ENV 115 Exam 2

During the Pliocene (~5.3 to 2.6 million years ago) global average temperatures were 2-3°C warmer and sea level was as much as ____ higher.

25 meters

During the Cretaceous, about 94 million years ago, the poles were completely ice free and oceans reached _____ above those of today

250 meters

2020 is officially "tied" with 2016 as having the highest global average temperature ever recorded by thermometers, but 2016 had a massive weather event that moved lots of heat from the ocean into the atmosphere. What was the event?

El Niño

Which strategy is not one of the five denial strategies discussed in this video? Fake experts Logical fallacies Impossible expectations Fact avoiders

Fact Avoiders

Rosh points out that CO2 only follows warming temperatures in the southern hemisphere, not in the tropics or northern hemisphere. In fact, ___% of the warming globally occurs after the CO2 begins to rise.

90%

On the basis of at least one credible study, what percent of climate scientists agree that humans are causing global warming?

97%

Lake Sediment

A variety of physical and biological properties can be analyzed to interpret past climate and environmental changes of the surrounding watershed

Cherry-picked data is fake data made up by the denialist.

False

Global warming means cold days will cease to occur.

False

Orbital cycles alone can explain the warming observed during the last 300,000 years

False

Presently, the Sun is closest to the Earth on July 4th.

False

Since the Paris Accord of 2015, the world has dramatically cut the amount of fossil fuel emissions into the atmosphere.

False

The Earth is now warmer than it has been at any time in its history

False

The reduction in Arctic sea ice is contributing significantly to sea level rise

False

We can conclude that humans are responsible for the present warming because the Earth has never been as warm as it is today

False

"El Niño" is associated with which of the following:

Fluctuations of heat between the ocean and the atmosphere

The recent catastrophic glacier collapse in northern India was "predicted" in the video. Problems cited include all of the following except: lack of water in the future floods food insecurity avalanches

Food Insecurity

Examine the graph above. What does the blue line/curve represent?

CO2 concentration

The two most important factors influencing global temperature over geological time are:

Carbon dioxide and solar luminosity

Considering all types of aerosols, what is their overall or net effect on the climate system?

Cooling

Over the past 1 million years or so, about how frequently have major ice ages occurred?

. every 100,000 years

About how much has the climate warmed over the last 130 years?

0.9 C

Milankovitch showed that, over hundreds of thousands of years, the amount of summer sunlight at a given latitude can shift up or down by:

15%

Closely compare the CO2 concentration (blue line) and temperature (red line). Note that the two lines mainly coincide with one another; higher temperatures are associated with higher CO2 concentrations. In detail, however, the temperature seems to slightly lead CO2 concentration (red line shifted to the left of the blue line). What does this suggest?

Deglaciation is initiated by changes in the orbital cycles, but CO2 amplifies the warming.

How long did the physical and ecological changes caused by warming during the PETM last before they returned to prior conditions?

Hundreds of thousands of years

Which of the following did not occur during 2020? massive fires in Australia record hot temperatures in Siberia US Hurricane Katrina massive fires on the US West coast

Hurricane Katrina

Which is the only natural archive where you would find information of past greenhouse gases?

Ice Cores

Using this image from the video, which one is NOT a cause of reduced radiative forcing (cooling) since industrialization?

Increase in black carbon

In the coming decades, a possible decrease in the Sun's energy output would ___

Reduce the warming effect of greenhouse gas emissions slightly

Climate scientists have determined that four atomic bombs worth of heat are building up within Earth's climate system every ______

Second

Animals: Did mammals during the PETM become smaller or larger? What might be the cause of this?

Smaller, because plants in high CO2 environments produce less protein and are less nutritious

About 700 million years ago, the Earth was covered by ice from the poles to near the equator - a period/condition referred to as _____________?

Snowball Earth

Tree Rings

The thickness of each annual layer is used to interpret site temperature and precipitation during the past

The term "committed warming" refers to:

The warming that is likely to happen even if humans stopped emitting greenhouse gases today

Soils: What does the evidence from iron nodules indicate about the change in precipitation that occurred 56 million years ago at the beginning of the PETM?

There was less rain (increased aridity)

Pollen

This proxy is used to identify which plant species were living in an area through time, which can be used to infer past environments and climate

What is the WEAKEST evidence that recent warming is due to increased greenhouse effect?

Tropical storms and fires have become more frequent

2019 was the first year since 1885 that the energy generated by renewables surpassed the energy generated by coal in the US.

True

According to the IPCC, it is extremely likely that more than half of the observed increase in global average surface temperature from 1951-2010 was caused by humans.

True

Atmospheric CO2 rose by 2.5 ppm in 2020.

True

BP's (old British Petroleum) annual outlook suggests that 2019 may have been the peak in oil demand.

