Around 93% of the additional heat trapped by greenhouse gases in the atmosphere ends up being absorbed by the oceans. Ocean heat content is a critical measure of climate change, and shows the warming signal much more clearly than the more noisy surface record.
The chart below (from Hausfather's tweet) shows surface air temperatures vs the heat stored in the top 2000 metres of the oceans. The green line is the surface air temperature with various trend lines and a centred moving average. The purple line shows ocean heat. Note how since the last El Niño, air temperatures have fallen but the ocean heat content hasn't. Note also that if you start at the peak of the previous El Niño (1998) and end before the latest El Niño (2014) you can say that there has been a "pause". It is obvious if you add more data before and after this period that there has been no pause. If anything since 1998 the trend increase appears to be accelerating.
This second chart shows ocean heat content anomaly vs the "Keeling curve"--the level of CO2 in the atmosphere. Note how the error range (error bar; the pink area) gets wider as you go further back in time because of more primitive measurement methods. Note also that 2018 is the hottest year ever for the oceans.
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