It’s been awhile, so back by popular demand (and my inbox is full and I must delete stuff), it’s time for another edition of the Weather Free-for-All! This is where I pass along generally weather-related articles that are sent to me. So, hang on, here we go….

Urban Runoff: When the snow melts or the rain falls, where does the water go?  On a typical city block – with pavement and rooftops – more than half runs off into storm drains instead of soaking into the soil. On the way to the storm drain, water picks up oil, chemicals, pet waste, road salts and other pollutants.  In many cities, water in the storm system travels directly to local streams and rivers, untreated. That means that pollutants end up in public waters used for fishing, swimming and drinking. Tip: Let the water soak.  At home, point downspouts towards grass instead of pavement to allow rain water and snow melt to soak into the ground.

Climate Fact: Lake Erie and PNA: North Pacific sea surface temperatures control storm track behavior and ultimately the interannual variability of precipitation in the Great Lakes region.

Records dating back to 1900 display a seven foot range in the variability of Lake Erie’s water levels, with the lowest values being reached in the early 1930’s and mid-1960’s, and high levels being seen 1950’s and 1980’s. Levels since 1999 have been below their long-term average. Periods of low water levels correspond to positive Pacific North American (PNA) teleconnection pattern values and periods of high water levels correspond to negative PNA values. The PNA is the periodic (30-year) shift in North Pacific sea surface temperatures (SSTs) from predominately warm (positive) phases to predominately cool (negative) phases. During warm phases, the Pacific storm track is channeled in such a way that dry continental air masses from Alberta dominate the Great Lakes region during winter, reducing precipitation there. During cool phases, this air mass is less dominant, allowing moisture from the Gulf of Mexico to more easily bring winter precipitation to Lake Erie. The PNA also causes annual variability in Alaska’s weather, and thus interannual variability in vegetation growth there. Tree ring records from old growth Alaskan forests can serve as a proxy for PNA variability in years before SST records were kept.  Proxy data over 265 years indicate that Lake Erie water levels were probably particularly high during the mid-1700’s, the mid- to late 1800’s and the late 1900’s, with the highest values occurring in the last few decades. Especially low water levels probably occurred during the late 1700’s and early 1900’s.

Ocean CO₂ Uptake Update: The pH level of the world’s oceans has declined from 8.2 in the late 18th century, to about 8.1 today.

When carbon dioxide (CO₂) enters the ocean, it bonds with water to create carbonic acid, releasing an extra proton in the process. The extra proton bonds to a carbonate molecule in the water, creating more carbonic acid and leaving fewer carbonate molecules for coral to use to build skeletons. Coral reefs are some of the most biodiverse ecosystems on Earth. In Asia alone, over one billion people depend on the marine species that live in coral reefs as their primary source of protein. The oceans are currently absorbing about 22 million tons of CO₂ each day and have absorbed an estimated 525 billion tons of CO₂ over the last 200 years. As a result, over this same period, the oceans have become more acidic. On the pH acidity scale (which ranges from zero to 14, with zero being the most acidic and seven being neutral) the world’s oceans have fallen from a pH of 8.2 in the late 18^th century to a pH of 8.1 today, a 30 percent increase in acidity.

Lyme Disease and Spring Rains: A particularly wet spring in the Northeast generally means a particularly high number of Lyme disease occurrences two years later.

Lyme disease, the most common vector-borne disease in the United States, is mainly confined to the habitat of the deer tick (the disease’s most common transmission source), which is concentrated in the Northeast. In the Northeast since the 1970’s, average spring rainfall has been increasing at a rate of about 0.5 inches per decade, and the number of Lyme disease occurrences in a particular year corresponds to the rainfall levels from two years earlier, particularly the spring rainfall levels. After an adult deer tick feeds on a host, it loses its ability to take up water and may die prematurely if its habitat remains unusually dry. Because a deer tick takes two years to develop from an egg into an adult, a lack of deer tick eggs being laid in a dry year would result in fewer adult deer ticks hatching two years later.