The team is researching the effects of ocean acidification on tiny marine snails, known as pteropods, and planktonic, single-celled, shell-forming organisms called foraminifera. Pteropods are an important food source for marine predators in the Antarctic food web and sometimes replace krill as the dominant zooplankton group in parts of the Southern Ocean. Foraminifera are prey for many small marine invertebrates and fish. Both organisms are indicators of changes in the ecosystem that could have profound implications for commercial fish species, seals and whales.

About 40% of man-made carbon dioxide is absorbed by the Southern Ocean and forms a weak acid (carbonic acid) when it mixes with water. This acid readily releases hydrogen ions, and as acidity is determined by the concentration of hydrogen ions (measured on the pH scale), the more acidic a solution, the more hydrogen ions are present and the lower the pH. Increasing hydrogen ions affect the ability of pteropods and foraminifera to form shells, resulting in thinner, lighter, and pitted or etched shells. As colder water absorbs more carbon dioxide than warmer water, the effects of ocean acidification will be seen first in the Southern Ocean.  According to Dr John Baxter, a scientific advisor to government from the Scottish Natural Heritage who has joined ‘Team Acid’ on the ship, ocean acidity has increased by 30% (a pH change of 0.1) since the beginning of the Industrial Revolution and is already affecting shell-forming marine organisms. Observed effects include thinner shells, fewer pteropods in areas where they were previously common, and an increase in gelatinous organisms such as jellyfish and salps.

Team Acid is undertaking the first study of the effects of ocean acidification on pteropods and foraminifera in their natural environment (previous studies have been conducted in the laboratory or through modelling). ACE CRC pteropod biologist, Dr Donna Roberts, says the team want to establish a baseline of the health of these organisms in the ocean now, so that they can detect changes in the future.

Team Acid leader Dr Donna Roberts (right) and engineer Alex Pentony Vran

To do this they are deploying a ‘rectangular midwater trawl’ (RMT) – a pair of rectangular mesh nets – at different latitudes, from 47– 54°S, along a line from Hobart to Casey. They hope to catch larger pteropods with a 4 mm mesh net, but the main species they’re looking for is the tiny (0.5–1 mm) Limacina helicina antarctica, which will be caught in a 150 micron mesh net. The microscopic foraminifera will also be sieved from the water brought up in the trawl and preserved for later shell integrity analysis.

Team Acid will conduct seven trawls; three in subantarctic waters (45–49°S), two in polar waters (54–56°S) and one in the narrow channel of water where the subantarctic and polar waters meet (51°S). They expect to see a change in the shell weight, size and species of pteropods as we move further south into the colder and more acidified water, and hope to collect a good sample of the common Limacina helicina antarctica.

On the trawl deck the ship’s crew winch the two RMTs into the heaving seas. Each net has a ‘cod end’ attached to it – cylindrical canisters to contain the sample. The nets remain closed until they reach the required depth, between 20 and 200 m below the surface, at which time the team can remotely open the net to collect the sample.

Up in a control room above the trawl deck, the team hover around a pair of monitors displaying information about the temperature, depth, salinity and biomass as the nets descend. This information is relayed from a ‘CTD’ (conductivity, temperature, depth) instrument attached to the nets, and the ship’s acoustic echosounders, which can detect organisms in the water, such as swarms of krill or phytoplankton. When an area of high biomass is reached, dots and blobs appear on the screen and the team open the nets up.

Large Pteropod Clio Recurva

The team has chosen to sample between 20 and 200 m as this is the region where scientists think the pteropods construct their shells. This hypothesis is based on an analysis of pteropod shells collected in ocean sediment traps. These shells contained isotopes (different forms of molecules such as carbon and oxygen) typical of the water column at these depths.

Fifteen minutes after deployment, the RMTs are retrieved.  Team Acid and their accompanying paparazzi crowd into the ship’s ‘wet lab’ and begin bucketing and sieving through the samples. Both cod ends contain a glutinous mass of salps – ‘another bucket of snot’ as one crew member describes it – but this subantarctic sample also yields some surprises – about 12 large pteropods (Clio recurva) and six of the smaller Limacina helicina antarctica. A tiny squid, a large selection of amphipods (small crustaceans) and some translucent predatory worms called chaetognaths, also appear. The huge abundance of salps and other gelatinous creatures is typical of these waters. Some theories suggest an increase in salps is occurring, creating a ‘jellyfish ocean’.

