No Way to Slow Down: Silence Howling in Antarctica

11 04 2016

rickyroodRicky Rood is a professor at University of Michigan and leads a course on climate change problem solving. His articles often come from and contribute to the course.

This article was originally published here.

 

I am nearing the end of the tenth time I have taught my climate change class. This year we focused on climate change science and the Paris Agreement. In particular, we thought about how climate science would contribute to the execution of the Paris Agreement. Towards the end of class, I do what I call a strategic summary and organize some resources to provide memory cues on how to think about climate change and our responses. At the end of that summary, I present my personal analysis. Here are the bullets.

* It will be difficult to avoid a world that is four degrees warmer.
* We have, in fact, underestimated the impacts of warming.
* We have some control over how fast and how far the warming will go.
* We are committed to irreversible changes, for example, sea-level rise.
* We can “cope” with this. We must. There is opportunity.

This list has been largely the same since 2010, and the class analysis of the Paris Agreement did little to change the list.

Realizing the consistency of the list over the years, I went on a search for another list that I made at the end of 2008. We had a presidential transition in the works, and someone working on that transition asked me what I thought the strategic climate-science issues would be for the new president. Here is the list I put together in late 2008.

1) Land (and sea) ice is melting faster than predicted in the IPCC Assessment Report 4. This is due to the over simplification of the melting of ice in previous models. (Things Going Fast)

2) Because of the underestimation of ice melt, sea level rise has been underestimated. We are committed to sea level rise, and we need to plan accordingly.

3) The terrestrial and ocean sinks of carbon dioxide are likely to be less effective than previously stated.

4) The acidification of the ocean is likely to be more disruptive sooner than expected.

Eight years later, I am satisfied that that was a good list. Also, I am shocked that it has been eight years, but that’s a more existential issue. Going into the Conference of the Parties in Paris, I felt that one of the most defining new science-based results was the evidence of loss of some of the West Antarctic Glaciers. (A brief mention in my September 2014 blog) Loss, here, means that we have reached a point where these glaciers will continue to melt, and there is no identified physical mechanism that will stop this melting.

The primary paper mentioned in the excellent NASA press release is by Eric Rignot et al. Widespread, rapid grounding line retreat of Pine Island, Thwaites, Smith, and Kohler glaciers, West Antarctica, from 1992 to 2011. (I don’t see any reference to the actual paper in an otherwise excellent press release, so I assume this is the correct paper.) Rignot and his research colleagues have many excellent publications on both Greenland and Antarctic ice sheets. I also bring attention to a paper by lead author Jeremie Mouginot entitled, Sustained increase in ice discharge from the Amundsen Sea Embayment, West Antarctica, from 1973 to 2013.

It has long been known that some of the glaciers in West Antarctica are “unstable.” This is, primarily, due to the fact that these glaciers are grounded below sea level. Basically, the glaciers extend into the sea. They can extend to the rock surface at the bottom of the sea; they are grounded on bedrock. Alternatively, they can float in water; that is they have water below them. If there is water below the glacier it melts faster. The combination of warming ocean water and a grounding line below sea level, well, that’s a prescription for continuous melting – instability. Flowing warm water is always available to accelerate melting. Here is an explanation from AntarcticGlaciers.org on Marine Ice Shelf Instability.

At the core of these 2014 papers is the study of the bedrock topography; that is, what is the elevation of the rock surface at the bottom of the sea and the bottom of the glaciers. The bedrock topography is measured with space- and air-based radar. For the glaciers to be stable requires that there be some structure in the bedrock that acts, perhaps, like a dam. A conclusion of Rignot et al. paper is, “Upstream of the 2011 grounding line positions, we find no major bed obstacle that would prevent the glaciers from further retreat and draw down the entire basin.”

