Science SQRR Notes: Part 1: Evidence for Human Caused Climate Change (Nov 13)

Question 1

What is some evidence for human caused climate change

Answer 1

When humans burn fossil fuels- it releases carbon dioxide emissions into the air- this causes hotter temperatures

Question 2

How do we know that the Earth has warmed?

Answer 2

Scientists have taken widespread measurements of the Earth’s surface. They have found that the temperature has increased more than 1.4 degrees in the past 100 years. Satellites and ships carry instruments that are used to measure the temperature of the Earth. Temperatures can also be measured from stations on the Earth

Question 3

How do we know that greenhouse gases lead to global warming?

Answer 3

Greenhouse gases trap heat in the earth’s atmosphere- acting like a blanket over the Earth (keeping warmer temperatures in the lower atmosphere). The gases that trap heat are methane, nitrous oxide, water-vapor, and carbon dioxide

Question 4

What is NASA’s global surface temperature record

Answer 4

NASA estimates for global surface temperature change relative to the average global surface temperature from 1951-1980- which is about 14 degrees Celsius from the NASA Goddard Institute show a warming trend

Question 5

What is the carbon cycle

Answer 5

Carbon is continuously exchanged between the atmosphere, ocean, biosphere and land on a variety of timescales.

Question 6

how do we know that humans are causing greenhouse gas concentrations to increase

Answer 6

When humans dig up and burn fossil fuels, we disrupt the natural carbon cycle by releasing large amounts of fossil carbon over a sort time period

Question 7

What are the measurements of atmospheric carbon dioxide

Answer 7

When we measure the carbon dioxide in the air, there has been a steady annual increase. A curve called the “Keeling Curve” has shown this

Question 8

what has happened to greenhouse gases concentration in the last 2000 years

Answer 8

methane, nitrous oxide and carbon dioxide are rising- these measurements are taken by measuring the composition of air bubbles trapped inside ice cores

Question 9

Are emissions of carbon dioxide exceeding natures carbon dioxide drain

Answer 9

emissions of carbon dioxide due to fossil fuel burning and cement manufacturing are increasing. Natural sources like oceans cannot absorb the excess carbon dioxide released by human activities

Question 10

what clues do we have about the fingerprint of carbon dioxide

Answer 10

in a process that takes place over millions of years- carbon forms from the decay of plants and animals and is stored deep in the Earth’s crust in the form of coal, oil and natural gas. There is a form of carbon (carbon-14) that can be measured and scientists find that the levels millions of years ago are less than what is measured today

Question 11

How are human activities heating the Earth

Answer 11

Human activities (especially the burning of fossil fuels) have increased the number of aerosol particles in the atmosphere. Changes in land use also contributes- cutting down trees

Question 12

What are the cooling and warming effects of aerosols

Answer 12

most aerosols (tiny liquid or solid particles suspended in the atmosphere) make up air pollution cause a cooling effect because they scatter a part of incoming sunlight back into space. Sometimes they absorb solar energy (like in dust and soot) and act to warm the atmosphere

Question 13

What are the warming and cooling influences on the Earth since 1750

Answer 13

There has been an increase of more than 1.6 watts per square meter of Earth’s surface warming influence from human activities. This has happened since the industrial age

Question 14

What are climate feedback loops

Answer 14

The amount of warming that occurs because of increased greenhouses gases depends on feedback loops: positive feedback increases the temperature and negative feedback decreases the temperature

Question 15

How do we know that the current warming trend is not caused by the sun

Answer 15

the sun’s output has a strong influence on the Earth’s temperature. Scientists have examined records of solar activity to determine if changes in solar output might be responsible for the global warming trend. The Sun’s net output has not had a net increase in the last 30 years- so it could not cause any warming during that period

Question 16

how do we measure the sun’s energy

Answer 16

Satellites measure the sun’s energy. there has been no net increase in the new solar energy in the last 30 years.

Question 17

What are the warming patterns in the layers of the atmosphere

Answer 17

there has been a warming trend in the trophosphere and a cooling trend in the stratosphere

Question 18

how do we know that the current warming trend is not caused by natural causes

Answer 18

El Nino and La Nina heat and cool the Earth- however, these up and down fluctuations are smaller than the 20th century warming trend

Question 19

what are short term temperature effects of natural climate variations

Answer 19

Natural factors such as volcanic eruptions and elNino/la Nina can cause year to year temperature increases but that is not enough to explain overall warming trends of the last 60 years

Question 20

what are climate models based on

Answer 20

math equations that represent the laws of Physics- that compare the behavior of the land, ocean, atmosphere and other parts of the climate system

Question 21

what other climate changes and impacts have been observed

Answer 21

rising temperatures due to increasing green house concentrations have produced distinct patterns of warming on the Earth’s surface- with stronger warming in the Arctic

Question 22

what are patterns of warming in winter and summer

Answer 22

winter warming has been intense across parts of Canade, Alaska, Northern Europe and Asia. Summers have warmed across the Mediteranean and Middle East and some other places in the western US

Question 23

what happened to the ice in the Arctic Sea

Answer 23

Lots of the ice has melted. Satellite based measurements have shown a steady decline in the ice in the Arctic Sea- by at least 10% per decade since they started measuring in 1978

Question 24

what contributes to sea level rise

Answer 24

the sea level has risen over the past few decades because of the thermal expansion and melting water from glaciers and ice caps

Question 25

what is evidence of ocean acidification

Answer 25

excess carbon dioxide building up in the seawater will react to form carbonic acid when causes the ocean to become more acidic. Oceans have absorbed 1/4 to 1/3 of excess carbon dioxide from human activities

Question 26

what has happened to the carbon records in the past 800,000 years

Answer 26

atmospheric carbon levels in the air are higher than any other time in the past 800,000 years. This has been measured from analyzing ice core records

Question 27

How do weather balloons help measure the earths temperature

Answer 27

they measure humidity, winds and temperature in the atmosphere

Question 28

WHat are some indicators of global warming

Answer 28

heat waves are more frequent, cold snaps are shorter and milder, snow and ice covers are decreasing, glaciers and ice caps are melting, and many plants and animals are moving to colder climates because it is too warm where they live

Question 29

what are forcing agents

Answer 29

greenhouse gases. They are called this because the can change the Earth’s energy balance