IPCC - AR6-WGI

[GordMay]

IPCC - AR6 WGI - The Physics of Climate Change

Monday August 9, 2021 [tomorrow] marks the beginning, of the release of the sixth round of major reports, by the Intergovernmental Panel on Climate Change, the IPCC.

Established by the World Meteorological Society, and the United Nations Environment Programme, in 1988, the IPCC’s mandate is “to provide the world with a clear scientific view on the current state of knowledge in climate change and its potential environmental and socio-economic impacts.”

In the case of AR6, the report just about to be released, 721 scientists from 90 nations collaborated for almost eight years, to come to consensus on what the latest science says about climate change. As if that weren’t enough, the final stage before release of the report involves gaining consensus (line-by-line and word-by-word consensus) among the 195 member nations of the IPCC.

Once the 721 authors were identified, they began with reviewing many thousands of scientific studies. This in turn involved contributions from many many more scientists, than the 721 scientific authors. Those thousands of experts also got to submit comments, and editorial suggestions, on the draft reports. This input adds up to many more than 100,000 items that the IPCC authors are required to review, and take account of.

AR6 WGI, tomorrow's report, is focused on the the physics of climate change.
WGI stands for Working Group One.

WGII’s AR6 report looks at how we can stop contributing to climate change.
WGIII, in turn, reports on what the impacts of climate change will be, and how humanity might adapt to those changes;

Finally, the three WGI, WGII & WGIII reports are each massive tombs, so the IPCC will produce the AR6 Synthesis Report, to tie the earlier reports together, with language a little easier for non-scientists to understand.

These latter three reports are all due in 2022.

[GordMay]

The press conference to present the Summary for Policymakers of the Working Group I contribution to the Sixth Assessment Report entitled Climate Change 2021: the Physical Science Basis, will be held via livestream at 10am CEST [4:00 AM EDT] on 9 August on the IPCC Facebook page and IPCC YouTube channel.
More about ➥ https://www.ipcc.ch/2021/08/05/press...tails-wgi-ar6/

IPCC Facebook page ➥ https://www.facebook.com/events/349580060206616/

IPCC YouTube channel ➥ https://www.youtube.com/user/IPCCGeneva

[GordMay]

IPCC AR6 WGI Report ➥ https://www.ipcc.ch/report/ar6/wg1/

Climate Change 2021: the Physical Science Basis, the Working Group I contribution to the Sixth Assessment Report.
IPCC Press Conference [1.5 Hrs] ➥

https://www.youtube.com/watch?v=z149vLKn9d8

[GordMay]

AR6 Climate Change 2021: The Physical Science Basis
The Working Group I contribution to the Sixth Assessment Report addresses the most up-to-date physical understanding of the climate system and climate change, bringing together the latest advances in climate science, and combining multiple lines of evidence from paleoclimate, observations, process understanding, and global and regional climate simulations.
Links to downloads ➥ https://www.ipcc.ch/report/ar6/wg1/

Summary for Policymakers
The Summary for Policymakers (SPM) provides a high-level summary of the understanding of the current state of the climate, including how it is changing and the role of human influence, and the state of knowledge about possible climate futures, climate information relevant to regions and sectors, and limiting human-induced climate change. (39 pages)
Here ➥ https://www.ipcc.ch/report/ar6/wg1/d...R6_WGI_SPM.pdf


Including:

Headline Statements from the Summary for Policymakers
2 Pages Here ➥ https://www.ipcc.ch/report/ar6/wg1/d...Statements.pdf

A. The Current State of the Climate

A.1 It is unequivocal that human influence has warmed the atmosphere, ocean and land.
Widespread and rapid changes in the atmosphere, ocean, cryosphere and biosphere have
occurred.

A.2 The scale of recent changes across the climate system as a whole and the present state
of many aspects of the climate system are unprecedented over many centuries to many
thousands of years.

A.3 Human-induced climate change is already affecting many weather and climate extremes in
every region across the globe. Evidence of observed changes in extremes such as
heatwaves, heavy precipitation, droughts, and tropical cyclones, and, in particular, their
attribution to human influence, has strengthened since the Fifth Assessment Report (AR5).

A.4 Improved knowledge of climate processes, paleoclimate evidence and the response of the
climate system to increasing radiative forcing gives a best estimate of equilibrium climate
sensitivity of 3°C, with a narrower range compared to AR5.

B. Possible Climate Futures

B.1 Global surface temperature will continue to increase until at least the mid-century under all
emissions scenarios considered. Global warming of 1.5°C and 2°C will be exceeded
during the 21st century unless deep reductions in carbon dioxide (CO2) and other
greenhouse gas emissions occur in the coming decades.

