Years of Living Dangerously Season 2 Episode 2 This documentary television series shows 1) real estate in Miami under the con

Arctic Climate Change

The difference during summer is increasing as the sea ice extension is decreasing in

relation to the recent past.

http://nsidc.org/arcticseaicenews/

In lecture 1, we learned about the seasonal migration of Arctic sea ice extension. In this figure, it is very clear that 2012 was exceptional because the Arctic sea ice during that summer was at the greatest minimum ever observed, dropping far below the mean of the long term trend. Let’s take a look what happened after, particularly in 2016.

(National Snow and Ice Data Center)

This figure is based on a report of sea ice extension in November 2016. At the end of summer in 2016, the minimum sea ice extension was the second lowest after the 2012 extension (left red arrow). As the season migrates and turns colder, the sea ice did not grow back as fast as it should have relative to all previously measured patterns (right red arrow). By November, the sea ice extension was the lowest ever recorded in November.

What was happening in 2016?

Daily mean temperatures for the Arctic area north of the 80th northern parallel. (Danish Meteorological Institute)

Arctic temperatures are about 20 degrees Celsius higher than normal above 80 degrees North Latitude! (Nov 2016).

This figure shows daily temperature measurements in the Arctic at 80 degrees north in 2016 (red line) along with a computer simulation of temperature patterns based on long- term temperature measurements of the Arctic region (green line). The blue line is the point of freezing (0 degree Celsius). Please note that Y-axis identifies temperature shown in units Kelvin (K). Kelvin is a commonly used unit of measurement in science for temperature. Please see the following slide for more detail. The X-axis identifies the number of days in 2016. For example, the day 1 indicates January 1st, and the day 365 equates to December 31st.

As you can see, there is seasonal variation. You will also notice that, most of the year, the temperature remains below the freezing level (blue line), although it will slightly exceed freezing for a short period of time during summer. In November of 2016, the temperature north of 80 degrees latitude was around -5 degrees C. This is below freezing (not by much), but is anomalous to the normal temperature of around -25 degrees C (see vertical blue dashed line). The temperature difference between the long term mean (green line) and the observed temperature (red line) was as great as 20 degrees!!

(continue)

(continued) Why was this happening? Why did it happen in the Arctic? This phenomenon is known as polar amplification and it is important that we learn about this concept to understand how and why changes in our climate system affect different parts of the world unequally. For now, maintain an awareness of polar amplification as we will learn more about this concept in the following weeks.

In the meantime, please take a moment to think about whether such daily temperature changes north of 80 degrees latitude are considered “climate” or “weather”?

Further, please check the latest news from Arctic Sea Ice News and Analysis for additional information: https://nsidc.org/arcticseaicenews/

A recent science study reports that rapid warming in the Arctic is a likely driver of the recent extreme winter weather in the US. https://www.science.org/doi/10.11 26/science.abi9167?utm_campaign =SciMag&utm_source=Social&utm_ medium=Twitter

Fahrenheit is a temperature scale based on one proposed in 1724 by the German physicist Daniel Gabriel Fahrenheit. 0 F was the lowest temperature Dr. Fahrenheit could measure, 100 F is the average human core body temperature. In scientific measurement, Kelvin is more common because by definition 0 Kelvin is called absolute zero. Absolute zero is theoretically the lowest possible temperature where all molecules seize their motion (almost no heat is emitted by the molecule). In this slide, temperatures in Fahrenheit, Kelvin, and Celsius are compared in the same scale.

Weather Forecasting

• Weather affects nearly everyone, every day.

• Weather forecasts are issued: o To save lives o Reduce property damage o Reduce crop damage o To let the general public know what to expect

• Forecasts are often utilized to make many important decisions on a daily basis

• So how is it done, and how is it done correctly?

National Weather Service Mission:

• The NWS provides weather, hydrologic, and climate forecasts and warnings for the US, its territories, adjacent waters, and ocean areas for the protection of life and property and the enhancement of the national economy.

