COMMUNICATING THE DYNAMICS OF SEA LEVEL CHANGE TO GEOSCIENTISTS, EDUCATORS, POLICY MAKERS, AND THE PRESS (Invited Presentation)

One of the most significant consequence of Earth’s global change is sea level rise and fall. Since their origin, the level of Earth’s oceans has been determined by the dynamic relationship between climatic, eustatic, steric, geomorphic, tectonic, and isostatic factors.

Oceans and glaciers are the two largest reservoirs of water on Earth. Therefore, understanding how they collectively respond to today’s global change drivers is critical for communicating the resulting risks and realities to a broad and diverse global audience.

Four fundamental realities are: 1) currently >1,000,000,000 people live in the “low elevation coastal zone” (LECZ) at elevations <10 m ASL; 2) multiple assessments project that sea level may rise >1 m by the year 2100 AD; 3) during the past ~110,000 years, sea level has fluctuated by ~140 m, from ~ +7 m to ~ -130 m; and 4) water currently frozen in polar and temperate glaciers represents ~70 m of sea level rise.

To communicate this information to as broad an audience as possible, I developed an analogy in which I use “1000 water drops” and “1000 ice crystals” to represent all of the water and glacier ice on Earth. By varying the distribution and allocation of these drops and crystals in response to global glacier volume change, I convey the significance of this water – glacier ice – sea level relationship and the delicate balance between the factors that control it.

Having studied the consequences of glacier advance and retreat, I also describe the >50 ice-rafted-detritus-bearing geological formations that have been identified in Earth’s rock record. Spanning the Pre-Cambrian to the Quaternary, these distinctive rock units provide a ~2,000,000,000 year temporal dimension to the sea level-glacier story. These units document that Earth’s changing sea level is not new, is on-going, has been changing for nearly half of Earth’s existence, and is an unambiguous indicator that sea level and the aerial extent and volume of polar and terrestrial glaciers repeatedly fluctuate.

Lastly, as visual documentation, I present imagery time series depicting coastal inundation, landscape evolution, and glacier change. Sources of these images include: archives, my own photography, Landsat, Global Fiducial Library time series, and declassified National Imagery Systems images available from the USGS EarthExplorer website.