Accelerated global warming - climate change and the ice melt feedback loop
Downtown Jersey City today...
The speed of change
I recently wrote a hub called Humanity - The Closing Years, that gave a very general evidence based view of the changes coming our way, from ice melt to the huge reduction in bio-diversity. For such a big topic, it was impossible to put everything in or even explore each area in any great detail. The main gist was to look at a variety of indicators of massive change coming our way.
One of the most important areas that's worth looking into in more detail, is the speed of ice melt. Our current models predict that even if greenhouse gases are slashed to a minimum, sea levels will rise by 1 meter by 2100.
However, more recently data has come out that shows our models to be woefully conservative. In 2015 global temperatures, while exacerbated by El Nino, were at record levels across the board - and that is despite the unusual solar minimum.
The ice melt feedback loop has a key role to play in progressive warming.
The speed of change could be anything but gentle - in fact, it may follow a snowballing effect where the increase in ice melt creates more ice melt, to eventually and suddenly unleash massive sea level rise. Another possibility would be the effect of changing sea currents, and thus precipitating Europe into an ice age.
Whichever the scenarios, once considered incredible, the notion that climate can change rapidly is becoming respectable. There is a lot of data now available showing that past climate changes were often quite sudden, having passed a tipping point.
Glaciers are often seen as indicators of climate health, so these are the first places to look to understand the effects of climate change. While it's true that a very few glaciers have increased in size, the truth is that overall, glaciers around the world have been melting rapidly.
On a local level this can be difficult on local communities who rely on the water provided by the glacier. On a wider level it's a symptom of our changing climate and an indicator of sea level rise.
Since records began most glaciers have shown large amounts of melt.
Key points from:
- On average, glaciers worldwide have been losing mass since at least the 1970. A longer measurement record from a smaller number of glaciers suggests that they have been shrinking since the 1940s. The rate at which glaciers are losing mass appears to have accelerated over roughly the last decade.
- All three U.S. benchmark glaciers have shown an overall decline in mass balance since the 1950s and 1960s and an accelerated rate of decline in recent years.
- Trends for the three benchmark glaciers are consistent with the retreat of glaciers observed throughout the western United States, Alaska, and other parts of the world. Observations of glaciers losing mass are also consistent with warming trends in U.S. and global temperatures during this time period.
Huge glacial retreat, Alaska
Chasing Ice - a moving and visually stunning account of glacial melt
The Greenland ice sheet is the second largest ice body in the world, after the Antarctic ice sheet. Many scientists who study the ice melt in Greenland consider that a two or three degrees C in temperature rise would be enough to completely melt the ice. If all of this ice melted, it would contribute 6 metres (20 feet) to sea level rise.
The facts with respect to Greenland are there for anyone to see. We are fast approaching a 2 degree increase in average world temperature already. In fact, this past February 2016 saw temperatures 1.35C higher than average - way higher than the predicted level - warmer in fact than the average temperature for the month between 1951-1980, a far bigger margin than ever seen before. While it's true that El Nino is a contributing factor, the steady rise in temperatures is obviously real.
In fact, models so far have difficulty of including any feedback loops. The Guardian newspaper ran an article recently entitled February breaks global temperature records by 'shocking' amount. The article comes directly from Nasa data.
As the Greenland ice sheet sheds ice, it is uncovering darker older ice, which does not reflect the sun so readily, and this increases melt. This is the albedo effect, explained in greater detail below.
Greenland: "Chasing Ice" film captures largest glacier calving ever filmed. Incredible footage.
Jump to 3:33 to get a sense of the gigantic scale of the calving - blocks of ice the size of manhattan breaking off
Antarctic ice melt could double sea level rise
There was a time when worst case scenarios were seen as exaggerations. However, as more study and more data has been coming to the fore, we've been discovering that in fact, these worse case scenarios have in some cases been under estimated. To be clear, this isn't about all of the Antarctic ice melting (which would be unimaginable in its consequences), but with regards to just a certain amount - which is quite enough to radically alter our coastlines.
To date, models have been looking at ice melt separate from the warmer atmosphere, but now that these measurements are actually coming in, extrapolating new data is being made possible.
"One reason that other models didn't include the atmospheric warming is because it hasn't started to happen just yet," said the co-author of a new study, Dr David Pollard from Penn State University. "In Antarctica, around the edges at sea level, it's just beginning to get up to the melt point in summer. "With that warming, the flanks of Antarctica will start to melt drastically in about 50 to 100 years - and then it will start to kick in according to our model."
According to the study, by the year 2500 sea levels across the world could rise by 13 meters.
North Pole sea ice over 100 years
National Oceanic and Atmospheric Administration scientists have said that the Arctic could have entirely ice-free summers by 2040. Others contend that in fact ice free summers will happen as soon as 2030. The increase in water temperature will have a profound impact on the wildlife living in the Arctic. Polar bears feed off seals who in turn feed off fish and who in turn feed off zooplankton - but this whole cycle will be broken.
Arctic sea ice is part of a yearly cycle and is an indicator of climate change, as freezing is happening later each year. Water run off from land based ice masses in the Arctic contribute to sea level rise enormously.
The momentum driving ice melt in the Arctic is driven by the albedo effect as well, as less ice allows the sun's radiation to melt even more.
The albedo effect: the ice-melt feedback loop
The basic concept of the ice-albedo climate feedback mechanism is that dark surfaces absorb the sun's energy while light colours reflect this energy. In terms of the two polar regions this is of massive significance, as these regions are covered with extremely vast (and yet diminishing) areas of ice, keeping the earth's temperature down.
