Climate change is making seasonal allergies worse, and pollen season is about to get longer and more intense, a new study finds. University of Michigan scientists Yingxiao Zhang and Allison Steiner examined multiple types of trees and grasses, as well as effects across different regions, to gauge the risks ahead. Allergies, of course, are more than a nuisance and can trigger asthma and other serious health problems. If there’s a sliver of good news from study, authors Yingxiao Zhang and Allison Steiner say, it’s that researchers expect to be able to improve pollen forecasting.

Last week the first person to receive a transplant of a heart from a genetically altered pig died. David Kaczorowski, a University of Pittsburgh Health Sciences Cardiac transplant surgeon, provides both a look back and roadmap to the field of xenotransplantation. Despite significant challenges and sad outcomes like the one from last week, Kaczorowski notes “how far science has come toward making animal-to-human transplants a viable treatment possibility.”

Cloud seeding has its origin in the 1940s but remains an active area of interest for states and countries looking to combat drought. Colorado State University atmospheric scientist William Cotton, who has studied weather modification for decades, says the states now conducting cloud seeding tests should not expect great results. “The percentage increases in precipitation are small, and it’s difficult to tell when snow or rain fell naturally and when it was triggered by seeding,” he writes.

Also in this week’s science and research news:

• The real story of the first patient treated with penicillin
• How the Ebola virus can ‘hide’ in brains
• Treating arthritis in dogs

If there’s a subject you’d like our team of science editors to investigate, please reply to this email.