Antarctic Tipping Point

Robert Hunziker reports on research into the stability of the Thwaites and Pine Island glaciers. He quotes an article published in The Cryosphere.

Mass loss from the Antarctic Ice Sheet is the main source of uncertainty in projections of future sea-level rise, with important implications for coastal regions worldwide. Central to ongoing and future changes is the marine ice sheet instability: once a critical threshold, or tipping point, is crossed, ice internal dynamics can drive a self-sustaining retreat committing a glacier to irreversible, rapid and substantial ice loss.

Thwaites' "pinning points" are being undermined by warm currents. It's collapse threatens the entire West Antarctic Ice Sheet and could lead to a 3 meter sea level rise.

Update (June 13):  A study published in Science Advances finds the breakup of the ice shelf protecting the Pine Island glacier is accelerating.

[Our] data show a >12% speedup over the past 3 years, coincident with a 19-km retreat of the ice shelf. We use an ice-flow model to simulate this loss, finding that accelerated calving can explain the recent speedup, independent of the grounding-line, melt-driven processes responsible for past speedups. If the ice shelf’s rapid retreat continues, it could further destabilize the glacier far sooner than would be expected due to surface- or ocean-melting processes.

Update (December 13):  Satellite images presented at the American Geophysical Union meeting show cracks across the ice shelf protecting the Thwaites glacier. The shelf could shatter into hundreds of icebergs within three to five years.

Update (December 17):  Robert Hunziker reiterates how precarious the situation is.

Once the ice shelf collapses, it’ll lead to massive "ice cliff collapsing," ongoing collapse of towering walls of ice directly overlooking the ocean that crumbles into the sea. And, once ice cliff collapsing starts, it will likely become a self-sustaining "runaway collapse."

[T]he biggest unknown in this grisly affair is timing, assuming Thwaites does collapse within a decade, how soon will ice cliff collapses bring on sea level rise that drowns the world’s coastal metropolises?

Satellite images from 2015 and 2021:

Update (June 12, 2022):  A paper published in Nature Geoscience finds that Antarctic glaciers are retreating at the fastest rate in 5500 years. Ted Scambos explains why the flow rate for Thwaites has doubled in the past 30 years.

Update (September 6, 2022):  A study published in Nature Geoscience finds that the Thwaites glacier has retreated very quickly in the past and could do so again.

Update (September 7, 2022):  Matthew Rozsa reports on the Thwaites study and a Greenland study.

Extreme Drought

As the carbon dioxide concentration reaches it's highest level in 3.6 million years, much of the western United States is on the verge of a permanent drought.

Update (April 17):  Decreased flow in the Colorado River may prompt the U.S Bureau of Reclamation to declare an official water shortage for Nevada and Arizona.

Declining Church Membership

Amanda Marcotte notes that the failure to recruit younger generations has resulted in a steep drop in religious affiliation in the past couple decades. The trend in Gallup polls shows 73 percent participation in 1937, 71 percent in 1975, 70 percent in 1999, but only 47 percent by 2020.

It's a story with a moral so blunt that it could very well be a biblical fable: Christian leaders, driven by their hunger for power and cultural dominance, become so grasping and hypocritical that it backfires and they lose their cultural relevance. ... [I]t's undeniable that this decline is tied up with objectively good trends: increasing liberalism, hostility to bigotry, and support for science in the U.S.

Update (April 3):  While "creeping secularism" might be pushing the religious right toward increasingly anti-democratic views, John Stoehr argues it's a mistake to view secularization as being opposed to religion.

The same person can be religious and secular at the same time. Secularization is not, or should not, be a goal in and of itself. It is a means, rather, to an end, namely liberty.

I suspect many [non-religious liberals] believe religion itself is the problem, and they believe this, because they have accepted uncritically what the zealots themselves believe when they say the only way to be a religious person is by first being a conservative person.

All religions have liberal traditions. They may be buried. They may have been silenced. But they are there. More importantly, for liberals, is that these traditions be given oxygen, which is to say, be given the freedom they need to thrive. For the zealots, the point of religion is not doing unto others as you would have done unto you. It is not bringing the greatest good to the greatest number. It's about dominance. To the extent the liberals know this, it's from the inside of the zealots' preferred view, which means they are fighting against freedom even as they fight for a secularized America.

A secular society is not one in which religion is absent. A secular society is one in which there is enough room for the vast varieties of religious feeling to be expressed openly and safely, inside and outside the realm of politics. Liberals should pursue religious diversity with the same oomph with which they pursue racial diversity. With enough time and effort, perhaps religion will stop being a byword for conservative. That would be good for religion. That would also be good for American politics.

Amazon Tipping Point

A study published in Frontiers in Forests and Global Change finds that the Amazon rainforest may have already tipped from a carbon sink to a net source of greenhouse gasses.

