"As the sea ice retreats, exposed water absorbs more sunshine, heating the water and causing further melt of the sea ice in a vicious cycle. This appears to be the dominant positive feedback loop in the Arctic, although snow retreat may contribute nearly as much to the warming of the Arctic generally in a second feedback loop.
A further feedback loop is ominous: as the Arctic warms, the thawing of land and subsea permafrost allows the discharge of growing quantities of the potent greenhouse gas, methane, which in turn causes further warming in a vicious cycle. This cycle is not yet noticeable. However there is over a trillion tons of carbon stored in permafrost in the form of organic material, which is liable to decompose anaerobically to form methane. And the permafrost forms the cap on an even larger carbon store already in the form of methane. Most scientists now accept that Northern Hemisphere land permafrost will thaw entirely this century. There is the potential for the release of enough methane into the atmosphere to cause runaway global warming, with temperatures rising well over ten degrees C.
The most immediate negative impact of these cycles and the resultant rapid warming of the Arctic atmosphere is a disruption of polar jet stream from its normal behaviour, such that there are more frequent and more severe weather extremes experienced in the Northern Hemisphere. This impact has grown so conspicuously over the past few years that we can honestly say that we are now experiencing abrupt climate change. The result of this climate change is widespread crop failure and an ever deepening food crisis.
A measure of the worsening situation is the food price index. This has spikes when the price of oil rises, but the underlying value has been rising steadily since 2006. Today, the index is slightly more than the critical price level above which food riots are liable to break out – an example having been the Arab Spring. Largely as a result of the crop failures this year, the FAO forecast that the index will rise higher in 2013 and higher again in 2014. If the trend in weather extremes continues, then these figures could prove optimistic. With a billion people on the edge of starvation today, we could see 2 billion by this time next year. It will be a humanitarian disaster. Furthermore, social unrest will rise, and economic growth and stability compromised in the developed and developing countries.
However there are longer term impacts and threats of Arctic warming, in particular (i) Greenland Ice Sheet destabilisation, (ii) accelerated methane discharge, (iii) loss of biodiversity and habitat, and (iv) heat absorption making it more difficult to keep to global warming targets.
As the snow and sea ice retreat from their levels in the 70s, more solar energy is absorbed. Taking the 70s as the baseline (zero forcing), this year's retreat produced as much as 0.4 petawatts of climate forcing averaged over the year. Much of this heat energy is retained in the Arctic, causing ice to melt and sea and land temperatures to rise. As temperatures rise, there will be slightly more thermal radiation into space, dissipating some of this energy. However most of this heat energy will slowly dissipate across the planet - and 0.4 petawatts is equivalent to half the forcing producing by anthropogenic CO2 emissions (1.6 watts per square metre). Peter Wadhams has estimated that the sea ice retreat by itself is equivalent to the forcing from 20 years of CO2 emissions, thus making it much more difficult for the global temperature to be kept below the so-called safe limit of 2 degrees warming.
However these long term effects are somewhat academic, if the immediate impact is to raise food prices far above a safe level.
It is much easier to think about and quantify the longer term impacts of Arctic warming than the more immediate impacts. This is a trap for the unwary. Therefore AMEG is trying to bring the world's attention to the immediate impacts, as they turn out to be colossal even this year, and are likely to be worse in 2013 and even worse than that in 2014.
It is clear that abrupt climate change has started, but not in the way we had been told to expect. Yes, there would be more climate extremes as the planet heated, but we were expecting a linear or near linear behaviour of the climate system, with gradual temperature change over the century. Instead we have striking non-linearity, with exponential growth in frequency and severity of climate extremes. This non-linearity is almost certain to have arisen from the exponential decline in sea ice, as shown in the PIOMAS sea ice volume trend. The trend is for September ice to fall to zero by 2015. Thus we can expect one month without sea ice in 2015, with the possibility for this event in 2014 or even in 2013.