True

Even if you don't live near the ocean, the impacts of warming oceans are felt inland through hurricanes and other extreme weather.

True

Global emissions dropped by about 7% in 2020 primarily due to the economic downturn associated with COVID-19.

True

On an annual basis, nature emits more CO2 than humans.

True

Solar luminosity has overall increased gradually over billions of years. Hint: See the graph on solar luminosity (8:26). Note that solar luminosity is the total power emitted from the sun. This is related to solar irradiance which is the power per unit area that is received by the Earth.

True

The cryosphere is basically the area of earth with frozen water (ice) and/or soil (permafrost)

True

The evidence for increasing temperatures over the past 150 years is "unequivocal".

True

The ocean has absorbed (taken up) over 90% of the excess heat in the climate system since 1970.

True

The warming of the late 20th century is unprecedented in at least the last thousand years.

True

Radiative forcing is measured in which units?

W/m2

Why does this chapter focus on global average temperature as a key indicator of climate change?

Warming is the direct result, and therefore a key indicator of the addition of greenhouse gases to the atmosphere. Temperature is among the best known and of all climate records Local variations related to weather patterns are usually balanced out when focusing on global averages, thereby isolating small signals of climate change.

Changes in internal variability (e.g., ENSO) affect climate, .

and are fast enough to explain the recent warming, and may explain some of the observed changes, particularly interannual variations in climate

Changes in greenhouse gas concentrations affect climate, ...

and are most likely responsible for the recent warming

Which of the following is FALSE about why scientists collect sediment cores from Arctic lakes to study past environmental changes? a. Climate change is happening quickly in the Arctic; the Arctic environment is sensitive to climate b. Because the Arctic is so cold little organic matter is deposited in the lake, which makes analyzing the sediment easier c. The lakes are pristine, so they can be studied to better understand natural changes unrelated to human activities

b. Because the Arctic is so cold little organic matter is deposited in the lake, which makes analyzing the sediment easier

Which is FALSE about climate and Earth system models? a. they are based on mathematical equations encoded into computers b. they are in their very early stages of development c. they simulate interactions between the ocean, atmosphere, biosphere, and cryosphere d. they are used to test the possible effects of different greenhouse gas emission scenarios

b. they are in their very early stages of development

Changes in Earth's orbit affect climate, ...

but are too slow to explain the recent warming

Tectonic changes affect climate, .

but are too slow to explain the recent warming

Milankovitch's theory is based on two key ideas: That the Earth's climate is strongly affected by how much sunlight the northern latitudes receive during the summer, and that this amount of sunlight varies based on:

changes in the Earth's orbit and rotation

During the last 400 years, the Earth has been:

cooler than today

Why do scientists want to study Earth's climate from the past? a. Knowledge about Earth's past helps scientists to understand Earth's current and future climate changes b. Future climate will be determined by both natural and human causes c. Instrumental records are too short to capture the full range of natural variability d. all of the above

d all of the above

During the last 70 million years, the Earth has been: a. warmer than today b. cooler than today c. we don't know d. both a and b

d- warmer than today and cooler than today

Which best describes the trend in global mean temperature during the 20th Century? a. There is no statistically significant trend in global mean temperature during the 20th Century. b. It increased at a fairly steady pace over the century c. It increased rapidly during the first half of the century, then the rate of warming slowed down and has leveled off , with very little warming in the last half of the century d. Although the warming has not been uniform, warming has basically been continuous with each decade warmer than the last

d. Although the warming has not been uniform, warming has basically been continuous with each decade warmer than the last

What is the advantage of using multiple (more than one) proxy record for global climate reconstructions? a. different proxies give complementary information (e.g. temperature, moisture) b. different proxies cover different time periods c. different proxies give information from different places (e.g. arctic, tropics) d. all of the above are advantages

d. all of the above are advantages

Which of the following is a cause of sea level rise? a. Global warming causes water in the ocean to expand b. Meltwater from ground or land ice c. Increased rainfall or precipitation d. both a and b e. All of the above

d. both a and b: Global warming causes water in the ocean to expand Meltwater from ground or land ice

Which of the following is not a key point made in the video: the ocean has been, and is presently, absorbing a LOT of Earth's excess heat significant numbers of people live in areas affected by the cryosphere and the ocean climate change is significantly affecting the cryosphere and the oceans deep ocean circulation is at risk of shutting down completely

deep ocean circulation is at risk of shutting down completely

Climate models that are programed to simulate Earth's temperature over the 20th century:

fail to correctly simulate the actual temperature unless they include forcing by greenhouse gases

