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Atmospheric Measurements at Mauna Lao & Cape Grim

Cape Grimm

Atmospheric Measurements at Mauna Lao & Cape Grim

An Antipodean travel company serving World Travellers since 1983

Carbon Dioxide Measurements at Mauna Lao and Cape Grim

In May 2013, the Mauna Lao Observatory in Hawaii recorded an historic milestone.  Carbon dioxide (CO2) levels in the atmosphere had exceeded 400 parts per million (ppm) for the first time in 55 years of measurement – and possibly in the last 15 million years. Then three years later, an isolated scientific outpost at Cape Grim, north-west Tasmania, recorded the same measurement for the first time in the Southern hemisphere. A sombre reminder of the effects of human behaviour on the atmosphere was laid out in data for all to see.

The Mauna Lao Observatory and Cape Grim are two of the premier Baseline Air Pollution Stations in the World Meteorological Organization-Global Atmosphere Watch  (WMO-GAW) network. Baseline stations are defined by the WMO to meet a specific set of criteria for measuring changes in greenhouse gases (GHGs), ozone depleting gases, and aerosols in clean air environments.

Changes in Earth’s atmospheric composition are a serious cause of concern for humanity as they impact weather and climate, human and ecosystem health, water supply and quality, agricultural production, and many socio-economic sectors.  The most pressing of the related problems include climate change, the hole in the ozone layer, and urban air pollution. By studying the variability and trends in atmospheric composition and its consequences, stations such as those at Mauna Lao and Cape Grim are able to advance critical scientific understanding to address these challenges.

Mauna Loa Observatory

The Mauna Loa Observatory has been monitoring and collecting data relating to climate change, atmospheric composition, and air quality in the northern hemisphere since 1958. Today it is especially known for its continuous monitoring of atmospheric carbon dioxide concentrations. Indeed, Mauna Loa is the world’s oldest continuous CO2 monitoring station and the world’s primary benchmark site for measurement of the gas. These measurements  are displayed in a graph known as the “Keeling Curve”, named after Charles Keeling, the American scientist who started the project and the first to report that the levels of CO2 in the atmosphere were consistently rising on Earth

The Observatory is located on the north flank of Mauna Loa Volcano, the world’s largest active volcano, on the Big Island of Hawaii. This is a prime location for sampling Earth’s uncontaminated background air as it is remotely situated in the Pacific Ocean, far from the continent. Also being high, approximately 3,400 metres (11,141 feet) above sea level, the observatory protrudes through the inversion layer, which separates the more polluted lower portions of the atmosphere from the much cleaner free troposphere. This all means the air is relatively clean making it easier for scientists to study.

Aerial view of the crater of the Mauna Loa volcano on Big Island, Hawaii

Cape Grim

The Cape Grim Baseline Air Pollution Station was established by the Australian government in 1976 to monitor and study key atmospheric gases driving long-term climate change and ozone depletion. It originated in response to the United Nations Environment Program (UNEP) calling for global governments to work together to set up a network of monitoring stations in the early 1970s.

Cape Grim was chosen as a site representative of the mid-latitudes of the Southern Hemisphere positioned just south of the isolated north-west tip of Tasmania (Woolnorth Point). This is an important site as it takes advantage of the “roaring forties” – the prevailing westerly winds that bring clean air over long trajectories over the Southern Ocean to the station under conditions described as ‘baseline’ having had no recent contact with land. This represents true background air, uncontaminated by regional pollution sources, perhaps some of the cleanest in the world.

Suicide Bay at Cape Grim with Trefoil Island in the distance / Ian Cochrane / CC BY 2.0

What Do These Stations Measure?

Both stations measure elements in the atmosphere that contribute to climate change on Earth. All major and minor greenhouse gas concentrations are measured, including carbon dioxide, methane, nitrous oxide and synthetic GHGs such as hydrofluorocarbons, perfluorocarbons, and sulfur hexafluoride. Most GHGs have shown continuous increases in atmospheric concentration since measurements began.

These measurements are important as increasing GHGs in the atmosphere leads to climate change. Trends that are identified in the measurements are used to drive climate change models and identify processes that influence changes to the atmosphere. They also help to predict how the climate will change under different scenarios of future GHG loading.

Chemicals which deplete the ozone layer are also measured, including chlorofluorocarbons (CFCs) and halons, which are themselves some of the most potent GHGs. This data is critical because the ozone layer protects us from harmful radiation produced by the sun’s ultraviolet rays. Owing to a ban on their production under the Montreal Protocol developed to protect the ozone layer, the data has shown that these chemicals are now in decline.

