Yes, your car, and your toaster and television, too, if your electrical utility includes coal- or gas-fired power plants in its portfolio, are contributing to a shift in the Earth's axis by changing the distribution of water in the oceans. This according to a new paper in Geophysical Research Letters (in press).
The effect isn't large enough for anyone to worry about -- at just 1.5 cm, or less than a inch per year, Polaris will still be the North Pole star for a while yet -- but the authors of paper write that
The proposed polar motion signal is therefore not negligible in comparison to other decadal and secular signals, and should be accounted for in the interpretation of polar motion observations.
Felix W. Landerer and Johann H. Jungclaus of the Max Planck Institute for Meteorology even speculate that, if other complicating factors can be nailed down, it might be possible to work backwards from measurements of changes in the axis of rotation to determine sea level rise. So, again, not a major cause for concern in terms of effects on civilization, but more evidence of the power that humans have to change the big picture.
In some circles, skepticism over the science of anthropogenic global warming can be linked to the difficulty people have getting their minds around the idea that humans are capable of altering something as big as a planet-scale ecosystem. This is understandable because, for most of our 200,000-year history as a species, our numbers were fall too small to have a measurable effect.
But there is evidence that even thousands of years ago our forest-clearing activities changed regional and even global weather and climate patterns. And now, with nearly 7 billion humans on Earth, the cumulative impact goes well beyond measurable. Recently released analysis by the U.S. National Climatic Data Center has discovered that the world's oceans are warmer now that at any time since data-collection began 130 years ago, with July's 62.5°F beating the 1998 record. While air temperatures have remained relatively stable for the last decade -- leading less informed observers to wonder if global warming was just a short-term blip -- the finding is an important reminder that GLOBAL warming continues apace, and that things are little more complicated than whatever your backyard thermometer is telling you.
Warming oceans expand, and gravity ensures that the extra volume is distributed as close to the Earth's center as possible. The upshot being that the oceans' mass gets shifted around, a phenomenon that can change the speed of the Earth's rotation, and, now we learn, can tilt the planet's axis of rotation.
New Scientist's Rachel Courtland explains that
The changing climate has long been known to move Earth's axis. The planet's north pole, for example, is migrating along 79 °W - a line of longitude that runs through Toronto and Panama City - at a rate of about 10 centimetres each year as the Earth rebounds from ice sheets that once weighed down large swaths of North America, Europe, and Asia.
The influx of fresh water from shrinking ice sheets also causes the planet to pitch over. Landerer and colleagues estimate that the melting of Greenland's ice is already causing Earth's axis to tilt at an annual rate of about 2.6 centimetres - and that rate may increase significantly in the coming years.
Now, they calculate that oceans warmed by the rise in greenhouse gases can also cause the Earth to tilt - a conclusion that runs counter to older models, which suggested that ocean expansion would not create a large shift in the distribution of the Earth's mass.
...
The team found that as the oceans warm and expand, more water will be pushed up and onto the Earth's shallower ocean shelves. Over the next century, the subtle effect is expected to cause the northern pole of Earth's spin axis to shift by roughly 1.5 centimetres per year in the direction of Alaska and Hawaii.
I'll wrap up by pointing out that the Earth's oceans have been expanding, and therefore rising and falling, by dozens of meters over the eons, and there's nothing unusual in that. Consequently, the axis has been shifting around, too. This is not another catastrophe in the making. But it is a humbling finding, one that should give us pause when we think about our species' place in the universe.
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And yet they're perfectly happy to scream "butterfly effect!" in order to claim that climate is inherently unpredictable...
Global Warming
Is this a man made problem or is it a natural tendency of our planet? Does the answer matter for any reason other than to know how to control it and engineer a sea level solution? Sea levels just 20,000 years ago were 130 meters lower than they are today. Over millions of years sea levels have changed by hundreds of meters up and down. Even if carbon emissions are the cause I do not believe the third world will cut back until the effects are obvious and damaging. The first world wonât either.
Until a few hundred years ago, the world was flat, many bacterial infections were deadly, the earth was the center of the universe and the universe was 5,000 years old (some people still believe this one). I do not pretend to know more than people of just a few hundred years ago because many scientific theories and hypothesis continue to be changed and adapted to new data every year. However, we are among the first generations to be able to leave the planet, we are among the first generations to be able to dramatically extend life spans and we now understand human history better than any of our predecessors.