Dr Roberts is surprised at the catch, saying she expected more of the smaller pteropods and less of the larger ones. It will be interesting to see if this trend continues.

At the seventh RMT site at 54°S, Team Acid hit the jackpot. One large Clio recurva shell and a whopping six small Clio pyramidata antarctica shells are captured. Dr Roberts wears a huge grin as she preserves the impressive specimens in ethanol.

The final RMT goes in at 58°S – inside waters managed by the Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR) – and pulls up an amazing array of species – a magnificent pelagic polychaete (worm), lots of amphipods, juvenile krill, ctenophores (small jellyfish-like creatures), two naked (shell-less) pteropods, small salps and some mysterious, gelatinous, eyeball-like spheres, which someone suggests could be fish eggs.  The naked pteropods are particularly interesting.  Scientific theory suggests that these may become the dominant pteropods in the ocean as ocean acidification increases.

Clio Pyramidata Antarctica

When they return to Australia, team member Alex Pentony Vran, an engineer from the Australian National University, will examine the mechanical properties of the captured pteropod shells to provide definitive evidence that they are becoming more fragile. Previous work has focussed on changes in shell weight and the use of optical microscopy to examine shell thickness. In contrast, Vran will take the shells captured on this trip, apply force to them with an extremely fine diamond-tipped probe, and measure their response to this force.  This will allow him to put a figure on how strong or weak the shells are.

The team has plenty of work ahead of them, but after five days of frenetic activity, they can now enjoy the voyage at a snail’s pace. 

Written by Wendy Pyper, editor of the Australian Antarctic Magazine
For more information, go to: www.aad.gov.au/magazine
Photos supplied by Keith Martin-Smith

For further research on ocean acidifcation, the references below are a great starting point.

For a summary of the issue of ocean acidification for policy makers:

• Howard W Sandford R Haward M Trull T (2008) ‘Position Analysis: CO2 emissions and climate change: ocean impacts and adaptation issues’ ACE CRC 16pp. http://www.acecrc.org.au/uploaded/117/797619_20pa02_acidification_0805.pdf

To read the first paper to demonstrate in nature (not a lab experiment or model) that ocean acidification is already having an impact on marine biota: 

• Moy, A.D., Howard, W. R., Trull, T. W., Bray, S., 2009. Reduced calcification in modern Southern Ocean planktonic foraminifera, Nature Geoscience, v. 2, p. 276-280, doi: 10.1038/ngeo460; http://www.nature.com/ngeo/journal/v2/n4/abs/ngeo460.html

To read an analysis of the policy challenges presented by ocean acidification, how they overlap and how they differ from climate change policy:

• Howard, W. and Sandford, R., 2008, Developing Ocean Acidification Policy, Australian Antarctic Magazine, Issue 15.
  

In 1998 the world saw its hottest year on record up to that point, as measured by average global air temperatures[1]. This has led some to falsely conclude that world has stopped warming ever since.  Global warming has not stopped.  Here are the facts. 

First, climate change (including global warming) is defined as long-term changes in the average parameters of the climate, not shorter year-to-year variability.  Air temperatures were somewhat cooler in the years following the extremely hot year in 1998, largely due to a natural effect called La Niña (see breakout box). But to say that this represents a halt to global warming is like saying that just because we have a cool summer day it is not summer any more. 

Second, when averaging over the decadal time scales that scientists use to study climate change, the past decade was not only warmer than historical averages, it was the hottest on record.  In fact, 8 of the 10 hottest years on record have occurred in the decade after 1998[2].

Finally, the atmosphere (air) in which we live contains only a very small fraction of the total heat associated with the surface of the earth.  The vast majority of the heat, about 85% of it is contained in the oceans, and observations show that ocean heat content has been rising over the past decade[3]. 

