How long do you think it will take for most sea ice in the Arctic to disappear? How much change in temperature you think this would result in?
Professor Peter Wadhams
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Peter Wadhams Sc.D., Professor of Ocean Physics
and head of the Polar Ocean Physics group at the
University of Cambridge, U.K., researching effects
of global warming on sea ice, icebergs and oceans |
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My own view of what will happen is:
- Summer sea ice disappears, except perhaps for small multiyear remnant north of Greenland and Ellesmere Island, by 2015-16.
- By 2020 the ice free season lasts at least a month and by 2030 has extended to 3 months.
- September sea surface temperatures are already elevated by 6-7°C over continental shelves of Arctic. As shrink back continues, the newly exposed surface water over abyssal depths warms up less in a single summer (say 2-3°C) because of deeper surface water layer (150 m) than over a shelf (50 m).
- The 6-7°C warming over the shelves causes offshore permafrost to shrink back and vanish over about 10 years. During this time there is elevated methane emission from offshore and from onshore warming, and global warming rates increase by about 50%.
- Result is that bad effects forecast for end of century (4°C warming worldwide, 10°C in Arctic) actually occur by about 2060. Speed of change is catastrophic for agriculture; warfare and population crashes ensue.
- Late in the day, the rapidly disintegrating civilised world tries desperate technofixes for warming and resource depletion, e.g. widespread use of nuclear power (thorium cycle), geoengineering. This may work, and bring us back from the brink of destruction after heavy losses.
Paul Beckwith
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Paul Beckwith, B.Eng, M.Sc. (Physics),
Ph. D. student (Climatology) and
Part-time Professor, University of Ottawa |
M
y projections for our planet conditions when the sea-ice has all vanished year round (PIOMAS graph projects about 2024 for this; I forecast 2020 for this) are:
- Average global temperature: 22°C (+/- 1°C)
(rise of 6-8°C above present day value of about 15°C)
- Average equatorial temperature: 32°C
(rise of 2 °C above present day value of 30°C)
- Average Arctic pole temperature: 10°C
(rise of 30°C above present day value of -20°C)
- Average Antarctica pole temperature: -46°C
(rise of 4°C above present day value of -50°C)
- Water vapor in atmosphere: higher by 50%
(rise of 4% over last 30 years, i.e. about 1.33% rise per decade)
- Average temperature gradient from equator to North pole: 22°C
(decrease of 28°C versus present day value of 50°C)
- Very weak jet streams (driven by N-S humidity gradient and weak temperature gradient as opposed to existing large temperature gradient)
- Result: very fragmented, disjointed weather systems
- Basic weather: tropical rainforest like in some regions; arid deserts in others with few regions in between
Note: This scenario would require significant emissions of methane from the Arctic. Without this methane, the scenario would still occur but would take longer. Disclaimer: Best guess and subject to rolling revisions!
Peter Carter
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Dr. Peter Carter, MD, Canada
climate-emergency-institute.org |
If methane is the main driver of natural end glacial warming rather than carbon dioxide, projections of global temperature increases are out by orders of magnitude.
On sea ice:
According to Tim Lenton’s opinion that 2007 was the tipping point, the start of ice free summers would begin @2015 on a new linear trajectory. As we know the trajectory is not linear, it would probably be earlier. As most of the models project possible abrupt loss, I assume it could be any year now.
Whatever the additional warming may be [
because of already unavoidable committed warming], the multiple cascading Arctic positive feedback domino effect is already unstoppable except by cooling.
Sam Carana
Already now, temperature rises and levels of greenhouse gases are higher in the Arctic than elsewhere. The prospect is that we'll lose most sea ice within a few years, resulting in a lot more sunlight to be absorbed, adding to the temperature rise in the Arctic.
This would push up Arctic temperatures by over 10°C within a few decades, but in some places such rises could occur in a matter of years, rather than decades.