What if we thought of global warming as the biggest environmental engineering opportunity of our lifetimes? Throughout the history of man we have been unable to measure and much less coordinate a reaction to the cumulative effects of manâs existence on this planet. Even though sea level has changed both up and down by hundreds of meters from todayâs level almost no one in the developing world is willing to accept the reality, and say it out loud, that most of the planets inhabitants will not follow the US and Europe to a world of limited carbon emissions via severely limited growth in order to control a sea level change that will (may?) occur over a period of decades to centuries.
Over the last ten or twenty years a mentality of the end is near has made materialism a bad word. Too many writers and pseudo scientists refer to the unhappiness of the first world and cite its materialistic mentality as the cause. The recession has forced many of us to live with less and appreciate more of the non-monetary things that our limited time on this planet can offer. Learn to be happy with what you have when you have is a good way to live, however almost none of us would permanently give up the hope of earning more to get more.
How many of the third world population living on $2 or less a day answers that they are happy and do not need or want more, whether or not they watch TV and whether or not they are exposed to the âbrainwashingâ of the advertisers? How many of those in the first world promoting the three Râs would trade in their SUVâs for a bicycle and public transportation? How many in the third world would turn down some more material goods for the âhappinessâ of going without or getting along with less?
A mentality of scarcity is not the solution. Never in the history of man has collective downsizing or cutting back led to societal, economical or any other type of growth. We must be ready and try to educate the third world to be part of the solution through environmental engineering as a proactive solution instead of self deprivation and skipping the benefits industrialization has brought.
For an even more ambitious engineering solution to the global warming issue, atmospheric engineering on a planetary level is a worthy goal. Over geologic time asteroids and meteors have wiped out large numbers of species on this planet. We need to leave the planet or at least be able to so that we can avoid being next. We can use the knowledge gained by learning how to control our own atmosphere to develop strategies to engineer livable atmospheres elsewhere. With the knowledge of the cause of sea level change the focus can become how we can âcauseâ the sea level to remain where we want it as opposed to becoming terrified by a possible rise of a few meters over the next hundred or so years.
On a societal note, hate is a way bigger problem than global warming. Hate can lead to war and over a period of just a few years allow justification for the use of the ultimate weapon. Forget about changes in sea level caused by centuries or millennia of human intervention affecting the chemical composition of our atmosphere or millions of years in geologic time periods which have lowered and raised the sea level hundreds of meters many times, just a few radical thoughts germinated over a generation or two can create an atmosphere of hatred which allows us to commit genocide or allows us to use weapons and philosophies that would make this planet really uninhabitable and make global warming look like childâs play.
We have plenty of time to get and maintain the sea level where we need it. Because of historic changes it would probably be a great idea for the human race to learn to do this anyway. Letâs get the engineers to work on environmental engineering at the planetary level and lets try to avoid distractions being proffered by our politicians looking to win in the next election cycle or the media who has a time horizon of minutes, hours or days as opposed to decades, centuries or millennia which is what is needed to properly control sea levels to maximize human potential and investment for the human race.
How can we develop alternate energy resources? How can we remove carbon dioxide from the atmosphere? How can we better prove/measure how human activity is contributing to global warming? What are some other ways to control sea level? These are the questions engineers should be asking and answering. Letâs stop scaring the educated population into coercing the underdeveloped to do as we say and not as we do on underdeveloped science and hypothesis.
Space travel, planetary engineering, worldwide common goals of sustainable development (with as much emphasis on development as sustainable), not quotas or carbon credits (which transmit a mentality of scarcity and self deprivation), are goals that can create harmony on the planet while continuing to improve the lives of hundreds of millions more. Letâs continue to help the poor become âunhappyâ by helping them get a car, a bigger home, a better education, see the world, get better medical care and accumulate more stuff. Letâs leave the bogeymen creating the âglobal disaster of the yearâ for the horror movies of Hollywood.
Jeff Sherman
"Until a few hundred years ago, the world was flat"
Actually, it was common knowledge among the educated (and seafarers) that the world wasn't flat since at least the time of the Greeks. Eratosthenes even calculated the approximate circumference of the Earth.
To take an extreme example of atmospheric effects on planetary rotation, there have been studies which suggest the fairly substantial Venusian atmosphere makes a synchronous rotation period for the planet unstable, and actually increases the likelihood of Venus ending up in its current retrograde rotation state.
I remember for a test once a question asking "what happens to the temperature of water in a glass with ice in it when you add heat? What happens when you run out ice?"
The tilt of the Earth's axis has varied in the past, without human intervention.
andy @ 4:
If you've got any links to support that then I'd appreciate them (I'm studying physics/astronomy at the moment).
S2: If you have access to the other side of the Nature paywall, there's a paper titled "On the four final rotation states of Venus" by Correia and Laskar worth checking out.