On April 20 Cabrillo Astronomy Instructor and department chair Richard Nolthenius gave a talk in the Erica Schilling Forum, room 450, on developments in climate science since the last assessment report (AR5) of the International Panel on Climate Change (IPCC) in 2013.
The consensus among climate scientists now is that the report understates the problems in human caused global warming. One reason is that carbon release from permafrost wasn’t included in the report. Another is that some climate forcings were understated or omitted, such as the rate of Greenland surface melt, Antarctica ice melt, and greater than predicted risk of methane release.
Another understatement is the ECS – equilibrium climate sensitivity. If the amount of carbon in the atmosphere doubles, the earlier estimate was that this would raise global temperature 2 or 3 degrees centigrade by 2100 – now that increase appears to be much higher because the effects of amplifying feedbacks (problems that increase themselves) were also underestimated.
The report was considered “alarmist” by climate change denialists, but the problem is now worse than predicted by the report. The IPCC report is a consensus document agreed on by some with a political agenda, so only the lowest level of alarm gets through.
Politicians have also changed some of the numbers the scientists agreed on.
One of the tragedies is that geo-engineering solutions could at least be tried if the problem were admitted to exist. Politicians deny climate change even after the arctic ice has melted, and are replacing the EPA with climate deniers. This seems like quite a sense of “humor”, but too slapstick for me. I came away from the talk wondering if it would do any good to estimate how many people this action murders. Earlier I thought estimating this was impossible because of chaos theory (“sensitive dependence on initial conditions, or the “butterfly effect”) but was assured that it is just hard, not impossible, to make this estimate.
The complete Powerpoint transcript for the talk is at
To get a fast overview of climate science, see the link https://www.cabrillo.edu/~rnolthenius/astro7/index.html
for Astronomy 7 and take the course if you have time!