Ch. 8: The accelerating effects of Arctic feedbacks

[Chris OConnor]

A Farewell to Ice: A Report from the Arctic
by Peter Wadhams

Please use this thread to discuss Ch. 8: The accelerating effects of Arctic feedbacks.

[Robert Tulip]

The retreat of sea ice may seem to be a direct economic boon for ease of access to oil, trade and fish, but the indirect damage far outweighs these short term benefits. Melting the pole is an unmitigated disaster, due to the sensitivity of the whole climate system to what happens at the pole.

This chapter details seven major Arctic feedback processes.

1. Ice-albedo: Open water reflects 10% of incoming light back to space, while ice reflects up to 90%, with the dazzling brightness of fresh snow in sunlight. The albedo falls as the ice gets darker, as the fallen snow melts and the soot in it accumulates on the surface. As the climate warms, the snow falls later and melts earlier, darkening both the sea and land surfaces, especially in the hot mid summer months. The biggest factor is the area of sea ice in summer, which is fairly white compared to the wine dark sea.

Wadhams cites a study that found the loss of ice from the 1970s to 2012 produced radiative forcing equal to 25% of CO2 emissions over that period.

[Robert Tulip]

2. Snowline Retreat Feedback: By June 2012 the extent of midsummer snow was 6 million km2 less than in 1980. This albedo change means the snowline retreat and the sea ice retreat each add about the same amount of global warming. The overall ice/snow-albedo feedback is therefore adding 50 % to the direct global heating effect from GHGs. This means that even without adding more CO2 to the atmosphere this feedback is now driving climate changing climate. Such a runaway warming process seems to have made Venus the planet it is, why is why James Hansen switched career from study of the climate of Venus for NASA to campaigning to stop global warming.

[Robert Tulip]

3. Water vapor feedback:
Water vapor is the main greenhouse gas. Its content goes up and down with temperature, producing more than half of all warming. But water vapor only stays in the air for a week, compared to a thousand years for CO2, so it is completely dependent on other factors. A good summary is at https://en.wikipedia.org/wiki/Greenhous ... ater_vapor. Wadhams comments that the Arctic temperature rise produces a major water vapour feedback, holding the heat closer to the surface of the ice and ocean. The recent Arctic temperature increase of 3oC has increased the water vapor concentration by 20 %. The confusing thing is that more water vapor means more clouds, and cloudy days are usually cooler, due to shade, but the overall effect of water in the air is to increase warming.

[Taylor]

Hey mate

Thanks for chugging along with this current read.
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Quote: ‘the confusing thing means more water vapor means more clouds, and cloudy days are usually cooler, due to shade, but the overall effect of water is to increase warming’

When I read this line it reminds me of what happens here on the South West Florida coastal islands. During our winter months we get these cold humid days. The humidity comes when we get winds coming off the Gulf. Typically during winters we get dryer winds coming down from the north over the peninsula which is dryer. Air pressure is also comes into play when combined with the humidity, this is the dew point.

I’m further reminded of winters I lived through in Northeast Ohio. Early winter snows would be heavy with water almost slushy, but as the months go by and the air becomes dryer the snows became fluffy, lighter, often called powder.

It makes sense to me that the Arctic has these higher levels of humidity, the feedback, although the mechanisms are complex to read of or describe boils down to the warming conditions beget more warming conditions. The relationship of air,sea and land, they feed each other and when their inclination is towards higher temperatures that’s the direction they’re going to move. Wadhams is showing how the trend has gone over a tipping point, as it is, warming will increase the those processes that allow for a higher number of days of warming, increasing days of warming, increases days of warming which again increases days of warming increasing days of warming increasing days of warming......

[Robert Tulip]

Hey mate Thanks for chugging along with this current read.
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Quote: ‘the confusing thing means more water vapor means more clouds, and cloudy days are usually cooler, due to shade, but the overall effect of water is to increase warming’

Thanks very much Taylor. This is important material for the future of human existence on this planet, and it is a shame that people find it so hard to engage on.
The point of this discussion is to find practical methods to explain and address climate change. Practical solutions do not include the Extinction Rebellion alarm of the destruction of capitalism or head in the sand denial. Peter Wadhams is presenting practical solutions that don’t line up with either of these tribal emotions, so he just gets ignored.
The quote you attributed to me has a couple of small mistakes which could confuse readers. The main one is that it is just the water in the air that increases warming, not all water.

