In the past week or so I have been reading a few articles and social media posts on the subject of Antarctica gaining ice mass. The articles are talking about information from a study released by NASA in 2015 showing that snowfall on the Eastern part of the continent is more than enough to offset the melting of glaciers in the West. The social media posts have been talking about how this proves that climate change was a hoax all along. After all, how can sea levels be rising from glaciers melting if Antarctica is gaining mass year after year? I took some time to research the issue and read the actual study and today I thought I would take some time and write a few paragraphs to help set the record straight on this topic.
The study in question
In 2015 a study was published by NASA, the lead author was Jay Zwally, a glaciologist with NASA Goddard Space Flight Center. The study showed evidence that Antarctica had experienced a net gain of 112 billion tons of ice annually between 1992 and 2001 and a gain of 82 billion tons annually between 2003 and 2008. This information was not at all in line with previous findings on the subject which insisted that Antarctica has been losing ice mass because of global warming.
These new findings were based on data that came from studying changes in the surface height of the Antarctic ice sheet using radar altimeters. The data was collected using two European Space Agency European Remote Sensing satellites and NASA’s Ice, Cloud, and land Elevation Satellite.
Basically, the study shows that gains in snowfall in East Antarctica are more than enough to offset the losses from melting glaciers on the West side of the continent. These gains were not just in recent years but had been the result of increased snowfall over the past 10,000 years or since the last ice age. The study goes on to say that sea levels cannot be rising because of glaciers melting in Antarctica because its actually gaining ice.
Seems simple enough right? If the southern ice cap isn’t losing ice but is instead gaining mass then maybe this global warming thing isn’t so bad. Well, sadly that is just not the case. The study would turn out to not be accurate.
Issues with the study
This information came as a bit of a shock. After all the International Panel on Climate Change had been releasing reports for a long time stating that Antarctica has been losing mass and causing sea levels to rise. With this study saying the opposite it’s clear that somebody had to be wrong. With that in mind, the scientific community was cautious with this new information.
Since 2015 scientists have had a chance to look over the data and have had time to do a few follow-up studies and the results are clear.
It is agreed among scientists studying the situation that the Eastern area is gaining a lot of ice due to thousands of years of continued snowfall. However, measuring the size of that gain can be difficult at best. The major issues with Zwally’s study are that it used altimeter data from satellites, which is subject to systematic errors such as snowpack penetration and telling the difference between snow that is on the ground and snow that is still falling. Also, in order to calibrate their measurements, Zwally’s team bounced lasers of the Southern Ocean which may not have been reliable.
Follow up studies
In a study published in 2017 scientists were able to combine information from satellite altimetry, gravimetry, and GPS to measure the ice balance in East Antarctica from 2003-2013 When looking at this data they were unable to confirm Zwally’s findings. This study concluded that gains in East Antarctica are smaller than losses in West Antarctica. In fact, the gains in East Antarctica were about a third of what Zwally’s study believed them to be.
The graph below is from information in another study done in 2018 and it shows the change in the rates of ice sheet loss over the years. You can see that the line for East Antarctica did show a positive rate of change for much of the past few decades. However, it was not enough to offset the losses in West Antarctica and the Antarctic Peninsula. We can clearly see that when these numbers are put together the continent is losing a lot of ice every year. Furthermore, the rate of loss is getting worse as time goes by.
Even with this information further study is still needed. In order to fit that need on September 15, 2018, NASA launched the Ice, Cloud and land Elevation Satellite-2, or ICESat-2. This satellite will use the Advanced Topographic Laser Altimeter System, or ATLAS to measure the height of the ice sheets in Antarctica and Greenland. It will accomplish this by firing 10,000 laser pulses per second toward the surface of the Earth and timing how long it takes for the pulses to get back to the satellite. This will collect a large amount of altimeter data that is accurate enough to estimate height changes within 4 millimeters.
What we know
When we look at all the available data the big picture becomes clear. Antarctica is losing far more ice than it’s gaining and the rates of loss are increasing as time goes on. In short, climate change is real and always has been.
But the truth is that Zwally’s findings never contradicted climate change. The International Panel on Climate Change (IPCC) stated in its report that a certain amount of sea level rise was due to the ice melting from Antarctica. Zwally’s finding didn’t dispute rising sea levels it just pointed out that the source may not be Antarctica.
Even Jay Zwally himself had this to say in an interview with Scientific American
“When our paper came out, I was very careful to emphasize that this is in no way contradictory to the findings of the IPCC report or conclusions that climate change is a serious problem that we need to do something about,”
In another article, he said “I know some of the climate deniers will jump on this, and say this means we don’t have to worry as much as some people have been making out,” he said. “It should not take away from the concern about climate warming.”
The 2015 study was never meant to challenge people’s opinion of climate change but it did represent the best information available at the time. For this reason, the study was worth publishing. The information we have today is much more accurate and I have to think its because of the 2015 study.