Tools available to a forecaster…

• Weather Observations (including surface data, satellite data, and radar data)

• Commercial aircraft data

• Wind profilers

• Numerical Model Output

…There are a lot of sources for data!

Forecasting technique – Persistence

13Image from WW2010 Online Guide

The most primitive method of forecasting is to observe and estimate that there will be no changes to the present. Today is sunny, therefore, tomorrow will also be sunny. This may work relatively well in a dry and arid region, but does it work in the New England region? Probably not.

The Trend Technique

15Image from Meteorology Today by C. Donald Ahrens

Another method of forecasting that has been used in the more recent past is to understand trends. As we all know, however, weather systems migrate from west to east in the mid latitude, where we live, due to prevailing wind called the westerly (we will cover this in the following weeks). The atmospheric pressure system, in general, crosses over North America in 3 to 5 days. With this, the system travels approximately 800 miles per day. With this understanding, we can broadly predict when a storm will approach a specified region. Can this be used to make an accurate prediction? Although this maybe not be a desirable way to forecast for a long-term period, it may work for a shorter and current time interval.

The Analogue Technique

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The analogue technique is a combination of climate and weather. Based on long- term observations, you might be able to identify a clear pattern in the atmospheric system. For instance, you may notice that, statistically, when a dry and cold weather pattern is observed in the northwest (high pressure system), there is a tendency for stormy weather in the northeast (low pressure system). This method could be useful and may produce relatively reliable results for slightly longer time periods (few days to a week).

Accuracy and skill in forecasting After you learn about forecasting techniques, you may be asking yourself

– what is an ”accurate” forecast?

• What is an accurate forecast? o Your forecast for tonight’s minimum temp is 0F

If the actual minimum was 1F, is it inaccurate?? If the actual minimum was 10F, is it inaccurate??

o Accuracy (in forecasting) is arbitrary and relative – it is not clearly or objectively defined.

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Modern weather forecasts are based on model forecasts

– Numerical Weather Prediction In order to increase accuracy, we heavily rely on numerical weather prediction.

• Predict the state of the atmosphere (e.g., pressure, temperature, precip, winds, etc) in time

• Use mathematical equations – initialized with observational data

…Why are models often wrong?

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Problems with numerical modeling

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• Models represent a “simplified” atmosphere – not every real process in atmosphere can be resolved in models.

• Many are not global in coverage

• The initial atmospheric state is not well-known

• The data may also have errors in it

• The model equations compute quantities at grid points (30- 50km).

• The atmosphere is fundamentally chaotic!

So, the atmosphere is fundamentally chaotic and this is why weather forecasting, although state of the art, is still not perfect. Therefore, in order to understand the climate system, scientists focus on key phenomena and/or relationships that effectively control or alter the climate system of the Earth. Here, we call them the “climate knobs” and let’s talk more about it in the next lecture.

Here is a news from weather forecast development:

Artificial Intelligence May Be Key to Better Weather Forecasts Recent advances in machine learning hold great potential for converting a deluge of data into weather forecasts that are fast, accurate, and detailed. By Sid-Ahmed Boukabara, Vladimir Krasnopolsky, Jebb Q. Stewart, Stephen G. Penny, Ross N. Hoffman, and Eric Maddy, 1 August 2019

https://www.ncdc.noaa.gov/billions/overview

“In 2021, there were 20 weather/climate disaster events with losses exceeding $1 billion each to affect the United States.” “Overall, these events resulted in the deaths of 688 people and had significant economic effects on the areas impacted.”

https://www.noaa.gov/news/2021-was-worlds-6th- warmest-year-on-record

2021 was world’s 6th-warmest year says NOAA

https://medialibrary.climatecentral.org/resources/2020-in-review-global-temperature-rankings

– Could we have predicted that 2021 would become the 6nd warmest year on record or predict what 2022 temperatures will look like when the report becomes available? The answer is no. However, you can look into the long-term trend and anticipate what likely will happen in the future! (weather vs climate)

Please take a moment to read the article published in March 2017 about our perceptions of climate change. This was before the catastrophes caused by Hurricane Harvey and Hurricane Irma in 2017.