[1] World Meteorological Organization (2009) WMO Statement on the status of the global climate in 2008, www.wmo.int/wcc3/documents/1039_en.pdf

[2] World Meteorological Organization (2009) WMO Statement on the status of the global climate in 2008, www.wmo.int/wcc3/documents/1039_en.pdf

[3] Levitus, Antonov and Boyer (2005), Geophysical Research Letters, Vol 32, L02604, ftp://ftp.nodc.noaa.gov/pub/data.nodc/woa/PUBLICATIONS/grlheat05.pdf

Since carbon dioxide is an important greenhouse gas, one strategy that can partially combat global warming and climate change is to increase the amount of carbon stored in plants.  By increasing the amount of plant life on earth, or altering it to plant types that store the most carbon, more carbon dioxide may be pulled out of the air and stored for a period of time. 

Scientists call anything that removes carbon from the atmosphere a ’sink’.  In order to be effective in combating climate change, the sink must be large and the carbon must stay in the sink.  So what is important for climate change is not the amount of carbon exchanged between the atmosphere and plants, but how much carbon stays in the total forest and total grassland ’sinks’. 

Australia has 149 million hectares of forest.  Of this, 147 million hectares is native forest, dominated by eucalypt (79%) and acacia (7%), and 1.82 million hectares is in plantations[i]. Grassland covers around 440 million hectares of land in Australia[ii]. 

The size of the difference in the total carbon storage between grasslands and woodlands depends not just on the amount of land covered by the plants, but on the capacity of the individual ecosystems to store carbon, and the depth to which the carbon sink is tested.   The sinks can be the plant material above ground, below ground (roots), and soil that is enriched in carbon by dead plant material.

Based on data from typical perennial grasslands and mature forests in Australia, forests are typically more than 10 times as effective as grasslands at storing carbon on a hectare per hectare basis.

[i] Bureau of Rural Science, (2008) http://adl.brs.gov.au/forestsaustralia/facts/type.html

[ii] Australian Government, (2007), National Inventory Report Vol 2 Part g,  Department of Climate Changehttp://www.climatechange.gov.au/publications/greenhouse-acctg/~/media/publications/greenhouse-acctg/national-inventory-report-vol-2-part-g.ashx

Carbon in plants

Carbon is continuously exchanged between various elements of the earth: atmosphere, soil, ocean and life, which is predominately plant material.  The length of time it takes for the carbon to be exchanged depends on the process involved.  In the process known as photosynthesis, plants generate their own ‘food’ by absorbing carbon dioxide (CO2), water (H2O) and sunlight to create sugars.  Excess oxygen is released, and carbon is stored in the sugars and starches (particular combinations of carbon (C), hydrogen (H) and oxygen (O) in the plant material.

Forests

The amount of carbon taken up every year by dry forests in Australia depends on the weather conditions and age of the trees.  Science tells us that the range for forests with continuous canopies is about 0.5-2 tonnes of carbon per year for each hectare.  Grasslands may have a similar annual rate of net carbon uptake[i], but the long-term storage of carbon per hectare of grasslands is less than that over an average hectare in woody trees. 

In other words, over the long haul, more carbon stays in the tree sink than in the grass sink.  Some Australian native eucalyptus forests store up to ten times more carbon per hectare than Australian native and introduced grasslands – both above and below ground[ii]. 

The Co-operative Research Centre for Greenhouse Accounting has estimated that Australian forests store about 10.5 billion tonnes of carbon (excluding soil carbon)[iii].  This store of solid carbon has accumulated over an assumed life of 100 years for native eucalypt regrowth.  That translates to our forests storing an amount of carbon equivalent to almost 38.5 billion tonnes of gaseous carbon dioxide from the atmosphere, about 70 times Australia’s annual net greenhouse gas emission. 

Grasses

Using data from a study of semi-arid Australian grasslands by the Queensland Department of Primary Industry[iv] that accounted for the amount of live grass above ground found that about 5 tonnes of carbon could be stored per hectare of perennial grass year, assuming little grazing.  This compares to carbon stocks of mature dry sclerophyll forest that contain about 100 tonnes of carbon per hectare (with wide variability).  A recent ANU study assembling data from Australia’s unlogged, natural eucalypt forests concluded that kind of ecosystem may even hold an average of 640 tonnes of carbon per hectare[v].

