The leading international body of climate change researchers released a major report on the impacts of global warming and what it would take to cap rising temperatures at 1.5 degrees Celsius, above preindustrial levels — a goal that’s exceedingly difficult, but not impossible.
Why examine the prospects for limiting global warming to 1.5°C? Because under the Paris climate agreement, countries agreed that the goal should be to limit warming to below 2°C by 2100, with a nice-to-have target of capping warming at 1.5°C.
The report finds that it would take a massive global effort, far more aggressive than any we’ve seen to date, to keep warming in line with 1.5°C. Without such effort, we will continue at our current trajectory toward 3°C of warming.
But the report is also a thunderous call to action, laying out what tools we have at our disposal (we have plenty) to mitigate global warming and to accelerate the turn toward cleaner energy. Let’s walk through the basics.
The planet has already warmed by 1°C due to human activity, and we’re seeing its consequences right now: Sea levels have risen more than 8 inches since 1880, we’re witnessing the fastest decline in Arctic sea ice in 1,500 years, and extreme weather events are becoming more damaging due to climate change — to name a few.
A key point to remember is that while we talk about climate change in terms of averages, buried in those averages are extremes: more frequent and intense heat waves. More damaging storms. Higher oceans. These events can have a compounding effect that costs society far more than lost lives and damaged property from the disasters themselves. Coastal flooding can create a refugee crisis which in turn can drive armed conflicts, for example.
Right now, though, only a handful of countries are on track to meet their targets set under the Paris agreement — targets, remember, that they set for themselves. Global greenhouse gas emissions are still increasing, and even climate change-fighting champions like Germany are on track to miss their goalposts.
Yet if every country were to meet its goals under Paris, that would still put the planet on a trajectory to warm by 3°C. Hitting the far more ambitious 1.5°C target is therefore a much heavier lift, in terms of politics, economics, and technology.
It would require replacing the bulk of the world’s fossil fuel generators with cleaner alternatives. It would drive the world to electrify everything. Planners would need to redesign cities to allow cleaner transportation. And governments would have to pay for their emissions at a price high enough to include the social costs of carbon.
The grimmest prognosis in the draft report is in the details of the effort it would take to actually limit warming to 1.5°C. Countries won’t just have to give up fossil fuels and stop emitting greenhouse gases; they’ll have to pull carbon dioxide straight out of the air.
“All pathways that limit global warming to 1.5°C with limited or no overshoot project the use of carbon dioxide removal (CDR),” according to the report. And not just a little, but a lot, upward of 1,000 gigatons of carbon dioxide removed from the atmosphere by the end of the century. This will require machines that scrub carbon dioxide out of the air as well as biofuels coupled with carbon capture and sequestration. These tactics have their own energy demands and environmental drawbacks, and we may not be able to deploy them in time.
We also don’t have much time to act. Because it takes decades for a buildup of carbon dioxide to influence the planet’s temperature, a 1.5°C warming trajectory demands cutting the planet’s emissions 45 percent below 2010 levels by 2030. The longer we wait, the more radical our options. And every fraction of a degree of warming matters.
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