Climate Change

Carbon Dioxide A. The concentration of carbon dioxide in Earth's atmosphere is at a record-breaking level. B. For the very first time in history, carbon dioxide levels have exceeded 400 parts per million. C. Carbon dioxide is a pollutant in the atmosphere.

Carbon Dioxide Answer C is a LIE. The concentration of CO2 in Earth's atmosphere is at a record-breaking level. Levels of CO2 have changed throughout Earth's history, reaching a max of about 300 ppm. Never in Earth's history has it gotten to the level it is today - over 400 ppm. Although CO2 is not a pollutant - it is a very natural part of the atmosphere and carbon cycle - this current level is not due to natural processes and has been caused by human activities.

Deforestation A. Clearcutting trees is considered deforestation. B. Trees and plants remove carbon dioxide from the atmosphere. C. Deforestation in places like the Amazon jungle is contributing to increased levels of carbon dioxide in the atmosphere.

Deforestation Answer A is a LIE. While clearcutting trees decreases the number of trees that remove CO2 from the air, it isn't considered deforestation. Deforestation is when the way the land is used changes, for example when jungle is turned into livestock feed lots. This is contributing to increased levels of carbon dioxide in the air because there is less carbon dioxide being removed by plants through photosynthesis. Up to 13% of global carbon emissions come from deforestation.

Emissions A. Emissions of methane are much lower than CO2 emissions, but methane is a much more powerful heat absorber than CO2 . B. Humans have released 2000 gigatons of extra CO2 into the atmosphere since 1870. C. Carbon dioxide levels in the atmosphere are up a solid 10% since the Industrial Revolution.

Emissions Answer C is a LIE. CO2 levels are up 40% since the Industrial Revolution! In fact, humans have released 2000 extra gigatons of CO2 into the air since 1870. Methane emissions, another greenhouse gas, are much lower than CO2 levels, but even at lower levels do have an effect on climate because methane is a more powerful heat absorber than CO2 . However, because the levels are so much higher, CO2 is the most important gas when it comes to warming.

Extreme Weather A. Heavy downpours and flooding events are increasing in some areas. B. Extreme weather proves the existence of global warming. C. Warmer temperatures amplify the impacts of droughts because increased temps enhance evaporation from soils, making droughts worse than they would be under cooler conditions.

Extreme Weather Answer B is a LIE. Extreme weather itself does not prove the existence of global warming, but is evidence it is occurring. Warming will exaggerate extreme weather by altering ocean currents, providing extra heat to form tornadoes and hurricanes, and causing more precipitation. Heavy downpours and flooding increase because warm air can hold more water vapor than cooler air. Warmer temps amplify droughts because they increase evaporation from soils.

Food Chains A. Human food sources will be impacted by climate change even though much is grown on farms. B. Changes in arctic sea ice is leading to less ice algae - an important base of the arctic food chain. C. Organisms at the top of the food chain (humans, hawks) will be at the least risk when food chains are disrupted.

Food Chains Answer C is a LIE. Food will be impacted even though much is farm grown. Droughts may decrease available water for crops and changing rain patterns may alter planting/harvest patterns. In natural food chains, there are already effects. Changes in sea ice is leading to less ice algae - a base of the arctic food chain. Organisms at the top of food chains, large consumers, are at the most risk when food chains are disrupted because as a group they have the least energy available to them in the first place.

Fossil Fuels A. The biggest reason people burn fossil fuels is for cars and other types of transportation. B. Fossil fuels are natural, and were formed by the process of decaying ancient plants and animals. C. Burning fossil fuels releases carbon dioxide into the atmosphere that would otherwise have been trapped underground.

Fossil Fuels Answer A is a LIE. The biggest reason people burn fossil fuels is for electricity production, but transportation is in pretty close second place. Combined, they account for about 60% of carbon emissions. Although fossil fuels are natural, burning them releases carbon dioxide into the atmosphere that would otherwise have been trapped underground. This adds more carbon dioxide to the carbon cycle than would occur naturally without people burning fossil fuels.

Future Temps A. Doubling atmospheric CO2 would lead to a 1°C bump in Earth's average temperature. B. Melting polar ice will slow down warming trends because heat is absorbed in the process. C. Temperature and CO2 levels are proven to be related, so the increasing levels of CO2 currently being observed will lead to more warming.

Future Temps Answer B is a LIE. Temperature and CO2 levels are related, so the increasing levels of CO2 being observed will lead to more warming. Doubling atmospheric CO2 would lead to a 1°C bump in the Earth's average temperature. However, there's a catch. If temperatures increased that much, ice would melt much more, and ice reflects the sun's heat. More heat would be absorbed, causing an even bigger increase in global temps - an estimated 3°C versus 1°C.

