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Simone Alin @SimoneAlin
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I’ve been glad to see so much public discussion of #NCA4 over the last several days, with #ClimateFriday paralleling Black Friday. Since “Cyber Tuesday” is apparently now a thing, I’d like to declare today #CarbonTuesday. (THREAD 1 see part 2 next)
When the #NCA4 report was quietly released on Friday, it received MUCH more press than some of us expected. I’ve seen far less coverage about the closely related #SOCCR2 carbon budget report, also released on Friday and important!
I’ll highlight some #SOCCR2 findings from chapters I worked on and note some links between it and #NCA4. Would love to see colleagues from @NACP_Carbon join in to highlight interesting and important findings from your areas of research and expertise!
Climate and oceans are changing, and fast! Underpinning this rapid change is our CARBON habit. We need to DE-carbonize immediately to avert the worst consequences of climate/ocean change. Google “decarbonization” to learn about various proposals for how.
#NCA4 highlights impacts of climate/ocean change. #SOCCR2 describes what we do/don’t know about the continental carbon budget – including both the natural carbon budget and how human activities are changing it.
Sidebar: I do “get” why #NCA4 is the headliner. While #SOCCR2: The Movie resembles a detailed docudrama in which a family budgeteer tries to balance an out-of-control checkbook, #NCA4: The Movie shocks and excites (the bank repossesses your car, your house gets foreclosed, etc.)!
Ins and outs to the budget are definitely out of whack. To make matters worse, we are missing some of the bank statements. But we’ve got to get our budget back under control if we want to get our house and car back! End sidebar.
While a budgeting exercise may not be as headline-worthy, we need our carbon accounting to get back in order to mitigate climate and ocean changes before we experience even greater climate/ocean chaos and disruptions to human and ecosystem wellbeing.
We need to reduce CO2 emissions to zero as quickly as possible to mitigate and ultimately reverse climate change and its many direct ecosystem impacts, as well as those separate and significant impacts of rising CO2 on Earth’s ecosystems, our life support systems.
Given how overdrawn our account is, we actually need to start a carbon savings account, where we go into “negative emissions” before we can get back to what many of us adults think of as “the good old days” with respect to how healthy climate and ocean ecosystems behave.
Okay enough of the personal budget analogy. Now I’ll highlight key findings from #SOCCR2 chapters I co-authored, including the North American C budget (Ch2), tidal wetlands/estuaries (Ch15), coastal ocean/continental shelves (Ch16), and effects of rising atmospheric CO2 (Ch17).
Ch2: On the whole, North America was still a large net source of carbon from 2004 to 2013 (the time frame for #SOCCR2), due mostly to fossil fuels, and with USA contributing 84% of the continental total (average = 1774 teragrams C/yr). 1 teragram (Tg) = 10^12 g = a billion grams.
Continental “sinks” – those ecosystems that capture more C than they release and may store it long term – are estimated at an average of 766 Tg C/year (43% of sources), with biggest N Am sinks being inland waters (lakes and freshwater wetlands), forests, and the coastal ocean.
Ch15: There is a*HUGE* amount of C stored in the top 1 m (39”) of N Am tidal wetland soils and estuary sediment (1886 Tg C). How much is this, you ask? About as much as the total weight of 10-14 MILLION blue whales, the largest animals to have ever existed!
Sidebar: the tongue of a blue whale can weigh as much as an elephant – its heart an automobile, per National Geographic! I’m using total live weights rather than just the carbon weights for these comparisons to make them more graspable for non-scientists.
However, dealing with continental (not to mention global) carbon budgets inevitably results in wacky & surreal comparisons, because who has found themselves next to a blue whale? Not I. So there’s only so much we can do to make these numbers truly relatable. End sidebar.
Carbon accumulates in tidal wetlands around all of North America at a rate that SOUNDS much smaller (9 Tg C/yr), but that’s still equivalent to about 50-66 THOUSAND blue whales being interred intact in our coastal wetland habitats….
(You might recall what a disaster one smaller whale washing up on one Oregon beach in the 1970s was: But I digress.)
Blue whale-equivalents of carbon buried in North American estuary sediments each year: 28-37 thousand. Amount transferred from tidal wetlands to estuaries (in blue whales, of course): 89-117 thousand.
