You may assume climate proxies, such as ice cores, are only used to collect approximate temperature data for the centuries before real time thermometer measurements began (late 1800s)
... and for CO2 level estimates, before accurate real time measurements began in the late 1950s.
In fact, climate proxy data can be used for recent decades too.
The press release for a recent peer-reviewed scientific paper, by Australian scientist Dr. Jennifer Marohasy, revealed one of climate science’s well kept secrets:
-- Northern Hemisphere climate proxy evidence from tree-rings, bore holes, pollen, etc., consistently fails to show sharply rising temperatures after 1940.
Paper abstract:
One example:
In 2016, Dr. Pei Xing and co-authors unveiled a new method (MVDM) for calibrating low-frequency Northern Hemisphere tree-ring data for the last 1,200 years, in
'The Extratropical Northern Hemisphere Temperature Reconstruction during the Last Millennium Based on a Novel Method.'
'The Extratropical Northern Hemisphere Temperature Reconstruction during the Last Millennium Based on a Novel Method.'
Using 126 proxy temperature records from the Northern Hemisphere, they found a clearly visible Medieval Warm Period (950-1150) and Little Ice Age (1450-1850).
The smoothed MDVM reconstruction also exhibited a general agreement with reconstructed total solar irradiance, or TSI.
The Xing et al. reconstruction of Northern Hemisphere temperatures revealed no net warming for the past 60 years, following a 1930s and 1940s temperature peak.
In fact, there are many smarmy climate proxy temperature reconstructions that stop at 1980 or 1990, and then splice on hockey-stick-shaped rising surface temperatures using surface thermometer records
(from US-NASA, US-NAAO GISS, or England-HadCRUT).
(from US-NASA, US-NAAO GISS, or England-HadCRUT).
As a result, the recent decades on the right side of their charts show significant warming, even though their climate proxy, on the rest of their chart, did not.
The purpose of splicing two completely different data sources together on the same chart is global warming propaganda:
-- Constructing a temperature chart with an upward trend from left (the old days) to right (today) is used to suggest dangerous warming ahead ... something that would not be suggested by a 100% climate proxy chart that showed no upward trend after 1940.
The most famous spliced data source chart was the now thoroughly discredited Michael Mann "Hockey Stick Chart", that Al Gore loved, and probably still uses to scare people.
Mann's multi-century "Hockey Stick Chart" didn't even bother to mention that his tree ring data showed no trend for many centuries, and then showed cooling in the past century -- he simply cut off the tree ring cooling century and replaced it with surface thermometer data that showed warming in the past century !
Deceptions like that are typical of government bureaucrat "scientists".
The lack of recently rising temperatures in most climate proxy evidence is called the “divergence problem”.
The “trick” of splicing on surface thermometer data for recent decades, even when proxy data are available, is called “Hiding the Decline”.
There were many "Hide the Decline" conversations found in 2009 and 2011 in the hacked "Climate Gate" eMails:
“…you really ought to replace the values from 1961 onwards with observed [instrumental] temperatures due to the decline.”
“I’ve just completed Mike’s (Michael Mann's) Nature trick of adding in the real temps to each series for the last 20 years (ie; from 1981 onwards) and from 1961 for Keith’s to hide the decline.”
“Also we have applied a completely artificial adjustment to the data after 1960, so they look closer to observed temperatures than the tree-ring data actually were”
…. “Also, we set all post-1960 values to missing in the MXD data set (due to decline), and the method will infill these, estimating them from the real temperatures – another way of ‘correcting’ for the decline, though may be not defensible!”
There is a large and growing discrepancy between surface thermometer temperature data and all other temperature data, both real time data and climate proxy reconstructions:
(1)
Data that show little or no warming since 1940:
-- Most climate proxy studies
(2)
Data that show warming from 1975 to the late 1990s,
but little or no warming from the late 1990s to 2015:
but little or no warming from the late 1990s to 2015:
-- Weather Satellite data, and
-- Weather Balloon data
(3)
Data that show significant warming since 1980:
-- Surface thermometer data, based on measurements that sample less than half of Earth's surface, using wild guesses to "infill" all other areas, and frequent arbitrary "adjustments" of historical temperature data going back to the 1800s!
Given the data choices, (1), (2) and (3), only a smarmy government bureaucrat "scientist" would chose (3), while completely ignoring (1) and (2).
And they do !
I would ignore (3).
And I bet you would too.
This post has helps explain why I launched this free climate blog a few years ago:
(A) The claim that CO2 levels control the average temperature is a hoax because it is based on almost no scientific evidence.
(B) The claim that rising CO2 levels will cause runaway global warming, that will end all life on Earth, is a hoax because it is based on absolutely no scientific evidence.
There is no scientific evidence of runaway warming in the past 4.5 billion years, with CO2 levels higher than today almost the whole time -- 10x to 20x higher at the peak.
When Democrats and other leftists say "climate change", they really mean (A) and (B), above, although many don't realize what they mean!
The generic term "climate change" is otherwise meaningless, because the climate on our planet has been constantly changing for all 4.5 billion years!
Right now Earth's climate is the best it has ever been for humans and their pets.
Plants, and the people and farm animals who eat them, would prefer CO2 levels (now 400 parts per million) to double or triple, which would significantly accelerate growth (CO2-enrichment is already done inside many greenhouses).
Based on real science, not the "CO2 is evil" fantasies, adding CO2 to the air was the best thing humans have ever done (although inadvertently) to improve life on our planet, which is 'greening' from the added CO2, based on satellite data.
Air, land and water pollution are the worst things humans have done to our planet.
CO2 is not pollution.
CO2 is not pollution.
So why do so many so-called "environmentalists" demonize harmless plant food (CO2), while ignoring harmful air, land, and water pollution, especially in Asia?
Answer:
-- Fixing real pollution is hard work, and very expensive.
-- Demonizing beneficial CO2 is easy, and very profitable:
You predict a future climate disaster with great confidence,
you silence skepticism with character attacks,
you "adjust" historical surface temperature data to show more warming,
you virtue signal by falsely claiming you are trying to save the planet for the children,
and you write phony reports predicting climate doom.
If you do all that, left wing politicians / governments will throw money at you:
-- They will hire only "scientists" who claim to be 'CO2 is Evil' believers,
-- They will Issue study grants to other scientists who are believers, and
-- They will heavily subsidize their left wing friends in the huge 'green industry'