Northern New England Climate: Past, Present, and Future Basic Concepts Weather instantaneous or synoptic measurements Climate time / space average
Weather - the state of the air and atmosphere at a particular time and place : the temperature and other outside conditions (such as rain, cloudiness, etc.) at a particular time and place Measurements of the following variables are used to quantify weather temperature (average energy, C) humidity (water vapor, g/kg) pressure (force/area, mb = 100 N/m 2 ) winds (circulation, m/s) cloud cover (liquid/solid water) precipitation rate (mm/day)
A Definition of Climate Climate is often defined as average weather, usually described in terms of the mean and variability of temperature, precipitation and wind over a period of time (typically 30 years). Climate is also characterized by the frequency and magnitude of extreme weather events
air temperature data hourly (synoptic) daily mean daily range (diurnal cycle) monthly mean annual mean annual range (seasonal cycle)
Climate defined The average, or mean, of a meteorological variable is: And, the variance (a measure of how far a set of numbers is spread out:
average daily temperature 30-year annual average = 51.7 F
average daily temperature 30-year annual average = 51.7 F
average daily temperature
average monthly temperature
internal dynamics example - persistent ridging over western North America
internal dynamics example - persistent ridging over western North America
average monthly temperature
external forcing example - Mt. Pinatubo
What Factors Are Involved In Changing Earth s Climate? The climate system evolves over time under the influence of its own internal dynamics and due to changes in external forcing. Examples of external forcing include: solar variations volcanic eruptions changes in atmospheric composition
by changing the amount of incoming solar radiation by changing the fraction of solar radiation that is reflected back to space by altering the longwave radiation from Earth back towards space IPCC, FAQ 1.3, Figure 1
Radiative forcing of global climate IPCC, FAQ 2.1, Figures 1 & 2
Greenhouse gases increase dramatically since industrial revolution
IPCC, FAQ 2.1, Figure 1
+1.2 F/century Long-term record of globally averaged annual temperature
Long-term record of annual average temperature for Massachusetts
Long-term record of annual average precipitation for Massachusetts
Long-term record of annual average temperature for Vermont
Long-term record of annual average precipitation for Vermont
Long-term record of annual average temperature for Maine
Long-term record of annual average precipitation for Maine
Average ice-out dates for lakes in Maine come about two weeks earlier than they did in the late 19th century Lake iceout dates
The length of the growing season in Maine has increased over the last 150 years Plant hardiness zones have shifted northward over the past few decades -40 to -30ºF -30 to -20ºF -20 to -10ºF -10 to 0ºF 0 to 10ºF
Over the past 50 years flow has tended to increase in early spring and decrease in late spring/early summer River flow
Model projections of globally averaged surface temperature for three emissions scenarios
Future climate (21st century) NCAR climate model
Observational Record of Global and Regional Climate: Key Facts it has changed we see the impacts some of the change thus far is attributable to human activity northern New England, like the rest of the planet will experience significantly more change in the future the change impacts things that we care about we would like to predict future climate change
Summary Greenhouse gas warming is evident across northern New England It will continue, at an accelerated rate Precipitation across the state is likely to increase, less snow, more rain Climate will be more variable
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