How Americans Think About Climate Change, in Six Maps

By NADJA POPOVICH, JOHN SCHWARTZ and TATIANA SCHLOSSBERG

MARCH 21, 2017 https://www.nytimes.com/interactive/201 7/03/21/climate/how-americans-think- about-climate-change-in-six-maps.html

Example Test 1 question: Climate differs from weather in that

A. climate is a broad composite of temperature conditions, while weather addresses temperature as well as precipitation, snow and ice cover, and wind conditions.

B. climate change occurs over longer durations than do weather changes.

C. climate change is exclusively global, whereas weather is exclusively regional.

D. climate and weather do not differ, they are interchangeable terms.

At last, here is an example questions in preparation for the test. The questions in test 1 will be similar in format to this question, but not necessarily the same question.

The answer is B.

This is likely to be one of the most well-cited pictures of Earth called “Blue Marble”. It was taken on December 7, 1972, by the crew of the Apollo 17 spacecraft. It has a distinct color of blue, because the Earth uniquely carries an atmosphere and 70% of the Earth’s surface is covered by the ocean.

Atmosphere from Space

We can see our atmosphere even from space. In this figure, the bright layer is the atmosphere between space and Earth; both are shown here in black. Please note how thin the atmospheric layer is relative to Earth’s diameter!

Another view of the Atmosphere from Space

This is a zoomed-in image of the atmosphere. You will notice that there is a gradual color change ranging from a brownish color closer to the Earth’s surface that transitions to a pale blue and eventually fades into space. The atmosphere extends about 10,000km into space. There is no exact top to the atmosphere. Due to the Earth’s gravity, the number of molecules, which individually each carry mass, gradually decreases outward into space. Most of the gas molecules are within the lower atmosphere. 90% of the atmosphere’s mass is in its lower 10km and 99.9997% is within the lower 100km. You will also notice that there are little blobs in the brownish colored layer close to the surface. This layer is called the troposphere, the lowest layer of the atmosphere ranging from 6-10km above sea level. This is where we live, clouds are formed, daily weather is observed, and the majority of the molecules exist. The blobs you see are seemingly giant cumulonimbus – dense towering clouds – often associated with thunderstorms.

Composition of the Atmosphere including variable components (by volume)

The three elements that make up over 99.9% of the atmosphere – nitrogen, oxygen, and argon. These elements are abundant in the atmosphere and have many uses.

Pure nitrogen (N2) is used in its very cold, liquid state as it boils at -195.8 C (or -320F). Ted Williams, a baseball player who played for the Boston Red Sox for 22 years, and deceased in 2002, is preserved in liquid nitrogen since his family members chose to have his remains frozen.

Pure oxygen (O2) is used to achieve higher temperatures, to increase the efficiency of waste incinerators. It is also used as an oxidizing agent, and in medical applications to assist and sustain a person’s respiratory functions.

Argon (Ar) is a colorless, odorless, nontoxic, and nonreactive gas. It creates inert environments for growing crystals, often used in semiconductors. It protects materials against corrosion. It also fills the air space in double-pane insulating windows.

Earth’s climate system and interactions of its

components

Two key ideas for this course, especially for the first half is:

1st: Climate is regulated by complex interactions amongst components of the Earth’s system.

2nd: Understanding climate change can be reduced to understanding how “the control knobs” function

Climate change

The knobs that control earth’s climate: • Atmospheric composition (greenhouse effect) • Amount of solar radiation (luminosity) • What parts of Earth get radiation (orbit) • Atmospheric and ocean circulation • Earth’s albedo (fraction of solar energy reflected off earth’s

surface) • Volcanoes • Plate tectonics

Greenhouse Effect

We are here.

First, a bit about radiation . . .

How the control knobs work

Amount of energy reaching earth determines the climate. Dominant source of energy is sunlight, which when reaching Earth can heat the land, ocean, and atmosphere.

