Chapter 2. Climate Tipping Points With Some Geology on the Side
We live in an ice age. This is the Quaternary Period of Earth’s history. Just like the Jurassic Period was one of the period’s that the dinosaurs lived in, the period we live in is the Quaternary. The Quaternary is one of Earth’s few ice ages and it started 2.6 million years ago. So we have to worry about temperature increases while living in an ice age, lucky us.
A number of geological factors have played a role in creating this ice age. These include; most of the earth’s land mass ends up in the northern hemisphere, the Arctic Ocean gets surrounded and blocked off, the Isthmus of Panama forms dividing the Atlantic and Pacific, Antarctica ends up on the South Pole. The Himalayas formed causing weathering which slowly reduced atmospheric CO2 levels. Weathering happens as rain and snow melt carve out the mountains releasing minerals. These minerals can then react with CO2 to form carbonates. This is one reason we ended up with the low atmospheric CO2 levels that have existed throughout the Quaternary. (See Fig. 5)
One last bit of geology is that there are 100,000 year glaciation cycles that have been occurring during the Quaternay’s last one million years. These are brought on by small changes in Earth’s orbit caused by Saturn and Jupiter and are part of the Milinkovitch cycles.
Each 100,000 year cycle goes like this; the first 70,000 years are increasingly colder with a buildup of glaciers in the far northern latitudes.Then the glaciers move south for 10,000 to 15,000. The most recent glaciation covered New York, Chicago, Scotland and northern Europe. The cycle concludes with a rapid warming causing the glaciers to melt back to the far north and leaving the Earth in a warm interglacial period lasting 10,000 to 15,000 years. Then the cycle starts over. We’re just ending the current interglacial period and starting into what would be the next glacial build up.
But you probably saw the Al Gore movie. I hope he explained this better than I did, though his movie doesn’t seem to be available on youtube for free. This shows the man has some serious marketing muscle behind him, but prioritizing royalties over climate sends an oddly mixed message.
I bring up geology because the same tipping points caused by our fossil fuel emissions also existed during each of the 100,000 year cycles. One time in each cycle there were rapidly rising temperatures which then produced large increases in CO2 levels.
There have been about ten of these cycles in the last million years, which shows that through all of these cycles the tipping points haven’t produced a runaway climate. True, we’re at a higher atmospheric CO2 level than any of the previous cycles, but it indicates that conditions on Earth have acted as a backstop to prohibit any climate runaways in the past 2.5 million years.
But runaway climate change is not the only concern, though that seems unlikely. What will happen with certainty is the damage done to Earth’s eight billion and counting human population due to anthropogenic climate change and its associated tipping points.
Tipping Points (1 is most damaging, 8 is least damaging)
A climate tipping point is when global warming causes an abrupt change that can’t be reversed at all or can’t be reversed until global temperatures have decreased sufficiently. These changes can be a condition, like a drought, or they can establish a feedback loop like thawing permafrost.
Thawing Permafrost (2). Much of the Earth’s landmass is in the Arctic and under normal circumstances it’s frozen. A warming Earth will begin to melt the frozen land. When permafrost that’s been frozen for thousands of years begins to melt, that is a tipping point. These areas contain organic carbon, and once the permafrost is thawed microbes will eat the organic carbon releasing the greenhouse gasses methane and CO2. These greenhouse gasses further increase the warming which causes even more permafrost to melt and now the tipping point has produced a feedback loop.
Methane Hydrates (1). Methane hydrates are methane containing ice formations found in the ocean floor sediment on Earth’s continental shelves. There’s probably as much of this methane as there is oil, but the estimates jump around. Companies and countries have been trying to extract methane hydrates for fuel, but it’s hard to do. As temperatures rise, the oceans begin to heat and eventually methane hydrates in the shallowest parts of the ocean start to melt, which releases methane. The released methane causes more warming which causes more hydrate melting. This is a tipping point and like permafrost this starts a feedback loop.
West Antarctic Ice Sheet (3). As temperatures rise they can weaken parts of the ice sheet. If a large part of the ice sheet falls into the ocean, that’s the tipping point. This will cause a rise in sea level that can’t be undone for thousands of years, when an equal amount of water is finally frozen back into a glacier.
