Thread by @MarinePolicy

Just finished reading the 45-page summary of the @IPCC Special Report on the Ocean and Cryosphere (#SROCC). Full report is over 1,000 pages and cites 700+ scientific papers. Here's a short(ish) summary of the summary:

The #SROCC) follows two other recent special reports:
- The @IPCC report on Climate Change and Land
- The @IPBES Global Assessment Report on Biodiversity

report.ipcc.ch/srocc/pdf/SROC…
ipbes.net/global-assessm…
ipcc.ch/report/srccl/

The summary covers observed changes and impacts, projected changes and risks, and responses. It uses the usual language of confidence levels, e.g. "virtually certain" (99-100%), "very likely" (90-100%), "likely" (66-100%. I'll focus on conclusions in these three categories.

Why care at all? Because 71% of our planet is ocean and 10% is covered by glaciers or ice sheets. That's a lot of water. These areas support unique species and invaluable ecosystems, regulate the climate, and give us food, water, energy, culture, tourism... the list goes on.

Around 10% of us (680 million people) live in low-lying coastal areas, and another 10% in high mountain regions. 4 million people live in the Arctic and 65 million on small islands. 100% of us are ultimately dependant on the Ocean in one way or another (e.g. we all like oxygen).

This is why we have a Sustainable Development Goal (SDG) specifically for the Ocean.

So what is happening to our ocean and ice? Buckle up, it's not pretty...

The Ocean has warmed unabated since 1970, absorbing 90% of the excess heat in the climate system, and the rate of warming is increasing rapidly. Marine heatwaves are becoming more intense and more frequent and the Ocean is acidifying.

A huge chunk of this excess heat, 35-43%, has been taken up by the Southern Ocean. The Ocean as a whole has absorbed around a quarter of our carbon emissions since the 1980s.

As for the ice, we are seeing massive shrinkage and less snow, while permafrost is warming (this is very, very bad news).

The Greenland and Antarctic ice sheets are losing mass at unprecedented rates, raising sea-level by 0.77 and 0.43mm a year respectively. Might not sound like much, but this could mean a total rise of almost a metre by the end of the century (and as much as 5m by 2300).

Many glaciers will disappear even in best-case scenarios.

In the business-as-usual scenario, melting permafrost could release hundreds of billions of tons of carbon into the atmosphere (our total emissions are currently around 10 billion a year).

We will get bigger waves (good for surfing, bad for everything else), more extreme seal-level events, and more Category 4 and 5 tropical cyclones.

I don't think I've ever even heard of a Category 5.

Species are on the move as habitats shift. On mountains, species are migrating upslope as the climate warms, and in the sea species have moved poleward by around 50km a decade since the 1950s.

Wildfires are increasing due to loss of ice/snow cover and hotter temperatures. E.g. Sweden and Siberia, regions not known for their balmy summers, have seen unprecedented fires in recent years.
en.wikipedia.org/wiki/2018_Swed…
bbc.com/news/world-eur…

Upwelling systems, amongst the most productive marine ecosystems, are under threat, there are less fish to catch, and we've lost half of our coastal wetlands in the last century.

The future is perhaps most bleak for coral reefs, which are being decimated by the warming waters and intense marine heatwaves. They can't take much more, and might not survive even if we limit global temperature rise to 1.5°C.

Seagrass meadows and kelp forests are also at high risk. Which sucks because dugongs and seals are SO. DAMN. CUTE.

The impact on humans is almost unthinkable. Food and water shortages, flooding, displacement, infrastructure failure, toxic seafood...

There are some bright spots in the report, mostly of the "it could be worse" variety. In short, we can:
1. Adapt (in some cases); and
2. make things less horrible by rapidly reducing our emissions.

"Ambitious adaptation, including governance for transformative change, has the potential to reduce risks in many locations". E.g. Coastal protection can reduce flood risk by 2–3 orders of magnitude this century (assuming we invest billions of dollars a year).

And, thank goodness, "In some places, artificial snowmaking has reduced negative impacts on ski tourism". Phew, I can sleep easy now.

What can we do?
1. Listen to @GretaThunberg:
2. SCREAM. First with existential dread, then at politicians.
3. Strike: globalclimatestrike.net
4. Fly less. Drive less.
5. Eat more plants.
6. Make less humans.

bbc.com/future/story/2…

🐙🦑🦞🦀🦐🐠🐟🐡🐬🦈🐋🌊
Uplifting news and views written by young ocean leaders: LittleBlueLetter.com

The ocean in a spreadsheet: docs.google.com/spreadsheets/d…

Oops... @IPCC_CH

Seal-level 😂