If a chunk of matter oscillates and interacts with light at all possible frequencies, it is called blackbody. And the light (energy) that is emitted by a blackbody is called blackbody radiation. In this manner, although “blackbody” is originally named for an ideal object, we consider the Earth as a blackbody. In fact, many objects that radiate energy back when they are heated are considered as a blackbody.

The Greenhouse Effect Greenhouse gases don’t “trap” heat; they absorb heat and re- radiate it out to space and back to Earth.

So, some of that sunlight is reflected back to space by the Earth’s surface, clouds, or ice. But much of the sunlight that reaches Earth is absorbed and warms the planet. When Earth emits the same amount of energy that it absorbs, its energy budget is in balance, and its average temperature remains stable.

The discrepancy between incoming solar energy and outgoing radiation energy is the greenhouse effect. Earth’s atmosphere contains greenhouse gases (e.g. CO2, CH4, etc.) that absorb 95% of the longwave (we will learn more about this later) back radiation emitted from the surface.

Earth’s radiation budget

Here is a breakdown of the numbers… Solar radia)on arriving at the top of Earth’s atmosphere averages 342 W/m2, indicated here as 100% (upper leB). About 30% of the incoming radia)on is reflected and scaHered back into space, and the other 240 W/m2 (70%) enters the climate system. Some of this entering radia=on warms Earth’s surface and causes it to radiate heat upward (right). The greenhouse effect (lower right) retains 96% of the heat radiated back from Earth’s heated surface and warms Earth by 31 C̊.

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http://berkeleyearth.org/2018- temperatures/

(Upper figure) Mean global air temperature variation from 1850 to 2018 In 2018, 9 of the 10 warmest years have occurred since 1990.

(Lower figure) Atmospheric CO2 variation during the same interval From 1960 to present: the atmospheric CO2 concentration has been measured in Mauna Loa, Hawaii. Before 1960, the CO2 concentration is a reconstructed value based upon CO2 preserved in ice cores.

Ice core records

Temp.

CO2

Dust

Annually laminated

bands within ice

core

Thousands of years ago

Why do we use ice core records instead of observed data (which seems to be the more direct and reliable approach)?

This is because, unfortunately, we only have a limited number of observed records for us to understand the natural cycle of the Earth’s climate – most of the data are available only for the past 50 years of which a few extend past a couple hundred years. This means, for instance, if we would like to discuss our climate system in relation to the El Nino cycle, which likely occurs every 3-5 years on average, we can only refer to a few of those events. For this reason, we need a longer record than the observational record.

By using ice core records, as shown in this figure, we can study and argue climate/environmental variability of the past 400,000 years. If the ice core preserves annual layers (like tree rings), the record you are looking at is basically a sub-seasonal resolution of climate variability.

Climate Change in New England

Weider and Boutt, 2010

What is happening in New England?

This figure shows 12 month moving averages of temperature data

measured at 43 observational sites across New England between

1920 and 2009. Please note that this data is an average of 12

months, and any seasonal variability is expressed much less obvious.

There maybe a warming trend? This may be correct. However,

importantly, local temperature variability can be quite different from

global temperature variability – it maybe even cooling in some areas.

Receding mountain glacier due to recent warming.

0

1000

2000

3000

4000

5000

6000

7000

1000 1200 1400 1600 1800 2000

P op

ul at

io n

(M ill

io ns

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Time (Years)

World Population (http://www.census.gov/ipc/www/idb/worldpopinfo.html)

1967

1920 1850

Today 7 billion

Is this temperature trend related to population growth?

Popula'on growth

If so, what will the future population be? Check today’s population: https://www.census.gov/popclock/

MMD-A1B 2080-2099 vs 1980-1999 IPCC 2007

Effects on Agriculture and the Ocean?

Also figures from the IPCC (Intergovernmental Panel on Climate Change) showing the discrepancy between simulated climate model results 2080-2099 and observational data 1980-1999. Precipitation, soil moisture, runoff, and evaporation. Some areas experience drier conditions.