So, in order for grasslands to have a greater carbon stock than an equivalent acreage of Australian forest, the roots of a summer pasture grass such as kangaroo grass, panic or weeping grass, would have to contain more than 10 times the mass of the grass that you can see above the ground[vi], which is not the case.

Soil carbon

Carbon can also be stored in the soil itself in the form of old organic matter.  Depending on the depth of soil investigated, the nutrient level of the soil and the availability of water, grassland soil can have either a similar or much lower amount of carbon than does the soil beneath forests.

As an example, studies done in 1999[vii] and again in 2005 show that reducing the amount of tree cover tends to decrease the amount of organic carbon in deep soil sinks[viii].  The 2005 study showed that about 1 metre underground, grassland sites contained only 25 tonnes of carbon in the soil per hectare compared with the soil in treed savannah sites, which stored 30 to 70 tonnes per hectare. 

The NSW Department of Primary Industry has compared soil organic carbon under perennial pasture in high rainfall areas in the mid-north coast of NSW to native hardwood forests within a 100km radius.  They found that for the high-rainfall areas studied, there was no significant difference between soil organic carbon in the pastures and native forests at 20 centimetres depth, with an average storage of 72.9 tonnes per hectare in the pasture versus 76.5 tonnes per hectare in the native forest sites[ix].

[i] Potter KN, Potter SR, Atwood JD and Williams JR, (2004) Comparing Simulated and Measured Soil Organic Carbon Content of Clay Soils for Time Periods Up to 60 Years, Environmental Management Vol. 33, Supplement 1, pp. S457–S461,  http://www.springerlink.com/content/8u6h76lr73p8eh6c/ 

Potter, K. N.; Torbert, H. A.; Johnson, H. B.; Tischler, C. R. (1999), Carbon Storage After Long-Term Grass Establishment on Degraded Soils, Soil Science: October 1999 – Volume 164 – Issue 10 – pp 718-725 http://journals.lww.com/soilsci/Abstract/1999/10000/Carbon_Storage_After_Long_Term_Grass_Establishment.2.aspx

Scurlock, J.M.O.; Johnson, K. and Olson, R.J. (2002). “Estimating net primary productivity from grassland biomass dynamics measurements”. Global Change Biology 8: 736. doi:10.1046/j.1365-2486.2002.00512.x, http://www3.interscience.wiley.com/journal/118961406/abstract?CRETRY=1&SRETRY=0 

[ii] Mackey BG, Keith H, Berry SL and Lindenmayer DB, (2008) Green Carbon – The role of natural forests in carbon storage, A green carbon account of Australia’s south-eastern Eucalypt forest, and policy implications, ANU E Press, http://epress.anu.edu.au/green_carbon/pdf/whole_book.pdf 

Keith H, Mackey BG and Lindenmayer DB, (2009), Re-evaluation of forest biomass carbon stocks and lessons from the world’s most carbon-dense forests, PNAS Early Edition,  http://www.pnas.org/content/early/2009/06/24/0901970106.full.pdf

[iii] Ximenes F, Robinson M, and Wright B, (2007) Forests, Wood and Australia’s carbon balance, Australian Government Forest and Wood Products Research and Development Corporation and Cooperative Research Centre for Greenhouse Accounting , http://www.plantations2020.com.au/assets/acrobat/Forests,Wood&CarbonBalance.pdf

[iv] Christie EK, (1981), Biomass and nutrient dynamics in a c4. semi-arid Australian grassland community,  Journal of Applied Ecology (1981), 18, 907-918, http://www.jstor.org/pss/2402381

[v] Mackey BG, Keith H, Berry SL and Lindenmayer DB, (2008) Green Carbon – The role of natural forests in carbon storage, A green carbon account of Australia’s south-eastern Eucalypt forest, and policy implications, ANU E Press, http://epress.anu.edu.au/green_carbon/pdf/whole_book.pdf 

[vi] CSIRO Sustainable Agriculture Flagship, (2009), An Analysis of Greenhouse Gas Mitigation and Carbon Sequestration Opportunities from Rural Land Use, edited by Sandra Eady, Mike Grundy, Michael Battaglia and Brian Keating, http://www.csiro.au/files/files/prdz.pdf