Despite uncertainty in their responses to change, we conclude that current warming from non-CO2 agents (especially CH4 and N2O) in the Amazon Basin largely offsets—and most likely exceeds—the climate service provided by atmospheric CO2 uptake.

Update (May 5):  Matthew Rozsa reports on a study published in Nature Climate Change that finds the Brazilian Amazon became a net carbon emitter in the past decade largely due to forest degradation.

[T]he rain forest absorbed 13.9 metric tons of carbon dioxide between 2010 and 2019 — but released 16.6 billion metric tons during that same period. (To put that in context, human fossil fuel combustion is believed to produce around 35 billion metric tons of carbon dioxide [per year].)

Forest degradation happens when a forest's biological diversity and wealth is permanently diminished. [That has] contributed 73% of the "gross biomass loss" of the Amazon, compared to deforestation, which contributed 27% of that loss.

Minimum Wage Defeat

Do these eight Senators actually believe their vote against a $15 minimum wage will win them votes in their next election?  Or are they just happy to condemn Democrats to minority status for the foreseeable future?

Democratic opponents to the minimum wage boost included two close Biden allies from his home state, Chris Coons and Tom Carper of Delaware, along with moderates Jon Tester of Montana, Jeanne Shaheen of New Hampshire, Kyrsten Sinema of Arizona and Maggie Hassan of New Hampshire. Sen. Angus King, a Maine independent who caucuses with Democrats, also opposed it.

All of them voted alongside Sen. Joe Manchin of West Virginia, who has been called the unofficial majority leader based on his outsize influence in an evenly-split Senate.

Update (March 8):  While Amanda Marcotte acknowledges some disappointment with the American Rescue Plan such as the defeat of the minimum wage increase, she notes the $1.9 trillion package is still a major progressive victory which not one Republican voted for. Marcotte is hopeful that that intransigence opens the door for further vital legislation.

[B]oth [Senators] Manchin and Sinema are already softening their pro-fiilbuster stances, indicating that they are open to "reform" that allows them to say they "saved" the filibuster while removing most, if not all, Republican uses of it. What seemed impossible a week ago — that actual bills to save democracy, protect the environment, etc. would get a floor debate in the Senate — now is coming into view. And that's huge!

Update (July 15, 2022):  The Economic Policy Institute finds that the federal minimum wage is at the lowest value since February 1956 when is was $0.75 per hour ($7.19 in June 2022 dollars). The current period without an increase is the longest since the policy was established.

Emissions Reductions Falling Short

An initial synthesis report from the United Nations about the voluntary nationally determined contributions (NDCs) from the Paris climate agreement finds that, so far, the pledges would reduce emissions by only one percent.

Update (March 5):  Robert Hunziker elaborates on the report.

According to data provided by the 74 nations that have reported to the much-heralded Paris climate accord, collectively, their plans are to reduce emissions by 2030 by 0.5% of 2010 levels. But, the Intergovernmental Panel on Climate Change (IPCC) clearly stated that global emissions must fall by 45%, not a measly 0.5%. Otherwise, there’s no chance of staying below 1.5°C [increase].

Ocean Current Disruption

A study published in Nature Geoscience finds that the Atlantic Meridional Overturning Circulation is at its weakest since 400 CE. Co-author Stefan Rahmstorf:

We risk triggering [a tipping point] in this century, and the circulation would spin down within the next century. It is extremely unlikely that we have already triggered it, but if we do not stop global warming, it is increasingly likely that we will trigger it.

The consequences of this are so massive that even a 10% chance of triggering a breakdown would be an unacceptable risk.

Update (August 6):  A study published in Nature Climate Change suggests there has been a loss of stability in the AMOC. Author Niklas Boers:

We already know from some computer simulations and from data from Earth's past, so-called paleoclimate proxy records, that the AMOC can exhibit—in addition to the currently attained strong mode—an alternative, substantially weaker mode of operation. This bi-stability implies that abrupt transitions between the two circulation modes are in principle possible.

The findings support the assessment that the AMOC decline is not just a fluctuation or a linear response to increasing temperatures, but likely means the approaching of a critical threshold beyond which the circulation system could collapse.

Update (October 3):  A study published in Paleoceanography and Paleoclimatology finds that Pacific Ocean currents are also shifting due to climate change.

[R]esearchers conclusively found, using observational data and modeling studies, that [the Kuroshio Current and Extension] is warming, adjusting its latitudinal position northward, and possibly increasing the amount of warm water that it moves north in the process.

Update (July 25, 2023):  A study published in Nature Communications concludes that the AMOC could collapse sometime between 2025 and 2095 (95% confidence interval).

Hali Kilbourne:

It is very plausible that we've fallen off a cliff already and don't know it.