Source: IPCC 2007

Black line: observed temperatures Blue: expected changes due to natural factors Pink: expected changes due to natural factors plus greenhouse gases

Comparison of observed continental- and global-scale changes in surface temperature with results simulated by climate models using either natural or both natural and anthropogenic forcings. Averages of observations are shown for the period 1906-2005 (black line) plotted against the center of the decade and relative to the corresponding average for 1901-1950. Lines are dashed where spatial coverage is less than 50%. Blue shaded bands show the 5 to 95% range for 19 simulations from five climate models using only natural forcings due to solar activity and volcanoes. Red shaded bands show the 5 to 95% range for 58 simulations from 14 climate models using both natural and anthropogenic forcings (like CO2)

Change in Snow Depth CRCM-A2 2070 Results from another climate model showing changes in snow depth in

North America.

An example of a positive feedback

Warming reduces the cover of snow and sea ice in the Arctic from 2005 (right) to 2007 (left), increases the amount of heat absorbed by exposed water, reduces albedo, and thereby further warms the climate. This is called a positive feedback process.

We will learn more about “albedo” and “feedback process” later this semester.

November Arctic Ocean Ice Extent

Source: NSIDC

Monthly November ice extent for 1979 to 2014 shows a decline of 4.7% per decade relative to the 1981 to 2010 average.

Source: Steffen et al., 2008

Area of Melting on the Greenland Ice Sheet: increasing Greenland ice sheet is also increasingly melting from 1979 to 2008.

Maps of maximum annual surface melt on the Greenland Ice Sheet derived from monthly ice surface temperature product of Greenland (2000-2016). Greenland ice sheet is also increasingly melBng!

A Multilayer Surface Temperature, Surface Albedo, and Water Vapor Product of Greenland from MODIS, April 2018, Remote Sensing 10(4):555, DOI: 10.3390/rs10040555

This figure shows the amount of ice sheet lost in Greenland and Antarctica between 2002 and 2009.

Velicogna (2009), Geophysical Research Letters, v.36. L19503, DOI: 10.1029GL040222

https://www.antarcticglaciers.org/2020/01/what-is-the-ice- volume-of-thwaites-glacier/

Ice streams of Antarctica

Recent observations show that incursions of warm ocean water cause melting of the undersides of floating ice shelves in West Antarctica. This could cause a rapid and irreversible rise in sea level. Reference: Hillenbrand, CD., Smith, J., Hodell, D. et al. West Antarctic Ice Sheet retreat driven by Holocene warm water incursions. Nature 547, 43– 48 (2017). https://doi.org/10.1038/nature22995

Our own UMass faculty, Prof. DeConto published in Nature journal in 2021 a suggestion that if emissions continue at their current pace, by approximately 2060, the Antarctic Ice Sheet will have crossed a critical threshold that will cause irreversible global sea level rise within a human timescale. Reference: DeConto, R.M., Pollard, D., Alley, R.B. et al. The Paris Climate Agreement and future sea- level rise from Antarctica. Nature 593, 83–89 (2021). https://doi- org.silk.library.umass.edu/10.1038/s41586-021- 03427-0

Future Sea Level? If we lose all ice in the world – what will happen to the sea level?

Bamber et al., 2009

A simula)on model result shows what happens to the sea level, if all sea ice/con)nental ice (ice sheet) fully collapsed. Most of the northern hemisphere experiences an increase in sea level of over 1 m.

What happens with 1 m sea level rise?

Here are links that include recent research outcome about ice loss from

Earth’s ice sheets. Check out the amazing and disturbing videos in this NASA

briefing….

Snow over Antarctica Buffered Sea Level Rise during Last Century

https://go.nasa.gov/2GeaWZb

Carbon Brief.org

http://www.carbonbrief.org/blog/2015/08/new-nasa-videos-show-stark-ice-

loss-from-earths-ice-sheets/

Annual Arctic sea ice minimum 1979-2018 with area graph

https://climate.nasa.gov/climate_resources/155/video-annual-arctic-sea-

ice-minimum-1979-2018-with-area-graph/

Antarctic ice loss: 2002-2016

https://climate.nasa.gov/climate_resources/154/video-antarctic-ice-loss-

2002-2016/