Greatest warming is in the north, but biggest impact on life is in the tropics

Oct 06, 2010

In recent decades documented biological changes in the far Northern Hemisphere have been attributed to global warming, changes from species extinctions to shifting geographic ranges. Such changes were expected because warming has been fastest in the northern temperate zone and the Arctic.

But new research published in the Oct. 7 edition of Nature adds to growing evidence that, even though the temperature increase has been smaller in the tropics, the impact of warming on life could be much greater there than in colder climates.

The study focused on ectothermic, or cold-blooded, organisms (those whose body temperature approximates the temperature of their surroundings). Researchers used nearly 500 million temperature readings from more than 3,000 stations around the world to chart temperature increases from 1961 through 2009, then examined the effect of those increases on metabolism.

"The expectation was that physiological changes would also be greatest in the north temperate-Arctic region, but when we ran the numbers that expectation was flipped on its head," said lead author Michael Dillon, an assistant professor of zoology and physiology at the University of Wyoming.

are key to understanding some major impacts of because a higher requires more food and more oxygen, said co-author Raymond Huey, a University of Washington biology professor. If, for example, an organism has to spend more time eating or conserving energy, it might have less time and energy for reproduction.

"Metabolic rate tells you how fast the animal is living and thus its intensity of life," Huey said.

Using a well-documented, century-old understanding that metabolic rates for cold-blooded animals increase faster the warmer the temperature, the researchers determined that the effects on metabolism will be greatest in the tropics, even though that region has the smallest actual warming. Metabolic impacts will be less in the Arctic, even though it has shown the most warming. In essence, organisms in the tropics show greater effects because they start at much higher temperatures than animals in the Arctic.

Dillon and co-author George Wang of the Max Planck Institute for Developmental Biology in Tübingen, Germany, sifted through temperature data maintained by the National Oceanic and Atmospheric Administration's National Climatic Data Center. They came up with readings from 3,186 stations that met their criteria of recording temperature at least every six hours during every season from 1961 through 2009. The stations, though not evenly spaced, represented every region of the globe except Antarctica.

The data, the scientists said, reflect temperature changes since 1980 that are consistent with other recent findings that show the Earth is getting warmer. Temperatures rose fastest in the Arctic, not quite as fast in the northern temperate zone and even more slowly in the tropics.

"Just because the temperature change in the tropics is small doesn't mean the biological impacts will be small," Huey said. "All of the studies we're doing suggest the opposite is true."

In fact, previous research from the University of Washington has indicated that small temperature changes can push organisms beyond their optimal and cause substantial stress, while organisms in temperate and polar regions can tolerate much larger increases because they already are used to large seasonal temperature swings.

The scientists say the effects of warming temperatures in the tropics have largely been ignored because temperature increases have been much greater farther north and because so few researchers work in the tropics.

"I think this argues strongly that we need more studies of the impacts of warming on organisms in the tropics," Dillon said.

Explore further: 2014 Antarctic ozone hole holds steady

Related Stories

Tropical lizards can't take the heat of climate warming

Mar 03, 2009

From geckos and iguanas to Gila monsters and Komodo dragons, lizards are among the most common reptiles on Earth. They are found on every continent except Antarctica. One even pitches car insurance in TV ads. ...

New Ice Age maps point to climate change patterns

Jan 19, 2009

(PhysOrg.com) -- New climate maps of the Earth’s surface during the height of the last Ice Age support predictions that northern Australia will become wetter and southern Australia drier due to climate change.

Recommended for you

2014 Antarctic ozone hole holds steady

11 hours ago

The Antarctic ozone hole reached its annual peak size on Sept. 11, according to scientists from NASA and the National Oceanic and Atmospheric Administration (NOAA). The size of this year's hole was 24.1 million ...

New study finds oceans arrived early to Earth

14 hours ago

Earth is known as the Blue Planet because of its oceans, which cover more than 70 percent of the planet's surface and are home to the world's greatest diversity of life. While water is essential for life ...

Magma pancakes beneath Lake Toba

14 hours ago

Where do the tremendous amounts of material that are ejected to from huge volcanic calderas during super-eruptions actually originate?

User comments : 7

Adjust slider to filter visible comments by rank

Display comments: newest first

Loodt
1.6 / 5 (7) Oct 06, 2010
I agree with lead author Michael Dillon that we need more studies of the impacts of warming on organisms in the tropics!

There is only so much you can look at penguins and polar bears before you get bored.

Another aspect Dillon failed to mention is that these study sites must be close to a beach. That way tidal and wave movements, sea-level rises, can be incorporated in the study.

The job description is so tough that I doubt that they will be able to fill the position!
stealthc
1.8 / 5 (10) Oct 06, 2010
read climategate before you subscribe to this rubbish.
Caliban
4.2 / 5 (5) Oct 06, 2010
It has long been known that sealife in the tropics has developed more narrowly bounded tolerance to changes in temperature, salinity, et c -so, upon reflection, this comes as no surprise, since temperature varies only slightly over time in the tropics.

So, even a relatively small increase in average temperature is bound to place stress upon organisms adapted for a tropical environment- not only heat stress, but decreasing available oxygen, and increasing salinity through evaporation.

Add to that increasing acidification, changes in water column stratification, et c, and the stresses are multiplied to the point of making survival for many, if not most, nearly impossible.

Trouble.

bbd
1 / 5 (7) Oct 06, 2010
this argues strongly that we need more studies

... and isn't this what it always comes down to ... more money for research. No wonder so many "scientists" are proponents of the AGW hypothesis ... job security.
Caliban
4.2 / 5 (5) Oct 07, 2010
this argues strongly that we need more studies

... and isn't this what it always comes down to ... more money for research. No wonder so many "scientists" are proponents of the AGW hypothesis ... job security.


Research costs money, usually in the form of grants. Part of the process requires preliminary research to identify areas where further research is needed.

That's how it works, and it all costs money.
deepsand
5 / 5 (1) Oct 07, 2010
read climategate before you subscribe to this rubbish.

Learn Physics before spouting such tripe.
deepsand
5 / 5 (1) Oct 07, 2010
this argues strongly that we need more studies

... and isn't this what it always comes down to ... more money for research. No wonder so many "scientists" are proponents of the AGW hypothesis ... job security.

Is that also why you are given to non-substantive speculation rather than substantive rebuttal?

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.