Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Coral Reveals Long-Term Link Between Pacific Winds, Global Climate

22.12.2014

New research indicates that shifts in Pacific trade winds played a key role in twentieth century climate variation, a sign that they may again be influencing global temperatures.

The study, led by scientists at the National Center for Atmospheric Research (NCAR) and the University of Arizona (UA), uses a novel method of analyzing chemical changes in coral to show that weak tropical Pacific trade winds coincided with globally warming temperatures early in the twentieth century. When the natural pattern shifted and winds began to strengthen after 1940, the warming slowed.


Photo courtesy J. Warren Beck

In the equatorial atolls of western Kiribati in the Pacific Ocean, a coral record has revealed the importance of Pacific winds on global temperatures. New research has found that weak trade winds from 1910-1940 caused an increase in warming, while stronger winds 1940-1970 led to temperatures leveling off.

The finding gives support to the theory that strong Pacific trade winds are currently helping to prevent global temperatures from climbing, even as society continues to emit carbon dioxide and other greenhouse gases. When the winds weaken as part of a natural cycle, warming will likely resume once again, the authors say.

“Strong winds in the tropical Pacific are playing a role in the slowdown of warming over the past 15 years,” said lead author Diane Thompson, a postdoctoral scientist at NCAR. “When the winds inevitably change to a weaker state, warming will start to accelerate again.”

“Mother Nature is always going to inject little ups and downs along our path to a warmer world,” said University of Arizona professor Julia Cole, a co-author. “We’re trying to understand how those natural variations work so that scientists can do a better job of predicting the actual course of climate change into the future.”

The study is being published this week in Nature Geoscience. It was funded by the National Science Foundation, NCAR’s sponsor, as well as by the National Oceanic and Atmospheric Administration, University of Arizona, Philanthropic Education Organization, U.K. Natural Environment Research Council, and U.S. Department of Energy.

-----Where is the heat going?-----

Despite increases in greenhouse gases, global surface temperatures have not risen significantly since 2001. This pause in global warming, often called the hiatus, has become the focus of research by climate scientists who are trying to track the missing heat.

By using climate models and observations, scientists are finding evidence that the heat is going into the subsurface ocean, perhaps as a result of changes in atmospheric circulation. A study earlier this year in Nature Climate Change, by an international team of climate scientists, pointed to unusually strong trade winds along the equator in the Pacific Ocean that are driving heat into the ocean while bringing cooler water to the surface. This is leaving less heat in the air, thereby temporarily offsetting warming from increasing greenhouse gases.

The study by Thompson and her colleagues indicates that this process has happened before, and in the opposite direction: weaker winds allowed warming to accelerate.

The research team focused on the early twentieth century – a time when a third of the century’s global warming took place, even though major accumulations of greenhouse gases were not yet occurring. Some previous research suggested that rising sea-surface temperatures in the Atlantic Ocean were to blame. That warming did not begin until the mid-1920s, however, when the global atmospheric warming was already well underway.

As it turned out, the researchers had access to an important piece of evidence. Sitting in a UA lab was an old core drawn from a coral skeleton near a western tropical Pacific island. It had been chemically analyzed in the 1990s and then largely forgotten.

Thompson, while working on her doctoral dissertation, realized that the core could reveal tropical Pacific wind patterns during the period from 1894 to 1982 when it had grown just outside of the island’s lagoon.

The reason has to do with the effects of wind on water chemistry. When strong bursts of wind came in from the west, they stirred up manganese in the sediment at the bottom of the lagoon. The local corals took up the manganese in their skeletons as they grew. Such wind bursts from the west occur more commonly when the trade winds, which normally blow from the east, are weak.

Chemical analysis of the yearly banded coral skeleton showed a comparatively high occurrence of these spikes in manganese to calcium from about 1910 to 1940—the same period when Earth experienced significant warming. However, the number of these events dropped between the 1940s and 1970s, when temperatures leveled off.

Thompson and her co-authors compared the ratio to wind observations since 1960, when observations became more reliable, and verified that the high manganese-to-calcium ratio correlated with weaker trade winds. They also combed through more scattered records before 1960 and again found a correlation of the chemical ratio to wind strength.

Thompson stressed that the winds are just one contributor to changes in global climate. Another reason that temperatures leveled off in mid-century likely has to do with increased industrialization and emissions of particles that block sunlight and exert a cooling influence. Later in the century, increased emissions of greenhouse gases played a dominant role.

“This research shows that the influence of winds on climate is not anything new. These mechanisms have been at work earlier,” Thompson said. “We believe this is a significant contribution to understanding the role of natural processes in modulating global temperature change.”

The University Corporation for Atmospheric Research manages the National Center for Atmospheric Research under sponsorship by the National Science Foundation. Any opinions, findings and conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the views of the National Science Foundation.

