CLIMATE CHANGE World Meteorological Organization Age 10-14

What is climate variability ? “Climate variability” refers to changes in climate from one year to another. It can be caused by changes in ocean conditions far away, which can affect climate all over the world (for ex: el Niño) Climate variability is natural and occurs on a regular basis.

What is climate change ? Climate change is the change in climate over a time period from 10 to 100s of years. Climate change involves both natural changes and changes caused by people.

Why does our climate change? Over the history of the Planet, the climate has changed naturally. It happened during the ice ages, and maybe also when the dinosaurs disappeared. In addition, human activities have warmed the climate.

I. The Earth's Climate has changed many times, due to natural causes. **There have been at least 4 Ice Ages in the last 3 million years - with only a 5 degree Celsius cooler difference!

Climatic Change associated with Feedback Mechanisms Positive Feedback Mechanisms – A process whereby an initial change in an atmospheric process will tend to reinforce the overall effect.Positive Feedback Mechanisms – A process whereby an initial change in an atmospheric process will tend to reinforce the overall effect. –Water vapor-greenhouse effect Increase in water vapor content will lead to warmer temperature which will lead to more evaporation.Increase in water vapor content will lead to warmer temperature which will lead to more evaporation. –Snow-albedo effect As the snow and ice melts from the polar regions, the albedo of the earth will be reduced. Temperature will increase.As the snow and ice melts from the polar regions, the albedo of the earth will be reduced. Temperature will increase. Negative Feedback Mechanisms – A process whereby an initial change in an atmospheric process will tend to weaken the overall effect.Negative Feedback Mechanisms – A process whereby an initial change in an atmospheric process will tend to weaken the overall effect. –Increased warming of the earth surface will lead higher emission of IR radiation The higher the IR surface output, the slower the rise in temperature in the atmosphere.The higher the IR surface output, the slower the rise in temperature in the atmosphere. –Increase in clouds Warmer surface will lead to more evaporation which leads to more clouds.Warmer surface will lead to more evaporation which leads to more clouds.

Just 18,000 years ago, the Earth was in an ice age where continental glaciers reached as far south as the Ohio River Valley over North America.Just 18,000 years ago, the Earth was in an ice age where continental glaciers reached as far south as the Ohio River Valley over North America. Over Europe, the northern region and higher terrain were covered in thick sheet as well.Over Europe, the northern region and higher terrain were covered in thick sheet as well. The glacial advance/retreat occurred about 10 times over a 2 million year period.The glacial advance/retreat occurred about 10 times over a 2 million year period.

Main Natural Factors that Affect Climate

Milankovitch Theory of Climate Change Climate change may be driven by changes in earth's: Climate change may be driven by changes in earth's: a) orbit (eccentricity) → from ellipse to circle at a 100,000 year cycle. b) wobble (precession) → from the north pole pointing toward or away from the sun in a 23,000 year cycle. c) tilt (obliquity) → from 22° to 24.5° at a 41,000 year cycle. Eccentricity is the major forcing factor for the timing of ice ages.

The Sun The amount of energy coming off the Sun is not constant but keeps changing Slow changes in the Earth's distance from the Sun affect the amount of energy received from the Sun. Those variations are believed to be one of the causes that start ice ages. Main Natural Factors

Solar Output Variation and Climate Change The sun usually experiences a 11-year cycle of maximum and minimum in sunspots. The sun usually experiences a 11-year cycle of maximum and minimum in sunspots. From 1645 to 1715, the sun went through a long duration of minimum sunspots which coincided with a cooling spell called the Maunder Minimum.From 1645 to 1715, the sun went through a long duration of minimum sunspots which coincided with a cooling spell called the Maunder Minimum. Recent researchers have found the 11-year sunspot cycle and the weather pattern in North American can be related to:Recent researchers have found the 11-year sunspot cycle and the weather pattern in North American can be related to: Warmer winterWarmer winter Reversal of the stratospheric wind pattern over the tropicsReversal of the stratospheric wind pattern over the tropics

Volcanoes - when a volcano erupts it throws out large amounts of sulphur dioxide (SO2), water vapour, dust, and ash into the atmosphere. The climate system is made up of many components that all affect climate: this includes ocean currents, atmospheric circulation, sea ice and land covers (trees, grass…) Main Natural Factors

Mt. Pinatubo Eruption & Impact Three months after the June 1991 eruption of this Philippine volcano, much of the 20 million tons of ejected sulfur dioxide had been directed by zonal stratospheric winds and inundated the equatorial region.Three months after the June 1991 eruption of this Philippine volcano, much of the 20 million tons of ejected sulfur dioxide had been directed by zonal stratospheric winds and inundated the equatorial region. Recorded changes in air temperature indicate the volcanic eruptions on climate.Recorded changes in air temperature indicate the volcanic eruptions on climate. “The year without the summer” (1816) brought heavy snow in June and killing frost with respect to the vegetation in July and August over the northeast United States. These freakish events coincided with a massive volcanic eruption of Mount Tambora.“The year without the summer” (1816) brought heavy snow in June and killing frost with respect to the vegetation in July and August over the northeast United States. These freakish events coincided with a massive volcanic eruption of Mount Tambora.

The two major variations of temperature in the atmosphere are due to the eruption of El Chichon volcano in Mexico (1982) and Pinatubo volcano in the Philippines (1991).

An eruption can cause warming and cooling. –An addition of carbon dioxide contributes to greenhouse warming. –An addition to sulfurous gases induces cooling, because they turn into droplets of sulfuric acid that absorb and reflect sunlight, and cut down the amount of heat that reaches the ground. But most documented cases show a net cooling effect.

