The article says that SB 50 was supported by environmentalist groups.
>The bill also garnered support from environmental organizations, including Natural Resources Defense Council and California PIRG, because of its potential to reduce the carbon pollution that comes from long driving commutes.
>"It is extremely likely that human activities caused more than half of the
observed increase in global average surface temperature from 1951 to
2010. This assessment is supported by robust evidence from multiple
studies using different methods. In particular, the temperature trend
attributable to all anthropogenic forcings combined can be more closely constrained in multi-signal detection and attribution analyses. "
In order for climate change to be primarily driven by EPP or particle forcing instead of anthroprogenic forcing, it would have to be the case that either:
A. Somehow, anthroprogenic forcing is much less than the multiple avenues of evidence show.
Here:
B. There is something unknown that offsets the impact of anthroprogenic forcing, but would not have offset the impact of particle forcing in the absence of anthroprogenic forcing.
In the absence of evidence, it is a big claim to make that either of these things are the case.
>"Solar forcing is the only known natural forcing acting to warm the
climate over the 1951–2010 period but it has increased much less
than WMGHG forcing, and the observed pattern of long-term tropospheric warming and stratospheric cooling is not consistent with the
expected response to solar irradiance variations. Considering this
evidence together with the assessed contribution of natural forcings
to observed trends over this period, it is assessed that the contribution from solar forcing to the observed global warming since 1951
is extremely unlikely to be larger than that from WMGHGs. Because
solar forcing has very likely decreased over a period with direct satellite measurements of solar output from 1986 to 2008, there is high
confidence that changes in total solar irradiance have not contributed
to global warming during that period. However, there is medium confidence that the 11-year cycle of solar variability influences decadal
climate fluctuations in some regions through amplifying mechanisms.
{8.4, 10.3; Box 10.2}
"
So there are multiple avenues of evidence that conclude that solar forcing isn't the cause of the temperature increase. This includes direct measurements of "total solar irradiance" (TSI).
And the numbers at the bottom in brackets? Those are sources for the claims made in that paragraph!
The above source even has an explanation for how the causes are determined:
"FAQ 10.1 | Climate Is Always Changing. How Do We Determine the Causes of Observed
Changes?"
>"Total solar irradiance (TSI) measured by the Total Irradiance Monitor
(TIM) on the spaceborne Solar Radiation and Climate Experiment
(SORCE) is 1360.8 ± 0.5 W m–2 during 2008 (Kopp and Lean, 2011)
which is ~4.5 W m–2 lower than the Physikalisch-Meteorologisches
Observatorium Davos (PMOD) TSI composite during 2008 (Frohlich,
2009).The difference is probably due to instrumental biases in measurements prior to TIM."
The don't rely on single measurements of "total solar irradiance" either.
> "Since 1978, several independent space-based instruments have directly measured the TSI. Three main composite series were constructed,
referred to as the Active Cavity Radiometer Irradiance Monitor (ACRIM)
(Willson and Mordvinov, 2003), the Royal Meteorological Institute of
Belgium (RMIB) (Dewitte et al., 2004) and the PMOD (Frohlich, 2006)
series. "
The above claim that "all energy from the sun that is not a part of a specific EMR spectrum" is missing when the conclusions were drawn is just plain wrong.
from 8.4:
>"Solar spectral irradiance (SSI) variations in the far (120 to 200 nm)
and middle (200 to 300 nm) ultraviolet (UV) are the primary driver for
heating, composition, and dynamic changes of the stratosphere, and
although these wavelengths compose a small portion of the incoming
radiation they show large relative variations between the maximum
and minimum of the SC compared to the corresponding TSI changes. As UV heating of the stratosphere over a SC has the potential to
influence the troposphere indirectly, through dynamic coupling, and
therefore climate (Haigh, 1996; Gray et al., 2010), the UV may have a
more significant impact on climate than changes in TSI alone would
suggest. Although this indicates that metrics based only on TSI are not
appropriate, UV measurements present several controversial issues
and modelling is not yet robust.
Multiple space-based measurements made in the past 30 years indicated that UV variations account for about 30% of the SC TSI variations, while about 70% were produced within the visible and infrared
(Rottman, 2006).
"
It is correct that UV is only 30% of TSI. Hence why TSI was used to make conclusions about the impact of "solar forcing" on the climate instead of just UV.
The links I give are to just a couple sections of just one of the reports (the "physical science basis" one).
I think you are seeing an artifact of how difficult it is to explain things to non-scientists (and non-scientists misinterpreting the claims).
It also tends to be difficult to find these kinds of good sources with a generic google search and no prior knowledge of the appropriate search terms. Using google scholar instead can be helpful sometimes in weeding out non-science answers for science questions.
>The bill also garnered support from environmental organizations, including Natural Resources Defense Council and California PIRG, because of its potential to reduce the carbon pollution that comes from long driving commutes.