With Donald Trump rising in the polls, it's not unthinkable the world will give up on climate change. Trump has called global warming "a total, and very expensive, hoax," and his election could kibosh international climate agreements, including the one signed in Paris last year.
What would that mean for the planet? We can get a taste from a new paper that considers the effect of burning all remaining fossil fuels and boosting carbon emissions in the atmosphere from about 540 billion tons now to 5 trillion tons.
In short, it isn't pleasant. The paper, published in Nature Climate Change, shows mean global temperatures rising by between 6.4 and 9.5 Celsius, and by up to 17 Celsius in the Arctic region, which bears the brunt of the changes. Ecosystems would become unrecognizable and uninhabitable to all but the most climate-resilient animals and plants.
"It is relevant to know what would happen if we do not take actions to mitigate climate change—for example, if we do not ever implement the Paris Agreement or other similar agreements," writes Kasia Tokarska, a PhD student at the University of Victoria, in Canada, and lead author of the paper, in an email. "Our study shows a profound climate change in the absence of further mitigation actions."
The study shows higher temperature increases than other worst-scenario research for several reasons. One, the researchers consider all fossil fuel "resources" known to exist, not just the "reserves" reported by major oil, gas and coal producers. Two, they model a more linear relationship between greenhouse gases and temperatures increases. Other research sees a tail-off in climate effects after 2 trillion tons of emissions; the new work sees the trend continuing as before because of the ocean continuing to heat up.
The paper paints a dark, though far-off scenario. While we might need until 2300 until we put 5 trillion tons of greenhouse gas into the air, dangerous conditions are of course likely this century anyway. Even if we burn known reserves of oil, gas and coal in the next few decades, we'll be well beyond what scientists think is reasonably safe.
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