Greenhouse Gases A. Naturally occurring water vapor is a greenhouse gas, and there is more of it in the atmosphere than CO2 . B. Greenhouse gases are dangerous and must be reduced by at least twothirds to halt global warming. C. CFCs are man-made gases used in aerosol cans, refrigeration and A/C that trap heat in the atmosphere.

Greenhouse Gases Answer B is a LIE. There are naturally occurring greenhouse gases, including water vapor (3%), CO2 (0.04%), and methane. At normal levels they are necessary for life because they trap heat and keep Earth the perfect temperature for living things. Reducing their levels a lot would make Earth too cold. But, human activities have added extra CO2 , methane and man-made CFCs so more heat is trapped and the greenhouse effect is exaggerated.

Historical Temps A. Ice core data shows that Earth's climate has always changed. B. Earth has experienced warmer periods in the past. C. Earth's temperatures have never been as high as they are today.

Historical Temps Answer C is a LIE. Ice core data shows that Earth's climate has always changed. Earth had warmer periods in the past, like in the Neoproterozoic period (600 - 800 mya) and the Paleocene-Eocene Thermal Maximum (56 mya). However, Earth's temps are warming fast - faster than at the end of an ice age. In the 2000's some places experienced twice as many record high temperatures than low.

Measuring Change A. Scientists can study Earth's climate up to almost a million years ago - before people even existed. B. NASA uses space satellite data to study climate issues and sea ice on the surface of Earth. C. Scientists collect temperature data from 15 land-based data stations around the world.

Measuring Change Answer C is a LIE. The U.S. Air Force Climatology Center has over 9,000 worldwide stations collecting data every day. Other climate organizations have thousands more locations collecting data. Scientists also study Earth's climate and carbon dioxide levels up to almost a million years ago by obtaining ice cores. NASA uses space satellite data to study climate issues on the surface of Earth, especially sea ice data.

Natural Causes of Warming A. Changes in the brightness of the sun and solar activity could account for climate change. B. Volcanoes emit 200 million tons of carbon dioxide each year. C. Natural land and ocean processes emit 780 gigatons of carbon dioxide per year.

Natural Causes of Warming Answer A is a LIE. Changes in solar activity could not account for climate change because as Earth has gotten warmer since 1950, solar activity has decreased. Volcanoes and natural land and ocean processes do emit carbon dioxide, but these emissions were previously balanced in the carbon cycle. Now, humans are adding an extra 35 gigatons of CO2 to the atmosphere, leading to warming.

Oceans A. Oceans contribute to atmospheric carbon dioxide levels by emitting CO2 . B. Oceans have been getting more acidic due to warmer global temperatures. C. The temperature of the upper layer of the ocean has increased by about 0.13°C per decade over the last 100 years.

Oceans Answer B is a LIE. The oceans have been getting more acidic - a huge concern for marine life, especially animals with shells and coral. However this change is not due to temperature but rather to the ocean absorbing more CO2 . (Human activity has made atmospheric levels higher.) This causes carbonic acid to form. The oceans do contribute to atmospheric carbon dioxide, however this is a natural process that previously was a part of a balanced carbon cycle.

Polar Bears A. Loss of sea ice makes it difficult for polar bears to hunt for seals. B. Polar bears are an endangered species. C. Some populations of polar bears are actually increasing.

Polar Bears Answer B is a LIE. There are several separate populations of polar bears in the arctic. Some of these populations are actually increasing, while others remain constant or are decreasing. Polar bears are not on the endangered species list. They are listed as "vulnerable" by the IUCN, the International Union for Conservation of Nature. Decreasing sea ice could affect polar bears in the future because they do use sea ice as a platform to hunt for seals.

Sea Ice A. How far sea ice extends (its range) is more important to climatologists than its volume. B. In 2018, NASA reported that wintertime ice has been growing, slowing down a more long-term decline. C. NASA says that since 1958 the artic sea ice has lost on average around two-thirds of its thickness.

Sea Ice Answer A is a LIE. Scientists don't worry as much about how much "sea ice extent" changes, because it is affected by wind and ocean currents, not just temps. They're very concerned with how much ice volume has been lost. NASA says that since 1958 the artic sea ice lost on average around 2/3 its thickness and 3,100 cubic kilometers of volume per decade. However, in 2018, NASA reported that wintertime ice has been growing, slowing a more long-term decline.

Sea Levels A. Sea levels have been rising at unprecedented rates, up to an inch per year. B. Sea levels increase when the planet warms because water expands when it is heated, making it take up more space. C. Sea levels rise because polar ice is melting, leading to more water in the oceans.

Sea Levels Answer A is a LIE. Sea levels have been rising at alarming rates, about one tenth of an inch per year, or an inch a decade, over the last 100 years. This is caused two ways: sea levels increase when the planet warms because water expands when it is heated, making it take up more space, and because polar ice is melting, leading to more water in the oceans.