About the article

Title: Early 20th century global warming linked to tropical Pacific wind strength

Authors: Diane M. Thompson, Julia E. Cole, Glen T. Shen, Alexander W. Tudhope, Gerald A. Meethl

Journal: Nature Geoscience

On the Web

For news releases, images, and more:
www.ucar.edu/atmosnews
 

Contact Information
David Hosansky, NCAR/UCAR Media Relations
303-497-8611
hosansky@ucar.edu

Mari N. Jensen, University of Arizona Media Relations
520-626-9636
mnjensen@email.arizona.edu

Diane Thompson, NCAR Scientist
303-497-1703
thompsod@ucar.edu

Julia Cole, University of Arizona Professor
520-626-2341
jecole@email.arizona.edu

David Hosansky | newswise

More articles from Earth Sciences:

nachricht In times of climate change: What a lake’s colour can tell about its condition
21.09.2017 | Leibniz-Institut für Gewässerökologie und Binnenfischerei (IGB)

nachricht Did marine sponges trigger the ‘Cambrian explosion’ through ‘ecosystem engineering’?
21.09.2017 | Helmholtz-Zentrum Potsdam - Deutsches GeoForschungsZentrum GFZ

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: The pyrenoid is a carbon-fixing liquid droplet

Plants and algae use the enzyme Rubisco to fix carbon dioxide, removing it from the atmosphere and converting it into biomass. Algae have figured out a way to increase the efficiency of carbon fixation. They gather most of their Rubisco into a ball-shaped microcompartment called the pyrenoid, which they flood with a high local concentration of carbon dioxide. A team of scientists at Princeton University, the Carnegie Institution for Science, Stanford University and the Max Plank Institute of Biochemistry have unravelled the mysteries of how the pyrenoid is assembled. These insights can help to engineer crops that remove more carbon dioxide from the atmosphere while producing more food.

A warming planet

Im Focus: Highly precise wiring in the Cerebral Cortex

Our brains house extremely complex neuronal circuits, whose detailed structures are still largely unknown. This is especially true for the so-called cerebral cortex of mammals, where among other things vision, thoughts or spatial orientation are being computed. Here the rules by which nerve cells are connected to each other are only partly understood. A team of scientists around Moritz Helmstaedter at the Frankfiurt Max Planck Institute for Brain Research and Helene Schmidt (Humboldt University in Berlin) have now discovered a surprisingly precise nerve cell connectivity pattern in the part of the cerebral cortex that is responsible for orienting the individual animal or human in space.

The researchers report online in Nature (Schmidt et al., 2017. Axonal synapse sorting in medial entorhinal cortex, DOI: 10.1038/nature24005) that synapses in...

Im Focus: Tiny lasers from a gallery of whispers

New technique promises tunable laser devices

Whispering gallery mode (WGM) resonators are used to make tiny micro-lasers, sensors, switches, routers and other devices. These tiny structures rely on a...

Im Focus: Ultrafast snapshots of relaxing electrons in solids

Using ultrafast flashes of laser and x-ray radiation, scientists at the Max Planck Institute of Quantum Optics (Garching, Germany) took snapshots of the briefest electron motion inside a solid material to date. The electron motion lasted only 750 billionths of the billionth of a second before it fainted, setting a new record of human capability to capture ultrafast processes inside solids!

When x-rays shine onto solid materials or large molecules, an electron is pushed away from its original place near the nucleus of the atom, leaving a hole...

Im Focus: Quantum Sensors Decipher Magnetic Ordering in a New Semiconducting Material

For the first time, physicists have successfully imaged spiral magnetic ordering in a multiferroic material. These materials are considered highly promising candidates for future data storage media. The researchers were able to prove their findings using unique quantum sensors that were developed at Basel University and that can analyze electromagnetic fields on the nanometer scale. The results – obtained by scientists from the University of Basel’s Department of Physics, the Swiss Nanoscience Institute, the University of Montpellier and several laboratories from University Paris-Saclay – were recently published in the journal Nature.

Multiferroics are materials that simultaneously react to electric and magnetic fields. These two properties are rarely found together, and their combined...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

“Lasers in Composites Symposium” in Aachen – from Science to Application

19.09.2017 | Event News

I-ESA 2018 – Call for Papers

12.09.2017 | Event News

EMBO at Basel Life, a new conference on current and emerging life science research

06.09.2017 | Event News

 
Latest News

Rainbow colors reveal cell history: Uncovering β-cell heterogeneity

22.09.2017 | Life Sciences

Penn first in world to treat patient with new radiation technology

22.09.2017 | Medical Engineering

Calculating quietness

22.09.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>