[vii] Boutton T W, Archer S R and Midwood A J 1999 Stable isotopes in ecosystem science: structure, function and dynamics of a subtropical Savanna. Rapid Commun. Mass Spectrom. 13, 1263–1277

[viii] Chen X, Hutley LB and Eamus D, (2005), Soil organic carbon content at a range of north Australian tropical savannas with contrasting site histories, Plant and Soil, Volume 268, Number 1 / January, 2005, http://www.springerlink.com/content/p0123502p0515w05/ 

[ix] McCoy D, Ky C, (2009) Australian Society for Soil Science Inc, http://www.asssi.asn.au/downloads/soils2008/Tu42%20107-G-McCoy%20et%20al.pdf

The world is at a crossroads.

We must contain and then reduce our greenhouse gas emissions so that our farmers, graziers and fishermen have the best chance to feed the world, and our industries have the best opportunities for sustainable growth and new green markets.

So that we – along with the rest of Earth’s inhabitants – are best able to flourish in good health, and the world’s poorest have the best opportunity for hope.

The leading climate scientists from the world over warn that we have about five years to avoid the dangerous climate change that would be generated if average global temperatures increase by more than 2°C above pre-industrial levels.

Australia will be one of the most affected regions in the world if we exceed this ‘guardrail’ temperature.

For example, regional climate change projections indicate that we are likely to see an increase in the frequency and intensity of wildfires (predominately in south-eastern Australia), an increase in the severity of cyclones, decreased rainfall (except in the far north), increased incidence of drought, and an increase in extreme temperatures. 

To avoid hitting the guardrail, annual global emissions must reverse from increasing every year, as they do now, to decreasing every year.

The globe has warmed by nearly 0.8°C over pre-industrial levels. Global temperatures will increase by another 0.5°C as the Earth continues to react to the emissions that we have already emitted in the atmosphere, much of which lingers there for a century or more.

Taken together, this means that climate change corresponding to a 1.3°C temperature rise is now ‘locked in’. Our previous actions have already placed us more than half way to the 2°C guardrail, and yet rather than putting our foot on the brake, we have it on the accelerator.

The greenhouse effect

The sun continuously bathes the Earth with energy in the form of sunlight. Much of this energy is absorbed by the Earth, and then emitted as infrared radiation, or heat. Greenhouse gases prevent the Earth from discarding as much of this heat as it otherwise would back into space.

Without naturally occurring greenhouse gases, the Earth would be a much colder place, inhospitable to modern human existence. But by the same token, the additional greenhouse gases added to this store by humans is slowly increasing the average temperature of the Earth system.

Due to the quantity in which it is emitted by humans, its longevity in the atmosphere, and its effects in trapping heat, carbon dioxide is the most important of the greenhouse gases currently causing changes in the Earth’s climate.

While the growth of human carbon dioxide emissions slowed in 2008, a slight reprieve attributed to the global financial crisis, they are still tracking above the worst-case scenario considered by the Intergovernmental Panel on Climate Change (IPCC) in their 2007 report.

In fact, atmospheric levels of the greenhouse gases carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) are higher now than at any time since modern humans have evolved.

Too much energy

This growing store of greenhouse gases, is leading to extremes in our weather and changing the long-term climate. Summers are becoming hotter, and droughts are longer and drier. The oceans are becoming more acidic. Sea levels are rising as glaciers melt and the warmer water expands.

If we do not act now, the newest and best science indicates that the average global sea level in 2100 will be 75 to 190 centimetres above 1990 levels, and continue to rise thereafter.

In Australia, extreme fire danger days are already becoming more numerous in many parts of the country, and floods and cyclones more intense.

Research by the CSIRO indicates that the frequency of days with very high and extreme Forest Fire Danger Index ratings is likely to increase by 15 to 70 per cent by 2050 in southeast Australia.

With much of Earth’s biosphere already ‘feeling the heat’, the Great Barrier Reef ecosystem is in grave danger both due to increased water temperatures, and increased acidification as the ocean absorbs some of the additional carbon we have placed in the atmosphere.

