Global warming is the term used to describe a gradual increase in the average temperature of the Earth's atmosphere and its oceans, a change that is believed to be permanently changing the Earth's climate. (Articles, Facts, Causes and Effects)
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Before 2000, Earth's spin axis was drifting toward Canada (left globe). Climate change-driven ice loss in Greenland, Antarctica and elsewhere is pulling the direction of drift eastward.
Credit: NASA Jet Propulsion Laboratory
The spin of the Earth is a constant in our lives. It’s quite literally why night follows day.
And while that cycle isn’t going away, climate change is messing with the axis upon which our fair planet spins. Ice melting has caused a drift in polar motion, a somewhat esoteric term that tells scientists a lot about past and future climate and is crucial in GPS calculations and satellite communication.
Polar motion refers to the periodic wobble and drift of the poles. It’s been observed for more than 130 years, but the process has been going on for eons driven by mass shifts inside the Earth as well as ones on the surface. For decades, the north pole had been slowly drifting toward Canada, but there was a shift in the drift about 15 years ago. Now it’s headed almost directly down the Greenwich Meridian (sorry Canada no pole for you, eh).
Like many other natural processes large and small, from sea levels to wildfires, climate change is also playing a role in this shift.
“Since about 2000, there has been a dramatic shift in this general direction,” Surendra Adhikari, a researcher at NASA’s Jet Propulsion Laboratory, said. “It is due to climate change without a doubt. It’s related to ice sheets, in particular the Greenland ice sheet.”
That ice sheet has seen its ice loss speed up and has lost an average of 278 gigatons of ice a year since 2000 as temperatures warm. The Antarctic has lost 92 gigatons a year over that time while other stashes of ice from Alaska to Patagonia are also melting and sending water to the oceans, redistributing the weight of the planet.
Adhikari and his colleague Erik Ivins published their findings in Science Advances on Friday, showing that melting ice explains about 66 percent of the change in the shift of the Earth's spin axis, particularly the rapid losses occurring in Greenland.
It’s a huge, mind boggling process on the global scale, but imagine it like a top. Spinning a top with a bunch of pennies on it will cause wobble and drift in a certain pattern. If you rearrange the pennies, the wobble and drift will be slightly different.
That’s essentially what climate change is doing, except instead of pennies, it’s ice and instead of a top, it’s the planet. Suffice to say, the stakes are a little higher.
Ice loss explains most but not all of the shift. The rest can mostly be chalked up to droughts and heavy rains in certain parts of the globe. Adhikari said this knowledge could be used to help scientists analyze past instances of polar motion shifts and rainfall patterns as well as answer questions about future hydrological cycle changes.
Ice is expected to continue melting and with it, polar motion is expected to continue changing as well.
“What I can tell you is we anticipate a big loss of mass from West Antarctic and Greenland ice sheets and that will mean that the general direction of the pole won’t go back to Canada for sure,” Adhikari said.
If it continues moving down the Greenwich Meridian or meanders another way remains to be seen, though.
“This depends highly on the region where ice melts, or if the effect of ice melt would be counterbalanced by another effect (for example sea level rise, increased water storage on continents, changes of climate zones),” Florian Seitz, the director of German Geodetic Research Institute, said in an email.
In the here and now, polar motion shifts matter for astronomical observations and perhaps even more importantly for the average person, GPS calculations.
Map: Land and ocean temperature departure from average for March 2016. (NOAA NCEI)
Our ever-warming planet just passed another climate record.
The National Oceanic and Atmospheric Administration (NOAA) said Tuesday that March 2016 was the warmest March since records began in 1880.
It also marked an 11-month of streak of record-breaking global temperatures.
And at 1.22°C (2.20°F) above the 20th century average of 12.7°C (54.9°F), March 2016 distinguished itself from all 1,635 months on record by having the highest monthly temperature departure. Meteorologists Jeff Masters and Bob Henson wrote, "This is a huge margin for breaking a monthly global temperature record, as they are typically broken by just a few hundredths of a degree. The margin was just a shade larger than NOAA's previous record for any month of 1.21°C (2.18°F) above average, set in February 2016."
NOAA itself noted that "global temperature records are piling up," and said it announced the record warm month "[a]t the risk of sounding like a broken record."
"It's becoming monotonous in a way," said Jason Furtado, a meteorology professor at the University of Oklahoma. "It's absolutely disturbing ... We're losing critical elements of our climate system."
