Climate experts agree that the seriousness of manmade global warming depends greatly upon how clouds in the climate system respond to the small warming tendency from the extra carbon dioxide mankind produces.
To figure that out, climate researchers usually examine natural, year-to-year fluctuations in clouds and temperature to estimate how clouds will respond to humanity’s production of greenhouse gases.
When researchers observe natural changes in clouds and temperature, they have traditionally assumed that the temperature change caused the clouds to change, and not the other way around. To the extent that the cloud changes actually cause temperature change, this can ultimately lead to overestimates of how sensitive Earth's climate is to our greenhouse gas emissions.
This seemingly simple mix-up between cause and effect is the basis of a new paper that will appear in the "Journal of Climate." The paper¹s lead author, Dr. Roy W. Spencer, a principal research scientist at The University of Alabama in Huntsville, believes the work is the first step in demonstrating why climate models produce too much global warming.
Spencer and his co-author, principal research scientist William (Danny) Braswell, used a simple climate model to demonstrate that something as seemingly innocuous as daily random variations in cloud cover can cause year-to-year variation in ocean temperature that looks like -- but isn't -- "positive cloud feedback," a warmth-magnifying process that exists in all major climate models.
"Our paper is an important step toward validating a gut instinct that many meteorologists like myself have had over the years," said Spencer, "that the climate system is dominated by stabilizing processes, rather than destabilizing processes -- that is, negative feedback rather than positive feedback."
The paper doesn't disprove the theory that global warming is manmade.
Instead, it offers an alternative explanation for what we see in the climate system which has the potential for greatly reducing estimates of mankind's impact on Earth's climate.
"Since the cloud changes could conceivably be caused by known long-term modes of climate variability -- such as the Pacific Decadal Oscillation, or El Nino and La Nina -- some, or even most, of the global warming seen in the last century could simply be due to natural fluctuations in the climate system," Spencer said.
While the paper's two peer reviewers, both climate model experts, agreed that the issue is a legitimate one, Spencer knows the new paper will be controversial, with some claiming that the impact of the mix-up between cause and effect will be small.
"But we really won't know until much more work is done," Spencer said.
"Unfortunately, so far we have been unable to figure out a way to separate cause and effect when observing natural climate variability. That's why most climate experts don't like to think in terms of causality, and instead just examine how clouds and temperature vary together.
"Our work has convinced me that cause and effect really do matter. If we get the causation wrong, it can greatly impact our interpretation of what nature has been trying to tell us. Unfortunately, in the process it also makes the whole global warming problem much more difficult to figure out."
Phil Gentry | newswise
More than 100 years of flooding and erosion in 1 event
28.03.2017 | Geological Society of America
Satellites reveal bird habitat loss in California
28.03.2017 | Duke University
The Institute of Semiconductor Technology and the Institute of Physical and Theoretical Chemistry, both members of the Laboratory for Emerging Nanometrology (LENA), at Technische Universität Braunschweig are partners in a new European research project entitled ChipScope, which aims to develop a completely new and extremely small optical microscope capable of observing the interior of living cells in real time. A consortium of 7 partners from 5 countries will tackle this issue with very ambitious objectives during a four-year research program.
To demonstrate the usefulness of this new scientific tool, at the end of the project the developed chip-sized microscope will be used to observe in real-time...
Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.
The results will be published on March 22 in the journal „Astronomy & Astrophysics“.
Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...
Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.
Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...
In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...
Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.
Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...
20.03.2017 | Event News
14.03.2017 | Event News
07.03.2017 | Event News
28.03.2017 | Life Sciences
28.03.2017 | Information Technology
28.03.2017 | Physics and Astronomy