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https://twitter.com/ryankatzrosene/status/1222024940540571648

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Ryan Katz-Rosene, PhD

@ryankatzrosene

Jun 20

What happened here?

It's actually the subject of a fascinating and potentially morbid debate about the relationship between humans and Earth's biogeochemical cycles.

Thread🧵

2) One of the leading theories is that this dramatic decline in global CO2 concentrations was actually caused by the 'Great Dying' in the Americas - the mass mortality event caused by European viruses which wiped out 56 million Indigenous people of the "Americas"...

"The resulting near-cessation of farming across a continent and re-growth of Latin American forests and other vegetation removed enough carbon dioxide from the atmosphere to produce a pronounced dip in CO2 seen in Antarctic ice core records."

3) This theory was proposed by Mark Maslin and Simon Lewis about a decade ago in a Nature article titled "Defining the Anthropocene". They argued that this massive CO2 drop, caused by the Great Dying (and subsequent expansion of forests from abandoned human settlements), was a marker of the onset of The Anthropocene.

"In geological terms the 1610 drop in atmospheric carbon dioxide is also associated with the coolest period of the Little Ice Age – a period between about 1300 and 1870 when North America and Europe experienced colder winters – when many changes occurred in geological deposits worldwide. The boundary therefore also marks Earth’s last globally synchronous cool moment before the onset of the long-term global warmth of the Anthropocene."

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Ryan Katz-Rosene, PhD

@ryankatzrosene

Jun 19

Woah! Such an important study published in Nature today! Quick thread with some of their key figures!
🧵

2) The study makes an empirical estimate of the impact of global producer climate adaptations on yields of six staple crops spanning 12,658 regions, capturing two-thirds of global crop calories! It essentially tries to figure out not just how climate change will affect yields, but farmer adaptations as well!

3) “We project that adaptation and income growth alleviate 23% of global losses in 2050 and 34% at the end of the century (6% and 12%, respectively; moderate-emissions scenario), but substantial residual losses remain for all staples except rice.”

Read 10 tweets

Ryan Katz-Rosene, PhD

@ryankatzrosene

Mar 30

🧵Twelve conceptual 'problems' that make dealing with climate change super difficult:

1) The Small Numbers Problem: Heading for 2.7 degrees of warming? An increase of up to 0.04% of CO2 in the atmosphere? These numbers SOUND small to most people. In reality, these are absolutely *MASSIVE* changes for Earth over such a relatively short period.

2) The Domestic-International Responsibility Problem: At the national level, policymakers say their country contributes only a small share, so their actions won’t make a difference. Yet at the international level, action can only be genuinely enforced through nation-states.

Read 13 tweets

Ryan Katz-Rosene, PhD

@ryankatzrosene

Mar 2

🧵Thread with a few zingers from this January’s report on climate risk by the Actuaries…

[h/t @James7jackson and @AndrewsonEarth]

“Commonly used ‘net zero’ budgets only give a 50/50 chance of limiting warming to well below 2°C. Put another way, the chance of them failing to limit warming is as high as the chance of them limiting warming.”

“Damages already outweigh the mitigation costs required to limit global warming to 2°C, i.e., it will be overwhelmingly positive economically to limit global warming”

Read 6 tweets

Ryan Katz-Rosene, PhD

@ryankatzrosene

Mar 1

Gulp… “The rate of natural sequestration of CO2from the atmosphere by the terrestrial biosphere peaked in 2008. Atmospheric concentrations will rise more rapidly than previously, in proportion to annual CO2emissions, as natural sequestration is now declining by 0.25% per year.”

“This analysis confirms that the rate of natural sequestration of CO2 from the atmosphere by the terrestrial biosphere is now declining, having reached a peak in 2008”… “This effect will accelerate climate change”

If this is true, it would mark a catastrophic future given current rates of anthropogenic CO2 and CH4 emissions. There is, however, another view about the trend in the land sink in recent years:

Read 5 tweets

Ryan Katz-Rosene, PhD

@ryankatzrosene

Feb 16

Each year, Arctic Sea Ice Extent reaches a low point in September. But over the last 15 years or so, the September minimum extent *appears* to have plateaued...

🧵Thread on this why this is happening, and how it's hiding catastrophic changes...

2) To be clear, the Arctic Sea Ice Extent is still declining. At this very moment it is at record low levels (which is deeply alarming given that it's currently experiencing a La Niña Winter)... but the RATE of Sea Ice Extent decline *is* indeed slowing down.

3) The reason why the rate of change is slowing is because the ice is getting thinner. NASA explains: The Arctic Ocean has "already lost most of its old ice and two-thirds of its thickness. [So] The younger ice is thinning more slowly and variably."

Read 10 tweets

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