For the first time, researchers have identified a genetic form of late-in-life Alzheimer's disease. Most cases of the mind-robbing disease occur after age 65. A gene called APOE4 has long been considered a key risk factor. But new research says if people inherit two copies of that gene it's not just a risk — it appears to be the underlying cause. About 15% of Alzheimer's patients are thought to carry the gene pair. Scientists say the distinction could have implications for both research and treatment. The findings were published Monday in Nature Medicine.

A new study says climate change is making giant heat waves crawl slower across the globe and they are baking more people for a longer time with higher temperatures over larger areas. Friday's study calculates that since 1979, global heat waves are moving 20% more slowly meaning more people stay hot longer and they are happening 67% more often. The study finds the highest temperatures in the heat waves are warmer than they were 40 years ago and the area under a heat dome is larger. Heat waves used to last eight days, now on average they stretch to 12 days.

Areas across the globe have seen spring snowpack shrink over the last 40 years, and a new study says for many of them climate change is clearly to blame. Wednesday's study in the journal Nature finds a key threshold for the future of snowpacks in the Northern Hemisphere: 17.6 degrees. In places where the winter averages colder than that, often the snowpack survives because it's cold enough. But areas warmer than 17.6 degrees for a winter average, like the Upper Colorado River basin, tend to see their winter wonderland dreams melt. And it's bad news for water supply.