When I read this line it reminds me of what happens here on the South West Florida coastal islands. During our winter months we get these cold humid days. The humidity comes when we get winds coming off the Gulf. Typically during winters we get dryer winds coming down from the north over the peninsula which is dryer. Air pressure is also comes into play when combined with the humidity, this is the dew point.

In my earlier post on the Greenhouse Effect thread I included a diagram which shows how the escape of heat from the top of the atmosphere is affected by various greenhouse gases - https://www.booktalk.org/post173622.html#p173622 As Wadhams explains, when scientists several centuries ago started to research this, they were mystified to find that oxygen and nitrogen did not trap any heat. They knew these gases are 99% of the air, and they could not imagine at first that the remaining 1% does all the heat trapping to make us warmer than the moon. It is only the tiny gases like CO2, methane and water vapour that stop heat escaping to space, functioning like a blanket. That is a complex function of the physics of the molecules, but quite easy to prove with basic physics.
It goes to show how important it is to trust the science – like the explanation that the earth orbits the sun. The intuitive observation that clouds bring cooler weather has the same relevance as the intuitive observation that the sun rises and sets. At first glance it seems obvious, but a bit of study proves it creates a wrong answer.

warming conditions beget more warming conditions. The relationship of air, sea and land, they feed each other and when their inclination is towards higher temperatures that’s the direction they’re going to move.

Scientists have calculated that the earth system always moves toward an equilibrium between temperature and chemistry. However, the suddenness in geological terms of the current shift away from equilibrium means that there is debate over what the equilibrium temperature is for the current atmospheric load of GHGs, and over how long it might take. The likely equilibrium temperature, based on climate sensitivity, is about 4°C above the Holocene average, but Wadhams explains that it might be more than 7°C, according to a paper titled Sensitivity and the Carbon Budget.

Leaving all that poison in the air would be about as responsible as storing 3000 tonnes of ammonium nitrate explosive on the docks together with fireworks for a decade...

The complex unknown feedbacks make it impossible to know how long it will take to achieve equilibrium. But we do know that the last time the air had the current amount of CO2 (not counting the 25% forcing from added methane), the sea level was more than ten metres higher.

[Robert Tulip]

Konrad Steffen, the leading Swiss Polar scientist who recently died by falling into an invisible crack in the ice in Greenland, made this short four minute video about his work. Have a look at how their research station has been put on stilts as the ice has melted out from under it.

[Robert Tulip]

4. Ice sheet melt feedback and sea level rise

This section explains the severe complacency that has infested the IPCC about the major risks of the rapid melting of the Greenland ice sheet and how the feedbacks went unnoticed and are accelerating.

All the glacier systems in the world are in retreat due to global warming. The Greenland ice sheet is 2-3 km thick, containing enough ice to raise sea level by seven metres if it melted. It used to be frozen solidly all year round, apart from a small amount of melt around the edges.

In the 1980s the top of the ice sheet started melting in summer, and by 2012, almost all the surface melted in high summer. Climate modellers at IPCC weren't worried though, as they expected the meltwater to refreeze in winter. They did not realise that this surface melt could turn the entire sheet into a fragile sliding lattice, with potential for much more sudden collapse.

A new surprising phenomenon appeared: drain holes that take water from the ice surface ponds down to bedrock 3 km below. These holes, known as moulins, had not been imagined before the ice started to melt. They increase the heat at all depths of the ice sheet, weakening the entire glacial structure by expanding tiny cracks. Like in a granite boulder, when the water melts and refreezes it gradually makes the whole glacier more fragile. The moulin holes then drain to the sea, lubricating the glacier on its rocky underside so it often flows twice as fast. The accelerating shrinking of the ice sheet is measured by satellites, which showed annual loss estimated at about 300 gigatonnes of ice from Greenland until 2016. More recent data is at https://www.carbonbrief.org/guest-post- ... ed-in-2020

These unforeseen rapid melting processes in Greenland show how models that project a linear rate of sea level rise are wrong, since the warming processes create new instabilities that speed up the whole melting process.

