Sea Level Rise

C. Fletcher University of Hawai‘i at Mānoa Greenhouse Gas Emissions

1. Global emissions >39.7 billion tons of CO2 per year – this continues to increase.

2. China is world’s largest CO2 emitter, >25% a. USA (15%), EU (10%), India (7%), Russia (5%)

3. USA largest cumulative CO2 emitter ~25% a. EU (22%), China (13%), Russia (6%), Japan (4%) 4. The poorest countries emit <1% each but suffer the greatest impacts 5. Under current policies, expected warming will be 3.1 to 3.7℃ 6. From 2020 to 2024 there is a 20% chance mean annual temperature will exceed 1.5°C in at least one year

Dec. 2019, Our World in Data: https://ourworldindata.org/co2-and-other-greenhouse-gas-emissions WMO - https://public.wmo.int/en/media/press-release/new-climate-predictions-assess-global-temperatures-coming-five-years Energy Consumption

Wind-Solar-Geothermal-Biomass

Fossil - 84.7% Hydroelectric Nuclear - 4.4% Nuclear Renewable - 10.9% Gas

Oil

Coal

BP Sta's'cal Review of World Energy: h;ps://www.bp.com/en/global/corporate/energy-economics/sta's'cal-review-of-world-energy.html Fossil fuel use is accelerating faster than renewable fuel use Renewable energy is not replacing fossil fuels, it is helping meet the demand for NEW energy

2019

Faster Growth

Slower Growth

Global Carbon Project (2019) Global energy growth is outpacing decarbonization: https://www.globalcarbonproject.org CO2 emissions are on a path to far exceed the Paris Agreement.

“Under most scenarios, carbon dioxide (CO2) emissions from the global energy system are onEnergy a path- relatedto far exceed net international targets of theCO Paris2 emissions Agreement.” Resources for the Future Institute – non-partisan Congressional Think Tank, 2019 https://www.rff.org

Global Energy Outlook 2019, The Next Generation of Energy: https://media.rff.org/documents/GEO_Report_7-19-19.pdf What is the COVID impact on emissions? BloombergNEF – New Energy Outlook 2020

• Global CO2 emissions from energy may have peaked in 2019. • Emissions drop 8% in 2020. • Then rise again with economic recovery toward 2027. • After 2027, emissions decline 0.7% per year to 2050. • This puts global temperature on track for 3.3oC by 2100. • To keep warming well below 2oC, emissions must fall 10 times faster, at 6% per year to 2050. • To stop warming at 1.5 degrees, emissions must fall 10% per year. • In total, Covid-19 subtracts 2.5 years worth of aggregate emissions over the next 30 years.

BloombergNEF, New Energy Outlook 2020: https://about.bnef.com/new-energy-outlook/ 1.5oC – zero emissions by 2050 2.0oC – zero emissions by 2065

We must remove CO from the air for Historical CO2 2 next several Emissions centuries.

1850 1875 1900 1925 1950 1975 2000 2025 2050 2075 CO2 Emissions Continue to Grow

Economic indicators and trends in gas & oil indicate we are on-track for 3 - 3.5oC warming before end of the century

Global Carbon Project (2019) Global energy growth is outpacing decarbonization: https://www.globalcarbonproject.org Accelerated Global Warming

J. Hansen: http://www.columbia.edu/~mhs119/Temperature/Emails/September2020.pdf Satellite Al)metry 1993-2019 3.4 mm/yr 1 ft/century 2010-2019 4.6 mm/yr 1.5 ft/century Table 1. Global Mean Sea Level Components 2006-2015 Special Report on the Ocean and Cryosphere in a Changing Climate, IPCC 2019 - Chapter 4, Table 4.1 https://www.ipcc.ch/srocc/

Thermal Expansion 1.40 (1.08–1.72) mm/yr

Glaciers except in Greenland and Antarctica 0.61 (0.53–0.69) mm/yr Greenland Ice Sheet including peripheral glaciers 0.77 (0.72–0.82) mm/yr Antarctica ice sheet including peripheral glaciers 0.43 (0.34–0.52) mm/yr

Land water storage –0.21 (–0.36–0.06) mm/yr

Total Contributions 3.00 (2.62–3.38) mm/yr

Observed GMSLR 3.58 (3.10–4.06) mm/yr IPCC SLR Projections

• SLR by 2100 • SLR by 2300 • Low Emissions 0.4 m (0.3–0.6 m) • Low Emissions 0.6–1 m • High Emissions 0.8 m (0.6–1.1 m) • High Emissions 2.3–5.4 m

Oppenheimer, M., et al. (2019) Sea Level Rise and Implications for Low-Lying Islands, Coasts and Communities. In: IPCC Special Report on the Ocean and Cryosphere in a Changing Climate [H.-O. Portner̈ , et al. (eds.)]. In press: https://www.ipcc.ch/srocc/chapter/chapter-4-sea-level-rise-and-implications-for-low-lying-islands-coasts-and-communities/ Gravity Recovery and Climate Experiment – FO GRACE Follow-On Greenland,Greenland, AntarcticaAntarctica MeltingMelting SixSix TimesTimes FasterFaster ThanThan inin thethe 1990ʻs1990ʻs