This brings me to two recent papers that have gotten coverage. The first is Contribution of Antarctica to past and future sea-level rise. The authors are Robert DeConto and David Pollard. This paper concludes that if emissions continue on their current path, then past evidence suggests more than a meter of sea-level rise by 2100. The second paper is Ice melt, sea level rise and superstorms: evidence from paleoclimate data, climate modeling, and modern observations that 2 °C global warming could be dangerous. In this paper Hansen et al. conclude that we can see “nonlinearly growing sea level rise, reaching several meters over a timescale of 50–150 years.” These conclusions come from examination and analysis of observations of the climate at past times when the temperature was determined to be comparable to the 2-degree goal that is the policy definition of avoided dangerous climate change. (See also No Way to Slow Down) Both of these papers come with some controversy; however, taken in concert with alignment of present-day observations, theory, and modeling paint a picture of rising sea-level rise that will be measured in feet over the next several decades and continue into the next century. More than the specifics of these papers, there is little evidence of any moderating influences that slow the melting of ice, and the Earth is far more likely to be set up for rapidly melting ice.

In Things Going Fast, I documented other papers that suggested that the effects of warming had been underestimated than in our consensus climate assessments. My last summary bullet from class, above, is that we can and must cope. Here is how I think of this. We know that sea level is going to rise, and there is increasing knowledge that suggests that sea level will rise at or above the highest levels suggested in assessment reports. This rise will be on the time-scale of decades, and after a few decades, the rise will continue, not stabilize. As we make plans and take actions in the next few decades we will collect more knowledge, improve our predictions, and know how our energy portfolio changes. We are moving into a time where we will be required to consider climate change as an essential part of planning and management. In the best of circumstances, the societal impacts will be enormous. What frightens me more than the technological challenges or the cost of adaptation is the inability of governments and societies to take on new approaches to our valuation and use of resources, property, and services. I suspect that our motivations will ultimately follow from a series of increasingly costly weather disasters and the accumulation of smothering evidence of the impacts of a changing climate.

Here are some useful links on our melting ice.

Glaciers and Global Warming: A video by my faculty colleague Jeremy Bassis

Antarctic Glaciers . org: A comprehensive collection of information on the Antarctic’s ice.

Marine Ice Sheet Instability at AntarcticGlaciers.org

Figure 1: The Washington Post published this excellent graphic on melting of ice sheets, based on DeConto and Pollard, 2016. For description see Why some Antarctic glaciers are disappearing faster than we thought.

NASA Graphics on Melting of Antarctic Glaciers

NASA Discussion of Unstable Ice Sheets





Dan Britt – Orbits and Ice Ages: The History of Climate

23 07 2015

This video was posted on Peak Prosperity.  It’s over three years old now, but it’s an excellent talk that may clarify a lot of questions for DTM readers.  Enjoy…..





2014, hottest year on record

3 01 2015

Mark Cochrane

Mark Cochrane

Well, by NOAA’s measure at least, 2014 is officially the warmest year on record for the globe.This is primarily notable because it was not an El Nino year, when new highs are normally achieved. Still, the main reason we have achieved this dubious record is because of the rising temperatures of the world’s oceans, with 7, maybe 8, consecutive new highest monthly ocean temperatures. Some may quibble about the standing of 2014 in the global record depending on which temperature series they prefer (NOAA, NASA-GIS, HAD-CRU, etc) but all will show it as very high, regardless.

http://www.nbcnews.com/watch/nightly-news/2014-officially-the-warmest-year-on-record-378458691995

It is hard to be ‘shocked’ by this new record temperature because these ‘records’ seem to fall every couple of years and will continue to do so for the foreseeable future. What is under-appreciated is that these records are like trying to spin whether the US deficit is larger than the previous year or not. The key point is not whether it is a little bigger or smaller, it is the fact that we have a financial deficit that is the problem, our debts grow larger and larger year after year. In the case of the climate, what matters is the energy balance of the planet. We are gaining heat every single day of every single month of each and every year. December marks the 358th consecutive month that the planet was warmer than ‘average’. The end of February will mark 30 straight years where every month the Earth contains more energy than the previous year. If things were anywhere near stable, half of those months should have been below average to balance the years that were above average. Try to flip a coin and get heads or tails 360 times in a row. Good luck even getting 10 in a row (that’s a 1 in 1000 chance). Now try doing that 36 times in a row and you begin to get the mind bogglingly unlikeliness of this being a ‘natural’ variation. Anyone care to bet that we are going to experience 360 cooler than average monthly temperatures now?

During 2014, much of the continental United States was colder than normal but it was just about the only place on the planet experiencing cooler temperatures. It doesn’t matter what temperature one location experiences in any given year when we are talking about ‘global average temperatures’. It is the composite of all regions that make the difference. The cumulative warming is not only raising temperatures, it is also eroding the last vestiges of globally cooler times, as seen in the cumulative mass loss from the world’s alpine (mountain) glaciers. As glacial mass goes down, sea levels go up.

