The world needs to decide if it wants to push to climate warming to 2 degrees, or try to stop it at 1.5 degrees.
A recent study looked at the pledges made at the Paris climate talks in 2015, where countries agreed to keep warming below 2 degrees Celsius—and ideally below 1.5 degrees. The goal is what most scientists think is necessary to avoid the worst impacts of climate change. The problem is that the pledges each country has made so far will completely miss the target.
There is likely a big difference between the two outcomes. Extreme weather—like the climate change-linked heat wave that killed more than 70,000 people in Europe in 2003—is already more common than it was in the past, and the world is only about 0.8 degrees warmer than it was in the preindustrial age.
The kind of hot day that used to happen once in 1,000 days is already five times more common now, and one study found the risk may double at 1.5 degrees of warming and double again at 2 degrees. Keeping warming to 1.5 degrees might make the difference between coral reefs surviving and completely disappearing. It might save the Amazon rain forest and prevent the Arctic tundra from melting and releasing methane that speeds up warming more. In parts of Africa, if the planet warms up 2 degrees instead of 1.5, crop yields could drop twice as much. Droughts in Europe could be the worst in 10,000 years, rather than the worst they’ve been in 900 years. Some parts of the Middle East could become uninhabitable.
The good news: Countries can easily do more than they’ve promised so far. “If all countries were to replicate policies that are currently successfully implemented by some countries, the gap toward two degrees Celsius could almost be closed,” says Michel den Elzen, senior climate policy analyst at the Netherlands Environment Assessment Agency and one of the authors of the paper.
In addition, most of the pledges don’t include the work being done outside of national governments—either in cities, regional governments, or in business. “The recent unprecedented engagement of non-state actors illustrates a more profuse awareness of climate change and an increased momentum for climate action,” he says.
The massive corporation Unilever, for example, will be “carbon positive” by 2030, meaning that it will produce so much renewable energy that it can help power the cities around its factories. Sixty eight large companies, such as Ikea and Google, are also committed to using 100% renewable electricity through the RE100 initiative.
Some research says that “the window seems to have vanished” for limiting future warming to 1.5 degrees. But even if we pass that threshold, we may be able to bring temperatures back down—not necessarily through technology like machines that pull carbon out of the air, but perhaps by dramatically increasing the number of plants and trees sucking in carbon dioxide, and then preventing them from releasing that carbon into the atmosphere. And the sooner the world acts, the less it will have to attempt to use “negative emissions technology” later.
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