Climate Change Impacts on the HudsonArt DeGaetanoProfessor and Assoc. Chair Dept. of Earth and Atmospheric Science, Director Northeast Regional Climate Center

STEP 4: High-resolution regional climate projectionsTemp from global climate modelTemperature from downscaling

SeasonalProjections

Temperature

Precipitation

Regional Variation in Heavy Rain

Extreme Event Frequency

Spatial Variation of Days with Snow on Ground 1970-2000

Dates of Center-of-Volume River Flow

Drought SHORT MEDIUM LONG

Storms

Sea Level Rise

The IPCC model-based approach local land subsidence local relative ocean height global thermal expansion meltwater

Sea Level RiseThe rapid ice melt scenario replaces the model based meltwater term with sea level rise rates (43 +/- 4 in/century) observed during paleoclimate analogues

Questions?

STEP ONE: Future Emissions from Human Activities

A1fi (higher) continued dependence on fossil fuels with material-intensive economy, ~970ppm by 2100B1 (lower) shift to alternative energy sources with service & information-focused economy ~550ppm at 2100

STEP TWO: Global Climate ModelingBackcast to compare historical simulations with observed climate.

Forecast to develop future projections of changes in temperature, precipitation, extreme events, etc.

3 different climate models

STEP 3: Global Temperature ChangeLikely range:1.1oC to 6.4oC2oF to 11.5oF

**In order to project future climate conditions, scientists must predict what the world will look like politically, economically and environmentally in 100 years. Imagine trying to predict todays fossil fuel usage if you lived a little more than 100 years when air travel was unheard of and automobiles were in there infancy.

Given the uncertainty in such predictions scientists have developed a range of scenarios of future GHG emissions. These range from a fossil-fuel intense society that undergoes rapid economic growth and experiences a modest increase in population (top dashed red line in figure). In this case atmospheric CO2 levels increase to also 4 times their pre-industrial values by 2100.

A business-as-usual scenariocontinuing the present trend in GHG emissions leads to a similar increase in CO2 levels by 2100 (gold line).

More environmentally-friendly scenarios, with reductions in fossil fuel usage also lead to increases in atmospheric CO2 concentration. This results from the lifetime of CO2 in the atmosphere (about 100 years). Thus todays CO emissions are not removed from the atmosphere until 2106. Even the most environmentally friendly emission scenarios lead to an increase in atmospheric CO2 concentration over the next 100 years, to about double pre-industrial levels.