David Karoly, a climate researcher at Melbourne University, told the Sydney Morning Herald, "The extreme temperatures and extreme events, including the coral bleaching in the Great Barrier Reef, are indications that climate change is already happening with worse things in store."
When the Japan Meteorological Agency (JMA) announced its finding last week that March 2016 was the warmest since at least 1891, Michael Mann, a climate scientist and director of the Penn State Earth System Science Center, said the data offered "a reminder of how perilously close we now are to permanently crossing into dangerous territory," and added, "It underscores the urgency of reducing global carbon emissions."
The Washington Post similarly noted Wednesday that, since December when the global talks known as COP21 ended with a carbon emissions-slashing deal, "a drumbeat of grim scientific findings has underscored that staving off the worst consequences of global warming may take far more aggressive actions."
Indeed, a new analysis shows that even if countries implement their pledges laid out in the deal, which is expected to be signed by over 150 nations on Friday, it would result in expected warming by 2100 of 3.5°C (6.3°F)—far past the consensus threshold.
"The fossil fuel industry is pushing our climate to the brink faster than anyone expected, as record temperatures are proving, along with extreme weather related events," said 350.org executive director May Boeve. "We are all at risk from a warming planet, so we are left with no choice but to scale up nonviolent direct action."
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"I view my job a little like a legislator, supported by the taxpayer, to protect the interests of the taxpayer and to minimize the role of government."
In any case, as one of those rare contrarian climate scientists, Spencer is in a good position to present the best arguments against the global warming consensus. Conveniently, he recently did just that on his blog, listing what he considers the "Top Ten Good Skeptical Arguments," throwing in an 11th for good measure. He also conveniently posed each of these arguments as questions; it turns out they're all easy to answer.
1) No Recent Warming. If global warming science is so "settled", why did global warming stop 15 years ago, contrary to all "consensus" predictions?
Net human and natural percent contributions to the observed global surface warming over the past 50-65 years according to Tett et al. 2000 (T00, dark blue), Meehl et al. 2004 (M04, red), Stone et al. 2007 (S07, light green), Lean and Rind 2008 (LR08, purple), Huber and Knutti 2011 (HK11, light blue), Gillett et al. 2012 (G12, orange), Wigley and Santer 2012 (WS12, dark green), and Jones et al. 2013 (J12, pink). SkepticalScience.com
The IPCC stated with 95% confidence that most of the global warming since 1950 is human-caused, with a best estimate that 100% is due to humans over the past 60 years. The IPCC was able to draw this conclusion with such high confidence because that's what the scientific evidence and research clearly and consistently concludes.
3) IPCC Politics and Beliefs. Why does it take a political body (the IPCC) to tell us what scientists "believe"? And when did scientists' "beliefs" translate into proof? And when was scientific truth determined by a vote…especially when those allowed to vote are from the Global Warming Believers Party?
The IPCC merely organizes the world's top climate scientists every 5 to 7 years. It's those scientists who summarize the up-to-date status of the scientific research in their respective fields of expertise. The IPCC report and the 97% expert consensus on human-caused global warming are themselves not proof of anything. They summarize and reflect the scientific evidence – that vast body of evidence is the reason the consensus exists.
4) Climate Models Can't Even Hindcast. How did climate modelers, who already knew the answer, still fail to explain the lack of a significant temperature rise over the last 30+ years? In other words, how to you botch a hindcast?
5) …But We Should Believe Model Forecasts? Why should we believe model predictions of the future, when they can't even explain the past?
Climate models have accurately reproduced the past, but let's put them aside for a moment. We don't need climate models to project future global warming. We know from past climate change events the planet will warm between about 1.5 and 4.5°C from the increased greenhouse effect of a doubling of atmospheric carbon dioxide (the 'climate sensitivity').
In a business-as-usual scenario, atmospheric carbon dioxide levels are expected to surpass 900 ppm by 2100 – that's close to two doublings from the pre-industrial level of 280 ppm. Hence we know that business-as-usual will cause between 2.5 and 7.5°C (most likely 5°C) warming if we stop carbon dioxide levels from rising beyond about 900 ppm. This is based on simple math and what we know about the physics of the climate – no fancy models needed.