B.2 Many changes in the climate system become larger in direct relation to increasing global
warming. They include increases in the frequency and intensity of hot extremes, marine
heatwaves, and heavy precipitation, agricultural and ecological droughts in some regions,
and proportion of intense tropical cyclones, as well as reductions in Arctic sea ice, snow
cover and permafrost.

B.3 Continued global warming is projected to further intensify the global water cycle, including
its variability, global monsoon precipitation and the severity of wet and dry events.

B.4 Under scenarios with increasing CO2 emissions, the ocean and land carbon sinks are
projected to be less effective at slowing the accumulation of CO2 in the atmosphere.

B.5 Many changes due to past and future greenhouse gas emissions are irreversible for
centuries to millennia, especially changes in the ocean, ice sheets and global sea level.

C. Climate Information for Risk Assessment and Regional Adaptation

C.1 Natural drivers and internal variability will modulate human-caused changes, especially at
regional scales and in the near term, with little effect on centennial global warming. These
modulations are important to consider in planning for the full range of possible changes.

C.2 With further global warming, every region is projected to increasingly experience
concurrent and multiple changes in climatic impact-drivers. Changes in several climatic
impact-drivers would be more widespread at 2°C compared to 1.5°C global warming and
even more widespread and/or pronounced for higher warming levels.

C.3 Low-likelihood outcomes, such as ice sheet collapse, abrupt ocean circulation changes,
some compound extreme events and warming substantially larger than the assessed very
likely range of future warming cannot be ruled out and are part of risk assessment.

D. Limiting Future Climate Change

D.1 From a physical science perspective, limiting human-induced global warming to a specific
level requires limiting cumulative CO2 emissions, reaching at least net zero CO2
emissions, along with strong reductions in other greenhouse gas emissions. Strong, rapid
and sustained reductions in CH4 emissions would also limit the warming effect resulting
from declining aerosol pollution and would improve air quality.

D.2 Scenarios with low or very low greenhouse gas (GHG) emissions (SSP1-1.9 and SSP1-
2.6) lead within years to discernible effects on greenhouse gas and aerosol
concentrations, and air quality, relative to high and very high GHG emissions scenarios
(SSP3-7.0 or SSP5-8.5). Under these contrasting scenarios, discernible differences in
trends of global surface temperature would begin to emerge from natural variability within
around 20 years, and over longer time periods for many other climatic impact-drivers (high
confidence).

[GordMay]

Technical Summary

The Technical Summary (TS) is designed to bridge between the comprehensive assessment of the Working Group I Chapters and its Summary for Policymakers (SPM). It is primarily built from the Executive Summaries of the individual chapters and atlas and provides a synthesis of key findings based on multiple lines of evidence. (150 pages)
Here ➥ https://www.ipcc.ch/report/ar6/wg1/d...R6_WGI_SPM.pdf

[GordMay]

721 scientists from 90 nations collaborated for almost eight years, to come to consensus on what the latest science says about climate change. As if that weren’t enough, the final stage before release of the report involves gaining consensus (line-by-line and word-by-word consensus) among the 195 member nations of the IPCC.

Once the 721 authors were identified, they began with reviewing many thousands of scientific studies. This in turn involved contributions from many many more scientists, than the 721 scientific authors. Those thousands of experts also got to submit comments, and editorial suggestions, on the draft reports. This input adds up to many more than 100,000 items that the IPCC authors are required to review, and take account of.

The WG-I report comprises 1,800 pages, summarizing their findings.
It’s not a transcript of all the evidence reviewed, it’s just the consensus “verdict”.

AR6 WGI alone generated 74,849 review comments from hundreds of reviewers, representing a range of disciplines and scientific perspectives. For comparison, a paper published in a peer-reviewed journal is reviewed by only two or three experts.

Statistical background Working Group I ➥ https://www.ipcc.ch/site/assets/uplo..._sheet_AR6.pdf
234 Author team (Coordinating Lead Authors, Lead Authors, Review Editors)
Review comments
23,462 First order draft (experts)
51,387 Second order draft (experts and governments)
3,158 Final draft (governments)

Over 14,000 Number of citations

What more could one want, when even the 1,800 page report is too much for most to read?

[GordMay]

A new study [1], published in the Nature journal Scientific Reports, suggests that our oceans' climates [existing environments with delicately balanced ecosystems] face extreme change under climate-change scenarios.

When trying to predict how our climate will change, as a result of increased greenhouse gas emissions, scientists use something called the representative concentration pathway, or RCP. They represent different climate futures under varying levels of greenhouse gas emissions.

In this study [1], the authors looked at two: RCP 4.5 and RCP 8.5.

