Wednesday, October 25, 2017

Time's Up

Even 2 C of Warming is Highly Dangerous
I. Surges In Sea Level Change

It has been known for some time that instances of quick or sudden rises in sea level take place.

Recently a new study reaffirmed our understanding of the surge phenomenon with another discovery that sea level rise surges are part of the historical picture (Oceans Can Rise in Sudden Bursts).

Various Dredd Blog posts have pointed out that these surges have taken place recently, for example, the U.S. East Coast has experienced 'small' surges in recent years:
Coastal sea levels along continental margins often show significant year-to-year upward and downward fluctuations. These fluctuations are superimposed on a longer term upward trend associated with the rise in global mean sea level, with global mean sea level rising at roughly 3 mm per year during the recent 20 years of accurate satellite measures. For society, it is the regional changes along any particular coastal zone that are most important. Our analysis of multi-decadal tide gauge records along the North American east coast identified an extreme sea-level rise event during 2009–2010. Within this relatively brief two-year period, coastal sea level north of New York City jumped by up to 128 mm [5.05 inches]. This magnitude of inter-annual sea level rise is unprecedented in the tide gauge records, with statistical methods suggesting that it was a 1-in-850 year event.
However, meltwater pulse 1C (8,200-7,600 years ago) left traces at numerous locations in the United States, northwestern Europe, and China. It occurred soon after the 8200 year cold event, which resulted from the final catastrophic drainage of glacial Lakes Agassiz and Ojibway around 8400 years ago. The torrent of around 100,000 cubic kilometers unleashed within a few years or less amounted to barely a meter rise in global sea level, if evenly spread across the world's oceans (note 1). Yet the stratigraphic record preserves vestiges of this relatively minor pulse.
(The Surge: A Forgotten Aspect of Sea Level Rise). Recently, over a two year period (2009-2010), a 128 mm sea level rise took place @ the U.S. East Coast.

Further, a one meter sea level rise took place over a few years in the more distant past, so, it is not unsound to say that we can expect such surges at any time now (ibid).

Regular readers know that "a meter rise in global sea level, if evenly spread across the world's oceans" is a mythical event,

That is because, like the "2009–2010 ... two-year period [when]  sea level north of New York City jumped by up to 128 mm", these events do not happen as a global event.

That is because the ocean is not a bathtub that rises uniformly around the globe (The Bathtub Model Doesn't Hold Water, 2, 3, 4).

The reality is that sea level rises more in some places than in others when glacial melt water flows into the oceans (Sea Level Fall: The Forgotten Aspect of Sea Level Rise?).

II. What Does Global Warming Have To Do With It?

Scientists work hard to determine the future of our warming planet:
"The likely range of global temperature increase is 2.0–4.9 °C, with median 3.2 °C and a 5% (1%) chance that it will be less than 2 °C (1.5 °C)."
(Less than 2 °C warming by 2100 unlikely). We haven't heard much about that potential ~5 degree C increase in global mean average temperature have we?

Projections showing 4.9 C by 2100
The Paris Accord hopes for a 1.5 degree C limitation.

The quoted paper indicates that there is a very low likelihood that such a low increase will be what happens.

To top it off, even a 2 degree C increase is not safe, rather, it is dangerous; thus, it is unlikely that our future is a safe one under current circumstances and attitudes of denial (New Study Says Even 2 Degrees of Warming 'Highly Dangerous').

What will this warming force on our world, in terms of impact on ice sheets and sea level change?

I think it is likely that we will see more surges like the one off the coast of New York as the atmosphere warms and 93% of that warming enters the oceans.

III. Conclusion

These realities are a threat to civilization itself:
"Eminent Australian scientist Professor Frank Fenner, who helped to wipe out smallpox, predicts humans will probably be extinct within 100 years, because of overpopulation, environmental destruction and climate change."
(Professor Fenner, emphasis added; see also: Civilization Is Now On Suicide Watch, 2, 3, 4, 5, 6, 7, 8).