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Asked a question 10 months ago

Why do some people think that the rising seas due to climate change are already irreversible?

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Because they accept the science and what it shows.

Thankfully, we appear to have dodged the bullet of RCP8.5, but we’re stuck well into RCP6.0 with its 2.0 to 3.7 degrees Celsius of warming by 2100. Even if we stopped all emissions in 2022, we’d still be seeing close to 1.5 degrees of warming by 2100 due to all of the excess CO2 in the atmosphere and the pre-existing 1.1 degrees of warming. It takes a while for the Sun’s energy to be captured by the increased CO2, so there’s a lag between CO2 and warming.

And 1.5 degrees of warming is about 30% of the warming that melted the continent's glaciers completely starting about 25,000 years ago. Yeah, 30% of the warming that melted 5 km thick glaciers on the continents is still going to wreak havoc on the Greenland glaciers, mountain glaciers and Antarctica.

And the warming and melting are going to keep going into next century and the century after unless we draw down the atmospheric CO2, actually reducing concentrations.

So we’re going to experience sea level rise no matter what, it’s just a question of how bad and how fast. The RCP6.0 median is 60 cm, but that’s a stale number. Observations of increased ice melt in Greenland were excluded from the last UN IPCC report due to lack of an explanatory mechanism and confirming papers. Both have arisen. Ice is melting faster. I expect RCP6.0 will see a median of one meter of sea level rise by 2100.

This is part of the reason why so many people are trying to keep us under 1.5 degrees instead of hitting two degrees. That extra half degree has major impacts.

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