Wadhams says the Antarctic ice sheet, holding enough water for 60 metres of sea level rise, was estimated to be losing only about a third as much ice as Greenland. But more recent studies measure how the Antarctic ice sheets are melting from both above and below. Like in Greenland, meltwater is seeping into the ice and causing it to fracture and weaken when it freezes again. But unlike Greenland, Antarctica has vast ice glacial shelves jutting over the ocean, and the ocean currents are warming, accelerating the speed of loss of these glaciers, with chunks breaking off as big as US states.

The IPCC has been complacent, ignoring the scale of the melting threat, leading many cities to fail to plan for the expected speed of sea level rise. Countries like Bangladesh and Vietnam have millions of people living in areas that are expected to flood this century and that will be very difficult and expensive to protect.

Working out how to stop Greenland from melting should be a primary planetary security priority, given the global danger of sea level rise, but instead the political focus is on speeding up the melt to encourage trade and mining. When the Arctic Ocean is blue water rather than white ice, the whole regional climate warms up, speeding the loss of ice from fresh water glaciers as well as from the salt water sea ice.

[Robert Tulip]

Several small additional feedback processes

Arctic River Feedback: The rivers flowing north into the Arctic Ocean have warmed up due to the reduced snow duration in Siberia. As the permafrost and tundra melt, highly reflective snow is replaced by highly absorbing earth. Rivers in these newly warmer regions then warm up the ocean, which in turn absorbs more solar heat and feeds back to warm up the land as winds above open sea are warmer than above ice. Although small in overall climate terms, this river warming is a classic amplifying feedback mechanism.

Black carbon feedback: Pollution and fires deposit soot, also known as black carbon, which makes glaciers dirty and means they melt faster. A patch of dirt on a glacier will absorb heat and melt a small hole where bacteria can grow, giving the ice a black, green or pink tinge. As glaciers and sea ice melt, the accumulated dirt and soot gets more concentrated, making the surface darker, which increases its heat absorption.

Ocean Acidity Feedback: About one third of CO2 emissions dissolve into the ocean. The resulting acidification makes shells dissolve faster, so instead of settling on the ocean floor in stable form, more of the carbon in sea shells now returns to the atmosphere. With less Arctic sea ice, more CO2 gets dissolved, and over the long term this cuts the natural storage of carbon in shells.

The most serious of all the warming feedback processes is the melting of snow and ice, which together increase radiative forcing by half as much as CO2. Buy two warming molecules and get one free. It is essential to add in these warming feedbacks on top of the CO2 effect to understand that the speed of warming will continue to accelerate until stringent geoengineering methods are implemented.

[Robert Tulip]

In the concluding section of this chapter, Wadhams asks why climate feedback matters. As explained above in my last post, it adds 50% to the radiative forcing produced by greenhouse gases, so makes the climate problem far worse.

He also includes a version of the chart below, which shows that a small shift of temperature can dramatically increase the frequency of events associated with warming.
This bell curve measures standard deviations from the mean. Say at the moment an event occurs once in 50 years. A year containing such an extreme event is two standard deviations above the mean. But as this chart shows, with one degree of warming, that same year will now happen about ten times as often, every five years, while the new fifty year event will be far more extreme.

The one metre sea level rise expected this century has dire implications for poor countries like Bangladesh and Vietnam where tens of millions of people live in land that would be inundated. Wadhams explains that it doesn’t just mean making one metre dikes around all the flat coastal areas. The problem is that there will be new one in five year events, driven by the increased heat in the sea making hurricanes worse, which will overwhelm such defences.

My own view is that far bigger sea level rise, over five metres, is entirely possible this century. The weakening of the ice sheets in Greenland and Antarctica could see sudden widespread fracturing of coastal glaciers, as these formerly stable structures are hollowed out and undermined and melted. So we urgently need to start doing something about it yesterday, far more than the weak effort of slowing down future emissions, which only cause a tiny fraction of the problem.