Changes have been observed in the breeding and migratory patterns of birds, fish and animals; and plant species have spread into latitudes that were previously too cold for them.

Reaching a limit

Why is limiting the average global temperature rise to 2°C so important?

The primary answer is it will be very difficult to adapt to and thrive in temperatures any higher.

As a single example, an increase of surface wind speed of 5 metres per second, made possible with a 1°C rise in ocean temperature, would double the frequency of Category 5 tropical cyclones.

In 2006 Cyclone Larry, a marginal Category 5 cyclone, devastated approximately 12,500 square kilometres around the far north Queensland town of Innisfail and destroyed the region’s banana industry.

Exceeding the 2°C guardrail will also reduce Earth’s limited ability to counteract some of the effects of climate change. If the temperature rise is 2.5°C or more, land ecosystems may emit carbon rather than absorb it, contributing to rather than acting as a buffer against climate change.

Already, the fraction of anthropogenic carbon dioxide that is absorbed by the ocean ’sink’ (a form of ‘free’ climate change mitigation) has decreased in last 50 years, for reasons that scientists are still studying.

Time is short

And why must we act quickly?

Calculations catalogued by the 2007 IPCC report tell us that if global temperature rise is to be kept between 2.0 and 2.4°C, then the ‘CO2 equivalent’ concentration, which is used as a combined measure of all Kyoto greenhouse gases, must not be allowed to exceed the range between 445 and 490 parts per million (ppm).

Current CO2 equivalent emissions are 455 ppm and rising.

To meet the 2°C guardrail target, we must halt increases in global CO2 equivalent emissions by about 2015, and then decrease them dramatically and steadily thereafter. 

Around the world, individuals, communities and nations are implementing effective strategies to do their part to effect this change. Australians have a leading part to play in demonstrating how this can be done even in a society known for having the highest carbon emissions per capita. But we need more shoulders at the wheel, because time is short and the clock is ticking – loudly.

This article can be found on the ABC Science website.

Moving the World -- Science and leadership before and after Copenhagen

Presentation Slides

Video Highlights:

In Copenhagen on March 10-12 2009, the International Alliance of Research Universities came together to discuss the latest international scientific consensus on climate change. The result was this report featuring six key messages and conclusions which detail how we must continue to address the increasing challenges posed by climate change into 2010 and beyond.

Climate Change: Global Risks, Challenges and Decisions

For further information, please visit: www.climatecongress.ku.dk

When Captain Cook was exploring the east coast of Australia, he had with him a very talented young botanist, Joseph Banks. Banks quickly realised that he was observing thousands of plant species that were obviously unique. He and Cook went home excited by all the different plants and animals they had seen during the expedition. Soon the whole of Europe was talking and speculating about the strange flora and fauna of Terra Australis.

Since then hundreds of species have become extinct in Australia, including at least 50 bird and mammal species and more than 60 plant species. Biologists have now listed all those plants and animals that they know are at risk of extinction in Australia. These are called endangered species. The list includes 19 species of fish, 16 frogs, 16 reptiles, 47 birds, 39 mammals and 612 plants.

There are two main threats to the continuation of species in Australia, and these threats have already caused extinctions. They are:

• Loss of habitat – this may result from climate change, activities of humans or natural events;
• the introduction of alien species which prey on and compete with native species for food and habitat.

Why does extinction matter?

A certain level of biodiversity is necessary to keep our ecosystems healthy. This is because each species performs a different function within an ecosystem. Extinction has always occurred; the important thing today is that the rate has greatly accelerated. This increased rate of extinction has already led to unstable ecosystems as well as to the loss of potentially useful species.

Can we prevent extinctions?

If we are aware of the problem and are concerned for our unique plants and animals, there is a good chance that we will, at least, slow the rate at which organisms are becoming extinct. For example, in 1994 when the ancient Wollemi pine was discovered, only 40 trees existed in its natural habitat. Since then, the Mount Annan Botanic Garden has grown hundreds of trees from seeds and cuttings and the plants are now grown commercially.

