Experts reveal that clouds have moderated warming triggered by climate change

Experts reveal that clouds have moderated warming triggered by climate change
Trees are removed from cold lake beds in Scandinavia. Credit: Professor Mary Gagen, Swansea University

A new study has revealed how clouds are modifying the warming created by human-caused climate change in some parts of the world.

Led by Swansea University's Tree Ring Research Group, researchers from Sweden, Finland and Norway analysed information contained in the rings of ancient pine from northern Scandinavia to reveal how have reduced the impact of natural phases of warmth in the past and are doing so again now to moderate the caused by anthropogenic .

Even though northern Scandinavia should be strongly affected by , the area has experienced little summer warming over recent decades—in stark contrast to the hemispheric trend of warming temperatures, which is strongly linked to rising greenhouse gas emissions. According to the study, have been accompanied by an increase in cloudiness over northern Scandinavia, which in turn has reduced the impact of warming.

Mary Gagen, Professor of Geography at Swansea University, said: "The surface warming caused by rising greenhouse gases is modified by many complicated feedbacks—one thing changing in response to another—meaning that there are large geographical variations in the temperature of a particular place at a particular time, as the global average temperature rises. One of the most important, and most poorly understood, feedbacks is the relationship between temperature and clouds. We might think that, simply, when it is cool it is cloudy, and when it is warm it is sunny, but that is not always the case."

Experts reveal that clouds have moderated warming triggered by climate change
Professor Mary Gagen core sampling a tree. Credit: Professor Mary Gagen, Swansea University

The research team analysed tree ring records to find out what summer temperatures were like in the past, and how cloudy it was. Using their collected data, the team produced a new reconstruction of summer cloud cover for northern Scandinavia and compared it to existing temperature reconstructions to establish the relationship between temperature and cloud cover.

Professor Mary Gagen said: "Most people know that the width of a tree ring can tell us what the temperature was like in the summer that ring grew, but we can also measure other things in tree rings such as the isotopes of carbon and water that the wood is made from. Isotopes are just different types of an element, the amount of the different isotopes of carbon in the wood tells us how cloudy it was in the summer the tree ring grew. By combining the tree ring width and tree ring carbon measurements we built a record of both past and past summer cloud cover. Summer temperatures in Scandinavia have increased by less than the global average in recent decades because it also got cloudier at the same time, and that modified and reduced the warming. That turns out to also be the case back through time."

Author Professor Danny McCarroll explained: "We found that over short timescales, increased cloud cover lead to and vice versa in the past. However, over longer timescales -decades to centuries-we found that in warmer times, such as the medieval, there was increased cloud cover in this part of the world, which reduced local temperatures. The opposite being true in cool periods, such as the Little Ice Age.

Experts reveal that clouds have moderated warming triggered by climate change
The preserved rings of a pine tree, that started growing in 1369 and fell into a cold lake in 1716, allow scientists to measure what the temperature was like in the summers of each year's growth and how sunny it was. Credit: Risto Jalkanen
"These finding are important as they help to explain the feedback relationship between cloud cover and temperature, which is one of the major uncertainties in modelling future climate. Understanding the past relationship between temperature and cloud cover in this part of the world means we can now predict that, as the global temperature continues to rise, that warming will be moderated in northern Scandinavia by increasing cloud cover. The next step is to find out whether the same is true for other parts of the world."

Professor Mary Gagen added: "One of the main sources of uncertainty about future climate change is the way that clouds are going to respond to warming, has a really big influence on at the surface of the Earth.

"Clouds are going to be critical in modify warming of the climate. In some places, like Scandinavia, it turns out that the climate gets cloudier as the planet warms, in other places though it is likely that warming will be enhanced by a reduction in cloudiness which will make the surface of the Earth even warmer. What is really worrying is that climate models have shown that, if are allowed to continue until there is double or even triple the pre industrial amount of carbon dioxide in the atmosphere, then some of the most important clouds for cooling our planet, the big banks of oceanic clouds that reflect a lot of sunlight back to space, could stop forming altogether and this would really accelerate warming."

The study, Cloud Cover Feedback Moderates Fennoscandian Summer Temperature Changes Over the Past 1,000 Years, is published in Geophysical Research Letters.


