Imagine hurricane season without weather satellites. Since the satellite era we are not surprised about a storm the way the people of Galveston were over a century ago. Many climatologists are sounding the alarm that our fleet of satellites that monitor Arctic sea ice is on life support (and that may be generous). This matters to you and is frankly not just about polar bears.
Satellites carrying passive microwave sensors are essential for monitoring sea ice because only these sensors have the capability to see through clouds and dark of night to capture a continuous and complete record of sea ice every day. This sea ice time series is now nearing 40 years in length, making it one of the longest continuous satellite-derived climate datasets. The loss of these satellites would effectively end the consistent record of Arctic sea ice decline.
When I asked Dr. Meier about the current status of the fleet he told me,
DMSP-F19 (part of the Defense Meteorological Satellite Program) is definitely dead. DMSP-F17 is still operational except one channel (37 GHz, V polarization) of SSMIS. Unfortunately, that's an essential channel for the sea ice algorithms. DMSP-F18 is still fully capable, at least for the sea ice channels, which is what we're planning to switch to. The Japanese AMSR2 sensor is also available. That's not as optimal for the long-term record because, even though it's more modern, it's not as consistent
This is a patchwork fix. Long-term issues are clearly evident as F18 is an aging system A DMSP-F20 is built and in storage but funding was not allocated by Congress to launch it. We may need to rethink that decision. Many of us have warned of these looming gaps for weather and climate monitoring.
The National Snow and Ice Data Center (NSIDC) announced in March that Arctic sea ice was at a record low in terms of maximum extent for the second straight year (see this NASA animation for a good visual aid). NSIDC director Dr. Mark Serreze stated in a press release,
I’ve never seen such a warm, crazy winter in the Arctic....The heat was relentless.”
Arctic sea ice has a seasonal cycle. It typically increases through the cool seasons with a maximum around the middle of March. It retreats through the warm season months and is usually at a minimum extent by the middle of September. NSIDC notes,
The September Arctic minimum began drawing attention in 2005 when it first shrank to a record low extent over the period of satellite observations. It broke the record again in 2007, and then again in 2012. The March Arctic maximum has typically received less attention.
Ironically, 2012 was a record warm season minimum. It was amusing to watch some people make the argument with a straight face that 2013 and 2014 proved that things were getting better. Actually, 2013 and 2014 just reflected positions on the long term decreasing trend line over the past 30-40 years. Lesson here: Do not draw conclusions about long-term trends based on years immediately after an extreme value. Would you draw long-term conclusions in your retirement portfolio based on a 1-day market spike or decline? If you have not seen this outstanding video, Walking the Dog, please watch it. It does a nice job explaining trends. Also, whenever actual scientists talk about Arctic sea ice changes, inevitably someone brings up what is going on in the Antarctic as some counter perspective. The climate system doesn't respond linearly or uniformly like some may think. NSIDC has a nice "101" lesson on the differences, and NASA also has an excellent discussion.
The fact that shipping lines are planning cruises in the Arctic Ocean tells you everything you need to know about about the severity of the changes. By the way, emergency management organizations have significant concerns about the risks associated with these cruises. Beyond leisure, the U.S. Navy is also concerned about the Arctic opening up.
Sea ice affects the large scale global ocean circulation patterns as well as weather patterns. Professor Tom Mote is a hydroclimatologist and head of the Geography Department at the University of Georgia. He studies Greenland and other cryospheric processes. He says,
The long-term record of sea ice, in particular, is important to our understanding of the Arctic. Reductions in sea ice amplify warming in the Arctic by increasing the absorption of sunlight (i.e., the ice-albedo feedback). Some scientists believe that a warmer Arctic may change the path of the jet stream, altering weather over further south, including the U.S. (See this paper for a summary of the literature).
Climate models have been conservative with sea ice decline. They have underestimated the amount of change in many cases (see figure).
Doctors monitor a patient's heart rate trends after surgery. An abrupt disruption in such trend information places that patient in jeopardy. In this case, Earth is the patient.
Dr. Marshall Shepherd, Dir., Atmospheric Sciences Program/GA Athletic Assoc. Distinguished Professor (Univ of Georgia), Host, Weather Channel's Sunday Talk Show, Weather (Wx) Geeks, 2013 AMS President