A report published in this week’s issue of Nature offers the first ever comprehensive restructuring of 15,000 years of climate history in the Antarctic Peninsula, according to the British Antarctic Survey (BAS).
A team of polar scientists from Britain, Australia, and France revealed that the rapid warming of the Antarctic region over the last century has drastically accelerated any natural process of global warming that began 600 years ago—that is to say, by the time the Antarctic ice shelves were beginning to break up, they were already experiencing warmer temperatures. Apparently, global warming has only made matter worse, according to the team’s observations from the 1990’s onwards.
Reconstructing the climate history from an ice core collected from James Ross Island in the Antarctic Peninsula, scientists say the Antarctic Region is the most affected by global temperature increases. The BAS says temperatures from meteorological stations near James Ross Island indicate a two-degree Celsius increase in the past 50 years.
Lead author of the study, Dr. Robert Mulvaney OBE, of the BAS, says, “This is a really interesting result. One of the key questions that scientists are attempting to answer is how much of the Earth’s recently observed warming is due to natural climate variation and how much can be attributed to human activity since the industrial revolution.” This study adds to the enormous amount of scientific evidence backing global warming as the result of recent human activity. Dr. Mulvaney explains the role his research plays in the argument, saying, “The only way we can do this is by looking back through time when the Earth experienced ice ages and warm periods, and ice cores are a very good method for doing this.”
Dr. Mulvaney says, “We know that something unusual is happening in the Antarctic Peninsula. To find our more we mounted a scientific expedition to collect an ice core from James Ross Island—on the northernmost tip of the Peninsula.” Samples collected from this location should reveal how changes in global temperature effect what is one of the coldest regions on Earth.
By analyzing the amount of melt and snowfall in each layer of ice, scientists are able to look into the past for evidence of accelerated global warming. Until recently, global warming has been much more gradual. Dr. Mulvaney describes the process, saying, “Within the 364m long core are layers of snow that fell every year for the last 50,000 years. Sophisticated chemical analysis—at BAS and the NERC [National Environment Research Council] Isotope Geosciences Laboratory (part of the British Geological Survey)—was used to re-create a temperature record over this period.”
Dr. Mulvaney says the last comparable increase in temperature took 11,000 years, not 100— and even then, the temperature only increased by about 1.3 degrees Celsius. Additionally, Dr. Mulvaney said his team’s findings indicated a global cooling in the local climate, reaching a minimum 600 years ago, that expanded the ice shelves. Dr. Mulvaney says, “Approximately 600 years ago the local temperature started to warm again, followed by a more rapid warming in the last 50-100 years that coincides with present-day disintegration of ice shelves and glacier retreat.”
The BAS says the NERC funded the study, which makes a significant contribution to understanding the role Antarctica plays in the global climate. Study co-author, Dr. Nerilie Abram of the Research School of Earth Sciences at The Australian National University, adds, “The centuries of ongoing warming have meant that marginal ice shelves on the northern Peninsula were poised for the succession of collapses that we have witnessed over the last two decades. And if this rapid warming that we are now seeing continues, we can expect that ice shelves further south along the Peninsula that have been stable for thousands of years will also become vulnerable.”