Ever Wondered? Episode 8
In Episode 8 of Ever Wondered?, Dr John Watt investigates how
scientists monitor changes in atmospheric gas levels and looks at
some innovative ways to reduce greenhouse gas emissions.
Using ice cores to map past greenhouse gas levels
NIWA's Dr Katja Reidel collects ice cores from Antarctica. She shows John some glacial ice that is about 1,000 years old.
The ice core has gas bubbles that form in winter and summer,
like the growth rings on trees. To collect the gases, Katja slices
through the core and places a sample in an ice grater. This breaks
up the ice, releasing the bubbles into an airtight container.
Liquid helium traps the gases. Katja analyses the ice for gas
levels and to find out the temperature at the time the ice formed.
This enables her to compare past CO2 levels with corresponding
Measuring gases at ground level
Baring Head is a NIWA monitoring station near Wellington. Gordon Brailsford explains how the air arriving at Baring Head originates from the Southern Ocean. It hasn't been over land for 5-10 days, so it's not influenced by human activities. Baring Head began measuring CO2 in 1972 and has the longest continuous CO2 measurements in the Southern Hemisphere. Their data shows a steep rise in CO2 levels, fitting global trends.
Measuring gases at the atmospheric level
John visits a second NIWA monitoring station at Lauder, Central
Otago. Dr Vanessa Sherlock explains a new technique for measuring
greenhouse gases. The technique, total column measurement, uses a
telescope that points at the centre of the Sun. Individual
greenhouse gas molecules absorb sunlight in a unique way. By
splitting the sunlight into its full spectrum, she can see which
parts of the spectrum are missing, giving her very precise gas
Using phytoplankton as a carbon sink
Dr Cliff Law found that adding iron oxide to seawater promotes phytoplankton growth - microscopic plants capable of absorbing huge amounts of CO2. When phytoplankton dies, some of it sinks to the ocean floor, locking the carbon away for hundreds of years. Companies selling carbon credits are interested in Cliff's research. However, decaying phytoplankton produces nitrous oxide and methane, so Cliff is now investigating the overall effect of adding iron to seawater.
Reducing methane emissions
John moves inland, visiting the Agricultural Gas Research Centre in Palmerston North. Dr Harry Clark explains that each dairy cow emits 90kg of methane per year. The yearly emissions from a single cow have a CO2 equivalent of 860 litres of petrol. Demand for milk and meat means we can't eliminate animals but we can reduce the amount of methane they produce. Dr Gerald Cosgrove shows John test facilities that mimic animal digestion. He tests various plant materials to find correlations between food sources and methane production.
Dr Kerry Hancock is an AgResearch scientist also working to reduce animal methane emissions. Kerry's research involves genetically engineering white clover to produce condensed tannins, chemicals that decrease digestive methane in cows by up to 15%. Because of New Zealand's strict regulations regarding genetically engineered plants, field trials involving white clover take place offshore.
In conjunction with this episode of Ever Wondered?, your students may enjoy these activities.
In this activity, students interpret graphs using actual CO2 and
12C data from the Baring Head monitoring station.
Students explore this interactive diagram to learn more about the carbon cycle. Short video clips and images explain different parts of the cycle, including phytoplankton's role in sequestering carbon.
To further investigate climate change, check out these Science Learning Hub contexts.
Icy-Ecosystems: In this context, you'll find
research articles and videos of Dr Katja Reidel explaining how she
uses ice cores to learn more about climate change.
The Ocean in Action: In this context, you'll
find research articles and videos detailing the work of New Zealand
scientists in relation to CO2 in the atmosphere and the