38. Esther Duflo
for putting hard numbers to a bleeding-heart pursuit.
Economist, MIT | Cambridge, Mass.
"Imagine you have a few million dollars that you've raised.… You want to spend it on the poor. How do you go about it?" Esther Duflo, a French native who heads the Massachusetts Institute of Technology's Poverty Action Lab, asked in a talk this year. Her pathbreaking research aims to put hard numbers behind such decisions, identifying the most cost-effective ways to fight endemic problems such as poverty and malnutrition.
Now Duflo is trying to ensure that those ideas are put into practice. After teaming up with several colleagues to show that treating children for intestinal worms dramatically improves school attendance, her MIT lab helped launch Deworm the World, an NGO that has worked to raise money to treat 3.6 million children in Kenya. She has also devised a number of innovative methods to overcome people's natural tendency to procrastinate -- for example, providing time-limited discounts on fertilizer purchases to local farmers. By focusing on what works, Duflo is proving that the dismal science still has some relevance in the real world.
39. Mohamed Nasheed
for putting a face -- his own -- on the peril of climate change.
President | Maldives
In October 2009, shortly before the Copenhagen climate negotiations went bust, Mohamed Nasheed and a dozen of his cabinet ministers strapped on scuba tanks and wet suits and convened at an underwater conference table near the capital city of Malé. Communicating by hand signals, they signed a declaration calling on countries to cut their carbon emissions. Afterward, Nasheed was asked what would happen if they didn't. "We are going to die," he said.
Since taking office two years ago, Nasheed, a 43-year-old former human rights activist, has become the world's most environmentally outspoken president. He has made his tiny country -- a string of atolls in the Indian Ocean that sits an average of just 7 feet above sea level -- a poster child for the need to stop global warming. Last year he vowed to set a symbolic example by making the Maldives the world's first carbon-neutral country within a decade. Now he's accusing the United States of being the biggest obstacle to fighting climate change, calling for "'60s-style catalystic, dynamic street action."
"If the people in the U.S. wish to change," he told a British audience, "it can happen."
Read more: Nasheed talks to FP about battling climate change and saving his country from going under.
40. Abdolkarim Soroush
for driving a stake through the dark heart of Iran's theocracy.
Religious scholar | Washington
Speaking in London a decade ago, a then-obscure Iranian religious philosopher predicted that, along with the "red discourse" of the left and the "black discourse" of tyranny, a "green discourse" that embraced democracy and pluralism would rise in Iran. Abdolkarim Soroush could hardly have known then that the protesters who shook the Islamic Republic to its core in June 2009 would adopt not only the substance of his program, but also its name. But as the amorphous Green Movement struggles to make its voice heard against extraordinary repression, Soroush has been at the forefront of efforts to define its message, helping write an ambitious 10-point manifesto for it.
For Soroush, the end of the protests does not signal the movement's demise; he sees reformist views quietly embedding themselves in the public consciousness. When one critic ripped Soroush's vision of a secular republic in Iran, saying it reminded him of governments that existed throughout the world, he replied: "Yes, that's true. If everyone is walking on their legs, should we be walking on our heads?"
41. Mehdi Karroubi
for keeping the spirit of the Green Movement alive.
Cleric | Iran
Faced with an extraordinary crackdown by Iranian authorities, most leaders of Iran's Green Movement have faded from the public eye in the past year. This has left Mehdi Karroubi, a midranking cleric who finished well behind Mir Hossein Mousavi in Iran's disputed June 2009 presidential election, as one of the sole opposition figures left in the country.
A reformist with revolutionary credentials that date back to the Islamic Republic's founding, Karroubi was the first Green Movement leader to blast the regime for mistreating imprisoned opponents, and he's still going full tilt criticizing the government's mismanagement of the economy and the burgeoning influence of the Islamic Revolutionary Guard Corps. Karroubi's courage carries real risks: Late last year, a special tribunal investigated him on charges of sedition, a crime that carries the death penalty. Then in September, plainclothes militia attacked Karroubi's house and tussled with his bodyguards. Tehran's chief prosecutor has said that Karroubi will be tried "once public opinion is ready." But he says he would welcome being brought to court: "It will be a good opportunity for me to talk again about crimes that would make the shah look good."
OLIVIER LABAN-MATTEI/AFP/Getty Images