Weather stations
only record
local conditions.
Did you know about one third
of US weather stations
report a cooling trend ?
Global averages
obscure local trends.
As human populations grow,
landscapes lose increasing amounts
of natural vegetation, experience a loss
of soil moisture and are increasingly
covered by heat absorbing pavement
and structures.
Those factors raise temperatures
so a city’s downtown area can be
10°F warmer than nearby rural areas.
Urban areas are less than 3%
of the USA’s land surface,
but 82% of our weather stations
are located in urbanized
( urban and suburban ) areas.
In natural areas such as
Yosemite National Park,
maximum air temperatures
are cooler now than
during the 1930s:
In heavily forested California,
maximum air temperatures
across the northern two thirds
of the state have not exceeded
temperatures of the 1930s.
Recently urbanized communities
in China report rapid warming
of 3°F to 9°F in just 10 years,
associated with the loss of vegetation.
Changes in vegetation, wetness
and land use can can raise temperatures
in both rural and urban areas.
Heat from new nearby asphalt will increase
temperatures at rural weather stations
Humans are increasingly inhabiting
urban environments with 66% of people
projected to inhabit urban areas by 2030.
High population densities
reduce cooling vegetation,
reduce wetlands and soil moisture,
and increase areas covered by
heat retaining pavements.
Reducing CO2 concentrations
will cool hot city streets
in the summer.
in the summer.