The Greenhouse Effect controls our climate When energy from the Sun enters the Earth's atmosphere, about a third of it is reflected back to space. Of the remainder, most is absorbed by the Earth’s surface. Some also stays in the atmosphere, absorbed by water vapor and green house gases. This natural Greenhouse Effect is vital to life as we know it. Right now, the average temperature on the Earth is 15°C. If there was no greenhouse effect, the average temperature would be -18°C (33°C colder than it is now – too cold for most living beings). Main Natural Factors 3 is the Greenhouse Effect

Long Term Affects Volcanic particles can cause occurrences such as: –Global Cooling –Mass Extinctions –Ice Ages

Little Ice Ages 1783 – Skaftar in Iceland and Mount Asama in Japan erupted. These eruptions were followed by several very cold winters in Europe and America. They caused unusually thick polar ice to form.

Plate Tectonics Plate tectonics and drift concentrated continents at higher latitudes allowed for more ice cover, which reflected more sunlight and created a positive feedback to cause greater cooling. Periods of mountain building increase snow-covered high elevation areas producing a similar snow-albedo positive feedback. The position of continents, mountains, and oceans create complex changes in atmospheric (and oceanic circulation). 180 m.y.a.Present

Extinction of the Dinosaurs Billions of tons of dust and debris were injected into atmosphere around 65 m.y.a. from a giant meteorite collision with earth. Billions of tons of dust and debris were injected into atmosphere around 65 m.y.a. from a giant meteorite collision with earth. The reduction in sunlight from the dust and debris clouds caused photosynthesis to stop and broke down the food chain. The reduction in sunlight from the dust and debris clouds caused photosynthesis to stop and broke down the food chain. This catastrophic collision is evident around the world from a thin layer of sediment deposit called the K-T boundary where it separates the end of the Cretaceous period, and the beginning of the Tertiary Period. This catastrophic collision is evident around the world from a thin layer of sediment deposit called the K-T boundary where it separates the end of the Cretaceous period, and the beginning of the Tertiary Period. The K-T boundary is made up of iridium material which is commonly found in meteorite. The K-T boundary is made up of iridium material which is commonly found in meteorite.

Main Human Factors that Affect Climate

Greenhouse Gases Human activities send gases (for example methane, carbon dioxine CO 2 ) into the athmosphere that enhance the greenhouse effect. Many of the gases come from fossil fuels such as oil, coal and natural gas to run vehicles, and generate electricity for industries or households. When the atmosphere contains too much of those gases, the whole atmosphere and the Earth becomes hotter, like it does in a greenhouse. The atmosphere holds on to too much heat, instead of letting it escape into space. Main Human Factors This causes global warming !

The example of CO2 Today there is about 25% more Carbon dioxide (CO 2 ) in the atmosphere than in CO 2 is the greenhouse gas that people make the most of. The more CO 2 we put into the air, the more the temperature could rise. Two of the biggest sources of CO 2 are burning fossil fuels and cutting down and burning trees. Forests are called « carbon sinks » because they take CO 2 from the air and store it. When trees are cut down and burned, the CO 2 that is stored in them is released back into the air. Scientists believe that every year, 2 to 5 billion tonnes of CO 2 are released into the air from forests being cut down and burned. Main Human Factors

Aerosols Aerosols are tiny solid particles or liquid droplets that remain suspended in the atmosphere for a long time. Main Human Factors They originate naturally (for example from volcanoes) but also as a result of human activities (industries…). In the later case, aerosols are considered pollutants, which cause direct effects on the Earth’s radiation budget and also indirectly through changing the formation and behavior of clouds.

Land Use Change There are over 6 billion people on Earth. Humans continue replacing forests and natural vegetation with agricultural lands. More and more people move into cities, therefore more houses are built. All this has an impact on climate. For example, it affects the evaporation of water and therefore the rain cycle. Main Human Factors

What is global warming? It refers to an average increase in the Earth's temperature, which in turn causes changes in climate. A warmer Earth leads to a wide range of impacts on plants, wildlife, and humans. Observed data indicate that global temperature over land and ocean has increased by approximately 0.6°C (1.08°F) since the late nineteenth century. Do you know exemples of effects global warming has on our Planet?

Our future climate according to scientists According to meteorologists and climatologists (they are the scientists who study weather and climate), the changing climate very likely entail more: Heat waves Heavy rain and snow Droughts Tropical cyclones

Our future climate according to scientists Rising sea level Scientists also predict that global warming will cause the level of water in the oceans to rise between 15 and 95 cm in the next 100 years, because warmer temperature will cause sea ice and glaciers to melt, adding more water to oceans, and because as water gets warmer, it takes up more space

IPCC IPCC stands for the Intergovernmental Panel on Climate Change created by the World Meteorological Organisation (WMO) and the United Nations Environment Programme (UNEP). It brings together scientists from around the world to report on climate change. IPCC advises that for a better future, we need: to reduce greenhouse gas emissions to adapt to climate change (for example with better alert systems, water and food management). It won the nobel prize!

Through WMO, 188 Member countries worldwide produce, share and improve information on weather, water and climate, including forecasts and warnings. WMO organizes training for weather and climate professionals to bring you reliable and clear information. The Meteorological and Hydrological Services work together within WMO to improve the quality and safety of your life.

What can we do to improve our climate? Please tell us what you think

WMO comic book: « We care for our planet » - WMO-No. 975 WMO-No. 975 The World Meteorological Organization in your daily life A career in meteorology WMO-No WMO « Skies and Oceans » Youthfull perspectives WMO web site : IPCC web site : For more information