Study catalogues impact of manmade climate change

Anthropogenic climate change, that is change derived from human activities, is making an indelible mark on the earth's physical and biological systems. Based on data covering a 30-year period, an international team of researchers have catalogued for the first time in one place...

Anthropogenic climate change, that is change derived from human activities, is making an indelible mark on the earth's physical and biological systems. Based on data covering a 30-year period, an international team of researchers have catalogued for the first time in one place the array of changes that have occurred in the animal and plant kingdom as a result of human-generated climate change. Changes include shrinking glaciers, a decline in certain animal populations, changes in bird migration, and the early flowering of plants. The work was recently published in the journal Nature.

'Humans are influencing climate through increasing greenhouse gas emissions, and the warming world is causing impacts on physical and biological systems attributable at the global scale,' said lead author of the study Dr Cynthia Rosenzweig of the NASA Goddard Institute for Space Studies and the Columbia Center for Climate Systems Research.

The study brought together researchers from 11 institutions across the globe to analyse published data on over 800 physical systems and almost 29 000 plant and animal systems. Their work is an extension of the assessment made by the Intergovernmental Panel on Climate Change (IPCC) in 2007 that manmade climate warming is very likely to have discernible effects on biological and physical systems.

The team built and analysed a database of observations from peer-reviewed papers (published primarily since the IPCC Third Assessment Report in 2001). The 80 studies selected contained data for the period between 1970 and 2004. According to Dr Rosenzweig, the study is the first ever that links global temperature data sets, climate model results and observed changes (in a broad range of physical and biological systems) to show the connection between humans, climate and impacts.

The researchers observed changes in many different systems around the globe, as well as global climate model simulations of temperature changes. 'It was a real challenge to separate the influence of human-caused temperature increases from natural climate variations or other confounding factors, such as land-use changes or pollution,' said co-author Dr David Karoly of Australia's University of Melbourne. Dr Karoly credits the multidisciplinary efforts of the project team in making this distinction possible.

Their findings show that temperature-related changes occurred on all of the planet's continents. For physical systems, 95% of the 829 documented changes, such as glacier wastage, are consistent with warming. For biological systems, 90% of the 28 800 documented changes in plants and animals respond to temperature changes. Furthermore, warming in oceans, lakes and rivers is also affecting marine and freshwater biological systems, as well as migration habits.

The impacts of other driving forces on these systems, such as land use change, were small. The team concluded that it is unlikely that any force other than anthropogenic climate change could be predominantly responsible for the modifications to Earth's physical and biological systems.

The strongest patterns of change were noted in North America, Asia and Europe, where more studies have been conducted and, consequently, more data exists. On other continents, such as South America, Australia and Africa, documentation is sparse, and the researchers highlight the urgent need for more studies on these environmental systems, particularly in tropical and sub-tropical areas.