Lesson 5

1919 Jasper National Park

2005

Grinnell glacier, Glacier National Park, USA

Grinnell glacier, Glacier National Park, USA

Rhone glacier in the Kanton of Valais, Switzerland,

Rhone glacier in the Kanton of Valais, Switzerland,

The Pasterze, Austria's longest glacier

The Pasterze, Austria's longest glacier

Portage Glacier

Portage Glacier

Portage Glacier

Portage Glacier

Mt. Hood Oregon

Mt. Hood Oregon

Collecting Evidence on Climate ChangeThe increases in global average temperatures and in greenhouse gas levels are evidence that Earth is currently undergoing climate change. Scientists observations suggest that effects of these increases are the changes observed throughout Earths biosphere.

Effects of Climate Change in the Atmosphere- Heat WavesEarth has always experienced severe weather events, but they are becoming more frequent, more widespread, and more severe than in the past. When this happens, air conditioners are turned on high, resulting in an increased use of electricity and therefore the release of more greenhouse gases.

Warming conditions are not restricted to the atmosphere. As the air becomes warmer, the soil, lakes, and rivers also warm up. The borders of climatic zones can shift.

Heat Waves

In Canadas north, areas of permafrost (permanently frozen soil) are thawing much more in the summer than they used to. As a result, the soil becomes looser. Trees that tilt or fall over because of this are called drunken trees

DroughtDroughts are most severe when they affect regions near deserts. Until recently, many of these regions had seasonal rains that provided the water needed to grow crops and keep animals.

WildfiresWhen the weather is hot and dry for a long time, the trees may become so dry that they lose their leaves. The probability of wildfires increases. While the frequency of wildfires is low around the world compared with other natural disasters such as drought, it is increasing.

StormsChanges in the frequency and severity of storms are one potential effect of the rapid increase in average global temperature and the movement of energy throughout the world

FloodsWhen the air temperature warms rapidly in spring, the snow can melt too quickly for the rivers and streams to handle the run-off. These seasonal floods damage homes and cropland and are becoming more frequent.

Effects of Climate Change in the Hydrosphere -Melting IceAs the average global temperature increases, Earths ice, both sea ice and glacier ice, is melting. This has consequences for more than just the Arctic and Antarctic regions. Melting ice can affect Earth by:changing geographic coastlines and shapes of continental coastschanging habitats of shoreline plants, animals, and micro-organisms

Melting Icecausing the loss of propertyflooding land that is currently just above sea levelreducing the amount of fresh water available to communities

Melting Ice You Tube LinkIn the Arctic Ocean, the amount of sea ice in the summer has decreased substantially. The average level of the worlds oceans has increased by about 20 cm over the past century. This is caused by land glaciers melting and water expanding as it warms.

Ocean WarmingConvection currents in the oceans mix the cold and warm water.Over the past century, the average ocean temperature has increased by about 0.6C, a little less than the increase in air temperature over the same period. We should be concerned about warming oceans for a number of reasons.

Ocean WarmingAs the water warms, it expands, so warmer oceans mean higher sea levels, loss of coastal land.Warmer water absorbs less carbon dioxide (just as cold pop retains more carbon dioxide than warm pop does), so it is less effective as a carbon sink.

Ocean WarmingPhytoplankton undergo photosynthesis and therefore are an important carbon sink. Warmer oceans mean less phytoplankton, less carbon dioxide absorbed.Warmer water produces more intense hurricanes, which damage land and harm people.

Ocean CurrentsOceans act as Earths heating and cooling circulation system. As the temperature of Arctic water increases, it can lead to more extreme weather around the planet.

Melting ice and warming oceans can change the flow of the ocean currents. Ice is frozen fresh water, so as the sea ice, icebergs, and glaciers melt, they add fresh water to the oceans. This dilutes the salinity, or salt content, of the sea water. Fresh water is less dense (lighter) than salt water, so it remains on the surface.At present, at the surface of the North Atlantic, the dense, salty water sinks, pushing the currents through the deeper parts of the worlds oceans.

Effects of Climate Change on WildlifeWarming climates and oceans and melting sea ice are affecting Earths organisms. The ranges (home territories) of some animals and plants are shifting, and some organisms are threatened with extinction. Other organisms may actually benefit from climate change and increase in numbers.

Effects of Climate Change on WildlifePolar bears normally walk on the ice to hunt seals, because seals swim too quickly for the bears to catch them in open water. However, when the seals come up to a hole in the ice to breathe, the bears can capture them. Less ice means poorer hunting, and polar bears are going hungry.

Range ShiftsSome birds now have to move farther North as the climate warms. Grey Jays stored food will rot if the winter is too warm.

Range ShiftsTicks and other pests are also moving North as the climate warms. Wildflowers are blooming 26 days earlier now.

Threatened SpeciesAccording to the IPCC, between 40 percent and 70 percent of all species are at risk of extinction if the global average temperature increases by only 3.3C. 35 percent of frogs, toads, and salamanders are threatened with extinction due to climate change

Corals are ancient animals related to jellyfish. They secrete skeletons that remain long after the animals have died. These skeletons build up for thousands of years, forming coral reefs. Earth has already lost about 20 percent of its coral reefs due to warmer water, sedimentation, and storm damage.

As more CO2 is added to the atmosphere the oceans will become more acidic which will kill the coral reefs which would change fish stocks.

Organisms That Benefit from Climate ChangeSome organisms may find their environments improved as the climate changes. Several species of free-living jellyfish have increased up to 100 times in many coastal areas of the oceans.

Questions I (6)1. How does the melting of permafrost affect trees?2. Give two ways that melting ice can affect Earths climate.3. How does warming water affect plankton?4. What effects of climate change alter the flow of the ocean?5. Why does fresh water tend to float on salty water?6. How do increasing levels of dissolved carbon dioxide in ocean water threaten shelled creatures such as snails and clams?

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