Most worrying is that such intense local warming in the Arctic can cause large abrupt methane releases from sediments. This would add a lot of additional warming that would result in massive crop losses globally, threatening global fresh water supply and causing extinction at massive scale.
Clearly, action must be taken to reduce the danger that this will eventuate.
John Nissen
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John Nissen, MA (Cantab) Natural Sciences,
Director of Cloudworld Ltd, U.K., Chair of
Arctic Methane Emergency Group (AMEG)
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Of late, I have been basing my estimates of Arctic warming on a current rate of 1 degree per decade, doubling after sea ice collapse, and doubling again when ice is gone for five or six months of the year. Looking at PIOMAS data, I think we can safely assume 2015 for the first doubling, and around 2020 for the second doubling. This means that between 2015 and 2020, the rate would be 2°C per decade, i.e. 1°C per 5 years. After that, it would double to 4°C per decade, up to 2030. That gives 5°C warming over 15 years.
I am now wondering whether 1°C per decade is too small, since Peter says that the water has warmed 6-7°C. However 1°C per decade is already at least 5x global warming, reckoned to be at less or equal to 0.2°C per decade.
If today, there has been 0.8°C global warming temperature rise, then, by 2030, global warming will be around 1.2°C, neglecting methane and Arctic warming. If we take Flanner's higher figure of ~4 W/m2 increase, for the Northern Hemisphere, when sea ice has gone, then that is ~2 W/m2, globally. According to Hansen net the current net forcing imbalance is under 1 W/m2, producing the 0.2°C per decade, and nearly 1.0 degree global warming temperature rise by 2020. With complete loss of snow and ice, we'd only be doubling the global warming rate. Suppose we double the rate from 2020 to 2030, then the global warming temperature rise would be around 1.4°C by 2030.
A temperature rise of 1.4°C doesn't seem too bad, but then we have the disruptive effect of the Arctic warming disrupting the NH weather systems. This is already having a serious effect, so could be pretty catastrophic by 2020, let alone 2030.
Now we add in the methane, and there's more uncertainty, except things are going to be worse, and could be a lot worse, especially if that 50 Gt of methane comes out of ESAS this decade. That could send global forcing up to around 9W/m2 (averaged over 20 years?), and warming rate up to 2°C per decade, giving us over 3°C global warming temperature rise by 2030 in the worst case. So we'd be well beyond the so-called safety limit of 2°C!
I agree with Peter that some dramatic increase in methane emission is inevitable, so my conservative estimate would be an additional 400 Mt per year by 2020. This would nearly double the methane forcing by 2030, from current 1W/m2 (including indirect effects) to around 2W/m2. This would add a temperature rise of 0.1°C, taking the total from 1.4 to 1.5°C.
So my conclusion on global warming temperature rise is between 1.5°C and 3°C by 2030, while the Arctic warms at least 5°C above current temperatures. We must not go there! Geoengineering is essential!
BTW, the warming in the Arctic would guarantee collapse of the Greenland Ice Sheet this century, adding ~7 metre sea level rise and probably triggering the collapse of the WAIS adding a further 7 metres or so.
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Douglas Spence - Software Engineer,
interested party and concerned citizen |
Douglas Spence
Now
1. Even with the Arctic ice in the present state increasingly extreme weather is already moving us closer to a point of increasing risk to agricultural output.
2. For the last few years extreme weather has worsened year on year and since we have positive feedback processes in progress we have no reason to suppose this will do anything but accelerate rapidly.
2012-13
3. I expect significant to majority sea ice loss to occur in either 2012 or 2013, and expect this to dramatically worsen the weather, causing immediate stress to global food supplies. Combined with weak economic conditions we will see stress in countries dependent on food imports or aid triggering more "Arab spring" moments in previously stable regimes. Movement of refugees will cause knock on effects in neighbouring regions.
4. Modern civilisation is fragile and dependent on global supply chains that can be disrupted both by weather and politics. We will experience an increasing incidence of problems maintaining normal operation in technologically advanced societies. There is the potential for conflict in the Arctic as new resources open up.
