Nairobi, Kenya — With a week until Easter, chocolate lovers should brace themselves for higher prices when they purchase their favorite seasonal treats. A nonprofit environmental group says cocoa costs three times more than it did a year ago because of climate change and the El Nino weather effect. Prices reached $8,000 per ton this week, compared with $2,500 last year at this time. Amber Sawyer, a climate and energy analyst at the Energy and Climate Intelligence Unit, or ECIU, a U.K.-based nonprofit group, said the volatile weather patterns in the …