Guest essay by Eric Worrall
According to climatologist Brian Brettschneider only anthropogenic CO2 can possibly be the cause of recent global warming.
Global Warming Is Not Cosmic
Brian Brettschneider Contributor
“I heard that sunspots are the main driver of temperature changes.” “What about the Grand Solar Minimum?” “We’re headed for a new ice age based on orbital parameters.” “Cosmic rays are causing the Earth to heat up!”
There is no shortage of people in the online community who passionately advocate for cosmic explanations to account for the observed change in global temperatures since the Industrial Revolution. Why is this? Is there a kernel of truth to their arguments? Let’s separate fact from fiction.
What about cosmic rays? Speculation regarding the effect of cosmic rays on cloud formation received a fair amount of attention a decade ago. Since then, additional studies have poured cold water on the idea.
The majority of warming is a result of greenhouse gasses emitted by human activity. Period. There is overwhelming consensus on this point within the scientific community.
There is an appeal to attributing our warming climate to forces complete outside of our control. It a) absolves us of any responsibility for causing the observed warming, and b) provides some sort of assurance that eventually we will fall back to an equilibrium state. For several hundred years, a philosophical debate has raged on whether science and religion are compatible or mutually exclusive – or somewhere in-between. Ironically, those that place global warming attribution outside of the bounds of Earth are using the same arguments that creationists and other religion-based prognosticators use; namely, the causes lie in the heavens and we are at the mercy of forces beyond our control.Read More: https://www.forbes.com/sites/brianbrettschneider/2019/04/21/global-warming-is-not-cosmic/
The MWP and LIA are substantial climate shifts which occurred on century timescales over the last thousand years or so, well before anthropogenic CO2 could have been a significant contributor to global climate.
Despite numerous attempts to claim the MWP and LIA were regional, there is strong evidence the MWP and LIA were global – numerous sites in Australia and New Zealand demonstrate strong MWP and LIA signals. A study published in 2012 found MWP signals in Antarctica.
There is even mention of New Zealand MWP evidence in Climategate, though at the time consensus climate scientists were promoting a flawed narrative that the MWP was a local regional European climate event.
Here is the Oroko Swamp RCS chronology plot in an attached Word 98 file and actual data values below. It certainly looks pretty spooky to me with strong “Medieval Warm Period” and “Little Ice Age” signals in it. It’s based on substantially more replication than the series in the paper you have to review (hint, hint!). In terms of rbar, sample size, and eps, it is probably okay back to about AD 980 at this time. I still have 3-4 more subfossil sections to process, but it is doubtful that the story will change much. When I come over in October, I am thinking about askin Jonathan Palmer to come over from Belfast for a visit. What do you think about that?
EdClimategate Email: 3759.txt
Oroko Swamp is in New Zealand.
How large were the MWP and LIA climate shifts compared to today’s warming? The following 1998 email from a Russian dendrochronologist to Keith Briffa, a CRU academic who helped Michael Mann construct his iconic climate hockey stick, sheds some light on Russia’s interpretation of their climate proxies.
According to reconsructions most favorable conditions for tree growth have been marked during 5000-1700 BC. At that time position of tree line was far northward of recent one.
[Unfortunately, region of our research don’t include the whole area where trees grew during the Holocene. We can maintain that before 1700 BC tree line was northward of our research area. We have only 3 dated remnants of trees from Yuribey River sampled by our colleagues (70 km to the north from recent polar tree line) that grew during 4200-4016 and 3330-2986 BC.]
This period is pointed out by low interannual variability of tree growth and high trees abundance discontinued, however, by several short (50-100 years) unfavorable periods, most significant of them dated about 4060-3990 BC. Since about 2800 BC gradual worsening of tree growth condition has begun. Significant shift of the polar tree line to the south have been fixed between 1700 and 1600 BC. At the same time interannual tree growth variability increased appreciably. During last 3600 years most of reconstructed indices have been varying not so very significant. Tree line has been shifting within 3-5 km near recent one. Low abundance of trees has been fixed during 1410-1250 BC and 500-350 BC. Relatively high number of trees has been noted during 750-1450 AD.
There are no evidences of moving polar timberline to the north during last century.
Please, let me know if you need more data or detailed report.
Best regards, Rashit HantemirovClimategate Email: 0907975032.txt
Lab. of Dendrochronology Institute of Plant and Animal Ecology
8 Marta St., 202 Ekaterinburg,
Keith Briffa himself was convinced the MWP was significant, and said so in a Climategate email written in 1999, though as far as I know at the time he never shared this view in public.
… For the record, I do believe that the proxy data do show unusually warm conditions in recent decades. I am not sure that this unusual warming is so clear in the summer responsive data. I believe that the recent warmth was probably matched about 1000 years ago. I do not believe that global mean annual temperatures have simply cooled progressively over thousands of years as Mike appears to and I contend that that there is strong evidence for major changes in climate over the Holocene (not Milankovich) that require explanation and that could represent part of the current or future background variability of our climate. …
Climategate Email: 0938018124.txt
We even have evidence from the instrumental record which demonstrates warming periods comparable to recent warming, well before anthropogenic CO2 could have been a major influence.
A – Do you agree that according to the global temperature record used by the IPCC, the rates of global warming from 1860-1880, 1910-1940 and 1975-1998 were identical?
An initial point to make is that in the responses to these questions I’ve assumed that when you talk about the global temperature record, you mean the record that combines the estimates from land regions with those from the marine regions of the world. CRU produces the land component, with the Met Office Hadley Centre producing the marine component.
Temperature data for the period 1860-1880 are more uncertain, because of sparser coverage, than for later periods in the 20th Century. The 1860-1880 period is also only 21 years in length. As for the two periods 1910-40 and 1975-1998 the warming rates are not statistically significantly different (see numbers below).
I have also included the trend over the period 1975 to 2009, which has a very similar trend to the period 1975-1998.
So, in answer to the question, the warming rates for all 4 periods are similar and not statistically significantly different from each other.
Here are the trends and significances for each period:
Period Length Trend (Degrees C per decade) Significance 1860-1880 21 0.163 Yes 1910-1940 31 0.15 Yes 1975-1998 24 0.166 Yes 1975-2009 35 0.161 Yes
Read more: http://news.bbc.co.uk/2/hi/8511670.stm
In summary, there is evidence of recent substantial climate shifts on a similar scale to today which cannot be explained by anthropogenic CO2, including a global warming event a thousand years ago which matched today’s temperatures, and multi-decadal warming periods in the instrumental record. Evidence which “consensus” climate scientists sometimes seem reluctant to discuss.
I’m happy to accept anthropogenic CO2 is likely a contributing factor, but forgive me Brian, if I don’t find your casual dismissal of non-anthropogenic forcings entirely convincing.