The world must cut its greenhouse gas emissions to meet its goals, climate experts said Sunday. Members of the Intergovernmental Panel on Climate Change (left to right) Youba Sakona, Ramon Pichs Madruga, Ottmar Edenhofer and Rajendra Pachauri hold copies of their new report in Berlin. John MacDougall/AFP/Getty Images hide caption

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Farmers participate in a CGIAR climate training workshop on how to interpret seasonal rainfall forecasts in Kaffrine, Senegal. Courtesy of J. Hansen/CGIAR Climate hide caption

itoggle caption Courtesy of J. Hansen/CGIAR Climate

A tall, rubbery weed with golden flowers Dalmatian toadflax is encroaching on grasslands in 32 U.S. states. pverdonk/Flickr hide caption

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Cattle graze at a Brazilian Agricultural Research experimental farm in Planaltina in Goias state. To reduce emissions from deforestation, the Brazilian government is experimenting with grazing on integrated forest and pasture lands. Evaristo Sa/AFP/Getty Images hide caption

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The jet stream that circles Earth's north pole travels west to east. But when the jet stream interacts with a Rossby wave, as shown here, the winds can wander far north and south, bringing frigid air to normally mild southern states. NASA/GSFC hide caption

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Will the distant future give rise to exhibits of a human past long gone, much as we gawk today at representations of a dinosaur age we can only imagine? Aamir Qureshi/AFP/Getty Images hide caption

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Villages in the Lower Shire valley of Malawi, like this one named Jasi, rely heavily on subsistence farming and steady rainfall, and are struggling to produce steady harvests. Jennifer Ludden/NPR hide caption

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Somali refugees lead their herds of goats home for the night outside Dadaab, Kenya. A new study shows that animals in many parts of the developing world require more food — and generate more greenhouse emissions — than animals in wealthy countries. Rebecca Blackwell/AP hide caption

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