At the Group of Eight Summit in L’Aquila, Italy, on Thursday, the U.S. convened with seven other world economic powers to discuss global warming and ways to cap the rise in global temperature at 3.6 degrees Fahrenheit by 2020.

The leaders agreed to cut emissions of greenhouse gasses by 50% worldwide, and make an effort to cut it by 80% in industrialized nations by 2050. 

“Every nation on this planet is at risk. And just as no one nation is responsible for climate change, no one nation can address it alone,” said President Obama in his address. “I don't think I have to emphasize that climate change is one of the defining challenges of our time. The science is clear and conclusive, and the impacts can no longer be ignored.”

However, President Obama’s speech did not address the most talked-about goal of environmentalists, which is to make specific cuts in emissions by 2020. Furthermore, a planned meeting with high emissions-producing countries including India and China will not address specific ways to cut down on emissions.

Scientists have agreed that if the Earth’s temperature rises any more than the 3.6-degree limit, it will have dire environmental consequences for the world. That increase is based on measurements taken in 1900.

“The need for urgent action to address climate change is now indisputable," the U.S. National Academy of Sciences said in a statement.

The NAS also stated that carbon dioxide and other gases that are responsible for trapping heat beneath the earth’s ozone layer should be reduced by 50% before 2050, and urged that the international community commit to cutting the emissions of heat-trapping gases by 50% from 1990 levels by the year 2050.

President Obama acknowledged that not all the countries in the world are on the same playing field when it comes to combating global warming.

“Each of our nations comes to the table with different needs, different priorities, different levels of development. And developing nations have real and understandable concerns about the role they will play in these efforts. They want to make sure that they do not have to sacrifice their aspirations for development and higher living standards. Yet, with most of the growth in projected emissions coming from these countries, their active participation is a prerequisite for a solution,” the President said. 

Fuel-efficient cars and clean-energy technology were addressed in President Obama’s speech, as was the newly created national policy which will raise fuel efficiency standards and can save 1.8 billion barrels of oil during the lifetime of cars sold in the U.S. over the next five years.

“Developed countries, like my own, have a historic responsibility to take the lead. We have the much larger carbon footprint per capita. And I know that in the past the United States has sometimes fallen short of meeting our responsibilities. So let me be clear: Those days are over,” President Obama said.

President Obama closed by acknowledging the challenges of a united global front against climate change.

“We've made a good start, but I'm the first one to acknowledge that progress on this issue will not be easy. And I think that one of the things we're going to have to do is fight the temptation towards cynicism, to feel that the problem is so immense that somehow we cannot make significant strides,” he said.

Important documents from the summit:

G8 Summit Preliminary Accountability Report 8.7.09

G8 Summit Political Declaration

G8 Summit L'Aquila Non Pro

G8 Summit Econ Declaration 08-07-09

G8 Summit Declaration on Counter Terrorism

White House Release on Climate Change, Clean Energy