Straight from the Glacier National Park website:

It has been estimated that there were approximately 150 glaciers present in 1850, and most glaciers were still present in 1910 when the park was established. In 2010, we consider there to be only 25 glaciers larger than 25 acres remaining in GNP.

The changes in global temperatures and glacial mass are academic arguments that don’t show up in most people’s day to day lives but they are the underlying trends that tell all of us that the world is changing climates whether we choose to recognize this or not.

If we were suddenly to stop producing greenhouse gases (GHGs), the positive feedbacks for methane, for example, would barely change, ‘if’ we managed to hold the atmospheric aerosol level constant, but this is a really big caveat (more on this later)! The tundra melting is responding to excess heat already accrued, not the amount of new greenhouse gases each year. Even if we were able to somehow stop the growth of anthropogenic GHGs, this would be like stopping the deficit being run by the US (and every other country’s) government. While this would be better than having a deficit, you would still have to pay the annual interest on the total debt that you have already accrued. Our ‘interest’ payments are currently getting soaked up by the world’s oceans, and melting ice and permafrost areas. The debt we have already accrued (energy heat content) would still have us on a path for 3-4C and 40 m sea level rise over the next several hundred, to thousand years. However, if we really did stop all anthropogenic GHG emissions during that time, the planetary scrubbing system (slow feedbacks) would temper things a bit.

Back to that caveat on the aerosol levels though. If we somehow stopped all anthropogenic GHG emissions, the tundra melting would likely accelerate since we’d be facing a sudden pulse of heat equivalent to around 0.8C. Currently the aerosols (pollution) that we spew into the atmosphere create a haze that reflects about 50% of the excess solar heating that we should be receiving due to current GHG levels. While CO2 hangs around in the atmosphere for several hundred years, aerosols only stay floating around for weeks to months. Therefore, if we suddenly stop emitting GHGs then shortly thereafter we will experience a rapid doubling of the excess energy level reaching the surface of the planet. Although the sudden stopping of all greenhouse gas emissions is an unlikely event, anything that reduces the amount of atmospheric pollution (aerosols) will proportionally have the same effect. The biggest possibility I can see on the near horizon would be China implementing their version of the Clean Air Act. Good for local health of their populations but the world will warm more quickly. The same thing goes for any global shift to ‘green’ energy.

Cleaning up the atmosphere is not a bad thing to do but it will expose us more quickly to the climate debt that we have already accrued. Nature’s debt collectors will get their payments from us eventually.

As for 2015, if we get anything other than a very short and mild El Nino, then 2015 should rapidly supplant 2014 as the warmest year on record. Whenever the current phase of the Pacific Decadal Oscillation ends  (PDO) we will be due for another several years of rapid warming. Barring a mega-volcanic eruption near the equator or a massive meteor strike, we won’t be seeing any global temperatures below the ‘average’ any time soon.

Solar theories of recent global climate change, have at least one major problem – they do not match observations.

For the last 50+ years the average solar irradiance (bold blue line) has been stable or even dropping, especially in more recent years. However, as everyone knows, global temperatures have continued to rise during these decades. The sun cannot be the cause because unless the irradiance level is rising we are not going to be getting more heating.

When you try to model the Earth’s climate using only observed ‘natural’ forcings (e.g. the sun and volcanic eruptions), you do not get a very good match with global temperatures (Meehl 2004). That black line is global temperatures marching away from control by natural forcings.

If you only use anthropogenic forcings (man-made greenhouse gases, aerosols, ozone), you get a much better fit with temperature.

Finally, and not surprisingly, if you include natural and anthropogenic drivers you get a very good fit with observed temperature changes over the decades.

The sun is fundamental to life on Earth and is the engine that drives our climate but recent (and expected) changes in solar irradiance explain very little of recent global warming. We are amplifying the amount of heat that we get from the solar radiation that we receive by trapping it with more and more greenhouse gases.

We own this mess. Time we started doing something about it.

Happy New Year!

Mark





Everything you ever wanted to know about Climate Change.