Apart from volcanic eruptions and earthquakes with their step changes of state, the behaviour of the sea ice is possibly the most non-linear part of the Earth System because the melting is a threshold process. Until recently it was not well understood how the retreat of sea ice could cause a commensurate increase in weather extremes. But now it has become clear.
The retreat of sea ice is causing a non-linear rise in Arctic temperature, so that it is now rising at about 1 degree per decade, which is about 6x faster than global warming, reckoned to be rising at between 0.16 and 0.17 degree per decade. The temperature gradient between the tropics and the Arctic has reduced significantly over the past decade, as a result of this so-called ‘Arctic amplification of global warming’.
It now appears that the polar jet stream behaviour is critically dependent on this gradient. As the gradient diminishes, the jet stream meanders more, with greater amplitude of the Rossby waves and therefore with peaks further north and troughs further south. This effect alone produces weather extremes - hot weather further north than normal and cold weather further south than normal.
But as well as meandering more, the jet stream is also tending to get stuck in so-called 'blocking patterns', where, instead of moving gradually eastwards, the jet stream wave peak or wave trough stays in much the same place for months. This blocking may be due to stationary highs over land mass and lows over ocean, with the jet stream weaving round them. Here we may be a witnessing of a dynamic interaction between the effects of Arctic amplification and global warming.
Note that there was a similar dynamic interaction in the case of Sandy. Ocean surface warmed by global warming lent strength to the hurricane and provided a northerly storm track up the coast; and then a sharp left turn over New York was prompted by meeting a jet stream blocking pattern.
As a climate scientist, one might have expected a reduced gradient between tropics and pole to have some effect on weather systems, because there is less energy to drive them. The normal pattern comprises 3 bands of weather systems around the planet for each hemisphere, with each band having 'cells' of circulating air. The air rises at the tropics, falls at the next boundary, rises at the next, and falls at the pole. There has to be an odd number of bands, so that there is air rising at the equator and falling at the poles. The jet streams are at the boundary between the bands.
As the temperature gradient between tropics and pole reduces, one would expect the weather systems to spread in a chaotic manner, meandering more wildly. This is exactly what has been observed.
The sticking of the jet stream must be associated with non-uniformities of surface topology and heat distribution. Thus highs and/or lows are getting stuck over some feature or other, while the jet stream meanders around them.
Thus there is a reasonable explanation for how we are getting weather extremes, simply as a result of a reduced temperature gradient between Arctic and tropics. Another argument that has been given, most notably by Professor Hansen, is that the extreme weather events are simply a result of global warming - i.e. a general rise in temperature over the whole surface of the planet. Global warming can indeed explain a gradual increase in the average intensity of storms (whose energy is derived from sea surface warming) and in the peaks of temperature for heat waves. But global warming does not explain the observed meandering of the jet stream and associated weather extremes, both hot/dry and cold/wet, whereas the warming of the Arctic can explain these observations. Furthermore the non-linear warming of the Arctic can explain the non-linear increase of extreme events.
Since this hypothesis seems reasonable, it is fitting that the precautionary principle should be applied when it comes to trends. The forecasting of extreme events must take into account the trend towards more extreme events as the Arctic warms. And the Arctic is liable to be warm about twice as fast in 2015 as it in 2012, because of sea ice retreat.
This all adds up to a picture of abrupt climate change in the Arctic, now spreading to the Northern Hemisphere and soon to afflict the whole planet. These changes must be halted and then reversed. Meanwhile the effect on food security must be handled before the whole situation gets much worse.
Handling the food crisis
What should a country do, when faced by such a grave food crisis? The immediate response may be to become introspective and try and insulate the country from what is happening in the rest of the world. For a country like the UK, this is difficult, because of importing 40% of food and much of its energy requirements, such as natural gas from Kuwait. For the US, self-sufficiency has been a goal for energy, but there is a food problem from weather extremes, which particularly seem to affect the country.