This doesn’t produce a feedback loop but it can start a chain reaction. That first part of the ice sheet was probably helping to hold back other parts of the ice sheet. When the first one goes, it increases the chance that others will follow.
Greenland Ice Sheet (4). Same as the West Antarctic Ice Sheet except in Greenland.
Indian summer monsoon (5). The concern here is that climate change will reach a tipping point where the monsoons are permanently moved off their historic pattern. This could be a lessening of the rainfall, a large increase in rainfall or some combination such as heavy early rainfall and decreased later rainfall. Since a large percentage of the world’s population relies on the monsoons for food and fresh water, any permanent changes could be devastating.
Amazon Rainforest Dieback (Rank 6). There’s the possibility that rising temperatures will reach a tipping threshold causing the Amazon rainforest to start dying off. Microbes would eat the dead plant material releasing methane and CO2.
Atlantic Meridional Overturning Circulation (Rank 7). “The Atlantic Meridional Overturning Circulation (AMOC) is a large system of ocean currents that carry warm water from the tropics northwards into the North Atlantic. … As warm water flows northwards it cools and some evaporation occurs, which increases the amount of salt. Low temperature and a high salt content make the water denser, and this dense water sinks deep into the ocean. The cold, dense water slowly spreads southwards, several kilometers below the surface. Eventually, it gets pulled back to the surface and warms in a process called “upwelling” and the circulation is complete.” [metoffice.gov.uk]
Increasing temperatures would slow down this process which would result in cooler temperatures in western Europe. The cooling is counted as a positive effect as opposed to the tipping points previously discussed, which are all negative effects.
Surface Albedo Feedback (Rank not conclusively determined). Snow and ice in the arctic reflect sunlight back out of the atmosphere, which counteracts the warming effect of greenhouse gasses. Global warming melts this snow and ice creating a feedback loop as the melting allows more warming which causes more melting.
The Impacts Tipping Points Are Expected to Have.
The study we’ll look at represents the impacts of climate change in U.S. dollars.[S. Dietz, et al. 2021] These impacts are calculated in terms of the Social Cost of Carbon (SSC), and they start with the cost of emitting one ton of fossil fuel derived CO2. The cost is counted in U.S. dollars per ton of CO2 (US$/tCO2). This is shown in the top row as None which has a cost of 52.03. It’s called None because it’s the basic cost of one ton of CO2 with none of the tipping points included.
The largest tipping point is methane hydrates, which increases the basic cost by 13.1%. The second largest is permafrost, with an increase of 8.4%. These two tipping points have a much greater effect than all of the others and are the big bad boys of tipping points.
The Antarctic and Greenland ice sheets are next, followed by the monsoons. The Amazon dieback shows a negligible effect. The Amazon tipping point doesn’t include land use changes. The Atlantic circulation has a positive effect. Surface albedo feedback (SAF) presented a problem as the model they used already counted all the Arctic snow and ice as having been melted. To keep from adding this in twice, the effect is given a negative value.
The cost of emitting a ton of CO2, including the effects of the tipping points, comes to $64.80 per ton. This means that someone or some group will pay $64.80 to deal with the impacts caused by that one ton of CO2.
Total emissions of CO2 from fossil fuels in 2021 was 36.3 billion tons.[IEA] This brings the total social cost for just one year to $2.35 trillion dollars. So, the shareholders of the fossil fuel companies make hundreds of billions and they get to pass trillions of dollars in future costs to others. Yes there’s a problem here.
Climate Change and theTipping Points Require a Big Investment in Computers
The tipping points were less damaging than I’d expected, but they also show the need for continued study and refinement of the costs associated with each one.
Investment in better computing capability is urgently needed. Better computer resolution of ocean temperatures is needed for a better understanding of methane hydrate feedbacks, for instance. The same is true for permafrost and the other tipping points.
The U.S. is gearing up the Exascale Computing Project and climate change is part of its portfolio. But, given the huge costs in capital and human suffering associated with climate change, the study of climate change and its impacts should be the primary focus of this and similar research projects. At this point in history, the study of climate change is much more important than studies that can increase the corporate profits of manufacturing or defense companies. Hopefully, we can match their lobbying power sooner rather than later.