Northern Hemisphere getting warmer over a larger area due to global warming, report

Feb 09, 2006
Earth from space

The temperature of the northern hemisphere has increased over a larger area in the last century than at any time in the past millennium a report published in Science reveals this week.

The study finds that the number of “hot spots” has increased dramatically in the Northern Hemisphere in the last century compared to the past 1200 years – adding to the growing evidence of wide-scale global warming.

Dr Tim Osborn and Prof Keith Briffa, of the Climatic Research Unit team at the University of East Anglia, analyzed thermometer measurements of temperature from 1856 onwards to establish the spatial extent of recent warming, and compared it with evidence from as far back as AD 800 (from tree rings, ice cores and shells).

The study found evidence for periods of significant warmth (890 – 1170) in the Northern Hemisphere during medieval times and for clearly colder periods (1580 – 1850) during the so-called “Little Ice Age”.

Their key conclusion was that the 20th century stands out as having unusually widespread warmth, compared to all of the natural warming and cooling episodes during the past 1,200 years.

The research team gathered climate change data from a number of regions in the Northern Hemisphere especially:

Long life evergreen trees growing in Scandinavia, Siberia and the Rockies, which had been cored to reveal the patterns of wide and narrow tree rings over time – wider rings relating to warmer temperatures.

Ice from cores drilled in the Greenland ice sheets revealed which years were warmer than others by the chemical composition of the ice.

They also used a record developed from diaries of people living in the Netherlands and Belgium over the past 750 years that revealed for example the years when the canals froze.

Source: University of East Anglia

Explore further: Hoisting a telescope with helium

add to favorites email to friend print save as pdf

Related Stories

Cold snap in the tropics

Aug 25, 2014

Tropical glaciers have responded to episodes of cooling in Greenland and the Antarctic over the past 20,000 years, according to a study carried out mainly by researchers at the CNRS, Université Joseph Fourier, ...

Cosmic matters: Stormy weather on Uranus

Aug 07, 2014

(Phys.org) —Weather on any planet can be quite unpredictable. As hurricanes threaten the Aloha State, astronomers working at W. M. Keck Observatory on the island of Hawaii were surprised by the appearance ...

Recommended for you

Caterpillar comet poses for pictures en route to Mars

19 hours ago

Now that's pure gorgeous. As Comet C/2013 A1 Siding Spring sidles towards its October 19th encounter with Mars, it's passing a trio of sumptuous deep sky objects near the south celestial pole this week. ...

Hoisting a telescope with helium

19 hours ago

Many a child has forgotten to hold tight to the string of a helium balloon only to have it escape and rise until it disappeared in the glare of the sun. Helium balloons want to rise, but launching a balloon ...

User comments : 0