understanding of the biodiversity that’s out there.

Australia is developing a vast capacity for monitoring the natural environment through the Terrestrial Ecosystem Research Network. Image: Gregory Heath.

Australia is developing a vast capacity for monitoring the natural environment through the Terrestrial Ecosystem Research Network. Image: Gregory Heath.

But there are solutions. Since the concept of biodiversity first emerged in the 1980s, the science dedicated to understanding our natural systems has come a long way. With the emergence of new technologies it has become possible to find out far more about the species we share the planet with, and we can do it with far more efficiency.

It’s these big challenges and scientific solutions that we focused on in our book, Biodiversity: Science and Solutions for Australia. In the twelfth and final video in our Australia’s Biodiversity series, the book’s editors, Dr Steve Morton, Dr Mark Lonsdale and Dr Andy Sheppard, engage in a panel discussion about the future of biodiversity science in Australia:

You might like to read the concluding chapter of CSIRO’s Biodiversity Book to find out more about the scientific solutions that could help us address the big threats to Australia’s biodiversity.

And if you’ve been inspired to get more involved in the management of our biodiversity, there’s a lot you can do—even from your computer. Visit the Atlas of Living Australia to find out about volunteer opportunities.

You can find all the videos from our biodiversity series on our YouTube channel.


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