In terms of human cost, Paris climate goals are likely insufficient.

Yesterday I wrote about the danger of assuming, as the CEO of Shell apparently does, that we’ll be able to cool down the planet in the second half of the century, even if we overshoot the targets set in the Paris agreement by 2050. For those who don’t want to read the post, it’s pretty straightforward: The warmer it gets, the better the odds of passing a “tipping point”, beyond which the planet would continue warming without our help, and possibly even in spite of our efforts to cool it. That’s a danger to all of us, obviously, but even within that risky bet that’s apparently being made with our lives, there are people whose lives have already been written off altogether.

Keep in mind, going forward, that “serious” people consider it reasonable to allow us to pass 1.5-2°C, because we’ll just bring the temperature down after. Their best-case scenario still involves a huge amount of ice melt, as the temperature continues to rise. That, in turn, means significantly more sea level rise, and devastation for those most at risk. The problem is that Antarctica, being an entire continent of ice, is a literally massive heat sink. Keep in mind that all of the greenhouse gasses we’ve added to the atmosphere are trapping an amount of heat equivalent the heat of four Hiroshima-sized atomic explosions per second. That’s as of 2013, so it’s probably at least a bit higher now, but the other thing they note is that most of that energy is going straight into the oceans and ice. That doesn’t just get absorbed, it causes changes. In the oceans, it causes thermal expansion, and in the ice, of course, it causes melting. Both of those increase sea level, but that doesn’t affect everyone the same.

This video from Minute Physics is a good primer, but basically gravity affects sea level, so big chunks of mass, like mountains, draw the oceans toward them, raising local sea level above what it would have been without mountains. The ice sheets of Greenland and Antarctica are big chunks of mass, similar in scale to mountains, and as they melt, the gravitational force they exert on the oceans eases. This means that the ocean retreats from the melting ice, and “settles” towards a new center of gravity. The effect of this is that ice melting in Greenland is accelerating sea level rise in my old stomping grounds of New England (among other places), not just because it’s adding water to the oceans, but also because it’s effectively “tilting” the oceans by changing how gravity pulls at them.

That means that, as huge amounts of heat continue to be absorbed by ocean and by ice, sea level rise will continue accelerating, which will hit those areas in the gravitational “danger zones” the hardest. It’s something that, in theory, a nation like the U.S. can cope with easily, but when we move from Greenland south to Antarctica, the countries being put in danger have neither the land nor the wealth to survives casual attitudes about so-called “safe” amounts of warming:

While rising temperatures are having many deleterious effects on global ecosystems, economies and human wellbeing, an interdisciplinary team of researchers at the University of Massachusetts emphasize that temperature alone is not a sufficient basis for climate policy. The team focused on the Antarctic Ice Sheet, which holds the world’s largest store of freshwater—enough to raise the oceans by 58 meters, and which is melting at an accelerating pace. But the physics of the ice sheet itself also contribute to its liquification, which will continue for millennia, even if global carbon emissions are reigned in. And because melting ice can slow rising temperatures in the atmosphere, it is conceivable that the melting ice sheet could help maintain what is commonly considered a “safe” level of warming, 1.5 degrees, say, while actually allowing for devastating sea-level rise. Furthermore, all that Antarctic meltwater won’t cause the same amount of sea-level rise everywhere in the world. Some areas in the Caribbean Sea as well as the Indian and Pacific Oceans will experience a disproportionate share of the sea-level rise from Antarctic ice—up to 33% greater than the global average.

This gap between temperature and sea level has immediate repercussions for many places throughout the world, and especially for the Alliance of Small Island States (AOSIS), an organization of 39 island and coastal nations across the globe. Indeed, the paper’s authors show that, though AOSIS countries have emitted a negligible portion of the planet’s anthropogenic greenhouse gasses, they are bearing the brunt of the world’s rising waters.

“Temperature is not the only way to track global climate change,” says Shaina Sadai, the paper’s lead author, who completed this research as part of her doctoral studies in geosciences at UMass Amherst, “but it became the iconic metric in the Paris Agreement. Knowing that Antarctic melt can delay temperature rise while increasing sea levels, I wondered what it meant for climate justice. But climate science alone can’t answer that question of justice.”

I think that last point is worth dwelling on. It’s easy to forget that temperature isn’t the only metric to watch. Sea level rise is an important one as well, of course, but a huge portion of climate data, past and present, isn’t just from temperature measurements and a few physics equations. We know what’s likely to happen to the surface of our planet because we’ve been able to track what it’s already doing, and we can look at fossils from past warming events. Fossil pollen, for example, can give us an idea of past climates and climate change, by telling us about the plants that lived in a given area at the time. Likewise, things like the “insect apocalypse”, mass crab-death, reef bleaching, and a dozen other things can be a metric. Temperature tells us about energy buildup, but other data can tell us how that actually affects the complex systems of a planet’s biosphere.

One other such metric, arguably the most important to humans, is the degree to which climate change is affecting humanity. In that regard, I would say that we are actively failing, it’s guaranteed to get worse with the current crowd of crooks in charge. It really does seem as though they’ve just written off large portions of humanity (almost none of whom are white), and are betting that they can bullshit their way through hundreds of millions of deaths, and keep their power the whole time.

We have made progress in the right direction, but unless you have faith in The Invisible Hand of the Free Market, there’s no way it’s more than a baby step in the right direction, with a desperate hope that “nudging” the market will solve everything. We need to be doing more, and not as individuals – as a species. As I so often say, those to whom we’ve given most of the world’s wealth and power have already demonstrated that they value human life far, far less than maintaining the system that put them where they are. That does mean that it comes back to us doing more, but the “more” that we should be doing is less about power consumption, and more about our political power, as people who value both life, and freedom.

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  1. brian drayton says

    Nice piece of science writing! This is hard stuff to write about clearly, because [a] it can be complicated to explain, assuming that some readers are thinking about the content for the first time, and [b] because it’s upsetting stuff to think about, much less put into words.

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