The $1 trillion will be injected into the economy through the International Monetary Fund and other lending institutions.
The G-20 leaders agreed on more regulation for banks, new rules for executive bonus pay, interest rate cuts, corporate responsibility, and sanctions against tax havens that don't comply with G-20 rules.
"Today's decision will not immediately solve the crisis, but we've begun the process by which it will be solved," Brown said in the closing news conference of the G-20 sessions. "This is collective action, people working together at their best. ... I think a new world order is emerging. We will together manage the process of globalization."
Brown announced the formation of a new Financial Stability Board (FSB), with the International Monetary Fund monitoring progress of G-20's objectives, surveying the global economy and providing early warnings. But there wasn't a clear explanation of exactly what kind of powers the FSB would have.
The Obama administration contends that the FSB is not a "global regulator" but rather a "mechanism for international coordination."
Wall Street rallied more than 200 points and went over 8,000, partly in response to the G-20's announcement.
The communique was vague on details and fashioned so that all sides could claim victory, but the meeting was seen as a true test of President Obama's international role. Obama pressed for European countries to invest more heavily in a stimulus program with direct infusions of capital while others, particularly French President Nicolas Sarkozy and German Chancellor Angela Merkel, demanded tougher regulation of international firms.
Today, Obama also played the role of the peacemaker, stepping into an argument between Sarkozy and Chinese President Hu Jintao over tax havens.
Obama also showed his human side during his press conference Thursday, sneezing twice from a cold he said he's been fighting all week. Otherwise, the president answered questions from U.S. reporters and plucked out four members of the international press from the boisterous crowd of 2,500.
"I'm going to call one foreigner -- actually, I'm the foreigner," he said, smiling.
"That's why I smiled," the president said awkwardly, clarifying that he'd call upon "one correspondent not from America."
Some economists expressed skepticism about what these new measures would achieve.
"The immediate task at hand was how to immediately prevent this recession from getting worse and it's not clear they've done that," said Linda Yueh, a fellow in economics at the University of Oxford. "Obama pushed for everyone to spend 2 percent [of GDP] and what he got was counting for what countries have already agreed to spend. So this is not new money, this is money that countries have already spent before they came to the summit."
Stimulus plans were kept vague in the communique.
"Never we thought we would obtain such a large agreement," said Sarkozy, who had threatened to walk out of the summit if the group did not agree to stricter fiscal regulations.
"It is not the victory of one camp on another," said the French president, who called the meeting tense. "There is awareness from everyone that the world must change.The Anglo-Saxon countries are convinced there must be reasonable rules."