(CNN) -- Keeping global warming down to a level people can live with means cutting carbon emissions to "near zero" by the end of the century, even in an increasingly industrialized world, the top U.N. experts on the issue reported Sunday. That may be doable, but it will take "substantial investments" in everything from planting more trees to replacing fossil fuels with low-carbon power sources like solar, wind and nuclear energy, the Intergovernmental Panel on Climate Change announced in its latest report. "What this report clearly shows is that the challenges to resolve the global common problem are huge," said Ottmar Edenhofer, a German economist and one of the lead authors of Sunday's document. "But also this report shows that there are some steps to resolve this issue. I would say in that sense the report also outlines the challenges, but it provides hope -- modest hope."
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NEW: John Kerry calls the report a wake-up call to an economic opportunity
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NEW: Environmentalist says political will must change too
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U.N. panel holds out "modest hope" of heading off most global warming
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Sunday's report is the latest in a benchmark U.N. assessment of climate change
There's "a broad set of technologies" that could be deployed to head off that future, @placeholder said -- many of which are listed in the report.