However, not all species under threat of extinction are being protected, nor is there sufficient funding to do so. Deciding how to allocate funds for threatened species programs is a difficult problem. The Australian Government Department of the Environment, Water, Heritage and the Arts is responsible for policy issues and running programs aimed at protecting threatened species in Australia.
More information on this topic is available on the Australian Academy of Science’s Nova: Science in the news at. Australia’s threatened species. A glossary, student activities and useful resources are also available.

Nova covers the science that makes news — the exciting, and often controversial, research that has the potential to revolutionise the world we live in. Nova, developed by the Australian Academy of Science, is a website you can trust to provide accurate and up-to-date information on science, health, the environment, mathematics and technology. You can register free of charge on Nova’s home page to receive an email whenever a new topic is added. Nova can be used by teachers planning lessons, students doing assignments, parents helping children with projects, librarians answering reference queries, journalists researching stories – and anyone who wants to keep up-to-date in science and technology.

Pollution, overfishing, coastal development and climate change are putting the world’s coral reefs under increasing pressure. With millions of people relying on them, how can science help make our reefs sustainable?

A healthy coral reef is a thing of beauty and a wonder to behold. Coral reefs make a great holiday destination but for many of the world’s people they are so much more. Approximately 500 million people depend on coral reefs for food, coastal protection, building materials and income from tourism. But this precious resource is under growing pressure and in serious decline.

19 per cent of the world’s coral reefs have effectively been lost and a further 15 per cent are seriously threatened with loss within the next 10 to 20 years. In some regions the losses are significantly higher.

And what is threatening our coral reefs? Basically it’s us and our activities. Overfishing, pollution, disease and habitat destruction are some of the direct threats, but overarching and interacting with these are a suite of more serious problems connected with climate change – warming oceans, ocean acidification and rising sea levels.

However, it’s not all bad news, especially in the short term. As scientists investigate how coral reefs bounce back after major disturbances (such as storms) they’re discovering that healthy coral reefs can have enormous resilience. While healthy, biodiverse reefs can be resilient to disturbances such as warmer water, multiple threats to reefs decrease their ability to bounce back. Through effective management of reefs and their catchment areas and by establishing marine protected areas we can reduce the threats to the reef and help make them sustainable. However, in the longer term, the future of the Great Barrier Reef and other reefs of the world will depend on international initiatives to curb carbon dioxide emissions.

The future of the world’s coral reefs is looking grim on many fronts, and climate change will certainly redraw the coral distribution maps of the world. As this century unfolds, unless we curb our greenhouse gas emissions and promote resilience in our reefs, corals are going to deteriorate to the point where we could lose them altogether

More information on this topic is available on the Australian Academy of Science’s Nova: Science in the news at Science for sustainable reefs. A glossary, student activities and useful resources are also available.

This topic is sponsored by the Australian Research Council Centre of Excellence for Coral Reef Studies

This author of this article is Nova Science in the News. Nova covers the science that makes news — the exciting, and often controversial, research that has the potential to revolutionise the world we live in.Nova, developed by the Australian Academy of Science, is a website you can trust to provide accurate and up-to-date information on science, health, the environment, mathematics and technology. You can register free of charge on Nova’s home page to receive an email whenever a new topic is added. Nova can be used by teachers planning lessons, students doing assignments, parents helping children with projects, librarians answering reference queries, journalists researching stories – and anyone who wants to keep up-to-date in science and technology.

The data shows that more and larger fires can be predicted if we cannot change the trajectories of global warming. The Chief Scientist will explore the ways in which science can help us predict the frequency of bushfire weather in the future, as well as avoid or adapt to more frequent and more intense fires in the future.

While bushfires are part of Australia’s natural environment, we can help damaged ecosystems so they adapt more quickly after fires by enhancing their resilience through ecological engineering.

Science can also help with human recovery – not only helping rebuild infrastructure and redesigning suburbs so that homes and other buildings are less at risk from bushfires, but also with the recovery of people after a fire. Both the physical and emotional scars left by bushfires are potent and debilitating. It is hoped that science can assist many on their long and difficult recovery from trauma.

The full speech can be viewed or listened to below:

Our future climate – living with fires now and into the future