Seventh Annual Climate Change Forum
March 24, 2018
Video Part 1 - Annmarie Eldering
Video Part 2 - Ian Fenty
Photos are here
This year’s forum topic was “What Will Happen When Global Temperature Rises? New Scientific Insights.” Two distinguished young NASA/JPL scientists provided an interesting and educational overview of basic climate change concepts and recent results. If you missed attending the forum, the video is available on the LWV-PA website.
Annmarie Eldering, Orbiting Carbon Observatory 2 (OCO-2) Deputy Project Scientist, presented “Measuring Atmospheric CO-2 from Space: New Insights Help Prepare for the Future.” The OCO-2 Earth satellite was launched in 2014, during a strong El Niño weather event.
Eldering showed that CO-2 emissions do not all stay in the atmosphere; on average, 31% are taken up by land, 26% by oceans, and 44% remains in the atmosphere. Emissions removed by land vary widely year-to-year but accumulated atmospheric CO-2 changes more smoothly. A plot of atmospheric CO-2 measured at Mauna Loa Observatory showed a relatively smooth, steady increase from 330 parts per million (ppm) in 1980 to 410 ppm in 2018, with a rate of roughly 2 ppm/year.
OCO-2 results showed significantly more CO-2 when regional conditions are hot and dry, setting up a positive feedback loop between global warming and CO-2 production. Eldering explained that reduced CO-2 uptake by heat-stressed plants and trees will likely result in faster future atmospheric CO-2 growth rates.
JPL climate scientist Ian Fenty presented “Future Climate Change, Polar Ice Melting Tipping Points, and Sea Level Rise: Prevention Is the Best Cure.” He provided information about several important tipping points, including temperature vs. sea ice melting, permafrost melting, and polar ice-shelf melting.
The most significant sea-level tipping point was polar ice-shelf melting, which would allow polar glaciers to flow into the sea and melt. Most of the water that could increase sea level is currently frozen in polar glaciers. If Antarctic ice melts entirely (requiring much higher temperatures than today’s), sea level would increase by about 200 feet.
Fenty recommended the International Panel on Climate Change (IPCC) revised report (Climate Change 2013, chapters 5 and 13) for scientific information about ice melting and sea level. He presented the IPCC prediction of likely (probability >66%) sea level rise (0.5-1.2m by 2100), with caveats about uncertainty produced by currently inadequate ice-shelf melting models.
His presentation showed that even the most aggressive IPCC emission control scenario (RCP2.6) will require removal of some CO-2 from the atmosphere to meet the 2-deg global temperature limitation goal in 2100. IPCC scenario curves were published in 2007, so it is possible to compare their predictions with observations. Observed global CO-2 emissions in 2017 were much higher than predicted by RCP2.6 and instead were on the RCP8.5 “business as usual” high-emissions curve.
This suggests that meeting the temperature goal will require difficult and expensive removal of large amounts of CO-2 from the atmosphere or even more problematic geoengineering to reduce the amount of absorbed solar energy. Scientists agree that the least-risk, most cost-effective strategy is to reduce emissions and thus limit the extent of future CO-2 removal and geoengineering (prevention is the best cure).
Finally, the speaker gave “What you can do” recommendations:
Promote Climate Literacy
Vote
Understand and reduce your carbon footprint
Stay Positive!
—George Null, LWV-PA Natural Resources Chair
