I am so pleased to share @Sara_Sayedi's newest paper on subsea permafrost carbon! This is the first circumarctic assessment of the quantity and climate sensitivity of organic matter and methane hydrates on the continental shelves of the Arctic Ocean. 1/18 https://iopscience.iop.org/article/10.1088/1748-9326/abcc29

First, some of the scientific stuff. During the last glacial period, sea level was ~130 meters lower than today. This exposed an area the size of China around the Arctic Ocean. Steppe ecosystems accumulated ~500 billion tons of organic carbon in their frozen soil. 2/n

As the Earth came out of the glacial period due to natural orbital changes and ecosystem feedbacks, the ocean inundated this vast area. Liquid water is the enemy of permafrost, and the submarine soils (and the organic matter they contained) started to thaw immediately. 3/n

This permafrost organic matter started to decompose, producing methane and CO2. At the same time, widespread erosion of permafrost coastline and land deposited an extra ~100 billion tons of organic matter on top of the submerged continental shelves. 4/n

Fast forward to today. Researchers estimate that the Arctic shelves contain about 560 billion tons of carbon stored as organic matter and 45 billion tons of methane trapped in hydrate form (locked in ice). That is more carbon than all cumulative human emissions. 5/n

However, it's not the size of the pool, it's the rate of release that determines the climate feedback. Subsea permafrost greenhouse gas release is relatively modest: 140 million tons of CO2 and 5.3 million tons of CH4. That's about the same greenhouse gas footprint as Spain. 6/n

The fact that human emissions are WAY HUGER than subsea permafrost emissions contradicts what many armchair scientists (and a couple real ones) say about this climate feedback. For example, this bad news piece based on a phone call from an ice breaker by @TheGardianNews 7/n

This is so important to understand because the "methane bomb" narrative implies there is nothing we can do. That is not based on science. The science says: the more greenhouse gases we emit, the more extreme the climate risks and costs. @PeterWSinclair 8/n

But what about the future? The researchers estimated that under RCP8.5 (the no-mitigation scenario), emissions could double by 2300 (i.e. there could be an extra Spain's worth of greenhouse gas release). That is a substantial amount of GHG, but again, not a runaway train. 9/n

One important consideration is the high level of uncertainty surrounding this climate feedback. There are very few published observations of carbon stocks and climate sensitivity. Consequently, most of the numbers in this thread are ± 80% or more. 10/n

Another sobering insight: subsea permafrost emissions are not included in any of the international climate targets. If you combine their uncertainty with this exclusion, it means subsea permafrost could contribute to GHG overshoot (but still way less than human GHGs!). 11/n

Now, some non-science stuff. These community-based assessments are always tricky interpersonally. Some researchers are comfortable providing their best guess, while others are allergic to speculation. Check out our last paper for an example: https://www.mdpi.com/2073-4433/11/11/1238 12/n

However, I was shocked and alarmed by the level of conflict in the subsea permafrost community. When @Sara_Sayedi first proposed this project (as a 1st year PhD student), a senior researcher publicly called the effort dangerous and a waste of time. 13/n

Combining multiple assessments from diverse teams increases the reliability of overall estimates. Because of silly territoriality, some potential participants were intimated or outright forbidden from contributing their assessments. 14/n

Because of my involvement in the project, I was threatened to be pulled from another, unrelated manuscript, despite substantial contribution to analysis and writing. From what I understand, this kind of misconduct is not uncommon in this research field. 15/n

Besides being totally unethical and unacceptable, that kind of behavior slows our understanding of interlinked Earth systems. We are facing multiple ecological crises of planetary scales. We can't afford to let toxic behaviors hobble our progress. 16/n

Thankfully, the amazing co-author team from different countries and research groups showed amazing solidarity and resilience to these attacks (e.g. unfounded claims of misconduct during review). It was so uplifting and encouraging to see the commitment to quality research! 17/n

Conclusion
1. Human emissions dwarf ecosystem feedbacks. We gotta stop burning fossil fuels!
2. Subsea permafrost has a huge stock of carbon that is somewhat climate sensitive. More warming = more GHG release.
3. Be nice and work hard on things that matter.
pic by @victorleshyk