Climate Change

Have you noticed any change in our summer weather. Our winter weather Have you noticed any change in our summer weather? Our winter weather? The arrival of spring?

Do you believe that we will experience significant global warming during this century?

Questions Are global warming and climate change the same thing? What is the difference between climate and weather? What is the greenhouse effect? What is the most abundant greenhouse gas? Is climate change real? What evidence is there for climate change? Does the hole in the ozone layer cause climate change?

What’s the Difference? Global Climate Change Global Warming Any significant change in measures of climate (temperature, precipitation or wind) lasting for an extended period (decades or longer). Global Warming Average increase in the temperature of the atmosphere, which can contribute to changes in global climate patterns.

Weather vs. Climate Weather Climate Short-term (minutes to months) changes in the atmosphere Climate Long-term average pattern of weather in a particular area Typically use 30 years of data

What are the major Greenhouse Gases?

Greenhouse Gases Water Vapor: 0-4% Carbon Dioxide (CO2): 0.036% Methane (CH4): 0.00017% Nitrous Oxide (N2O): 0.00003% CFC’s

Greenhouse Effect Earth’s average temperature would be 0 ºF without the greenhouse effect compared to the average temperature of 60 ºF that we experience

Global Energy Budget

CLIMATE CHANGE AND HUMAN ACTIVITIES Warmer temperatures in Alaska, Russia, and the Arctic are melting permafrost releasing more CO2 and CH4 into the troposphere. During the last century, the world’s sea level rose by 10-20 cm, mostly due to runoff from melting and land-based ice and the expansion of ocean water as temperatures rise.

Burning of fossil fuels Methane from cattle—really!

Why Should We Be Concerned about a Warmer Earth? A rapid increase in the temperature of the troposphere during this century would give us little time to deal with its harmful effects. As a prevention strategy scientists urge to cut global CO2 emissions in half over the next 50 years. This could prevent changes in the earth’s climate system that would last for tens of thousands of years.

Effects of Higher CO2 Levels on Photosynthesis Increased CO2 in the troposphere can increase plant photosynthesis (PS) but: The increase in PS would slow as the plants reach maturity. Carbon stored by the plants would be returned to the atmosphere as CO2 when the plants die. Increased PS decreases the amount of carbon stored in the soil. Tree growth may temporarily slow CO2 emissions in the S. Hemisphere but is likely to increase CO2 emissions in the N. Hemisphere.

FACTORS AFFECTING THE EARTH’S TEMPERATURE Aerosol and soot pollutants produced by human activities can warm or cool the atmosphere, but such effects will decrease with any decline in outdoor air pollution. Warmer air can release methane gas stored in bogs, wetlands, and tundra soils and accelerate global warming.

EFFECTS OF GLOBAL CLIMATE CHANGE A warmer climate would have beneficial and harmful effects but poor nations in the tropics would suffer the most. Some of the world’s floating ice and land-based glaciers are slowly melting and are helping warm the troposphere by reflecting less sunlight back into space.

GLOBAL CLIMATE CHANGE Evidence that the earth’s troposphere is warming, mostly because of human actions: The last decade was the hottest in recorded history. Since 1900, the earth’s average tropospheric temperature has risen 0.6 C°. Over the past 50 years, Arctic temperatures have risen almost twice as fast as those in the rest of the world.

Key Indicators Sea Level Carbon Dioxide Concentration Global Surface Temperature Artic Sea Ice Land Ice

Evidence

Carbon Dioxide Levels in Relation to Global Temperature

Evidence Sea Level Rise Global Temperature Rise Global sea level rose 17 cm (6.7 in.) in the last century Rate in the last decade nearly double that of the last century Global Temperature Rise Earth has warmed since 1880 with most of warming occurring since the 1970s 20 warmest years occurred since 1981 10 warmest years occurred in the past 12 years.

Evidence Warming Oceans Shrinking Ice Sheets Top 700 m (2,300 ft) of ocean showing warming of 0.302 °F since 1969 Shrinking Ice Sheets Greenland: lost 150-250 km3 (36-60 cubic miles) of ice per year between 2002 and 2006 Antarctica: lost 152 km3 (36 cubic miles) of ice between 2002 and 2005

Evidence Declining Arctic sea ice Glacial retreat Extent and thickness of Arctic sea ice has declined rapidly over last several decades Glacial retreat Retreating almost everywhere around the world including Alps, Himalayas, Andes, Rockies, Alaska and Africa

Evidence Extreme Events Ocean Acidification Number of record high temps increasing since 1950 Number of record low temperature decreasing since 1950 Increasing numbers of intense rainfall events Ocean Acidification CO2 content of oceans increasing since 1750 Currently increasing 2 billion tons per year Increased ocean acidity by about 30%

NASA Interactives http://climate.nasa.gov/interactives/

IPCC Intergovernmental Panel on Climate Change Group of scientist from around the world that review and assess information on climate change Climate models and projections

EFFECTS OF GLOBAL WARMING A warmer climate would have harmful and beneficial effects. What do you think are some beneficial impacts?

Projections for North America Decreasing snowpack in the western mountains 5-20% increase in yields of rain-fed agriculture in some regions Increased frequency, intensity and duration of heat waves

Projections for Latin America Gradual replacement of tropical forest by savannah in eastern Amazon Risk of significant biodiversity loss through species extinction in many tropical areas Significant changes in water availability for human consumption, agriculture and energy generation

Projections for Europe Increased risk of inland flash floods More frequent coastal flooding and erosion Glacial retreat in mountainous areas Reduced snow cover and winter tourism Extensive species losses Reductions of crop productivity in S. Europe

Projections for Africa By 2020, 75-250 million people are projected to be exposed to increased water stress Yields from rain-fed agriculture could be reduced by up to 50% in some regions by 2020 Agricultural production, including access to food, may be severely compromised

Projections for Asia Freshwater availability projected to decrease by 2050 Coastal areas at risk for increased flooding Death rate from disease associated with floods and droughts expected to rise

Changing Ocean Currents Global warming could alter ocean currents and cause both excessive warming and severe cooling. Figure 20-12

Removing and Storing CO2 Methods for removing CO2 from the atmosphere or from smokestacks and storing (sequestering) it. Figure 20-15

Adaptation vs Mitigation

Wisconsin’s Climate 1950-2006 Average temperature increased 1.5 ºF Greatest amount of warming in winter and spring, especially NW Wisconsin Nighttime lows warming faster than daytime highs, especially in summer Decline in extremely cold winter nights, especially in NW Wisconsin Date of last spring freeze occurring 6-20 days earlier Date of first fall freeze occurring 3-8 days later Growing season increased up to 4 weeks Annual average precipitation increased 15% although parts of the N became drier

Wisconsin’s Future Climate Projections 4-9ºF increase by mid-21st Century Warming most pronounced in winter Fewer extremely cold winter nights and more hot summer days Probability of greater than 3 in. rainstorms will increase during spring and fall

Projected Change in the Frequency of 90 ºF Days Per Year from 1980 to 2055 Projected Change in the Frequency of 2" Precipitation Events (days/decade) from 1980 to 2055

Projected Change in Average Winter Temp from 1980 to 2055 Projected Change in Annual Temp from 1980 to 2055

Ice Cover on Madison Lakes http://climatewisconsin.org/story/ice-cover

Temperature Change http://climatewisconsin.org/story/temperature-change

Shipping on the Great Lakes http://climatewisconsin.org/story/great-lakes-shipping