Ice loss from Greenland and Antarctica is tracking the IPCC worst-case climate warming scenario. Sea level rise could leave 400 million people exposed to coastal flooding each year by the end of the century. Shepherd, A., Ivins, E., Rignot, E. et al. Mass balance of the Antarctic Ice Sheet from 1992 to 2017. Nature 558, 219–222 (2018). https://doi.org/10.1038/s41586- 018-0179-y

Shepherd, A., Ivins, E., Rignot, E. et al. Mass balance of the Greenland Ice Sheet from 1992 to 2018. Nature 579, 233–239 (2020). https://doi.org/10.1038/s41586- 019-1855-2 Greenland melting has quadrupled over the past decade

Ice loss, Gigatonnes

Greenland Mass Variation Since 2002

Bevis, M. et al. (2019) Accelerating changes in ice mass within Greenland, and the ice sheets sensitivity to atmospheric forcing. PNAS, 116, 1934-1939. 250% to 575% increase in Greenland runoff over the last 20 years

Trusel, et al., 2018 Nonlinear rise in Greenland runoff in response to post-industrial Arctic warming, 104, Nature, v564, 6 December: https://doi.org/10.1038/s41586-018-0752-4 The natural buffer system prevenFng Pine Island and Thwaites glaciers from flowing rapidly is breaking down. The ice shelves are showing new damage areas that are the first signs of structural weakening and precondiFon these ice shelves for disintegra3on.

Lhermitte, S., et al. (2020) Damage accelerates ice shelf instability and mass loss in Amundsen Sea Embayment. Proceedings of the National Academy of Sciences, Sept. 14; DOI: 10.1073/pnas.1912890117 Antarctic ice melt has tripled since 2010 ~14% of GMSLR West Antarctic Glaciers are in Irreversible Retreat IceIce loss,loss, billions Gigatons of tonnes

Antarctica Mass Variation Since 2002

The IMBIE team (2018) Mass Balance of the Antarctic Ice Sheet, Nature, 558, pages219–222, https://doi.org/10.1038/s41586-018-0179-y Record warming at the South Pole during the past three decades

• More than three times the global average (0.61 ± 0.34 °C per decade)

Clem, K.R., Fogt, R.L., Turner, J. et al. (2020) Record warming at the South Pole during the past three decades. Nat. Clim. Chang. 10, 762–770. https://doi.org/10.1038/s41558-020-0815-z Thwaites Glacier

Pine Island Glacier

Pine Island & Thwaites glaciers have Lhermitte, S., et al. (2020) Damage begun an accelerates ice shelf instability and mass loss in Amundsen Sea Embayment. Proceedings of the irreversible National Academy of Sciences, Sept. 14; decline DOI: 10.1073/pnas.1912890117 Rignot, E., Mouginot, J., Morlighem, M., Seroussi, H., Scheuchl, B. 2014. Widespread, rapid grounding line retreat of Pine Island, Thwaites, Smith, and Kohler glaciers, West Antarctica, from 1992 to 2011. Geophys. Res. Lett. 41, 3502–3509. “The natural buffer system preventing Pine Island and Thwaites glaciers from flowing rapidly is breaking down. The ice shelves are showing new damage areas that are the first signs of structural weakening and precondition these ice shelves for disintegration.”

Alaska Andes Iceland

Russia Himalayas Svalbard

Ciracì, E., Velicogna, I., & Swenson, S. (2020) Continuity of the mass loss of the world's glaciers and ice caps from the GRACE and GRACE Follow-On missions. Geophysical Research Letters, 47, e2019GL086926. https://doi.org/10.1029/2019GL086926 Over 90% of excess heat has been absorbed by the ocean

Thermal expansion ~1/3 of SLR

Cheng, L., et al. (2019) How fast are the oceans warming? Science, 2019 DOI: 10.1126/science.aav7619; Cheng L. J. Zhu, and J. Abraham, 2015: Global upper ocean heat content estimation: recent progress and the remaining challenges. Atmospheric and Oceanic Science Letters, 8. DOI:10.3878/AOSL20150031. ; Glecker, P.J., et al. (2016) Industrial era global ocean heat uptake doubles in recent decades. Nature Climate change. doi:10.1038/nclimate2915 SLR Flooding: Nuisance and Permanent

#2. Temporary high tide flooding • Arrives decades earlier than GMSL • Has already started • Accelerating frequency and magnitude

Sea level #1. Long term GMSLR • Permanent, accelerating inundation

Time Seasonal High Waves and Coastal Erosion Rain + High Tide = Flooding Why 3.2 ft of SLR?

https://www.pacioos.hawaii.edu/shoreline/slr-hawaii/

https://www.nature.com/articles/s41598-018-32658-x Summer wave run-up 2 ft Summer wave run-up 3.2 ft Sunset Beach 3.2 ft SLR

Annual wave Run-up

Erosion Still water “Bathtub” Flooding The 3.2 ft SLR-XA King Tide Flooding & Permanent Inundation

SLR Exposure Area 3.2SLR-XA