Air pollutants including natural and anthropogenic aerosols (particles such as sea salt, mineral dust and black carbon) and reactive gases are also measured along with weather and climate indicators like wind speed and direction, rainfall, temperature, humidity and solar radiation.

Data from the two stations is freely available from major global data archives and has underpinned hundreds of scientific papers as well as numerous international assessments on global emissions of GHGs and ozone depleting gases. It has also been used to inform key international policies, such as the Montreal Protocol to protect the ozone layer and the Paris Agreement to reduce GHGs.

Rising Carbon Dioxide Emissions

Perhaps most notable of all measurements is that of CO2 concentration. Both stations show a steadily increasing trend of CO2 measurements from year to year, combined with a seasonal cycle saw-tooth effect that is caused by changes in the rate of plant growth.

At Cape Grim CO2 levels have increased by 25% since the first measurements began in 1976, from 329 ppm to 410 ppm as of October 2020. Moana Loa meanwhile reached an all-time high of 418 ppm in June 2020 up from 315 ppm in 1959.

Atmospheric carbon dioxide concentrations at Mauna Loa, Hawaii since 1958 (plot in English) / Delorme / CC BY-SA 4.0

Atmospheric CO2 is now higher than at any time in the previous 200,000 years of human history. Even more sobering are the studies that show that CO2 levels may had not previously risen over 400 ppm in the last 15 million years. The higher level of this planet-heating gas is just one part of the problem. The other is the speed of the changes, more than a hundred times pre-human times, and faster than ecosystems can adapt to.  Currently levels are growing 2.5 ppm on average annually.

The measurements suggest that although CO2 levels in the atmosphere had been increasing since pre-industrial times, the rate of CO2 emissions has accelerated steadily since the Industrial Revolution began in 1750.

This increase is principally caused by human activities such as fossil fuel consumption, deforestation, and various agricultural practices. Levels are now 50% higher than in 1750 and the pace of the build-up has been quickening too: half of the rise is CO2 levels since the beginning of the industrial period has occurred since just 1980.

Scientists calculate that emissions must fall by half by 2030 to give a good chance of limiting global heating to 1.5C, beyond which hundreds of millions of people will face more heatwaves, droughts, floods and poverty.

But, if fossil-fuel burning continues at a business-as-usual rate, humanity will exhaust reserves over the next few centuries, and CO2 levels will continue to rise to levels over 1500 ppm. If this happens, the atmosphere will not be able to return to pre-industrial levels even tens of thousands of years into the future.

Eucalypt Dieback in Western Tasmania

A poignant impact of the chemical changes that we as humans are collectively making to the atmosphere is occurring In Tasmania’s north-west, the region where Cape Grim is located. Climate change and the increase in the intensity and frequency of draught is a major cause of Eucalypt trees dying in the region.

As the climate changes species ranges are shifting. Extinctions could occur when species are unable to keep pace with the rate of climate change or are unable to migrate across highly fragmented landscapes. Tree species are among the first to feel the impact of climate change: the long life cycles and typically short dispersal distances result in slow responses to change.

In north-west Tasmania insects such as weevils – more abundant and more widely distributed because of the changing climate – are devouring the leaves of the eucalypts. Usually if a eucalypt loses its crown it will recover by shooting out fast, new growth. However, recent years of drought have led to such high levels of water stress in the trees that they are running out of stored energy needed to flush out new growth and thus succumbing to death.

Impacts such as this, as well as data collected from Cape Grim, Moana Lua and other stations, invite people to take notice, reflect on the transformation that is happening in the wrong direction, and resolve to reverse these trends.

Dead trees add flashes of white to a green hillside in Cradle Mountain – Lake St Clair National Park, Tasmania.

Tour of Tasmania

Odyssey visits Tasmania as part of two of our small group tours for mature and senior travellers in Tasmania led by a local tour guide chosen for their local knowledge. Wildlife-rich destinations are found at regular intervals along the route of our 16-day tour of Tasmanian Wilderness. On this tour, we provide the opportunity to observe a variety of endemic species combined with dramatic scenery at the places we visit such as the Gordon RiverCradle MountainLake St Clair, the rugged South East coast, the South West coast, and Mount Field National Park. Meanwhile senior singles, couples and small groups of friends interested in history and historic sites will find the itinerary of our 19 day guided tour of colonial Tasmania suited to their needs for a great Tasmania holiday package.

Articles about Tasmania and Australia published by Odyssey Traveller:

For all the articles Odyssey Traveller has published for mature aged and senior travellers, click through on this link.

External articles to assist you on your visit to Tasmania:


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