The feedback mechanism works on the principle that the more ice melts, the more ice can melt. As ice melts it exposes the darker waters, and the sun's rays are absorbed more readily. Trying to model the feedback loop is very tricky, and so far, it's clear that equations have not factored in all the various variables inherent in the feedback mechanism.
While this mechanism is part of the yearly winter/summer cycle in the Arctic for example, the truth is that freezing is occurring a little later each year, giving the opportunity for the albedo feedback mechanism to occur a little longer. Each increment increases warmth a little, which in turn creates a greater warmth.
Marco Tedesco from the City College of New York:
"Albedo makes melting a non-linear process. As melting starts, the albedo of the ice reduces and therefore increases the rate of melting exponentially. This is called the positive albedo feedback mechanism and it had a major role to play in the record levels of melting we saw in Greenland in 2010."
A non-linear melting process is much harder to model - instead of a graph with a straight line, it might look more like a curve that becomes steeper and steeper, which is in line with a rapidly increasing acceleration of ice melt.
Other ice melt considerations
Something perhaps not considered sufficiently in a warming world, is how much water expands in response to temperature increase. Water is most dense at 4 degrees Celsius. Above and below this temperature, the density of water decreases (the same weight of water occupies a bigger space - i.e. as ice, or as 'expanded' water). So as the overall temperature of the water increases it naturally expands a little bit making the oceans rise. This is another factor which is very difficult to quantify exactly, and how it might affect coastal regions.
Permafrost melt and Methane gas
As the permafrost in polar regions continues to thaw, it is releasing vast quantities of methane gas that has been locked away in the ice. This too contributes to global warming and is yet another aspect which is hard to quantify. People in Siberia are already suffering from this problem- houses once built on solid ground are now slowly sinking. The permafrost started to form about 11,000 years ago, so what is happening how, is clearly out of the ordinary. Billions of tonnes of methane are locked in peat bogs, some of which run 25m deep. In fact, world-wide peat bogs store at least two trillion tons of CO2 which is is equivalent to a century of emissions from fossil fuels. In terms of sudden climate change and run away warming, leading to massive ice-melt, this is one of the most feared tipping points.
With land based ice masses melting, this reduces the salinity of sea water. Though saline water freezes at a lower temperature than freshwater, a less saline ocean his wider consequences that are hard to model.
There is an Atlantic ocean current at work which functions rather like a converyor belt, a system that exchanges cold water in the Arctic region for warm water from the tropics. If this is disrupted, it has significant impacts on world climate. Slight changes in the currents - both seasonal and longer-term variations - affect everything from hurricane formation to droughts and heat waves. Heat waves again, have an impact on ice melt...
Permafrost melting is causing houses to sink in Siberia
Why humans still pretend nothing is happening...
It's an interesting question as to why humans find it so hard to believe that massive climatic change is just around the corner. Perhaps it's because we find it hard to live with the idea that something very bad is just around the corner and so prefer not to believe it. So it's no wonder that we like to think that life will go on indefinitely - business as usual.
Sasha Wright (Phd, Plos) Blogs on the website phys.orgwebsite:
Unfortunately, the psychological research indicates that the real barrier to climate change mitigation may be more closely related to our limited cognitive abilities, branding, and preexisting cultural identities.
This is amusing and somewhat insulting at the same time, and requires a re-read to ensure the words are correct - limited cognitive abilities. The Phd graduate is basically saying, in flowery language: 'We're too stupid to understand the evidence, or do anything about it.' Thank you Sasha Wright for the thumbs up!
The next point is interesting. By branding and preexisting cultural identities, the author is saying that we're unable to see through the belief systems we were brought up with, and the learning that we've absorbed so far.
This is the very nub of the issue. Too many refuse to trust the science. People prefer to believe that global warming is a scam (whether human induced or not). People want to continue as they are - the party must go on!
Preparing for the future
Now is the time to take stock of the future, and think of our grandchildren - if not our own children, depending on the time scale.
There are certain things we should already be considering, such a selecting safe places to buy a house, or even better, start considering the real practicalities of establishing communities in safe places. Ice melt is only one aspect of climate change, but the truth is that climate change will impact the world in many different ways, driving refugees across boarders everywhere.
It surely makes sense to start planning for a safe future for our children/grand-children, and not be short sighted.
- 'Drastic' Antarctic melt could double global sea-level rise - BBC News
Sea levels could rise by more than double the current estimate over the next 100 years, according to a new analysis of climate change in Antarctica.
- All eyes on the oceans—James Hansen and sea level rise
- Global Warming Makes Sea Less Salty
Climate changes have melted glaciers and brought more rain, dumping more fresh water into the oceans.
- Darkening ice speeds up Greenland melt, new research suggests - Carbon Brief
- Rate of carbon emissions put in context - BBC News
Humans are now putting carbon into the atmosphere at a rate unprecedented since at least the age of the dinosaurs, scientists say.
- Arctic ice melting faster and earlier as scientists demand action | Environment | The Guardian
Arctic returns to warm period with trend over the decades continuing to show temperatures getting hotter and ice melting faster, scientists say
- Arctic Melt Raises Sea Levels and Reinforces Global Warming : Earth Matters : Blogs
climate change, global climate change, global warming, natural hazards, Earth, environment, remote sensing, atmosphere, land processes, oceans, volcanoes, land cover, Earth science data, NASA, environmental processes, Blue Marble, global maps
- Arctic Sea Ice News and Analysis | Sea ice data updated daily with one-day lag
- Home | Climate Change | US EPA
How many of us are worried enough to start doing something about it?
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