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Diana Liverman, co-director of The University of Arizona's Institute of the Environment, helped organize "4 Degrees and Beyond," a conference currently meeting abroad.

Diana Liverman, co-director of The University of Arizona's Institute of the Environment, is one of five researchers to organize a major meeting of 150 climate scientists and experts.

The conference, "4 Degrees and Beyond," has brought the experts together to consider the consequences of an increase in global temperatures of more than 4 degrees Celsius.

Currently underway, the conference is the first wide-ranging assessment of the impacts of 4 degrees of climate change, how society can prepare, and how energy emissions can be controlled to avoid this level of  warming – which is equivalent to 7 degrees Fahrenheit.

Hosted by Oxford University, the Tyndall Centre for Climate Change Research and the UK Met Office – all in the United Kingdom – the conference is being held in Oxford through Wednesday.

The meeting predates a December summit in Copenhagen where governments will discuss their progress on reaching a new international agreement  on climate change, including commitments to reduce greenhouse gas emissions and help the world adapt to warming should efforts to reduce emissions be inadequate.

The conference likely will receive worldwide attention, as scientists are becoming increasingly convinced that average global temperatures are likely to rise by at least 4 degrees C over this century.

"Most of our climate impact studies to date have only looked at lower-end temperature projections around 2 degrees C," said Liverman, also a UA geography and development professor who specializes in climate impacts, vulnerability and adaption, and climate policy.

"The conference will explore what will happen if, as now seems possible, we end up with an even warmer world," Liverman added. "Even at 2 degrees we anticipate serious effects on coastal areas, mountain ecosystems, and drought-prone areas such as the American Southwest, Australia, and southern Africa."

Liverman also said that 4 degrees introduces "even more worrying changes, which could cause widespread stresses on food, water, and ecosystems and even trigger more rapid climate changes.

She expects the conference discussions will add even more urgency to the need to agree on steep emission reductions in Copenhagen.

Researchers say the Earth already has warmed about 0.9 degrees C since the late 1800s – a warming of the climate system that a 2007 U.N. International Panel on Climate Change, or IPCC, assessment report called "unequivocal" and "very likely due" to human-caused emissions.

Some warming-related changes, including melting glaciers and shrinking polar ice, already are underway.

In the Southwest, projected climate changes associated with global warming include higher temperatures, more droughts but also more floods, an earlier spring with more large wildfires, and less snow cover and therefore more strain on water resources.

Most nations have committed to limiting a rise in global average temperatures to 2 degrees C, or 3.6 degrees Fahrenheit, to avoid dangerous climate change.

Nevertheless, emissions have risen by 3 percent per year in the 17 years since the 1992 Earth Summit in which countries first agreed to tackle global warming.

Recent research from the Tyndall Centre showed that limiting warming to 2 degrees C will require a complete reversal in emissions trends and concluded that hitting or exceeding 4 degrees C is now more likely.

Similarly, the Met Office has shown that to achieve a 2-degree C target, a 3 percent cut in emissions is needed annually, beginning in 2010.

"These cuts require rapid changes in technologies, behavior, and government policy to decarbonize economies in a short period of time," Liverman said.

"Some of these changes are well underway as a result of investments and incentives for more efficient energy use in houses and transport," she said, "and generating electricity from sources that emit fewer greenhouse gases such as solar energy."