warming up with little warning...

heat

During the Paleocene–Eocene Thermal Maximum (PETM) (56 Mya), the planet warmed by 5 to 8 °C, deep-sea organisms went extinct, and the oceans rapidly acidified. Geochemical records from fossil shells of a group of plankton called foraminifera record how much ocean pH decreased during the PETM. Here, we apply a geochemical indicator, the B/Ca content of foraminifera, to reconstruct the amount and makeup of the carbon added to the ocean. Our reconstruction invokes volcanic emissions as a driver of PETM warming and suggests that the buffering capacity of the ocean increased, which helped to remove carbon dioxide from the atmosphere. However, our estimates confirm that modern CO2 release is occurring much faster than PETM carbon release.

Abstract

The Paleocene–Eocene Thermal Maximum (PETM) (55.6 Mya) was a geologically rapid carbon-release event that is considered the closest natural analog to anthropogenic CO2 emissions. Recent work has used boron-based proxies in planktic foraminifera to characterize the extent of surface-ocean acidification that occurred during the event. However, seawater acidity alone provides an incomplete constraint on the nature and source of carbon release. Here, we apply previously undescribed culture calibrations for the B/Ca proxy in planktic foraminifera and use them to calculate relative changes in seawater-dissolved inorganic carbon (DIC) concentration, surmising that Pacific surface-ocean DIC increased by +1,010−646+1,415">+1,010+1,415−646+1,010−646+1,415 µmol/kg during the peak-PETM. Making reasonable assumptions for the pre-PETM oceanic DIC inventory, we provide a fully data-driven estimate of the PETM carbon source. Our reconstruction yields a mean source carbon δ13C of −10‰ and a mean increase in the oceanic C inventory of +14,900 petagrams of carbon (PgC), pointing to volcanic CO2 emissions as the main carbon source responsible for PETM warming.

The Paleocene–Eocene Thermal Maximum (PETM) (55.6 Ma) remains the closest geologic analog for anthropogenic carbon release and associated climate changes. During the event, isotopically depleted carbon was released into the surface ocean–atmosphere system, causing a decrease in terrestrial and marine δ13C records, prolonged warming, ocean acidification, and changes to ocean circulation (1 ⇓⇓–4). It has been suggested that the PETM carbon release was a response to internal carbon-cycle instabilities in a warmer world, such as the release of methane clathrates from the deep ocean (5) or the oxidation of organic carbon in melting permafrost (6), possibly triggered by orbital forcing (7). However, past data-driven reconstructions of the PETM’s carbon source have led to nonunique solutions. For example, interpretations of the carbon-isotope excursion (CIE) have been based on simple mixing models, constraining the possible size(s) of carbon release by assuming the δ13C of the source carbon (δ13Csource) (8). Given that the potential sources of PETM carbon—such as methane clathrates, oxidized organic matter, and volcanic emissions—all have distinct δ13C signatures (−60, −25, and −6‰, respectively), the respective choice of source δ13C leads to large differences in the amount of carbon released (8).

Reconstructions of the magnitude of ocean acidification using boron-isotope (δ11B) measurements of fossil planktic foraminifera shells have added a crucial constraint on the marine carbon system across the PETM (3, 9, 10). Experiments using the Grid Enabled Integrated Earth System Model (cGENIE) have paired these surface seawater-pH records with planktic foraminiferal δ13C to infer the carbon source and amount (10). These estimates suggest that 10,000 petagrams of carbon (PgC) were released with a source δ13C of −11 to −17‰, invoking large contributions from volcanism, likely caused by the emplacement of the North Atlantic Igneous Province (NAIP) (11, 12). However, quantitative inferences on the surface-ocean carbon reservoir and surface-ocean pCO2 require a second parameter of the ocean carbon system (13), which has not been available before now.

New opportunities to constrain a second parameter of the surface-ocean carbonate system arise with recent advances in our understanding of B/Ca ratios in planktic foraminifera shells. Laboratory culture studies first established that planktic foraminiferal B/Ca is controlled by the seawater borate concentration ([B(OH)4−]), which depends directly on pH (14). Planktic foraminiferal B/Ca records from geographically disparate locations display a large decrease in B/Ca across the PETM (3, 9), which is expected as seawater pH declined. However, these records have escaped quantitative interpretation because the use of culture calibrations from modern foraminifera cannot reasonably explain the data assuming only a pH control on the proxy (15). Barring other information, it could not be excluded that these B/Ca excursions may have been amplified by reduced photosymbiont activity or biased by diagenesis (3).

Recent culture studies show that instead of simple [B(OH)4−] control, B/Ca in planktic foraminifera is controlled by the [B(OH)4−]/dissolved inorganic-carbon (DIC) ratio of seawater (15 ⇓–17). Following this discovery, increased DIC across the event may have amplified the B/Ca excursion (3, 15, 16). Furthermore, the culture studies show that, in two modern foraminifera species, Trilobatus sacculifer and Orbulina universa, the sensitivity of B/Ca to [B(OH)4−]/DIC increases under simulated “Paleocene” seawater chemistry with lower seawater Mg/Ca and lower total-boron concentration ([B]T) (15, 16). Importantly, B/Ca in both foraminifera species responds to [B(OH)4−]/DIC with the same normalized sensitivity (Methods and SI Appendix, Fig. S1), enabling and increasing confidence in applying these calibrations to records from now-extinct species (15). In contrast to Pleistocene B/Ca downcore records, which show little consistency across glacial/interglacial cycles and between sites, PETM B/Ca data have been replicated at five sites (9) and display consistent results, suggesting that a strong environmental parameter unifies the records. Combining reconstructed [B(OH)4−] from δ11B-derived pH with B/Ca records, these calibrations present an opportunity to deconvolve pH and DIC contributions to B/Ca and quantitatively reconstruct the PETM DIC excursion.

https://www.pnas.org/content/117/39/24088

THE SCIENCE IS CORRECT: THE PRESENT GLOBAL WARMING IS REAL, ANTHROPOGENIC AND WE'RE IN DEEP SHIT...

scomo goes for it...

scomo...

