I've always been concerned about climate change and acted to reduce my carbon footprint. When I discovered the latest science, I was horrified to learn that, unless we can make the planet colder, we're heading for irreversible, devastating climate change.

What's The Arctic Death Spiral? 

The ice that used to cover the Arctic Ocean is disappearing fast:


The downward trend in Arctic sea-ice extent began around 1950. Reliable figures for sea-ice volume start in 1979. 

I admit that this circular plot provides a catchy name tag while masking noise on the chart. The square plot below is equally compelling.

What's The Problem?

The IPCC is almost certainly wrong with its claim in October 2018 that 
the likelihood of an Arctic Ocean free of sea ice in summer would be once per century with global warming of 1.5C, compared with at least once per decade with 2C
Despite the noise, the best-fit line on this chart of real data looks inexorable and suggests that Arctic ice-free Septembers could first appear from 2030 and will become a permanent feature around 2045, with the ice-free periods subsequently extending to last multiple months:


Maybe the IPCC know something the real data doesn't and this line is going to flatten out or curve up before hitting zero. Or maybe the current climate-change models don't work in the Arctic? They don't even match the recorded data for recent years!

Does This Matter?

As Arctic sea ice disappears, the following feedback effects have already started and probably explain why the Arctic is warming at about twice the global average rate:
  • less sunlight is reflected: the Arctic warms faster
  • methane locked in the Arctic seabed and neighbouring tundra for thousands of years is being released: just a small fraction of the estimated deposits would cause 0.5C of extra warming 
  • more open ocean means bigger waves, slowing and reducing the formation of the next year's ice
  • the sea channels out of the Arctic spend less of the year blocked by ice, allowing more ice to drift away
  • removing Arctic ice weakens a key driver for ocean currents and slows the rate at which dissolved CO2 is pulled into the deep ocean
Even if we stop further greenhouse gas emissions right now and stabilise atmospheric CO2 at current levels, a tipping-point has been passed: these feedbacks mean Arctic sea ice will continue to retreat and the global climate will continue to warm.

Our governments and economic modellers base their non-action on misinformation. The world's only Nobel-laureate climate economist, William Nordhaus, states:
There is virtually no chance that the rise in temperature will be less than the target 2°C even with immediate, universal, and ambitious climate change policies.
He suggests we deal with climate change by applying a carbon tax but admits:
If the damage function shows higher costs, or has sharp curvature at or around 2°C ... then the revised optimal policy would have much higher abatement costs
Nordhous's damage function is based on the IPCC's wrong predictions and furthermore does not include the Arctic feedbacks. The real damage function will have both higher costs and sharp curvature.

What Are The Consequences?

The temperature history of the Earth shows our planet has previously had two stable equilibria: an ice-covered ball reflecting most sunlight; and ice-free periods much hotter than today. For the past million years or so we've enjoyed an unstable equilibrium somewhere in the middle, cycling through ice ages and warm periods. It looks like we're about to upset that equilibrium and force the planet into a warm phase never before encountered by our species.

The highlights include:
  • The Greenland ice sheet is 3km thick; it's melting at a rate of 300km3 per year; when it's gone sea levels will rise 7m.
  • The Antarctic ice sheet (the result of 400,000 years of snowfall) is melting at a rate of 80km3 per year; when it's gone... sea levels will rise a further 60m.
  • These melt rates will only get faster, friction with the underlying land will reduce and vast chunks of ice sheet will slide into the sea.
  • Our agriculturally productive land area is going to shrink risking... large-scale starvation.
  • Needless to say this is also terrible news for polar bears.
It doesn't matter whether climate change is man-made or not: unless we act to make the world colder, these things will happen. If we continue with business as usual, they will accelerate.

What Should We Do?

  • A global carbon tax
  • Stop extracting fossil fuels asap
  • (Grudgingly) accept that, until we have more renewable energy, we need nuclear power
  • A massive research effort to work out the most cost-effective methods to remove CO2 from the atmosphere
  • Similarly devise and implement global-scale geo-engineering to reduce temperatures now eg cloud-seeding, reflecting vast amounts of sunlight
It seems fair to suggest that the biggest beneficiaries of the climate-changing gases released so far have the greatest moral obligation to act first. 

What Should I Do?

However, individual actions aren't going to help much. We need governments to radically change policy. So please:

Any Comments?

Please send any constructive comments to

References

Author

Ben Horton
Cambridge
April 2019