5. Other positive feedbacks such as methane release and forest burn off will accelerate.
2014-15
6. I expect total sea ice loss will occur during summer in either 2014 or 2015. By this time I expect agricultural output to have declined to a point where food supplies are inadequate and famine and conflict are rife. Farmers will not know what to plant or when and even acquiring seed from other climatic regions may be problematic.
7. Social conditions will be comparable to the Holomodor. People will try to eat anything and everything - earthworms, insects, each other - even in some cases their own children. Nation states will fragment and reform into smaller and increasingly violent competitive groups fighting over rapidly diminishing resources. Maintaining the supply chains required for the operation of modern technology including agriculture will be largely impossible.
8. If we see widespread war before nation states fragment there is a possibility of the use of nuclear and genetically enhanced biological weaponry. Whether through war or famine the human population will be in freefall.
2016+
9. The climate will continue to worsen as more heat flows into the system and this will become the new threat to survivors as population density becomes too low to sustain conflict. Most survivors will be eliminated, leaving the human race on the brink of extinction. A majority of the planet will cease to be habitable. The deserts will greatly expand, though this will help balance the planets thermal budget. Very few people will live to see the Arctic sea ice entirely gone throughout the year or the ruined cities drowned in the rising sea.
10. Assuming the collapse is as rapid and severe as I expect – I would expect the human population to collapse below the new carrying capacity of the planet and therefore for resource pressure to lighten once a sufficient number of people die (granted with few useful resources left and uncertainty about precisely which regions would be good prospects).
Finally
Theoretically there will be some isolated and scattered areas where the climate is still habitable, resources are sufficient and some form of agriculture can be practised. If small groups of people make it to these areas, there is a theoretical chance over many generations to recover civilisation, albeit at great disadvantage.
Disaster taxa will rapidly proliferate into the empty ecosystem, leaving the return of biodiversity to occur over a few million years, bringing the sixth great mass extinction to a close.
NB Since we are at a point where weather is a key effect, allow +/- 1 year for (good/bad) luck.
Malcolm Light
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Malcolm Light, PhD, University of London
Earth science consultant |
If left alone the subsea Arctic methane hydrates will explosively destabilize on their own due to global warming and produce a massive Arctic wide methane “blowout” that will lead to humanity’s total extinction, probably before the middle of this century. AIRS atmospheric methane concentration data between 2008 and 2012 (Yurganov 2012) show that the Arctic has already entered the early stages of a subsea methane “blowout” so we need to step in as soon as we can (e.g 2015) to prevent it escalating any further.
The Arctic Natural Gas Extraction, Liquefaction & Sales (ANGELS) Proposal aims to reduce the threat of large, abrupt releases of methane in the Arctic, by extracting methane from Arctic methane hydrates prone to destabilization.
After the Arctic sea ice has gone (probably around 2015) we propose that a large consortium of oil and gas companies/governments set up drilling platforms near the regions of maximum subsea methane emissions and drill a whole series of shallow directional production drill holes into the subsea subpermafost “free methane” reservoir in order to depressurize it in a controlled manner. This methane will be produced to the surface, liquefied, stored and transported on LNG tankers as a “green energy” source to all nations, totally replacing oil and coal as the major energy source. The subsea methane reserves are so large that they can supply the entire earth’s energy needs for several hundreds of years. By sufficiently depressurizing the Arctic subsea subpermafrost methane it will be possible to draw down Arctic ocean water through the old eruption sites and fracture systems and destabilize the methane hydrates in a controlled way thus shutting down the entire Arctic subsea methane blowout.
NASA adds that this heat wave, like all extreme weather events, has its direct cause in a complex set of atmospheric conditions that produce short-term weather. However, weather occurs within the broader context of the climate, and there’s a high level of agreement among scientists that global warming has made it more likely that heat waves of this magnitude will occur.
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