PrintOne of the biggest climate impacts on human health is through seasonal allergens. Over the past few decades, spring is coming earlier and fall is ending later in the Northern Hemisphere, increasing the length of the allergy season. (Do you hear the collective groan of the roughly 30% of the population who suffer from seasonal allergies?) Changing distributions of plants and molds (thanks to extreme precipitation events and changing temperature patterns) are causing the spread of allergens into areas where they did not exist earlier. There is also some evidence that the rising atmospheric CO2 concentration is fertilizing some allergen-rich species, like ragweed (Albertine et al., 2014).
What do you notice about this map? The northern latitudes of the US and the western part of the country are seeing rapidly expanding numbers of frost-free days relative to the southern US. It's just another reminder that while impacts are global in nature, they materialize very differently across smaller geographic scales.
