Thursday, March 15, 2018

Much longer than a couple centuries

I’ve finished reading Deep Future; The Next 100,000 Years of Life on Earth by Curt Stager. I asked for it as a Christmas present because it was described as thorough, balanced, and understandable description of global climate change. It was that. There were times I thought he might be taking the climate denier’s position. But he wants a clear and complete discussion more than he wants to advocate (though he does that too), which, he says, is what a scientist should be after.

When we hear climate change discussed we frequently hear the effects will last well into the next century. Some stories imply a longer timeline, perhaps two or three centuries. So Stanger starts there.

Scenario 1 is if we stop using carbon fuels rather quickly. From the time humans started dumping carbon dioxide until we stop this scenario says the total CO2 added to the atmosphere is about 1000 gigatons. Scenario 2 is if we keep using carbon fuels until we’ve used every crumb of coal and drop of oil. If we do this we would add 5000 gigatons to the atmosphere.

Stager reviews how CO2 eventually gets out of the atmosphere. I won’t repeat the chemical cycle, though I’ll say it includes a great deal dissolving into the oceans, making them more acidic. More on that later. But this takes time. In Scenario 1 to come back to our pre-industrial level of C02 would take 100,000 years. In Scenario 2 it would take 400,000 years. This is not a short-term situation.

A couple of the broad consequences of either scenario.

* Stager reviews the various mechanisms that contribute to an ice age. These include the slow wobble of earth’s rotation and changing eccentricity in earth’s orbit. These factors and others say we’re due for another ice age about 50,000 years from now. But a climate affected by human actions means this ice age has been canceled. That is good news for cities such as Winnipeg, Detroit, London, Berlin, and Moscow. This is where I questioned Stager’s efforts to get humans to change course, but I also see his efforts to be balanced, to talk about all aspects of climate change.

* Once the climate has warmed, which will happen in a couple thousand years, there will then be a long, slow cooling period, lasting 80-90 thousand years (for the short scenario). Humans living in that time will see the warm climate as natural and may be troubled by the cooling (though the cooling will be so slow it may not be noticed in a normal human lifespan).

* Lots of species of plants and animals may become extinct. But it will take something much more disastrous for humans to become extinct.

Stager looks at a couple times in earth history in which the climate got warm. One was before the last ice age, about 120,000 years ago. This certainly affected humans. The other was 55 million years ago, about 10 million years after the last of the dinosaurs. He uses both chapters to discuss levels of greenhouse gases, amount of glaciation (in the Arctic, Antarctic, and on mountains), sea level, and effects on life. As for that last one, only a few species became extinct because they were able to adjust their territories to what was comfortable. With this warming animals won’t be able to move to an appropriate territory because we’re in the way.

One of the big problems of climate change, also the one discussed least in mass media is the oceans becoming more acidic. Carbon dioxide dissolved in water makes it a bit more like an acid. That may not be much of a problem for fish, but it will be a big problem for most sea creatures with a shell. It isn’t so much that the acid eats the shell, more that the creatures will have difficulty forming a shell. In addition to all the shellfish we like to eat, this affects coral. A lot of these creatures will become extinct. It is for this reason, more than any other, we should get off carbon as quickly as possible.

Yes, sea levels will rise. And perhaps by quite a bit (say goodbye to much of Florida). The huge East Antarctic ice fields (where most of the earth’s ice is) may not melt, but West Antarctic fields, the Arctic, Greenland, and mountain glaciers probably will. But sea levels won’t rise so quickly that it will snatch your children off the beach. It will happen much more slowly than that. We may not notice those abandoning homes on the beach in amongst the people who routinely move during any given year. But as the waters rise there will be economic winners and losers as formerly inland real estate becomes beachfront, only to be submerged in time.

Another group of economic winners will be those who can exploit an ice-free Arctic. Possible ways to make money are with oil drilling and year-round shipping. Yes, it is possible we’ll lose the polar bears, though they may mate with brown bears farther south.

If you’ve got a *really long* investment timeline – say three thousand years or more – you could do quite well buying property in Greenland. The receding icepack will reveal fertile soil and mineral rich land. But don’t buy property in the center of this island. The weight from a mile or two of ice has pushed the land down. If all the ice melts this land will take a long time to rebound and will likely flood as a huge lake or giant fjord.

As for the tropics… Yes, they’ll get much hotter (though the amount of warming will be less than the poles). But people can and have adapted to such high heat. However, long-term forecasting of rainfall is much harder than forecasting temperature. We don’t know if rising temperatures will mean a wetter or drier climate.

Stager concludes by looking at two particular areas he’s familiar with, South Africa and the Adirondack Mountains, where he lives.

South Africa has two seasons, wet and dry. The rain is driven by a wind pattern. As the sun moves north in March, April, and May this wind pattern moves north too. When it blows across the land they have rain. As the sun moves south a few months later, the wind pattern does too. When it no longer blows across the land they no longer have rain. But in a warmer climate this wind pattern may shift farther south and never move far enough north to blow across the land. The result is no rain. Capetown is already under severe water rationing and may face a date in which the city says we have no water.

As research into the climate showed that global warming is a real thing coming soon, Stager asked what does the data show of it happening *here* in the Adirondacks? It is an important question for a region that makes a lot of money off snow sports. Mud sports don’t make as much. He found there was very little historical data. That leads to a discussion of accuracy in measuring and reporting. Stager explains with an example:
For instance, Jane runs the local weather station for twenty years. She awakens early each morning to record the temperature before heading off to work – unless she is on vacation or the kids are sick. That leaves a gap in the daily readings and distorts the monthly average temperature calculations.

When Jane retires, John offers to take over her duties. But John doesn’t like to get up early, so he takes his readings later in the morning when the sun starts to warm things up for the day. Automatically, and incorrectly, the daily temperature averages become warmer.

And then there are equipment upgrades, power outages, changes in the number of readings per day, changes in station location, and changes in local vegetation, all of which can affect temperature data.

Another issue is over what time period is the data analyzed? Should we start in the 1950s, which was a brief warm spell, or in the cooler 1970s? Do we look at just the ends of the time period? How do we analyze the data in between?

Stager did find other kinds of data to show the Adirondack region is warming like the rest of the world. Lake Champlain is along the eastern edge of the Adirondacks. During the 19th Century there were only 3 winters the lake did not freeze over. Since 1950 it hasn’t frozen over two dozen times.

So, Stager asks, what kind of future do we want? Warm enough to avoid the next ice age? Cool enough to avoid killing off the coral? We’re not talking about the issue. Scaring people to act isn’t good. Talking, in a clear manner, laying out everything we know, getting input from everyone affected (which is everyone), and doing it without partisan dogma, urgently needs to happen.

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