The Intergovernmental Panel on Climate Change released a report today showing the need to limit global warming to 1.5 degrees -- and the consequences if we don't.
The warning is clear: The world's carbon budget is nearly overspent, and we're facing a future fraught with climate change-driven death and disease.
To reverse course and keep global warming below 1.5 degrees, we must take swift action to keep fossil fuels in the ground. Failure to stem both fossil fuel production and consumption will cause untold human suffering and condemn polar bears, coral and other species to extinction.
According to the report, the difference between just 1.5 and 2 degrees of warming is stark. That extra half of a degree would almost entirely wipe out coral reefs. It would cause 10 more centimeters of global sea level rise. It would make heat waves deadlier. It would expand the range of mosquitoes carrying disease like malaria and dengue.
Extinction risk would increase dramatically. Of 105,000 species studied, the number of vertebrate, insect, and plant species projected to lose over half their geographic range would double or triple when warming increases from 1.5 to 2 degrees.
The report calculates that limiting global warming to 1.5 degrees would require global net human-caused emissions of carbon dioxide to fall by about 45 percent from 2010 levels by 2030, reaching 'net zero' around 2050.
This requires a global, coordinated effort to reduce emissions across all major sectors. The report names shifts to less meat-intensive diets, reductions in food waste and increased building efficiency as important emission reduction actions.
But a rapid end to fossil fuels is key. There is more than enough carbon in the world's already developed oil, gas and coal fields to push us past the Paris agreement's goal of "well below" 2 degrees of warming. To limit warming to 1.5 degrees, most of these fields must be shut down before they are fully depleted, even assuming no new fossil fuel development gets approved.
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Ramping down fossil fuel extraction has been made more difficult with a climate denier in charge of the U.S., currently the second largest annual carbon emitter in the world. From moving to expand drilling on public lands and in our oceans to trying to dismantle the Clean Power Plan and clean car rules, Trump is pushing the world closer and closer to the edge of catastrophe.
But equally problematic is that even some leaders at the forefront of the fight against climate change aren't doing enough. In fact, many are setting the bar for climate leadership dangerously low.
For example, California's governor Jerry Brown has continued to support fossil fuel development in his own state.
Behind its green image, California is one of the nation's top oil-producing states, extracting some of the dirtiest crude in the world. Three-quarters of the oil produced in California is at least as climate-damaging as Canada's tar sands crude. Yet Brown's regulators have issued more than 20,000 permits for new oil and gas wells since the governor took office in 2011.
The emissions from every barrel of California's oil burned make it more difficult to curb warming to 1.5 degrees. California must not be seen as a model of climate policy while oil producers in the state continue to extract millions of barrels per year of incredibly dirty crude.
Today's report draws a line in the sand -- real climate leaders must keep it in the ground. The choice is clear: A world that is unlivable for most of us or a just transition to 100 percent clean energy and a safer world for all of us.