Explore further

Declining sea ice to lead to cloudier Arctic: study

More information: Giles H. F. Young et al, Cloud cover feedback moderates Fennoscandian summer temperature changes over the past 1000 years, Geophysical Research Letters (2019). DOI: 10.1029/2018GL081046
Journal information: Geophysical Research Letters

Provided by Swansea University
Citation: Experts reveal that clouds have moderated warming triggered by climate change (2019, March 25) retrieved 25 April 2019 from https://phys.org/news/2019-03-experts-reveal-clouds-moderated-triggered.html
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Mar 25, 2019
Global warmists are backing tracking in tree rings

Mankind
1369 years ago
had no inkling
global warming
was caused by burning charcoal and wood
on their fires
to cook their fish and chips and roly-poly pudding
if
they did
we might never of heard of global warming
as
they would have shivered
and
saved the planet by eating raw food
and never developing to the stage of even worse
burning fossil fuels
fortunately no one told our ancestors
as
now we are prosperous well fed housed
and
we can tell the world with our mobile phones
The global warmists are back tracing
as
they're saying
its all in the clouds
the clouds are mitigating the global warming
because
these global warmists are backtracking
There never has been global warming, to the extent claimed

Mar 25, 2019
@granville583762

Seems you have no comprehension of scale. Those ancestors didn't come even close to our current emissions. Population back then has been estimated to be in the range of 300 - 500 million and they had hardly any industry at all to produce sufficient CO2 to matter. Even with extended industry in 1900, estimates are at around 2Gt of CO2, today it's over 35Gt annually.

It seems you also misunderstood what was discussed above. Only some areas are positively affected while others are not and other research has shown that cloud formation could be impeded at higher CO2 concentrations later this century which combined with this study that suggests cloud formation is important to warming mitigation, means that we are in an even deeper mess than if clouds had no influence at all.

In short, anthropogenic climate change/global warming that is happening has and will continue to happen, no backtracking whatsoever.

You are grasping at straws here.

Mar 25, 2019
Whoa! I thought global warming was settled science. How dare THIS crop up! What other nasty surprises are in store for us?

Mar 26, 2019
Moderated? They've measured a "whopping" 1 deg. increase in 100 years. That's assuming old instruments reliably recorded those temps. Meanwhile, 1/2 the measurement instruments are within urban heat islands. You can't moderate nothing.

Mar 26, 2019
Dorkium Boy once again shows his utter incompetency in understanding how climate change works.

Mar 26, 2019
Now we finally start getting the final data we need for a really integrated AOCM. It's a good thing we spent all this time getting the data for OCMs and currents and overturnings. That's already written in to the current GCMs. This is the last big piece, and now what we have to do is get historical data on cloud coverage.

Mar 26, 2019
Whoa! I thought global warming was settled science. How dare THIS crop up!
BobSage

You mean how does something crop up like this that doesn't contradict in the slightest the idea that there exists global warming?
Or was there something wrong with your basic reading skills when you read this above article?

Mar 26, 2019
So someone added clouds to their simulation, how scientific.

Mar 26, 2019
So someone added clouds to their simulation, how scientific.
Old_C_Code

1, They (climate scientists) ALWAYS HAVE added clouds to their simulations. This is because they aren't stupid.

2, The finding described in this article come much more from observations and data of the real world than simulations of it.

Mar 26, 2019
This Global Warming

Is claimed to be caused by burning fossil fuels
it is claimed
the CO2
so produced
reduces the amount of heat that escapes the atmosphere into space
so
regardless whether this is true or not
the solution
is
to produce energy without burning fuel
that
produces CO2
as
providing energy to warm our house and cook our food
requires
no fossil fuels
requires no CO2
the question, one and all to ask
is
when the ENERGY in the ATOM
can supply this Earth
for billions of years
as
in converting the sea into H2 and O
to burn in cylinders for propulsion
where this MIGHTY ATOM
will provide all the energy needed to separate the sea into H2 and O
the reason we have this global warming problem
Is
because
The Energy we crave is in this MIGHTY ATOM

Mar 26, 2019
This is such a duh...

This has been THE cause for catastrophic AGW skepticism since the 80's (Al Gore even admitted as much in a senate hearing).

More global cloud cover = cooler global temps. It really is that simple.

Mar 26, 2019
The Energy we crave is in this atom

Me thinks
these global warmists
have
trigger happy fingers
that
jump to conclusions
that
leap before they think
one
does not have to believe in global warming
to
see that a solution is required to this global warming
as
this comes down to energy
there is insufficient energy
in
solar-power, wind-power, hydro-electric, tidal, bio-mass, the list is endless
because
the Energy we crave is in this atom
and
there it will stay
if
we continue to bury our heads in the sand
like
the proverbial ostrich
no
progress
in the energy we require
for our daily lives
no progress in mitigating global warming
will be made
until
we crack this atom
because
The Energy we crave is in this MIGHTY ATOM

Mar 26, 2019
If only those clouds could mitigate the warming caused by the AGW Cult's HOT BULLSHIT.

Mar 28, 2019
If only Antigoracle can resize that Pea inside his head, he might actually understand the words he is saying.

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