Sometimes you read good news, sometimes you read the not-so-good news. This time, it’s unfortunately the latter. According to research led by Ohio University professor Ryan Fogt and OHIO alumnus Kyle Clem, the South Pole has been warming more than three times the global average over the last 30 years.
With an international team of scientists, Fogt and Clem coauthored a paper and published the findings in the journal Nature Climate Change. This study stated that the warming period was mainly driven by natural tropical climate variability and was likely intensified by increases in greenhouse gas.
“I’ve had a passion for understanding the weather and fascination of its power and unpredictability as far back as I can remember,” said Clem, who is currently a postdoctoral research fellow in climate science at Victoria University of Wellington in New Zealand.
“Working with Ryan I learned all about Antarctic and Southern Hemisphere climate, specifically how West Antarctica was warming and its ice sheet was thinning and contributing to global sea level rise,”
“I also learned that Antarctica experiences some of the most extreme weather and variability on the planet, and due to its remote location, we actually know very little about the continent, so there are constant surprises and new things to learn about Antarctica every year,” said Clem.
Climate in the Antarctic shows some of the largest ranges in temperature during the course of the year and some of the largest temperature trends on the planet, with strong regional contrasts.
West Antarctica and the Antarctic Peninsula experienced warming and ice sheet thinning during the late 20th century. In contrast, the South Pole (which is in the continent’s interior part and at its high altitude) has warmed substantially since the 1980s.
These things happen because of natural and anthropogenic climate change, but the individual contribution of each factor is not well understood.
Clem and his team analyzed weather station data at the South Pole, as well as climate models to examine the warming in the Antarctic interior. Turns out that between 1989 and 2018, the South Pole had warmed by about 1.8 degrees Celsius (35F) over the past 30 years.
The rate is +0.6 degrees Celcius (33F) per decade, which is three times the global average.
Additionally, this study found that the increasing warming over the Antarctic interior in the last 30 years was mainly driven by the tropics, especially warm ocean temperatures in the western tropical Pacific Ocean.
Tropical ocean changed winds in the South Atlantic near Antarctica and increased the delivery of warm air to the South Pole. These atmospheric changes are the ones responsible in driving climate anomalies.
Fogt and Clem argue that these warming trends were unlikely the result of natural climate change alone. Both emphasized that human-caused warming is also responsible to make this one of the strongest warming trends worldwide.
“From the very beginning, Kyle and I worked very well together and were able to accomplish more as a team than we were individually. We have published every year together since 2013, with one of our continuing collaborations being the annual State of the Climate reports,”
“Our work on this project together each year ultimately led to this publication documenting the warming at the South Pole, however, most importantly for me, apart from being a fantastic scientist and collaborator, my family and I are both honored to consider Kyle one of our closest friends,” said Fogt.
Global warming that has undone 6500 years of cooling
In a study led by four researchers of Northern Arizona University’s School of Earth and Sustainability (SES) and in collaboration with scientists from research institutions all over the world, it was found that 150-year global warming has undone six millennia of global cooling.
“Before global warming, there was global cooling. Previous work has shown convincingly that the world naturally and slowly cooled for at least 1,000 years prior to the middle of the 19th century, when the global average temperature reversed course along with the build-up of greenhouse gases,” said Darrell Kaufman the lead author.
“This study, based on a major new compilation of previously published paleoclimate data, combined with new statistical analyses, shows more confidently than ever that the millennial-scale global cooling began approximately 6,500 years ago,” Kaufman went on.
Just before, an international group of 93 paleoclimate scientists from 23 countries have published the most comprehensive set of paleoclimate data that compressed 1,319 data records based on samples taken from 679 sites globally.
At each site, researchers analyzed ecological, geochemical and biophysical evidence from both marine and terrestrial archives, such as lake deposits, marine sediments, peat, and glacier ice, to infer past temperature changes.
“The rate of cooling that followed the peak warmth was subtle, only around 0.1°C per 1,000 years. This cooling seems to be driven by slow cycles in the Earth’s orbit, which reduced the amount of summer sunlight in the Northern Hemisphere, culminating in the ‘Little Ice Age’ of recent centuries,” said Michael Erb, an assistant research professor who analyzed the temperature reconstructions.
Since the mid-19th century, global warming has gone up to about 1°C. Therefore, the average temperature of the last decade (2010-2019) was warmer than anytime during the present post-glacial period.
Nicholas McKay, an associate professor, has developed some of the statistical approaches to synthesizing data from around the world. He stated that individual decades are not resolved in the 12,000-year-long temperature reconstruction, making it difficult to compare it with any recent decade.
“On the other hand, this past decade was likely cooler than what the average temperatures will be for the rest of this century and beyond, which are very likely to continue to exceed 1°C above pre-industrial temperatures,” McKay said.
Kaufman added, “It’s possible that the last time the sustained average global temperature was 1°C above the 19th century was prior to the last Ice Age, back around 125,000 years ago when sea level was around 20 feet higher than today.”
Cody Routson, assistant research professor, said, “Investigating the patterns of natural temperature changes over space and time helps us understand and quantify the processes that cause climate to change, which is important as we prepare for the full range of future climate changes due to both human and natural causes.”
“Our future climate will largely depend on the influence of human factors, especially the build-up of greenhouse gases. However, future climate will also be influenced by natural factors, and it will be complicated by the natural variability within the climate system. Future projections of climate change will be improved by better accounting for both anthropogenic and natural factors,” he continued.