For countries which have been net exporters of basic foodstuffs, the response may be to halt exports, as Russia did for wheat recently to protect its citizens but pushing up the food price index in the process. If this type of response is widespread, then a vicious cycle of food price increase and protectionism could develop, with a stifling of world trade and an increase in strife between countries.
But what people must not do is to ignore the non-linear trends and blame the weather extremes either on random fluctuations or on essentially linear effects such as global warming. The danger is that governments will do nothing at all to address the underlying cause of the linearity, which lies in the vicious cycle of Arctic warming and sea ice retreat.
We believe that a sensible strategy is two-fold: to deal with the symptoms of the disease and the cause of the disease.
The most conspicuous symptoms are floods, droughts, food price increase, security of food supply and food shortages. Less conspicuous are the effects of food price increase on global unrest and the spread of disease among humans, animals and plants. Water shortages may also be a growing issue in many countries. The changing frequency, severity, path and predictability of tropical storms (hurricanes, typhoons, monsoons, etc) will be a major issue for many countries, especially those with large coastal conurbations and those who depend on regular monsoons. Coastal regions and cities that have hitherto been immune to such storms may suffer great damage, as happened with Sandy to New York and could happen to Dubai.
Countries which rely heavily on one crop for income are liable to be heavily hit by weather changes.
By studying trends, one can estimate how quickly the situation is likely to deteriorate. One can see an exponential rise in extreme weather events, and the food price index is liable to follow this trend because of reduced agricultural productivity.
The price of food is dependent on a number of factors besides agricultural productivity, and these are under human control.
The policy of “food for fuel” has undoubtedly driven up the price of food, so this policy needs to be changed. Biofuel can still be part of policy, but must come from sustainable sources and without competing with food. For example biofuel from the biochar process can actually benefit food production, because the residue from heating biomass and producing the biofuel is a form of charcoal that can be used for improving soils, water retention, and crop yields.
An important factor in the price of food is the price of oil, because of use of oil in agriculture, not only for farm machinery and food transport but also for artificial fertiliser. Unfortunately much oil comes from countries where much of the population is on the bread line, so the social unrest from food price increase can shut down access to the oil which further pushes up the cost of food in a vicious cycle.
Speculation on the price of oil can be a major factor in producing spikes in the food price index, so this needs to be discouraged in some way. Similarly speculation on food commodities needs to be discouraged.
Perhaps the most important factor is management of food stocks, seed stocks, planting practice (use of monoculture, GM crops, etc.), timing of planting and irrigation. The timing becomes increasingly problematic as global weirding increases and weather becomes more unpredictable. There needs to be advice to farmers on how to cope – e.g. by judicious diversification and reduced reliance on single crop planting.
Cooling the Arctic
Dealing with the underlying cause of the climate extremes turns out to be even more important than dealing with the consequences on food security, because the underlying cause is a process which is gaining momentum and could become unstoppable in 2013.
In effect, we are approaching a point of no return, after which it will be impossible to rescue the situation.
The speed of action is required because of the speed of sea ice retreat. All indications are that there will be a major collapse of sea ice next year, with a new record minimum. And September 2015 is likely to be virtually sea ice free.
This is the inescapable evidence from the PIOMAS sea ice volume data.
Even if there were no danger from passing a point of no return, rapid action would be worthwhile because of the financial and human cost of the abrupt climate change.
The only chance of halting this abrupt climate change in its tracks is to cool the Arctic, and prevent Arctic amplification disrupting the jet stream more than it is at the moment. Delay to such action would cost around a trillion dollars per year and put a billion people into starvation."
http://a-m-e-g.blogspot.com/Pan-Arctic Ice Ocean Modeling and Assimilation System = PIOMAS
http://psc.apl.washington.edu/wordp...tions-of-an-ice-diminished-arctic-ocean/Figure 3 ~ The trend analysis of PIOMAS data
