Atmospheric scientists worldwide are seeking to save Australia’s involvement in a NASA-led global network of instruments that monitor microscopic particles called “aerosols”, which play an important role in cooling and warming the Earth’s climate.
When most people think of aerosols, their mind turns to fly spray or deodorant. But the term has a much broader meaning, covering any microscopic particle that can remain airborne for long periods. Think of household dust floating in a ray of sun through your window. It’s an aerosol. So is smoke, salt spray from the sea, ultrafine sand from beaches and deserts, ash from volcanoes, and the carbon soot emitted from car and truck exhaust pipes.
These aerosols sometimes give us blazing red sunsets. But they are also crucial in controlling the Earth’s climate, acting as both warming and cooling agents. Although, molecular gases like methane and carbon dioxide garner more attention for their strong warming effect.
A stark example of the role atmospheric aerosols can play is the 1991 eruption of Mount Pinatubo in the Philippines. The 20 million tonnes of aerosol ejected into the atmosphere by this eruption reduced average global temperatures by 0.5℃ for the following two years.
An important tool in the study of atmospheric aerosols is an international monitoring network, led by NASA, called the Aerosol Robotic Network AERONET. It consists of more than 450 monitoring stations across seven continents, including several sites in Australia.
AERONET’s data help atmospheric scientists worldwide to understand how aerosols influence both the global climate, and the daily weather at local scales. The importance of aerosols in the weather is twofold. In addition to affecting atmospheric heat balance, aerosols are also responsible for seeding the formation of clouds.
CSIRO’s reported plans to withdraw from AERONET has dismayed atmospheric scientists, both at NASA and in Australia. CSIRO chief executive Larry Marshall has reportedly justified his planned changes to the agency’s climate science program on the need to divert resources towards a focus on climate change mitigation and adaptation.
A shift in focus towards action is certainly admirable. As any rational citizen knows, climate change is a clear and present danger to our future, and the need for compelling action towards mitigation and adaptation is urgent.
Government action on climate change is highly encouraged by atmospheric scientists. But it’s dangerous to develop climate policies without reference to reliable, up-to-date environmental data on global temperature, carbon dioxide levels and aerosols, just as it would be foolhardy to develop national economic policy without reliable economic data on national debt, government revenue and expenditure, and unemployment figures.
Whether it’s the economy or the climate, without an eye on the data, how can one be sure that policy is having the intended outcome?
Aerosol tracking is vital
Aerosol data of the kind that AERONET provides are vital to the climate change mitigation and adaptation goals upon which CSIRO is now focusing its efforts. Here are two clear reasons why.
A key strategy to reduce greenhouse emissions is the widespread uptake of renewable energy sources, particularly solar energy. Australia, the sunburnt country, has enough sunshine to power not just our own population, but with future storage technologies, enough to export for national profit.
Aerosols have a significant influence on how much sunlight makes it onto the surface of a solar panel. Aerosol particles scatter and absorb the Sun’s rays, and they also help to form clouds which can reduce solar panels’ effectiveness. Thus having precise data on atmospheric aerosols in Australian skies is vital to maximising the output, efficiency and stability of our solar energy facilities.
The second reason involves adapting to climate change, rather than mitigating it. Australia’s agriculture industry is highly dependent on rainfall. Droughts and floods are highly damaging, and both are predicted to become more frequent and severe due to climate change.
Once again, aerosols’ role in cloud formation is a crucial factor here. Aerosols also affect the properties of existing clouds, such as droplet size, which in turn has a significant impact on rainfall.
Adaptation to changing rainfall patterns and climatic events such as El Niño are vital to continued output and growth in Australian agriculture. Reliable aerosol data – obtained in Australia, by Australia, and specific to the Australian atmosphere – are vital to making informed decisions about how to protect agriculture in the future.
These two examples – one focused on energy and the other concerning agriculture – show how two of Australia’s key economic sectors each rely on atmospheric aerosol monitoring. CSIRO has for many years played a major role in providing these data, and NASA is right when it urges CSIRO not to stop now.
More broadly, it’s vital to realise that climate monitoring and modelling, and mitigation and adaptation go hand in hand. We can’t build proper policy for action without reliable data and forecast models. The government certainly knows this when it comes to the national economy; the same holds when it comes to climate policy.
Surya Karthik Mukkavilli, OCE Scholar, Oceans & Atmosphere Flagship, CSIRO + PhD Candidate, School of Photovoltaic & Renewable Energy Engineering, UNSW Australia and Merlinde Kay, Senior Lecturer, School of Photovoltaic and Renewable Energy Engineering, UNSW Australia
Newborn sea turtles do not have it easy. Hatchlings take nearly eight days to dig through 40 centimetres of sand to emerge from their nests, and then need extra energy to traverse a long stretch of beach to the ocean.
However, new research suggests turtle hatchlings work together with clutch mates to escape their underground nests – and the more they team up, the less energy they waste.
Researchers from the University of Queensland and the Universiti Malaysia Terengganu set out to measure the amount of energy used by green sea turtle hatchlings to burrow from the nest to the beach surface.
Experiments were conducted in specially designed egg chambers that carefully mimicked natural beach-hatching conditions – down to the grain quality of the sand. The researchers observed that the combined digging of hatchlings significantly reduced individual energy consumption.
The findings, published today in the Journal of Experimental Biology, may influence sea turtle conservation efforts worldwide, especially the practice of splitting egg clutches.
All the eggs in one basket
Scientists have long known that bird flocks and schools of fish work together to save energy when moving around.
Researchers first suggested that turtles gave each other a hand as newborns more than 50 years ago. They called it ‘social facilitation’ but had limited empirical evidence on the question.
“No investigation has been done to explore how ‘social facilitation’ might influence the energy spent by individual hatchlings escaping the nest,” said Mohd Uzair Rusli, lead researcher on the project.
The experiments conducted by Rusli and colleagues showed that large groups of green sea turtle hatchlings used considerably less energy than smaller clutches to escape the nest.
“In a big group of more than 60 hatchlings, hatchlings only used 10% of their reserve energy to escape the nest as compared to the smaller group, which used more than half of their reserve energy.”
The findings may help us better understand the “nest escape” process for other underground nesting reptiles like lizards, snakes and crocodiles, he said.
The research was conducted in two sites with eggs collected from Chagar Hutang Beach, Redang Island, and Heron Island in Queensland. Special chambers constructed of PVC were kept at a constant temperature. All the sand used was sieved to ensure it was a medium sand grade. Pipping eggs (eggs where the hatchling has “pipped” their shell with their egg tooth prior to hatching) were randomly selected and buried in the chambers under a column of beach sand in groups of between 10 and 60 eggs. Researchers were able to determine when hatching occurred and measured energy expended by the hatchlings by calculating oxygen consumption.
Rusli said the study findings were crucial for sea turtle conservation worldwide and may encourage a reconsideration of a common conservation strategy of splitting natural clutches into smaller clutches for relocation.