Yet there are ample reasons to suspect that climate change could result in a global catastrophe…Ĭatastrophic impacts, even if unlikely, have major implications for economic analysis, modeling, and society’s responses. Could anthropogenic climate change result in worldwide societal collapse or even eventual human extinction? At present, this is a dangerously underexplored topic. Yet, for climate change, such potential futures are poorly understood. Prudent risk management requires consideration of bad-to-worst-case scenarios. al (2022) published a letter today in the Proceedings of the National Academy of Sciences calling for an IPCC study of catastrophic climate change scenarios. In planning for adaptation to global increases in temperature above 3 degrees Centigrade, one must consider the deep uncertainties about potential global tipping points. do not include the extreme scenario of 2.5 meters (10.2 feet) of sea level rise by 2100 because it is “now viewed as less plausible in the coming decades before potentially becoming a factor toward the end of the 21st century and beyond.” But they also note that this threshold could potentially be reached “in the decades immediately following 2100 (and continue rising).” The probability of the high sea level rise increases with the very high emissions scenario. While the probability of the intermediate-high scenario is low, it is not negligible. al., for different projected increases in mean temperature.

The table below shows mean projections of sea level rise by Sweet et. The amount of additional warming required to trigger this is unknown because ice sheet instability is difficult to model and there is great variability in current modeling approaches. and globally because of the potential for rapid melting of ice sheets in Greenland and Antarctica. The high sea level rise estimates are 2 meters by 2100 – 6.9 feet, and intermediate-high estimates are 1.5 meters by 2100 – 4.9 feet.Ĭurrent and future emissions will determine the amount of additional rise in the future: the greater the emissions, the greater the warming, and the greater the likelihood of higher sea levels.Ībove 5.5☏ (3☌) of global warming, much greater sea level rise becomes possible for the U.S. 2022.) NOAA’s guidance is more recent than the 2018 Ocean Protection Council guidelines cited in DWR’s Sea Level Rise Study. How probable are the higher values of sea level rise by 2100? The current best available science is arguably NOAA’s March 2022 publication, Global and Regional Sea Level Rise Scenarios for the United States (Sweet et. That study estimated that one foot of sea level rise would require at least 475,000 acre-feet a year of additional outflow. There is a nonlinear increase.įor low values of sea level rise, the new study estimates less outflow to repel salinity than a 2008 study by William Fleenor et.

What if one increases Delta inflows and reduces exports to maintain current D1641 salinity standards at Emmaton? Figure 5AF-8 (reproduced below) shows the associated water costs. The area of dark gray area shading represents simulated EC values greater than recent historical experience. These extreme values largely occurred in droughts and outside the periods with D-1641 agricultural salinity standard (later in the season than August). The area of light gray shading shows the range of historical extreme EC value observed from the last two decades. The reproduced below (5AF-7) shows the monthly average increase in salinity at Emmaton with 7 different levels of sea level rise, if Delta inflows and exports are unchanged. The Emmaton station at Sherman Island in the western Delta is the furthest downstream compliance point on the Sacramento River for salinity. However, the study is useful in showing how salinity will increases with sea level rise, and how much additional outflow would be needed to repel salinity. The new SCHISM study has limitations, in that it assumes that Delta levees are raised to keep up with sea level rise. The study was done with Bay-Delta SCHISM, a 3-D hydrodynamic model of the San Francisco Bay and Delta. The Delta tunnel Draft Environmental Impact Report (DEIR) has a new Sea Level Rise Study in Technical Appendix 5A-F.

Delta conveyance project bad