The point being that, although it might not seem obvious to someone who isn’t inexplicably excited about carbon moving in water from one place to another like I am, there’s a lot more going on than meets the eye! Carbon gets around!
But we have to estimate these numbers from fewer measurements and computer simulations than we really need to keep tabs on the health of these important ecosystems, because carbon (much like phantom blue whales) is often difficult, inaccessible, and expensive to measure.
Wetlands are thought of as good places to lock up carbon for long periods of time (you know, to help with our extra carbon problem). But many of the ecosystems best for storing carbon, like these, are changing rapidly, such that carbon already stored in them could escape.
While some estuaries/wetlands have excellent observations & simulations in place, most are nowhere near sufficiently monitored to track accelerating changes to oxygen, carbon, nutrients, plants, animals in these ecosystems, which provide critical goods and services to society.
Ch16: On to the coastal ocean! We have made huge progress in understanding the annual balance of CO2 flow between coastal oceans and the atmosphere since #SOCCR1 (2007). Coastal oceans absorb an estimated 160 Tg C/yr (0.9-1.2 MILLION blue whales).
But increasing CO2 in coastal oceans can “acidify” the seawater (true in estuaries and open ocean too). This does NOT mean the water becomes acidic, just that acidity increases. See my acidity primer for more explanation:…
Many organisms are sensitive to changes in CO2, acidity, or calcium carbonate saturation states (many shells or skeletons in ocean critters are made of calcium carbonate). See:… or @OA_NOAA for more info.
An important distinction to keep in mind is that, while all “greenhouse gases” warm the atmosphere and through it the ocean, carbon dioxide (CO2) is the biggest culprit for ocean acidification (OA). We need to reduce all GHGs to reduce climate change but only CO2 helps with OA.
Given the importance of coastal ecosystems to human wellbeing, cultures, & livelihoods the world around, these changes matter and need to be understood (=need more science $$) to facilitate healthy, economically stable coastal futures!
Ch17 bridges into the ecosystem effects of rising atmospheric CO2 and its effects on carbon flows across earth’s natural boundaries (visualize the huge numbers of essentially invisible blue whales moving around each year on our vast continent).
We know that global temperatures are rising; this chapter addresses the separate but added effects of increasing CO2. These include the ocean acidification mentioned above. Rising CO2 is also expected increase plant photosynthesis on land.
Ingredients for plant production are water, CO2, and sunlight. Climate change could change the availability of all three in complex ways, but atmospheric CO2 is increasing everywhere, providing more of this raw ingredient.
Sidebar: Ecosystems are complex, with many species interacting with each other, and many processes – both natural and human-influenced – affecting each species’ wellbeing and relative success. So it is challenging to predict ecosystem outcomes with high certainty.
However, work on both ocean and land ecosystems suggests changes in human food security will be a big part of climate change. Just one of many reasons to care about changes in carbon.
For example, rising CO2 may reduce nutritional value of food (not my area of expertise but fascinating and concerning):…
And ocean acidification contributes to decreases in both shellfish and finfish populations in both the present and the future. See as one example:… And #NCA4 ocean chapter above. End sidebar.
Finally, a note on uncertainty on all estimates, which I’ve not included here because of the brevity favored by Twitter. For many of the numbers I mentioned, the “uncertainty” is LARGE (see for yourself in the key findings of each chapter of the report – link at top).
Large uncertainties can mean either that our information is incomplete across space or time (meaning more measurements or simulations would improve it) or that the number itself can have large variation across years.
You can learn more about how the numbers above and their uncertainties were estimated in the #SOCCR2 “supporting evidence” and #NCA4 “traceable accounts” #NCA4 sections of each chapter.
A particular area of uncertainty for tidal wetlands, estuary, and coastal ocean ecosystems is that we don’t have enough information to know how each number is changing with climate & other human-caused global change.
We are presently conducting the biggest experiment in the history of humankind and we are not monitoring it adequately to understand its effects on our home. While monitoring has long been perceived as not very “sexy” (=hard to sustain funding for), nothing is more important.
Phew! Thanks for reading my first Twitter thread (figured out how to extend so no 2nd thread - rookie!). I welcome constructive comments/corrections/updates throughout. If @threadreaderapp would Kindly unroll, you should see a more shareable link below if you are so inclined.
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