In my last post I talked about how knowing the science behind a picture makes it better. I still say that’s true, but also, sometimes, the beauty and awe of a picture can speak for itself.
Behold, swirls of sea ice off the coast of Greenland:
Breathtaking, isn’t it? [Click to phasechangenate.]
This was taken by NASA’s Aqua satellite on October 16, 2012. Aqua is designed to observe Earth’s water cycle: the oceans, evaporation, clouds, precipitation, snow cover, and, obviously, sea ice. It takes a vast amount of energy to move water from the ocean into the atmosphere and then move it around the planet, energy which comes from sunlight and steered by the Earth’s spin. Observations like those of Aqua show us how the constituents of the atmosphere change how that transport occurs, how that energy is stored, and how we humans affect that with our grand experiment of adding carbon dioxide to the air. That also affects our environment, how plants and animals eat, drink, live, and die.
We are animals, too, and we live in this environment created by sunlight, air, water, ice, and our own actions.
I am awed and moved when I see images like the one above. Its beauty is transcendent, and was made possible by our curiosity, our desire to learn more about the world we live in – an urge so strong we invented science, and engineering, and then built satellites that can look back at us from space and show us how surpassingly beautiful our world is, and how we need to take care of it.
Hmmm. I suppose I was wrong at the beginning of this post. Sometimes the picture doesn’t always speak for itself. It still helps to know the how and why of it. When you do, the picture speaks with far more authority, import, and wide-ranging impact.
Image Credit: NASA/GSFC/Jeff Schmaltz/MODIS Land Rapid Response Team
Earlier, I wrote that arctic sea ice had yesterday reached record low levels, blowing through the previous lowest-seen minimum in 2007, even though there’s still a lot of melting left to go.
NASA just released this visualization of the arctic region showing just how bad it is:
The white area is the extent of sea ice as of August 26, 2012. The orange line is the average minimum extent from 1979 – 2010, the time covered by satellite observations. In other words, every year they measure the outline of the ice when it reaches its minimum, usually in September, and then averaged those positions for that timespan.
As you can see, we’ve been well below the usual minimum ice extent for some time – not just where we usually are this time of year, but the actual minimum amount… and we still have weeks of melting yet to go.
I want to note that this does not necessarily mean we’ll see sea level rising from this. That ice is floating on the water, and in general when ice melts the water level stays the same. You can see this for yourself: put ice in a glass, then fill it with water. Mark the level. Wait until the ice melts and you’ll see the level hasn’t changed. The ice displaces (pushes aside) an amount of water exactly equal to its own weight, so when it melts that water fills up the same volume the ice displaced. The level stays the same.
However, because ice is frozen fresh water, and the sea is salt water, floating ice may actually raise the sea level a bit. Still, the far bigger concern is ice on land that melts and flows into the ocean. That certainly can raise the sea level. Greenland has the second largest reservoir of frozen water on Earth, and it’s seeing unprecedented melting.
So yeah, global warming is a concern, no matter how many people deny it. And it’s not something we should blow off and worry about later. It’s happening now.
Image credit: Scientific Visualization Studio, NASA Goddard Space Flight Center
In late August, sea ice extent was way below average for that time of year, and it was predicted we were headed for at least a near-record low this year. Those predictions have, unfortunately, turned out to be true. On September 9, sea ice extent reached its yearly minimum, the second lowest since satellite records began in 1979 — and so close to the record low in 2007 that it’s a statistical tie.
NASA has posted series of pictures of sea ice this year taken by its Aqua Earth-observing satellite. Here’s the Arctic ice as it was in March (top) and September 2011 (bottom):
They put together a series of the images into an animation that really gives you a clear picture of what’s going on:
Of course, you expect more ice in the winter and less in the summer and fall, so by itself those pictures don’t tell you what this means. You need to compare the current extent with how things were in the past. As it happens, the National Snow and Ice Data Center in Boulder does just that.
Geez, I hate to keep hitting this theme, but y’know what? It’s important.
Using a fleet of Earth-observing satellites, the European Space Agency is reporting that the ice in the Arctic circle is already retreating considerably, and will once again be below average in extent this summer. This has been going on for a few years now, which isn’t terribly surprising considering that global warming is real and that we keep seeing recent years tied or exceeding records as hottest years on record.
Here’s the map they made showing sea ice extent from June 1 to August 24, 2011:
Yikes. Back in 2007, the Northwest Passage became entirely navigable by sea (without using an icebreaker ship) for the first time in recorded history. It had already been thinning for years, but an icebreaker ship was still needed to get through all of it — that’s changed now.
Moreover, it’s not just that the extent — that is, the amount of area covered by the ice — has dropped, it’s also that it’s thinning, dropping in volume. The ice volume has decreased by unprecedented amounts as well recently.
What does this mean for the current Arctic summer?
"The minimum ice extent is still three to four weeks away, and a lot depends on the weather conditions over the Arctic during those weeks," says Leif Toudal Pedersen, a senior scientist at the Danish Meteorological Institute. "Whether we reach an absolute minimum or not, this year again confirms that we are in a new regime with substantially less summer ice than before. The last five summers are the five minimum ice extent summers on record."
Just to be clear: it’s OK to question the science of global warming. It’s OK to question any scientific findings, as long as that questioning is done with good intentions and in good faith (so to speak). While poking around the web I found denier sites trying to confuse the issue of sea ice extent — for example, some talking about the navigability of the Northwest Passage as far back as 2000, but not mentioning you needed an icebreaker to do it.
As usual, the evidence here is pretty clear: temperatures are increasing, sea ice is going away, glaciers are retreating, ocean levels are rising, and all the while we’re dumping greenhouse gases into the atmosphere while the spin doctors whirl away.
It’s maddening. But it will continue, as surely as the Earth itself turns.
One of the biggest predictors of global warming is the retreat of sea ice in the high northern latitudes. As oceans warm, the ice will take longer to form in the winter, and retreat faster in the spring. Scientists, therefore, have been watching the ice north of Canada very carefully.
What they’re seeing isn’t very hopeful.
This picture, from the Terra Earth-observing satellite, shows the state of sea ice as it was on August 17. This region is the so-called Northwest Passage — a waterway through the Canadian archipelago connecting the Atlantic and Pacific oceans. Usually the sea ice prevents regular trade routes from being utilized there. But over the past few years — <sarcasm>coincidentally</sarcasm> the time when scientists say global warming is accelerating — the sea ice has thinned considerably.