Under RCP 4.5, considered a moderate scenario, emissions peak in 2050, and are then followed by a slowed increase.
Under RCP 8.5, often considered as a "business-as-usual" scenario [the worst one], emissions peak in 2100, and are then followed by a slowed increase.

Under these scenarios, the authors suggest that 10 to 85 per cent of the surface ocean would see conditions never before seen, or a change in their "climate."

But under the RCP 4.5 scenario, 35.6 per cent of surface ocean climates may disappear altogether by 2100. Under RCP 8.5, that rises to 95 per cent.

Previous studies have looked at specific locations and found: this location's getting warmer, or this location is getting acidic.
What the new research did was, look at the whole climate of the global ocean.

When they looked at the ocean climates of today compared to 1800, they didn't see any emergence of "novel" climates or climates that had never been seen before. There were certainly changes, but nothing that was brand new.

But the same couldn't be said about looking toward the future. When they looked from today through 2100, depending on the climate-change scenario, and under more extreme climate change scenarios, a higher proportion of the ocean surface is going to experience these novel climates, they found.

And this has dire consequences for the organisms that reside in our vast oceans. As we produce more CO2, a lot of it is trapped in the atmosphere. However, our oceans actually absorb the majority of it.

A report [2], released by the National Oceanic and Atmospheric Administration (NOAA) this week found that in 2020, the ocean absorbed roughly three billion tonnes more CO2 than what was released, the highest amount since the start of records began in 1982, and roughly 30 per cent higher than the average over the past two decades.

And that changes the ocean's structure. Not only do our oceans warm, but the greater CO2 absorption also changes pH levels. This change is what is referred to as ocean acidification.

The Nature study [1] examined the level of pH, or acidity, and something that is called a saturation state, which relates to how difficult it is for organisms to make their shells.

They found that under the RCP 4.5 and RCP 8.5 scenarios, the ocean surface will become more acidic with a lower saturation of aragonite, which is a mineral used by corals and other marine organisms to form shells.

Just as we require calcium to make our bones, so do shelled organisms. They get this from seawater, but with ocean acidification, calcium becomes less available and hydrogen becomes more common.

And that presents a double whammy for organisms: it becomes harder to form their shells, and it also becomes more difficult to keep what shells they have from dissolving back into the seawater.

And while ocean acidification is rising around the globe, the study suggests that three regions will see the greatest change in novel climates first: the Indo-Pacific, Arctic and Antarctic.

Canada's Changing Climate Report [3], released by the federal government in 2019, found that the Pacific Northwest, for example, will experience more CO2, and lower pH, in the coming decades.

And the Arctic, which is often considered as the pulse of climate change as it warms at twice the rate of the rest of the world [in some places almost four times as much] is experiencing rapid increases in freshwater from melting ice. This, in turn, has reduced the aragonite saturation rate making shelled organisms particularly vulnerable.

It should be noted that the two different scenarios illustrate that, if we make changes and reduce CO2 emissions, we can have a huge impact.

[1] “Novel and disappearing climates in the global surface ocean from 1800 to 2100" ~ by Katie E. Lotterhos et al
➥ https://www.nature.com/articles/s41598-021-94872-4



[2] “International report confirms 2020 was among three warmest years on record” ~ NOAA
➥ https://www.ncei.noaa.gov/news/repor...e-climate-2020
[2]“State of the Climate in 2020" ~ AMS
➥ https://www.ametsoc.org/index.cfm/am...f-the-climate/

[3] “Canada’s Changing Climate Report”
➥ https://www.nrcan.gc.ca/sites/www.nr...T-EN-FINAL.pdf

[GordMay]

In June 2020, Ceres released “Addressing Climate as a Systemic Risk: A Call to Action for U.S. Financial Regulators”. It laid out how climate change threatens the stability of financial markets, and the overall economy, and how, and why, U.S. financial regulators must address this systemic risk as part of their existing responsibilities.
➥ https://www.ceres.org/resources/repo...-systemic-risk

In November 2020, the Federal Reserve identified climate as a near- term “financial stability risk.”
➥ https://www.federalreserve.gov/publi...t-20201109.pdf

The U.S. Commodity Futures Trading Commission (CFTC) climate risk subcommittee issued a comprehensive report, with an unequivocal warning: “Climate change poses a major risk to the stability of the U.S. financial system and its ability to sustain the US economy.”
➥ https://www.cftc.gov/sites/default/f...%20posting.pdf


A little dated, but still [somewhat] relevant:

“... But you tell me over and over and over again my friend
Ah, you don't believe we're on the eve of destruction ...”
➥

https://www.youtube.com/watch?v=qfZVu0alU0I