Study: link between tropical warming and greenhouse gases stronger than ever

October 13, 2005

New evidence from climate records of the past provides some of the strongest indications yet of a direct link between tropical warmth and higher greenhouse gas levels, say scientists at the University of California, Santa Barbara. The present steady rise in tropical temperatures due to global warming will have a major impact on global climate and could intensify destructive hurricanes like Katrina and Rita.

The new evidence linking past tropical ocean temperatures to levels of atmospheric greenhouse gases is published in this week's Science Express, the on-line publication of the journal Science. The authors are Martin Medina-Elizalde, graduate student in the Department of Earth Science and the Interdepartmental Program in Marine Science at UC Santa Barbara, and David Lea, professor in UCSB's Department of Earth Science and the Marine Science Institute.

The link between increased atmospheric greenhouse gas and global temperatures underlies the theory of global warming, explained the authors. This link can be established by computer climate models or modern observations. Another way to study the link is through paleoclimate observations where past climate is reconstructed through natural archives. This latest study is based on such paleoclimate observations; the scientists analyzed the chemical composition of fossil plankton shells from a deep sea core in the equatorial Pacific.

"The relationship between tropical climate and greenhouse gases is particularly critical because tropical regions receive the highest proportion of solar output and act as a heat engine for the rest of the earth," said Lea.

Modern observations of tropical sea surface temperature indicate a rise of one to two degrees Fahrenheit over the last 50 years, a trend consistent with rising carbon dioxide in the atmosphere due to fossil fuel combustion, according to the authors. The paleoclimate evidence from this new study supports the attribution of the tropical temperature trend to the ever-increasing greenhouse gas burden in the atmosphere.

The research described in this week's article demonstrates that over the last 1.3 million years, sea surface temperatures in the heart of the western tropical Pacific were controlled by the waxing and waning of the atmospheric greenhouse effect. The largest climate mode shift over this time interval, occurring ~950,000 years before the present (the mid-Pleistocene transition), has previously been attributed to changes in the pattern and frequency of ice sheets.

The new research suggests instead that this shift is due to a change in the oscillation frequency of atmospheric carbon dioxide abundances, a hypothesis that can be directly tested by deep drilling on the Antarctic Ice Cap. If proved correct, this theory would suggest that relatively small, naturally occurring fluctuations in greenhouse gases are the master variable that has driven global climate change on time scales of ten thousand to one million years.

Source: University of California - Santa Barbara

Explore further: Brazil builds climate tower in pristine Amazon jungle

Related Stories

1,800 years of global ocean cooling halted by global warming

August 17, 2015

Prior to the advent of human-caused global warming in the 19th century, the surface layer of Earth's oceans had undergone 1,800 years of a steady cooling trend, according to a new study. During the latter half of this cooling ...

'Snowball earth' might be slushy

August 3, 2015

Imagine a world without liquid water—just solid ice in all directions. It would certainly not be a place that most life forms would like to live.

Recommended for you

Quantum computing will bring immense processing possibilities

September 2, 2015

The one thing everyone knows about quantum mechanics is its legendary weirdness, in which the basic tenets of the world it describes seem alien to the world we live in. Superposition, where things can be in two states simultaneously, ...

Prawn Nebula: Cosmic recycling

September 2, 2015

Dominating this image is part of the nebula Gum 56, illuminated by the hot bright young stars that were born within it. For millions of years stars have been created out of the gas in this nebula, material which is later ...

Comet Hitchhiker would take tour of small bodies

September 2, 2015

Catching a ride from one solar system body to another isn't easy. You have to figure out how to land your spacecraft safely and then get it on its way to the next destination. The landing part is especially tricky for asteroids ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.