Some climate denialists incorrectly call the years 1998-2012 a climate ___

hiatus

Which of the following is considered a paleoproxy record? a. ice cores b. satellite temperature measurements c. sea level measurements d. all of the above

ice cores

The Earth began to experience regular ice age

in the last 3 million years

Land has a lower heat capacity than water, which means that:

it take longer/more energy for water to heat up and cool down than for land

Rosh illustrates the positive feedback effect where warmer temperatures increase ocean degassing, which then causes:

more atmospheric warming

Which of the following is not a cryosphere change discussed in the video: thawing permafrost shrinking glaciers (breaking off/melting) more frequent ice storms thinning Arctic sea ice

more frequent ice storms

Which of the following is not an oceanic change discussed in the video: more frequent tidal waves (tsunamis) migrating marine mammals migrating rising sea level more frequent marine heat waves

more frequent tidal waves (tsunamis)

he addition of sulfate aerosols to the atmosphere by burning of fossil fuels is a:

negative radiative forcing

The Greenhouse effect was discovered:

over a hundred years AGO

On human timescales, an increase in water vapor acts as:

positive feedback

On human timescales, increases in carbon dioxide is a:

positive radiative forcing

A fake expert is someone who ______

ppears to have expertise without actually having relevant expertise

Climate sensitivity is defined as:

the amount of warming that occurs in response to an imposed radiative imbalance

What is a temperature anomaly?

the difference between the actual temperature and a reference temperature

Which component of the climate system is primarily responsible for the lag between emission of greenhouse gases and the resultant warming?

the oceans

John Robson's theory is that ocean degassing is happening now - as a delayed reaction after the warming of the Medieval Warm Period ~800 years ago. This is his explanation for the increasing CO2 in the atmosphere. If this were true, then:

the oceans would contain less CO2 instead of more, as we see today

During glacial periods, the primary reason that more ice grows in the Northern Hemisphere is because:

there is more land on which to grow ice sheets

The "single-cause fallacy" is when we assume that ____

there is only one cause for a phenomenon even though there may be multiple

How do we know that variations in the output of the Sun cannot be causing the observed recent warming?

we have measurements of solar output, and they show no increase over the last couple decades

About how much colder is an ice age than our present climate?

~6 degrees C

What is the Earth's climate sensitivity? (i.e., how much warming eventually occurs if carbon dioxide is doubled)

1.5 - 4.5°C

During the past 350,000 years (x-axis), temperatures in Antarctica have cycled by about 20°F (10°C) three times. These are the major glacial-interglacial cycles. What is the typical range between high and low CO2 concentration -- the natural variability in atmospheric CO2 concentration -- as the Earth transitioned from glacial to interglacial periods?

100 ppm

Assuming that the pre-industrial level of atmospheric CO2 was about 280 ppm, about how much has the CO2 content of the atmosphere increased since pre-industrial levels as a result of human activities? I.e., what is the change in CO concentrations since the start of industrial revolution?

100 ppm`

All of these are reasons for optimism except: We know we can reduce carbon emissions because we did it. There is increasing global will to decarbonize There are increasingly economical and alternative energy sources available. All of these are reasons for optimism!

All of these are reasons for optimism!

Radiative forcing is defined as:

An imbalance in Ein - Eout as a result of some change imposed on the Earth system

The IPCC has released three special reports as part of its sixth assessment cycle. Name them

Climate Change and Land The Ocean and Cryosphere in a Changing Climate Global Warming of 1.5°C

While atmospheric temperatures show some annual dips, ocean temperatures show:

Constant trends upward

The tilt of the Earth's axis varies on a 41,000 year cycle. The Northern Hemisphere has more summer sun when the tilt is:

Greatest

The relatively warm period known from some places, especially Europe, around 1000 AD is known as the

Medieval Warm Period

The warmth during the Medieval Warm Period increased crop yields in parts of Europe, but what happened at the same time in the American Southwest?

Mega droughts and agricultural collapse

Over 90% of recent warming has gone into the:

Oceans

What is the causal factor that initiated the temperature increases as represented in the Vostok ice core?

Orbital cycles that changed the distribution of solar energy

Which one of the following is not an aerosol? sulfur gas that reacts with water vapor to form small sulfate droplets soot mineral dust ozone

Ozone

The geological period when a massive release of greenhouse gases occurred was the:

Paleocene-Eocene Thermal Maximum PETM

Examine the graph above. What does the red line/curve represent?

Temperature

The cold period 200-300 years ago is known as the

The Little Ice Age

During the Medieval Warm Period, ~950-1250 AD, temperatures were relatively high primarily in:

The North Atlantic

Which has warmed more over the last 150 years?

The Northern Hemisphere

Plants: What does the abundance of legumes during the PETM indicate about the change in climate and CO2 levels during the PETM?

The climate was more arid and there were higher levels of CO2 in the atmosphere

Which is not one of the three main factors that influence the amount of summer sunlight at a given latitude?

The magnetic poles switching places (magnetic reversal)

Sea Coral

The thickness of annual rings of calcium carbonate store a record of past conditions, including temperature.