Where we are:
Quote:Our current emissions trajectory locks Earth into a carbon dioxide level of at least 450 ppm, Ralph Keeling says. And burning fossil fuels at the same increasing rates through 2050 would drive those levels to their highest point in 50 million years, according to an April study in Nature Communications. Add a few more centuries of similar emissions, and carbon dioxide levels rise to those not seen in 420 million years, causing unprecedented sea level rise.
Keeling doesn’t think it’ll come to that. New efficiency standards and cleaner energy are already reducing emissions in the U.S. and other countries. If such efforts register at Mauna Loa, it could show humans still have some control. “It’s been an alarm bell so far — the curve,” Keeling says. “But if we start to take positive steps, it can become a sign of progress and hope.”
However, new research shows that reducing emissions isn’t a complete fix. “If you just stop emitting cold turkey, the temperature drops a little, but it doesn’t drop too much,” says MIT atmospheric scientist Susan Solomon. “The temperature stays almost as hot for 700 years.”
That’s because the carbon dioxide remains trapped in the atmosphere — much of it lingers a millennium later — pumping more and more energy into the ocean. So temperatures stabilize, but the seas keep rising.
This means humans actually have to remove greenhouse gases to reach levels scientists consider safe, roughly 350 ppm. And even short-lived greenhouses gases — methane lasts about a decade — will still cause sea levels to rise for centuries.
The reason is fairly simple. Greenhouse gases trap extra heat in our atmosphere, and oceans suck most of it up. As the warmer water expands, it causes sea levels to rise. And like a hot bath, the ocean must radiate its heat back out — through the atmosphere and into space — for it to cool.
Former NASA scientist James Hansen, now at Columbia University, helped launch climate change into the public sphere with his 1988 testimony before Congress. “[A level of] 450 ppm would guarantee disaster,” Hansen says now. “If you leave it in place long enough, it would guarantee that you do lose the coastal cities.”
http://discovermagazine.com/2017/jul-aug/what-carbon-really-costsSo fossil fuel use is on a downward trajectory. Good. Energy efficiency, the low hanging fruit, can do a lot. Building materials could incorporate locking up carbon (strawbale is the extreme of this: it could be encouraged with design rules etc.
But we need to actually remove CO2. Easy way, plant lots of trees. Bamboo might be better as it is faster growing. Only good if used in permanent structures. Bamboo makes good flooring.
Maybe some chemical engineering? Heartbreaking task to consider: the huge amount of CO2 but algae could be cultured in tanks with air bubbled through so it absorbs the CO2 and turns it into more algae which is eventually turned into biodiesel. Have seen proposals for this, no idea how feasible. Anyway, biodiesel doesn’t keep CO2 out the air.
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Action on AGW, is it enough? (Read 8839 times)
