Podcast episode 08 - Published 17 August, 2017 by Nicholas O'FlahertyTweet
Beginnings of climate change science
Anthropogenic Climate Change, we’ve known about it for some time. Ironically, it was the search for the cause of ice ages in the past, that led 19th century scientists to a realization. The thinking had been that previous lower levels of carbon dioxide in the atmosphere had triggered ice ages.
In 1896, amidst his ice age research, Swedish chemist Svante Arrhenius calculated that human-caused CO2 emissions from the burning of fossil fuels, were large enough to cause global warming. But many scientists at the time dismissed his theory.
Later on, in 1938, English engineer Guy Callendar argued that the level of carbon dioxide was climbing, increasing global temperatures. And in 1956, Canadian physicist Gilbert Plass published a series of papers which made predictions about increases in (CO2) and resultant increases in temperature.
The Keeling Curve
But the pivotal moment came in 1961, when US scientist Charles Keeling produced ground-breaking data that showed carbon dioxide levels were rising steadily in what became known as the Keeling Curve. Two years later, the National Science Foundation of the United States used Keeling's research in its warning of rapidly increasing amounts of heat-trapping gases.
Since then, there have been numerous milestones in the science of climate change, too many to mention here. However, of particular significance was the establishment in 1988 of the Intergovernmental Panel on Climate Change, (IPCC). It’s a joint initiative of the United Nations and World Meteorological Organization.
Identifying the knowledge gaps
In 1990 the IPCC issued its First Assessment Report on Climate Change. It concluded, among other things, that it is highly likely that sea level has been rising over the last 100 years due to climate change.
It also highlighted the fundamental gaps in our understanding of the Greenland and Antarctic ice sheets, and how these impact sea level rise forecasts.
In particular, the IPCC called for better research into measuring the mass balance of these ice sheets. What that means is calculating the balance between processes that add ice to the ice sheets versus processes that remove ice.
It specifically recommended a polar-orbiting satellite equipped with a radar altimeter that could be operated to measure the changing height of the ice sheets on a continuous basis. This would lead to accurate assessments of the changing volume of both Antarctic and Greenland ice sheets, and therefore better forecasts for sea level rise.
ICESat, launched in 2003
By the late 1990s, NASA was working on exactly such a satellite. It was called the Ice, Cloud, and land Elevation Satellite, or ICESat.
Launched in 2003, over a six year period ICESat provided multi-year elevation data needed to determine ice sheet mass balance for both Antarctica and Greenland. It also provided topography and vegetation data from around the globe. In 2010, the ICESat satellite finally burnt up in a controlled re-entry.
ICESat-2, scheduled for launch in 2018
In anticipation of the ICESat mission coming to an end, NASA began development of a new satellite, ICESat-2. Scheduled for launch in 2018, ICESat-2 will carry a photon-counting laser altimeter that will allow scientists to measure the elevation of ice sheets, glaciers, and sea ice in unprecedented detail.
But what about that gap in time? The original ICESat stopped collecting science data in 2009; and ICESat-2 won’t be operational until sometime next year, 2018. How did NASA ensure that a continuous series of observations of the ice sheets was maintained without the satellite cover?
This week on The Antarctic Report podcast, we speak to John Sonntag. He’s the mission scientist for NASA’s Operation IceBridge.
The aptly named Operation IceBridge is providing that valuable continuity of data for land and sea ice measurements from the first ICESat satellite, through to the launch of ICESat-2 next year.
Since 2009, Operation IceBridge has utilized a highly specialized fleet of research aircraft flying over both Greenland and Antarctica. It’s the largest airborne survey of Earth's polar ice ever flown
More information can be found at: Operation IceBridge
Image: Operation IceBridge flight over Antarctica, credit: Michael Studinger, NASA