20 06 2014

kerry-emanuel

Kerry Emanuel

This is a must view video that Mark Cochrane put me onto.  It’s by MIT’s Kerry Emanuel giving a ‘Climate 101’ talk over at Skeptical Science. The first hour is his talk. The rest is his answering questions. He was one of Mark’s professors at MIT 20+ years ago.  At that time, Mark tells me, he was not yet actually convinced about anthropogenic climate change.  He also has the shortest book with a solid overview of climate change science that I know of (link).

From Wikipedia…….

Kerry Andrew Emanuel (born April 21, 1955) is an American professor of meteorology currently working at the Massachusetts Institute of Technology in Cambridge. In particular he has specialized in atmospheric convection and the mechanisms acting to intensify hurricanes. He was named one of the Time 100 influential people of 2006.[1] In 2007, he was elected as a member of the U.S. National Academy of Sciences.[2]

He hypothesized in 1994 about a superpowerful type of hurricane which could be formed if average sea surface temperature increased another 15C more than it’s ever been (see “hypercane“).

In a March 2008 paper published in the Bulletin of the American Meteorological Society, he put forward the conclusion that global warming is likely to increase the intensity but decrease the frequency of hurricane and cyclone activity.[3] Gabriel Vecchi, of NOAA said of Emanuel’s announcement, “While his results don’t rule out the possibility that global warming has contributed to the recent increase in activity in the Atlantic, they suggest that other factors—possibly in addition to global warming—are likely to have been substantial contributors to the observed increase in activity.”[4]

In 2013, with other leading experts, he was co-author of an open letter to policy makers, which stated that “continued opposition to nuclear power threatens humanity’s ability to avoid dangerous climate change.”[5]





Five pieces of ice news revealing earth’s ice cover is in serious decline

22 05 2014

Reproduced Material is licensed under a Creative Commons Attribution No-Derivs 3.0 License.

Originally published here…..

Melting ice has filled the newspapers over the past couple of weeks, with a deluge of new research into how the planet’s ice cover is being altered by climate change making the headlines.

Coming just a few days after research showing West Antarctic glaciers are in irreversible collapse, today’s news that Antarctic ice melt has doubled in a decade was widely covered.

We’ve taken a look at several new papers that highlight the speed at which earth’s vast ice sheets, glaciers and ice caps are diminishing. Put them all together, and it makes for a stark picture.

1. Antarctic ice melt is twice as fast as ten years ago

‘Antarctic ice losses have DOUBLED in less than a decade with 159 billion tonnes of ice melting each year’, reads today’s  Daily Mail headline.  The Guardian opts for, ‘Doubling of Antarctic ice loss revealed by European satellite’.  The Times says ‘Antarctic melt rate worries scientists’.

All three headlines stem from a  paper published yesterday in Geophysical Research Letters, which finds the volume of ice melting into the ocean from Antarctica is twice as large the average between 1992 and 2011, now raising global sea levels by 0.45 millimetres a year.

Mc Millan Et Al ., (2014) Antractic _map

Change in height of ice, as measured by CryoSat-2. Blue shows areas losing ice, red show areas gaining ice in the last three years. The biggest ice loss is in the Amundsen Sea sector (numbers 21 and 22 in inset image. Source: McMillan et al., ( 2014)

The University of Leeds scientists study uses three years of data from the European Space Agency’s CryoSat-2 satellite, launched in 2010. The satellite now sees five times as much area as before, totalling 96 per cent of the total Antarctic continent.

David Vaughan from the British Antarctic Survey told The Guardian why this is so important:

“Through some very clever technical improvements, [the scientists] have produced the best maps of Antarctic ice-loss we have ever had. Prediction of the rate of future global sea-level rise must be begin with a thorough understanding of current changes in the ice sheets – this study puts us exactly where we need to be.”

Across Antarctica, the average height of the ice is dropping by 1.9 centimetres per year, the data shows. East Antarctica is staying roughly the same but West Antarctica is seeing big losses, where ice melt is 31 per cent faster now than between 2005 and 2011. Ice loss from glaciers along the Amundsen coast has tripled over the past two decades, the paper explains.

2. West Antarctic glaciers are collapsing, and it’s “unstoppable”

Eye-catching words like “collapse”, “irreversible”, “unstoppable” and “catastrophic” peppered media coverage last week of two papers charting the demise of West Antarctic glaciers.

