Tag Archives: environment

CCG Predictions for the Earth System

30 Jun

Currently albedo driven positive feedback is underway in the Arctic. The sea ice and land based snowpack are melting earlier and more than ever before (in human history) and the region is warming rapidly, especially in the winter when the extra heat accumulated into the ocean during the summer is releasing back to the atmosphere. We have already got a little taste of the sort of changes we can expect as the thermal gradient driving the jet stream has weakened imposing a significant increase in extreme weather on mid latitudes as more blocking patterns form.

Because of the long polar night the heat is released from the system and able to escape back out to space. Since the sea ice plays an insulating role on the ocean during the winter ice growth during the winter is paradoxically increasing as these changes occur but since the ice growth is from a lower base and more heat must be released back from the ocean to cool down this cannot compensate for the net loss of ice volume. It is our belief however that the Arctic will settle down into a new equilibrium regime where the sea ice is seasonal – forming during the winter and entirely melting during the summer.

We are currently predicting total ice loss in either 2014 or 2015 during the summer. We believe that in approximately five more years after this point the ice will be close to the equilibrium and that the ice free period will have extended out however many months into the summer season it is likely to. The substantially lower insolation in other seasons will put a brake on this process within a few years (quite possibly less than five) and the rate of change in the Arctic will start to slow – concluding the first abrupt climate shift we are going to experience.

At this point we will have an Arctic that is a lot warmer in the winter than usual, and a little warmer in the summer. We anticipate the effects upon the jet stream will be substantially worse than they are now but in essence simply more of the same.

If this was where all the changes stopped there might be a light at the end of the tunnel and the hope of adaptation to the new conditions for a significant portion of humanity. Unfortunately, we believe there are more rapid changes coming in the pipeline and after this time the focus of these changes will cease to be in the Arctic.

Atmospheric and thermohaline circulation play an important role in moving heat polewards. As the Arctic warms these processes slow (or theoretically stop, but we are not predicting this in the near future). This means that less heat is transported to the Arctic to be radiated back into space during the polar night. Although this helps ensure that the Arctic can form an equilibrium with a seasonal ice regime there is another important consequence.

Quite simply, less of the heat that was moving to the Arctic will be going there. Inasmuch as the Arctic changes are proceeding relatively abruptly this should also be expected to manifest relatively abruptly. Mid and low latitude regions will experience a certain amount of rapid warming. Although this warming will likely be relatively mild compared to the Arctic these regions contain tipping points relevant to both natural and manmade ecosystems (agriculture) that will cause great harm. For example the amount of additional warming required to destroy the Amazon rainforest (potentially rapidly adding over 100ppm to atmospheric carbon dioxide) is quite small. Likewise the American midwest – a key agricultural region – is likely to abruptly revert to desert. These are just two examples of the rapid and permanent changes in the rest of the world that we believe are likely to occur abruptly as the Arctic starts to settle.

It is also important to note that there will be a second stage of activity within the Arctic. Although there is almost certainly no scope for a true methane catastrophe in the near future it is likely that the normal cycle of increased atmospheric methane following removal of ice will occur as land permafrost melts and subsea permafrost weakens and releases both the accumulated methane free gas reservoir (currently contained under high pressure by the once frozen seabed) and decomposes methane clathrates over shallow continental shelves. An abrupt and large release of methane has the scope to deliver a substantial warming pulse of relatively short duration that is highly likely to substantially exascerbate problems in the rest of the system. This has the potential to substantially raise atmospheric carbon dioxide still further.

It is our assessment that human civilisation will be unable to maintain coherence beyond the start of this process. A fuller analysis of this will be done seperately.

There is some possibility that the conditions to create a full methane catastrophe are met later this century or within the next few centuries. At this point it depends mostly upon what happens with natural feedbacks within the earth system – manmade emissions have started the snowball rolling down the hill, but we can do little or nothing to stop further snow being collected if things proceed as far as have outlined above.

6-7C of warming above the baseline would be required to create the key factor to drive a true methane catastrophe that would release methane from clathrate reservoirs globally, even from relatively deeper water. It would take centuries to millennia to occur as it takes a long time for the ocean to absorb heat and warm up but the consequences would be devastating. The only regions in the planet that might still be theoretically capable of supporting human life would be the exteme polar regions in this scenario.

Proper planning for our children and their children requires us to look not just at the next few years – as extreme weather increases and civilisation starts to crumble – but at the indefinite future of our species.

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