
A Degree of Concern: Why Global Temperatures Matter - pier25
https://climate.nasa.gov/news/2878/a-degree-of-concern-why-global-temperatures-matter/
======
pier25
Unfortunately considering climate lag[1][2], feedbacks[3], and the fact that
aerosols are actually cooling the atmosphere[4] it's safe to say that +2ºC is
a given.

[1] [https://theconversation.com/if-we-stopped-emitting-
greenhous...](https://theconversation.com/if-we-stopped-emitting-greenhouse-
gases-right-now-would-we-stop-climate-change-78882)

[2] [https://skepticalscience.com/Climate-Change-The-40-Year-
Dela...](https://skepticalscience.com/Climate-Change-The-40-Year-Delay-
Between-Cause-and-Effect.html)

[3]
[https://en.wikipedia.org/wiki/Climate_change_feedback](https://en.wikipedia.org/wiki/Climate_change_feedback)

[4]
[https://www.nature.com/scitable/knowledge/library/aerosols-a...](https://www.nature.com/scitable/knowledge/library/aerosols-
and-their-relation-to-global-climate-102215345)

~~~
radford-neal
That's not true according to the latest IPCC report, which estimates
"equilibrium climate sensitivity" to a doubling of CO2 (which hasn't happened
so far) to be between 1.5 and 4.5 degrees C.

Incidentally, the 1.5 to 4.5 degree C uncertainty range is unchanged for
decades, illustrating the lack of progress in this field of science.

~~~
pier25
Not only the IPCC is extremely cautious and conservative but since it works by
committee it takes years to reach an agreement. Their reports are always full
of outdated data.

One example, the IPCC has ignored feedbacks in its latest reports something
which has been frequently criticized.

> _Mario Molina, who shared the Nobel prize in chemistry in 1995 for his work
> on depletion of the ozone layer, said: “The IPCC report demonstrates that it
> is still possible to keep the climate relatively safe, provided we muster an
> unprecedented level of cooperation, extraordinary speed and heroic scale of
> action. But even with its description of the increasing impacts that lie
> ahead, the IPCC understates a key risk: that self-reinforcing feedback loops
> could push the climate system into chaos before we have time to tame our
> energy system, and the other sources of climate pollution.”_

[https://www.theguardian.com/environment/2018/oct/09/tipping-...](https://www.theguardian.com/environment/2018/oct/09/tipping-
points-could-exacerbate-climate-crisis-scientists-fear)

Edit: "ignored" was probably a too strong word. "Understated" would have been
closer to reality.

Edit 2:

Here's what the founder of 350.org said about the last report:

> _This is the scariest thing about the IPCC Report — it’s the watered down,
> consensus version. The latest science is much, much, much more terrifying._

[https://twitter.com/Agent350/status/1049717120697753601](https://twitter.com/Agent350/status/1049717120697753601)

~~~
radford-neal
It's only by accounting for possible positive feedbacks that the IPCC gets up
to the 1.5 to 4.5 degrees C range. It's widely accepted that if there were no
positive feedbacks, the increase from doubling CO2 would be about 1 degree C.

So you're saying that after decades of not being able to decide how big the
net feedback is, scientists have suddenly established that it's "safe to say"
that for even less than a doubling of CO2, an increase of at least 2 degrees C
is "a given"?

~~~
pier25
It's a fact the IPCC has not considered feedbacks seriously. I have no
qualifications to declare this, but many high profile scientists have stated
it.

Also, the new models which will be presented in the 2021 report will show how
warming is occurring much faster than previously stated.

> _In earlier models, doubling atmospheric carbon dioxide (CO2) over
> preindustrial levels led models to predict somewhere between 2°C and 4.5°C
> of warming once the planet came into balance. But in at least eight of the
> next-generation models, produced by leading centers in the United States,
> the United Kingdom, Canada, and France, that “equilibrium climate
> sensitivity” has come in at 5°C or warmer. Modelers are struggling to
> identify which of their refinements explain this heightened sensitivity
> before the next assessment from the United Nations’s Intergovernmental Panel
> on Climate Change (IPCC). But the trend “is definitely real. There’s no
> question,” says Reto Knutti, a climate scientist at ETH Zurich in
> Switzerland. “Is that realistic or not? At this point, we don’t know.”_

[https://www.sciencemag.org/news/2019/04/new-climate-
models-p...](https://www.sciencemag.org/news/2019/04/new-climate-models-
predict-warming-surge)

Also, I've said from my first comment that there is more to it than feedbacks.

For example NASA said in 2010:

> _Scientists believe the cooling from sulfates and other reflective aerosols
> overwhelms the warming effect of black carbon and other absorbing aerosols
> over the planet. Models estimate that aerosols have had a cooling effect
> that has counteracted about half of the warming caused by the build-up of
> greenhouse gases since the 1880s._

[https://earthobservatory.nasa.gov/features/Aerosols/page3.ph...](https://earthobservatory.nasa.gov/features/Aerosols/page3.php)

A more recent paper from 2019 used a new method to determine how much cooling
is happening from aerosols and determined it to be about double over previous
estimations.

[https://www.sciencedaily.com/releases/2019/01/190122104611.h...](https://www.sciencedaily.com/releases/2019/01/190122104611.htm)

[https://science.sciencemag.org/content/363/6427/eaav0566](https://science.sciencemag.org/content/363/6427/eaav0566)

So this means that while the official observations indicate we are at 1ºC
above baseline, we may very well be actually much closer to 2ºC even ignoring
feedbacks and climate lag.

And then there is this whole business of how the IPCC defined what
preindustrial baseline is. So even the official 1ºC of current warming might
be wrong and we could be close to 1.2ºC.

See this twitter thread:
[https://twitter.com/MichaelEMann/status/1049702520984141824](https://twitter.com/MichaelEMann/status/1049702520984141824)

And finally you have to consider climate lag. Current warming has not yet been
affected by GHG emissions from the past 3-4 decades, and we have emitted more
GHG during that time than the previous 150 years.

------
username444
Lost interest in the article as soon as the globe locked on screen on the
smartphone.

Break it into paragraphs and pictures please. I don't have the desire to learn
how to interact with your piece of macromedia flash.