6) Modelers Lie About Their "Physics". Why do modelers insist their models are based upon established physics, but then hide the fact that the strong warming their models produce is actually based upon very uncertain "fudge factor" tuning?
Putting aside the accusation that hundreds of climate modelers are all liars – the answer is that their models are indeed based upon well established physics. NASA climate modeler Gavin Schmidt's TED talk on the subject is well worth watching.
Spencer's question likely refers to the uncertain size of the cooling influence of aerosols. However, that is a physical uncertainty. We don't have very good measurements of this effect; unfortunately the rocket carrying NASA's Glory satellite that had instruments to measure the climate effect of aerosols crashed two years ago. Nevertheless, climate models use the available data to account for their influence, and their projections include the associated uncertainties.
7) Is Warming Even Bad? Who decided that a small amount of warming is necessarily a bad thing?
We're headed for about 5°C global surface warming above pre-industrial temperatures by 2100 if we continue on a business-as-usual path. 5°C is the difference between average temperatures now and those during the last ice age. That's not "small" by any stretch of the imagination. As for who decided that amount warming is a bad thing – climate scientists researching the impacts of climate change.
8) Is CO2 Bad? How did carbon dioxide, necessary for life on Earth and only 4 parts in 10,000 of our atmosphere, get rebranded as some sort of dangerous gas?
Carbon dioxide itself is not "bad." Water is also necessary for life. Too much water will kill you. Too much carbon dioxide causes dangerous climate change. Greenhouse gases were determined to be pollutants as defined in the US Clean Air Act . This was a ruling of the (politically conservative) US Supreme Court.
9) Do We Look that Stupid? How do scientists expect to be taken seriously when their "theory" is supported by both floods AND droughts? Too much snow AND too little snow?
This question is a bit like asking, "Do I look fat?". Do you want an honest answer?
The warming of the atmosphere, happening especially at high latitudes, reduces the temperature difference between higher and lower latitudes. This tends to make storms move more slowly. This results in storms dumping more precipitation in localized areas, which causes more flooding in those areas and droughts outside of them. Higher temperatures also increase evaporation, exacerbating droughts and adding more moisture to the air for stronger storms. A climate scientist should understand these concepts.
10) Selective Pseudo-Explanations. How can scientists claim that the Medieval Warm Period (which lasted hundreds of years), was just a regional fluke…yet claim the single-summer (2003) heat wave in Europe had global significance?
There is no contradiction here – a regional event can have global significance, for example via economic impacts. In any case, the Medieval Warm Period was a regional phenomenon and the planet as a whole was cooler than today.
11) (Spinal Tap bonus) Just How Warm is it, Really? Why is it that every subsequent modification/adjustment to the global thermometer data leads to even more warming? What are the chances of that? Either a warmer-still present, or cooling down the past, both of which produce a greater warming trend over time. And none of the adjustments take out a gradual urban heat island (UHI) warming around thermometer sites, which likely exists at virtually all of them — because no one yet knows a good way to do that.
Ironically, most of the adjustments to Spencer's own satellite temperature data set have been in the warming direction, so this question may be an example of psychological projection. Scientists also recently identified a problem in Arctic temperature data analysis that's leading to an incorrect adjustment in the cooling direction, and there have of course been other cooling adjustments in the surface temperature record. The urban heat island effect has also been demonstrated over and over to have no significant influence on the surface temperature record.
Notice a Pattern?
You may have noticed some patterns in these questions. Most are based on false premises and are trivially simple to answer. These 'top ten good skeptic arguments' are frankly not very good or challenging. They also reveal a very one-sided skepticism, although to his credit Spencer did also list 10 'skeptic' arguments that don't hold water. These are glaringly wrong arguments like 'there is no greenhouse effect' and 'CO2 cools the atmosphere,' that some contrarians nevertheless believe. Interestingly, Spencer discusses the science disproving the 10 bad arguments, but there's no scientific discussion supporting his to 'good' arguments.
From reading and answering Spencer's questions, we learn that the basic science behind how we know humans are causing global warming and that it's a problem are quite well-established. There are some remaining uncertainties, like how much warming is being offset by aerosol cooling, but overall we have a very strong understanding of the big picture. For quite a while now we've understood the Earth's climate well enough to know that we can't continue on our current high-risk path.
When will we stop using these trivially wrong contrarian arguments as an excuse for climate inaction? Now that's a tough question to answer.
