The answer, according to a modeling study published in this week's issue of Nature, is "very soon"—as soon as 2047 under a "business-as-usual" emission scenario and only 22 years later under a reduced emissions scenario. Tropical countries will likely be the first to enter this new age of climatic erraticness and could experience extreme temperatures monthly after 2050. This, the authors argue, underscores the need for robust efforts targeted not only at protecting those vulnerable countries but also the rich biodiversity that they harbor.