The first paper in Science looked at how changes in wind and ocean circulations are bringing warm water in contact with the underside of the Thwaites glacier – one of the biggest in West Antarctica – melting it from the bottom up. Similar things are happening with other glaciers across West Antarctica, explained the second paper in Geophysical Research Letters.

               Joughin Et Al . (2014) Image1

Radar image showing the ice-shelf edge of the Thwaites glacier in West Antarctica (thick black line) and the position of the “grounding line” – where ice meets ocean and goes afloat – under a high warming scenario (red line). Source: Joughin et al,. (2014)

Not only are the glaciers shrinking, but there’s nothing to stop them melting completely. That’s why scientists are talking about the glaciers’ collapse as “irreversible” and “unstoppable”.

And without the huge glaciers to prop up the interior of the ice sheet, much larger areas of West Antarctic ice will start slipping into the ocean. This would ultimately raise sea levels by three to four metres, though that would take several centuries, say the scientists.

Here are some key questions on both bits of research answered by experts.

3. The Greenland ice sheet could melt faster than scientists first thought

The Greenland ice sheet may be more vulnerable to climate change than previously thought, scientists reported in a Nature Geoscience paper on Sunday.

The team of US scientists discovered deep channels extending horizontally below the surface of the Greenland sheet, which mean large parts of the glaciers lie on land that’s below sea level.

Just like in West Antarctic glaciers, warm water coming into contact with the edge of the glacier forms vast pools under the ice sheet, melting it from the bottom up, the paper explains.

Greenland _trenches

Map of Greenland elevation: Ice covered areas that sit below sea level are marked in blue. Smaller images show individual glaciers and submarine trenches. Source: Morlighem et al. ( 2014).

4. Other ice caps and glaciers in the northern hemisphere are melting faster too

As well as the Greenland and Antarctic ice sheets, glaciers and ice caps on land are also melting under the pressure of rising temperatures and contributing to sea level rise.

A new paper published today in the Journal of Climate looks at ice-covered areas greater or equal to 0.5 square kilometres in the Northern Hemisphere, excluding the Greenland Ice Sheet.

The researchers built a model of glacier and ice cap responses to past temperature and snowfall changes, testing it against nearly 1500 measurements from 78 locations worldwide.

The scientists estimated the total contribution to sea-level rise from ice caps and glaciers was 0.51 millimetres per year between 1979-2009. But it’s speeding up – looking just at the recent decade, 1999-2009, the contribution is 40 per cent higher, at around 0.71 millimetres per year.

Glacier _ice _cap _SMB_collage

Surface mass balance of ice caps and glaciers in the northern hemisphere – excluding the Greenland Ice Sheet – showing a loss (dashed line) between 1970 and 2009. Annual values are marked by black circles. The solid black line is the cumulative ice loss over the period. Source: Mernild et al., ( 2014)

5. Soot from forest fires contributed to unusually large Greenland surface melt in 2012

Finally, a new study published today explores the reasons for why an unusually large amount of the surface of the Greenland ice sheet melted in 2012. This exceptional summer saw more than 97 percent melt away, far more than the next biggest event almost a century before in 1889.

The team of US scientists examined the layers of ice and snow in six ice cores, concluding that a combination of exceptionally high temperatures and soot from northern hemisphere forest fires, known as black carbon, drove unusually extensive surface melt in both cases.

Greenland Surface Melt

Greenland surface melt on two separate days in July 2012, the latter after high temperatures and soot from forest fires triggered widespread  melting. Image courtesy of Dorothy Hall, NASA/GSFC.  Source: Keegan et al., ( 2014)

Surface melting doesn’t contribute to sea level rise because the water percolates back into the snow and refreezes. But it does reduce the reflectivity of the ice, known as albedo, with consequences for how much sunlight the Arctic region absorbs, and how much ice stays frozen.

Together, with soot which also decreases reflectivity, the ice albedo was pushed below a certain threshold in 1889 and 2012, making it vulnerable to rapid ice loss, say the authors. Lead author Kaitlin Keegan explains such big surface melting events won’t be out of place by 2100:

“With both the frequency of forest fires and warmer temperatures predicted to increase with climate change, widespread melt events are likely to happen much more frequently in the future.”