After 1.5-Degree Temperature Rise, What Happens Next?

Earth had its first year-long, 1.5-degree rise in temperature. But does this mean we've already missed our goal of limiting temperature increases to 1.5 degrees? No, argues the Washington Post:There's actually some disagreement about what exactly counts as breaching that threshold - but scientists and policymakers agree that it has to be a multiyear average, not a single 12-month period. Scientists estimate that without dramatic emissions reductions, that will happen sometime in the 2030s. But there could be other single years or 12-month periods that cross the line before then. Can we still avoid passing 1.5C? Most scientists say passing 1.5C is inevitable. "The 1.5-degree limit is deader than a doornail," Columbia University climate scientist James Hansen said in a call with reporters late last year.... The Washington Post analyzed 1,200 modeled pathways for the world to shift to clean energy and found that only four of them showed the world hitting the 1.5C target without substantially overshooting or using speculative technology (like large-scale carbon capture) that doesn't yet exist. At this point, many experts believe that the economy is too stuck on fossil fuels to transition fast enough for 1.5 degrees. Does that mean we'll pass catastrophic tipping points? That's a more difficult question. Scientists don't know exactly when certain tipping points - like the collapse of the Greenland ice sheet or the release of greenhouse gases from thawing permafrost - will occur. It's very hard to predict and model these types of catastrophic changes. And 1.5C isn't a magic threshold; it's not as though as soon as we pass that number, Antarctic ice sheets will collapse and ocean circulations will grind to a halt. But one thing is certain: For every tenth of a degree of warming, tipping points are more likely. Two degrees is worse than 1.9 degrees, which is worse than 1.8 degrees, and so on. And at each tenth of a degree, the infrastructure and systems that the world has built - electric grids, homes, livelihoods - will become more strained. Our modern world simply was not designed for temperatures this high. At some level, the final temperature of the planet isn't what matters most. It's where countries can actually get carbon emissions to zero - and stop contributing to future warming altogether.

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