Naturally Unprecedented

By Rachel Mehler

Yes, this has happened before. Over the course of its history, our planet has seen ice ages, “hothouse” climates, and everything in between. Climate changes of the past were generally caused by weak forcings, like changes in the earth’s orbit or the sun’s intensity. But now, human activities are strongly forcing our climate system—and it’s changing faster, and more globally, than ever.

When we emit greenhouse gases through the burning of fossil fuels, we are, in effect, clogging up the atmosphere with particles that absorb infrared radiation from the earth and then emit that radiation back to its surface—keeping more heat circulating in the system rather than letting it escape back into space, as other molecules like oxygen and nitrogen would. This extra, trapped heat, whose original source is the sunlight, provokes a number of interconnected, amplifying feedback loops. 

The ice albedo effect, for example, is a phenomenon in which the melting of ice by high air or water temperatures exposes the non-reflective ground or ocean underneath, which absorbs the sunlight that would have otherwise been reflected by ice—thereby warming the planet more. Another effect of melting ice is the release of frozen methane and carbon dioxide as it thaws, causing further warming by adding more greenhouse gas to the atmosphere. A different feedback involves water vapor: since warmer air can hold more water vapor, non-H2O greenhouse gas-caused warming increases the amount of it in the air, which in turn causes further warming (as well as more intense storms), as water vapor absorbs and re-emits infrared radiation, like any greenhouse gas. Clearly, our environment is vulnerable to many interconnected and hard-to-model impacts, almost all of which will be (or already are) devastating. 

Effects of warming range from wildfires, which are a function of decreased moisture, to disease, as plagues emerge from melting ice, to food supply threats like drought or ocean acidification (a pH imbalance resulting from too much CO2 uptake by the water, which threatens marine food chains.)

 Sea level rise, caused by both thermal water expansion and melting ice , will compromise water supplies due to salt contamination, cause flooding and infrastructure degradation, and may even drown entire countries. Extreme events have cost the United States over $1 trillion since 1980. And more importantly, the effects of climate change could give rise 14 to 100 million climate refugees by 2050.

Additional tragedy will come in the form of economic loss, global conflict (which will increase due to factors like forced migration and struggle for resources), and health hazards like extreme weather events, or heat stress itself. These will all be felt most acutely by already vulnerable groups.

So yes, while the earth may have seen major climate changes before, human civilization hasn’t. And because we don’t know if we’ll suffer the low end or “trail” end of these effects, we must plan for the worst: sudden, unpredictable, and irreversible change. It is upon us to reduce, as much as we possibly can, whatever devastation is in store. 

Charts graphing the loss of arctic ice over time have led to the conclusion that it takes 3 X 10^13 kWh/year to melt the ice at the observed rate. And because there is 1.7 X 10^18 kWh cycling within the climate system, the arctic is in serious peril. 

Because this extremely delicate structure is so pivotal in dictating the overall structure of our climate, every effort to draw back CO2 to preindustrial levels, of approximately 270 eff ppm, must be taken as soon as possible in order to slow its rate of melting.

The problem is, given the projected changes in population, per capita income, and energy demanded per dollar of input over the next 30 years, energy consumption is expected to increase from 6.3 X 10^20 J/yr in 2018 to 1.2 X 10^21 J/yr in 2050. Our demand for energy is slowing down for no one. 

And sadly, as human-caused climate change is a classic tragedy of the commons, we cannot trust the fossil fuel industry to simply give up $27 trillion of CO2-to-be for the sake of future generations or distant poor people. For that reason, it is necessary to institute large-scale public policy initiatives like a carbon tax in order to make it expensive for companies to supply carbon and consumers to buy it. This will aid a transition to clean energy that is as quick as possible.

Sources:

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“Climate Science Special Report: Fourth National Climate Assessment, Volume I.” 2017, doi:10.7930/j0j964j6. 

Deconto, Robert M., and David Pollard. “Contribution of Antarctica to Past and Future Sea-Level Rise.” Nature, vol. 531, no. 7596, 2016, pp. 591–597., doi:10.1038/nature17145. 

Lenton, Timothy M., et al. “Climate Tipping Points — Too Risky to Bet Against.” Nature, vol. 575, no. 7784, 2019, pp. 592–595., doi:10.1038/d41586-019-03595-0. 

Wallace-Wells, David. “When Will the Planet Be Too Hot for Humans? Much, Much Sooner Than You Imagine.” Intelligencer, 10 July 2017,  nymag.com/intelligencer/2017/07/climate-change-earth-too-hot-for-humans.html. 

McKibben, Bill. “Global Warming's Terrifying New Math.” Rolling Stone, Rolling Stone, 25 June 2018, www.rollingstone.com/politics/politics-news/global-warmings-terrifying-new-math-188550/. 

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