. Earth Science News .




.
CLIMATE SCIENCE
No simultaneous warming of northern and southern hemispheres as a result of climate change for 20 000 years
by Staff Writers
Lund, Sweden (SPX) Oct 27, 2011

File image.

A common argument against global warming is that the climate has always varied. Temperatures rise sometimes and this is perfectly natural is the usual line.

However, Svante Bjorck, a climate researcher at Lund University in Sweden, has now shown that global warming, i.e. simultaneous warming events in the northern and southern hemispheres, have not occurred in the past 20 000 years, which is as far back as it is possible to analyse with sufficient precision to compare with modern developments. Svante Bjorck's study thus goes 14 000 years further back in time than previous studies have done. "What is happening today is unique from a historical geological perspective", he says.

Svante Bjorck has gone through the global climate archives, which are presented in a large number of research publications, and looked for evidence that any of the climate events that have occurred since the end of the last Ice Age 20 000 years ago could have generated similar effects on both the northern and southern hemispheres simultaneously.

It has not, however, been possible to verify this. Instead, he has found that when, for example, the temperature rises in one hemisphere, it falls or remains unchanged in the other.

"My study shows that, apart from the larger-scale developments, such as the general change into warm periods and ice ages, climate change has previously only produced similar effects on local or regional level", says Svante Bjorck.

As an example, let us take the last clear climate change, which took place between the years 1600 and 1900 and which many know as the Little Ice Age.

Europe experienced some of its coldest centuries. While the extreme cold had serious consequences for agriculture, state economies and transport in the north, there is no evidence of corresponding simultaneous temperature changes and effects in the southern hemisphere.

The climate archives, in the form of core samples taken from marine and lake sediments and glacier ice, serve as a record of how temperature, precipitation and concentration of atmospheric gases and particles have varied over the course of history, and are full of similar examples.

Instead it is during 'calmer' climatic periods, when the climate system is influenced by external processes, that the researchers can see that the climate signals in the archives show similar trends in both the northern and southern hemispheres.

"This could be, for example, at the time of a meteorite crash, when an asteroid hits the earth or after a violent volcanic eruption when ash is spread across the globe. In these cases we can see similar effects around the world simultaneously", says Svante Bjorck.

Professor Bjorck draws parallels to today's situation. The levels of greenhouse gases in the atmosphere are currently changing very rapidly. At the same time, global warming is occurring.

"As long as we don't find any evidence for earlier climate changes leading to similar simultaneous effects on a global scale, we must see today's global warming as an exception caused by human influence on the earth's carbon cycle", says Svante Bjorck, continuing: "this is a good example of how geological knowledge can be used to understand our world. It offers perspectives on how the earth functions without our direct influence and thus how and to what extent human activity affects the system."

Svante Bjorck's results were published this summer in the scientific journal Climate Research.

Related Links
Lund University
Climate Science News - Modeling, Mitigation Adaptation




.
.
Get Our Free Newsletters Via Email
...
Buy Advertising Editorial Enquiries




.

. Comment on this article via your Facebook, Yahoo, AOL, Hotmail login.

Share this article via these popular social media networks
del.icio.usdel.icio.us DiggDigg RedditReddit GoogleGoogle



CLIMATE SCIENCE
Small nations push climate at Commonwealth talks
Perth, Australia (AFP) Oct 26, 2011
Pacific island and other small countries being punished by global warming will use a Commonwealth summit this week to ramp up pressure on powerful nations in the climate change debate. Setting the stage for the three-day event, Samoan Prime Minister Tuilaepa Sailele Malielegaoi hit out at major polluters the United States and China for not doing enough to cut their greenhouse gas emissions. ... read more


CLIMATE SCIENCE
Nuclear pollution of sea from Fukushima was world's biggest

Looting in Turkey as quake survivors seethe over aid

Teenager saved days after Turkey quake as toll reaches 550

Rice regrets shoe shopping amid Katrina disaster: book

CLIMATE SCIENCE
RIM stock suffers on new tablet software stall

Reversing course, Hewlett-Packard to keep PC unit

Video game makers ready barrage of blockbusters

Wearable depth-sensing projection system makes any surface capable of multitouch interaction

CLIMATE SCIENCE
Desalination part of solution for China?

US residents say Hawaii's coral reef ecosystems worth $33.57 billion per year

Brazil snub to OAS heightens row over dam

Record fine for VI firm caught trading protected coral

CLIMATE SCIENCE
Extreme Melting on Greenland Ice Sheet

China's glaciers in meltdown mode: study

Glaciers in China shrinking with warming

Polar bear habitats expected to shrink dramatically:

CLIMATE SCIENCE
Hong Kong foodie festival raises wine hub profile

Food Chemical Regulations Rely Heavily on Industry Self-Policing and Lack Transparency

Pastoralists in drought-stricken Kenya receive insurance payouts for massive livestock losses

Magnetic tongue ready to help produce tastier processed foods

CLIMATE SCIENCE
Bangkok exodus as floods advance on city centre

Five die in Italy flooding

Rina weakens as it heads for Cancun

Hurricane Rina weakens, holds course for Cancun

CLIMATE SCIENCE
700 protest over war pensions in Mozambique

US troops to advise front-line units on Uganda rebels

France denies Somali bombardment, admits helping Kenya

Sudden drop in Somali arrivals in Kenya: UNHCR

CLIMATE SCIENCE
World population to hit 10 bln, but 15 bln possible: UN

Study uncovers physiological nature of disgust in politics

Computer scientist cracks mysterious Copiale Cipher

Tracing the first North American hunters


.

The content herein, unless otherwise known to be public domain, are Copyright 1995-2011 - Space Media Network. AFP and UPI Wire Stories are copyright Agence France-Presse and United Press International. ESA Portal Reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement,agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. Privacy Statement