CO2 is trending: See the latest atmospheric concentrations data on Twitter

By Sophie Schmidt

28 February 2020

5 minute read

aerial view of the cape grim station on a cliff on the coast where we measure co2 emissions data

The Cape Grim Baseline Air Pollution Station in Tasmania

As your national science agency, we get lots of questions each month about climate change and greenhouse gases (GHGs). Like ‘what’s the latest carbon dioxide count?’

Our researchers collect important data on greenhouse gases from our own monitoring station. That data gets published each month on our website. So, we’re well equipped to answer the question!

The data we collect includes current levels of atmospheric concentrations of GHGs like carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O). They’re used by researchers around the world, including ours, to help understand climate change and our world.

But you might not be following that page, and even if you’re not a researcher, it’s information you might like to know.

So, this year, we’ll be publishing our CO2 observations in an even more accessible format. On Twitter. We’re calling it our #CapeGrimCO2update.

Keeping watch at Cape Grim

Hold up – where does this super important CO2 data come from? We capture the data at the Cape Grim Baseline Air Pollution Station in Tasmania. This location is bathed in some of the cleanest air in the world.

The Cape Grim station is just south of the isolated north-west tip (Woolnorth Point) of Tasmania. Amid the ‘roaring forties’, its location is as remote as it sounds.

Prevailing westerly winds frequently bring air masses that have travelled many thousands of kilometres across the Southern Ocean.

This means the ‘baseline air’ measured at Cape Grim has a composition representative of much of the Southern Hemisphere. And it’s as clean and free from recent human and terrestrial (natural) influences as anywhere on the planet.

That’s part of the reason the station is one of only three Premier Global Baseline Stations in the World Meteorological Organisation’s (WMO) Global Atmosphere Watch (GAW) program. And it’s the only one in the Southern Hemisphere. Together with Mauna Loa Observatory in Hawaii and Alert in the Canadian Arctic, these stations span the globe and monitor underlying global composition change. Cape Grim has been doing this since 1976 together with the Bureau of Meteorology.

Why is CO2 trending?

This is the part we’re keen to tell you about. Global average GHG concentrations have been trending upwards since the Industrial Revolution in the mid-18th century.

From our Antarctic ice core measurements, we know CO2 levels in the atmosphere were stable at around 278 parts per million (ppm) for millennia.

When measurements commenced at Cape Grim in 1976, CO2 concentrations had already risen to 328 ppm. They have been accelerating ever since, increasing almost 25 per cent over the past four decades to reach 408.3 ppm in January 2020.

Graph showing atmospheric carbon dioxide concentrations (in ppm) over the last 2000 years

The atmospheric carbon dioxide concentrations (in ppm) over the last 2000 years, based on measurements of air trapped in Antarctic ice and firn (the compacted snow layer that eventually forms solid ice), shown in blue-grey diamonds, and the modern Cape Grim in situ record, shown in orange.

The measured increases in CO2 and other GHGs (such as CH4 and N2O) are predominantly caused by human activities. This includes fossil fuel use, land clearing and various agricultural practices which emit GHGs.

Our future climate depends on if, when and how rapidly the world manages to reduce GHG emissions.

What about those wiggles?

The long-term trend of rising CO2 concentrations tells the story of ever-increasing human GHG emissions.

Chart showing Cape Grim monthly mean CO2 from 1980

But you can also see gentle wiggles in the Cape Grim baseline CO2 record, with an amplitude of about 1 ppm. Those wiggles are the natural seasonal cycle. Plants take up CO2 through photosynthesis most strongly during the warmer, wetter parts of the year, beginning in spring and lowering the average CO2.

After summer, when conditions tend to be drier and cooler, ecosystem respiration dominates, releasing CO2 back into the atmosphere.

So, the wiggles are a seasonal cycle, but the overall trend is relentlessly upwards.

Breathe easy – we’re helping to tackle climate change

Cape Grim CO2 data are available from major global data archives. Although we’re launching a new update format on Twitter, there won’t be any change to the way we release the latest GHG data on our website.

These data are already serving a vital purpose in global climate research. They are widely cited in international assessments of climate change, including reports by the World Meteorological Organization and the United Nations.

We also incorporate these data into our own climate and weather models. These models equip decision-makers with tools to navigate future climate impact and adaptation.

Follow the latest updates

To track the latest CO2 measurements, head to @CSIRO on Twitter and follow #CapeGrimCO2update. Or you can bookmark the page on our website.

We’ll keep publishing the latest CO2 data midway through each month. This will be after we’ve completed our regular analysis from our baseline monitoring station at Cape Grim. Our monthly update will include the previous month’s data as a comparison point, as well as historic carbon dioxide levels dating back to the ‘70s.

Chart showing Cape Grim monthly PPM compared to key historic dates

Here’s what our monthly tweet will looks like. If you have any suggestions about what you’d like to see, we’re keen to hear your thoughts.