Old cartoon by Moir....

Climate 200 founder Simon Holmes a Court has challenged the major parties to come clean on campaign funding, as a row over political donations widens.

Mr Holmes a Court told the National Press Club in Canberra on Wednesday that his organisation had received more than 10,000 donations to back climate-conscious independent candidates ahead of the imminent federal election.

He used his speech to attack the Coalition on its climate change credentials and integrity, saying independents – who are expected to hold considerable sway in some seats – had gathered a $7 million war chest to fix Australia’s “broken” political system.

Mr Holmes a Court said many Australians had had a “gutful” of politics.

“As we approach this upcoming election, Australian politics is broken. That’s the problem. That’s why we are here today,” he said.

“Engaged Australians are deeply frustrated that we are not making progress on the issues that matter … We are frustrated that so often our government is found to be either lying or incompetent, sometimes both. We have a government more interested in winning elections than improving our great nation. A government that seeks power, without purpose.

“We are frustrated about climate and action. We are frustrated about corruption in politics. We are frustrated about the treatment and safety of women.”

https://thenewdaily.com.au/news/politics/australian-politics/2022/02/16/simon-holmes-court-funding/

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By Gus Leonisky at 16 Feb 2022 - 5:08pm
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dry and dusty...

The megadrought which has gripped western U.S. states including California and Arizona over the past two decades has been made substantially worse by the human-caused climate crisis, new research shows, resulting in the region's driest period in about 1,200 years.

Scientists at University of California-Los Angeles, NASA, and Columbia University found that extreme heat and dryness in the West over the past two years have pushed the drought that began in 2000 past the conditions seen during a megadrought in the late 1500s.

The authors of the new study, which was published Monday in the journal Nature Climate Change, followed up on research they had conducted in 2020, when they found the current drought was the second-worst on record in the region after the one that lasted for several years in the 16th century.

Since that study was published, the American West has seen a heatwave so extreme it sparked dozens of wildfires and killed hundreds of people and drought conditions which affected more than 90% of the area as of last summer, pushing the region's conditions past "that extreme mark," according to the Los Angeles Times.

The scientists examined wood cores extracted from thousands of trees at about 1,600 sites across the West, using the data from growth rings in ancient trees to determine soil moisture levels going back to the 800s.

They then compared current conditions to seven other megadroughts—which are defined as droughts that are both severe and generally last a number of decades—that happened between the 800s and 1500s.

The researchers estimated that the extreme dry conditions facing tens of millions of people across the western U.S. have been made about 42% more severe by the climate crisis being driven by fossil fuel extraction and emissions.

"The results are really concerning, because it's showing that the drought conditions we are facing now are substantially worse because of climate change," Park Williams, a climate scientist at UCLA and the study's lead author, told the Los Angeles Times.

In the region Williams and his colleagues examined, the average temperature since the drought began in 2000 was 1.6° Fahrenheit warmer than the average in the previous 50 years. Without the climate crisis driving global temperatures up, the West would still have faced drought conditions, but based on climate models studied by the researchers, there would have been a reprieve from the drought in 2005 and 2006.

"Without climate change, the past 22 years would have probably still been the driest period in 300 years," Williams said in a statement. "But it wouldn't be holding a candle to the megadroughts of the 1500s, 1200s, or 1100s."

Rep. Pramila Jayapal (D-Wash.) said the new research must push the U.S. Congress to take far-reaching action to mitigate the climate crisis, as legislation containing measures to shift away from fossil fuel extraction and toward renewable energy is stalled largely due to objections from Republicans and right-wing Democratic Sen. Joe Manchin of West Virginia.

"It's time for Congress to act by making meaningful investments into climate action—before it's too late," she said.

The drought has had a variety of effects on the West, including declining water supplies in the largest reservoirs of the Colorado River—Lake Mead and Lake Powell— as well as reservoirs across California and the Great Salt Lake in Utah.

According to the U.S. Drought Monitor, 96% of the Western U.S. is now "abnormally dry" and 88% of the region is in a drought.

"We're experiencing this variability now within this long-term aridification due to anthropogenic climate change, which is going to make the events more severe," Isla Simpson, a climate scientist at the National Center for Atmospheric Research who was not involved in the study released Monday, told the Los Angeles Times.

The researchers also created simulations of other droughts they examined between 800 and 1500, superimposing the same amount of drying driven by climate change. In 94% of the simulations, the drought persisted for at least 23 years, and in 75% of the simulations, it lasted for at least three decades—suggesting that the current drought will continue for a number of years.

Williams said it is "extremely unlikely that this drought can be ended in one wet year."

"We're sort of shifting into basically unprecedented times relative to anything we've seen in the last several hundred years," Samantha Stevenson, a climate modeler at the University of California, Santa Barbara who was not involved in the study, told the New York Times.

https://www.commondreams.org/news/2022/02/14/climate-crisis-has-made-western-us-megadrought-worst-1200-years

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By Gus Leonisky at 21 Feb 2022 - 8:34pm
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