Global sea surface temperature data provides new measure of climate sensitivity

Dec 06, 2011

Scientists have developed important new insight into the sensitivity of global temperature to changes in the Earth's radiation balance over the last half million years.

The sensitivity of to changes in the Earth's () is a key parameter for understanding past natural climate changes as well as potential future climate change.

In a study in Journal of Climate, researchers from the Universities of Southampton and Bristol for the first time reconstructed climate sensitivity over five ice-age cycles based on a global suite of records of sea surface and polar change. These are compared with a new of changes in the Earth's radiation balance caused by changes in greenhouse gas concentrations, in surface reflectivity, and in insolation due to slow changes in the Earth-Sun orbital configuration. The study calculates global mean climate sensitivity, but ¬also considers its relationship with latitude. This is important because many of the past radiative changes were not equally distributed over the planet, in contrast to the more uniform distribution of the modern radiative changes due to rising greenhouse gas levels.

The researchers infer that Earth's climate sensitivity over the last half million years most likely amounted to a 3.1 to 3.9 °C temperature increase for the radiative equivalent of a modern doubling of atmospheric carbon-dioxide concentrations (with a total range of 1.7 to 5.7 °C).

Lead researcher Eelco Rohling, Professor of Ocean and at the University of Southampton, says: "We use long time-series of data that are each obtained using a single method. This reduces uncertainty in the estimates of , relative to previous work that contrasts reconstructions of a single past climate state with modern instrumental data. Our method can be especially improved by extending the global network of long records."

He continues: "Because our climate sensitivity values are based on real-world data from a substantial interval of time in the recent geological past, our results provide strong observational support to the climate sensitivities used in IPCC-class climate models. If anything, our results suggest slightly stronger sensitivity."

Dr Mark Siddall, from the Department of Earth Science at the University of Bristol, adds: "This study shows the increasing importance of using geological data to understand the climate system and how it responds as a whole to changes in greenhouse gasses."

The current study, which is funded by the Natural Environment Research Council (NERC), is based on marine results, but terrestrial information is also being sought in order to progress the study further. In addition, Professor Rohling is joint coordinator of the international Palaeosens effort that aims to establish a common approach for the reporting and comparison of climate sensitivity estimates from geological data, which started at the Royal Netherlands Academy of Arts and Sciences in March 2011.

Explore further: Indians rally against climate change ahead of UN talks

add to favorites email to friend print save as pdf

Related Stories

Explained: Climate sensitivity

Mar 19, 2010

Climate sensitivity is the term used by the Intergovernmental Panel on Climate Change (IPCC) to express the relationship between the human-caused emissions that add to the Earth's greenhouse effect -- carbon ...

Climate models make too hot forecasts of global warming

Jul 29, 2011

Data from NASA's Terra satellite shows that when the climate warms, Earth's atmosphere is apparently more efficient at releasing energy to space than models used to forecast climate change have been programmed to "believe."

Climate projections underestimate CO2 impact

Dec 10, 2009

The climate may be 30-50 percent more sensitive to atmospheric carbon dioxide in the long term than previously thought, according to a recent study published in Nature Geoscience.

Recommended for you

World greenhouse emissions threaten warming goal

1 hour ago

Emissions of greenhouse gases are rising so fast that within one generation the world will have used up its margin of safety for limiting global warming to 2°C (3.6°F), an international team of scientists ...

Tens of thousands join London climate march

2 hours ago

Tens of thousands of people in London joined a global day of protest Sunday to demand action on climate change, among them British actress Emma Thompson who said the challenge to save the planet was like ...

UN summit to test commitment to climate fund

2 hours ago

A global fund created to spearhead climate change financing faces a key test at a UN summit this week when it looks to the leaders of the industrialised world to stump up billions of dollars to fill its underflowing ...

User comments : 0