Dates for the upcoming Arctic GEOTRACES expedition (August–October) were selected to capture the annual period of minimum ice coverage in the Arctic Ocean. During fall and winter, the northern hemisphere tilts away from the sun and ice freezes over the Arctic Ocean reaching maximum coverage by March. In the spring and summer, the northern hemisphere tilts towards the sun and ice begins to melt reaching minimum coverage by September. The U.S. Arctic GEOTRACES team will attempt to reach the geographical North Pole during the ice minimum this September before turning back towards the Bering Strait as temperatures drop and the ice thickens.
U.S. Arctic GEOTRACES cruise plan: black arrows represent our path to the North Pole, white arrows show the return route.
Annual ice coverage in the Arctic Ocean is difficult to predict as sea ice extent can be affected by both local weather patterns and global climate change. Overall, Arctic sea ice appears to be declining. Satellite observations are used to determine the extent of ice coverage each year and below average measurements have been recorded since 2003.
Maximum ice coverage in the Arctic Ocean was measured this year on Feb. 25, two weeks ahead of schedule, and is the lowest ice-maximum measured since satellite records began nearly 40 years ago.
The blue line representing 2015 ice extent falls below average.
Those of you still recovering from this year’s brutal winter of record high snowfall and record low temperatures may find this unbelievable. However, the weak jet stream that caused the polar vortex has an oscillating pattern – while the east coast was inhaling a breath of cold Arctic air, warmth from the equator was pulled up in the western part of the continent. Warmer temperatures in the North Pacific may have decreased ice coverage in the Arctic this year, and together with an already decreasing trend partially attributed to a warming climate, a new low has been reached.
Record low ice coverage this winter does not necessarily guarantee a clear path for the GEOTRACES team to break through to the North Pole. The Arctic Ocean contains a mixture of thick multi-year ice that has been around for at least 5 years, and first-year ice that thaws and re-freezes annually. Record low ice coverage this year means there is less first-year ice than normal, but the thick multi-year ice may stand in our way.
Sea ice in the Arctic Ocean reflects incoming solar radiation (high albedo); seawater has a lower albedo and absorbs more energy from the sun than is reflected. Less ice in the Arctic Ocean could lead to greater absorption of energy from the sun which is stored as heat, warming seawater and melting even more ice. This amplified warming effect is known as a positive feedback loop.
Check out this great article from the Wright State newsroom – Ph.D. student Alison Agather will represent 1/3 of team Hg on the upcoming Arctic research expedition (myself and Principle Investigator Carl Lamborg from the University of California, Santa Cruz will complete the team). This will be Alison’s first research cruise but she is from Minnesota and has the warmest mittens I’ve ever had the pleasure of borrowing, so I know she’ll do just fine!
More cruise action coming your way! I will be participating in the U.S. GEOTRACES Arctic transect (map below) this summer (2015). The cruise will begin and end in Dutch Harbor, Alaska passing through the Bering Strait into the ice covered Arctic Ocean. We will collect water samples and venture out onto the ice onboard the Healy, an icebreaker owned and operated by the United States Coast Guard. Cross-over stations marked on the map (red crosses) will be sampled by separate GEOTRACES cruises from Canada and Germany to compare results with our international colleagues. More updates on cruise planning and preparations to come, sailing August 7-October 10 (that’s 70 days at sea!).
With Pacific GEOTRACES a year in the past and an Arctic cruise fast approaching (see countdown on the right panel)…it’s time for an update! This year between cruises has been quite eventful for me in all of the best ways possible. I defended my dissertation and became Dr. Bowman in December 2014. After writing a 300 page dissertation, I gave a public defense at Wright State University. The whole lab showed up in coordinated Hawaiian shirts and my committee members flew in from California and Connecticut for the big day.
The main bulk of my dissertation work was done on two cruises, in the Atlantic and Pacific Oceans, both chronicled in this blog. The Atlantic results are now published in a journal called Deep Sea Research II and the Pacific paper is in the works.
Looking at the chemistry of water in the deep ocean is like flipping through the pages of a history book. Water in the deep ocean comes from the surface of polar seas where dense cold water sinks and begins a 1000 year long journey around the globe. Physical properties and radioisotopes in deep water are used to determine age, or time since the water was last in contact with the atmosphere. The international GEOTRACES program has sampled deep water between 90 and 900 years old, creating a timeline for mercury in the ocean. Since the industrial revolution began some 200 years ago humans have increased the amount of mercury in the atmosphere and now from our timeline, we can see concentrations of mercury in the ocean have increased as well.
American Geophysical Meeting, San Francisco, CA (Dec 2014)
One week after my dissertation defense I walked across the stage at graduation . My family and friends traveled to Dayton to help me celebrate and the next day I jumped on a plane to California! This research business never stops. I presented my work from the Pacific cruise at the American Geophysical Union’s fall meeting as I had earlier in the year at Ocean Sciences in Hawaii.
A few weeks after graduation I loaded up Liberty Bell (my jeep) and drove 2,700 miles across the country to Santa Cruz, California. After six years working as a “Midwest Oceanographer” I’m happy to report that I’ve finally moved to the coast! I am currently working as a postdoctoral researcher at the University of California, Santa Cruz where I will continue to study mercury in the ocean, and of course run hginthesea!
Driving across the country
Hiking break from the great american road trip in the Grand Canyon
California, my new home :)
This week our research team published an article in Nature discussing the amount of mercury in the ocean from human activities. Surface ocean mercury concentrations have tripled since the dawn of the industrial revolution. Today, the main source of mercury from human activity comes from coal-fired power plants like those found in the United States and developing countries like China and India. Once in the ocean, mercury is transformed to a chemical compound called methylmercury, a neurotoxin that biomagnifies in fish and ends up on our dinner plates. In the United States alone, millions of women have blood mercury levels high enough to effect fetal neurodevelopment. Click here to read more about the study.
Data for this new publication was collected on the 2011 North Atlantic GEOTRACES cruise chronicled in this blog, and on other similar expeditions.Scroll down to read about life at sea and what’s it’s like to do science out in the middle of the ocean.