WxClimoEd Series, Post #1, Part 1: Understanding Global Climate Change

Hello Weather & Climate News readers! This post will be the first in what will be my ongoing education article series WxClimoEd. I hope to write educational posts on various topics related to weather and climate to help enhance your understanding of various phenomena and their impact on the environment, individuals and society. These posts will present key ideas and concepts and provide occasional linked sources to further, more detailed information.

Understanding Global Climate Change (Causes)

This article will deal with an introductory explanation of Global Climate Change as we currently understand it and the causes of it, specifically relating to human activity. Part 2 (in the next week) will discuss the known (and unknown) impacts on humanity and wildlife based on impacts on regional climates. Part 3 (in a couple weeks) will discuss mitigation efforts.

  1. Natural Climate Variability vs. Recent Global Climate Change

Earth’s climate has been evolving since the planet was born 4.6 billion years ago. These changes in Earth’s atmosphere have been largely the result of things such as biological modification of the atmosphere, volcanic eruptions, changes in ocean currents, movement of continents over tens of millions of years, variations in Earth’s orbit and other various phenomena. The most recent history of climate has featured periods of glaciation over much of the landmasses known as the Ice Ages.

Earth’s global climate has been in a “interglacial” period with a climate which warmed enough to end major continental glaciation around 11,000 yrs ago.

However, what scientists have seen in the recent climate records is a rate of change -both the climate conditions themselves and the atmospheric gases which can change the climate – at a rate accelerated and in some cases unprecedented in previous times.

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Carbon Dioxide (CO2) levels going back 450,000 yrs. There have been multiple periods of glaciation and interglacial periods as part of natural change (high/low CO2 = warm/cold), but CO2 has not exceeded much above 300 parts per million until the 20th century. (NASA)

What scientists in the second half of the 20th century discovered is that for the first time in the history of human civilization we are acting as a force influencing the climate. Human-induced climate change is real.

This has been found after accounting for the natural variability in climate cycles and from our understanding of how carbon dioxide works in the atmosphere. This extremely rapid change in global temperatures, a top signal of climate change, has been driven by CO2 pollution, beginning after 1850 and the during the Second Industrial Revolution.

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Graph showing the correlation between global temperatures (anomaly relative to the 1881-1910 average) and CO2 concentration 1880-2016. CO2 is known physically to be capable of “trapping” heat in higher concentration. (Climate Central)

One of the first questions which many non-scientists have about global climate change is “Well hasn’t the climate always been changing?” The answer is yes, but with a caveat…it has NOT changed this rapidly in the history of humanity on Earth (Homo sapiens sapiens have been around ~200,000 yrs). Since Earth began the process out of the last glaciation 22,000 yrs ago, global temperatures have varied up to a 4 degrees C. But this process of variability has occurred over the course of centuries to a couple of millennia because of the long cycling of natural processes. Human activity in the form of burning fossil fuels since the latter 19th century has caused around 1 degree C of warming within a 100-150 yr period. This comic comparing the average temperature of Earth to the end of the Ice Age and achievements of human civilization across millennia strongly illustrate the climate stability we’ve come to flourish under. (zoom in at the top and scroll down…it’s long, but worth the read and look!). Humans have essentially acted as a continuously spewing ‘volcano’ of carbon products. And as a result, we have compressed warming which would take nature nearly a millennia to do in recent geologic time and accomplished it within a century.

We are transforming our world before our eyes.

2. How does the greenhouse effect work?

The greenhouse effect is a simple concept, but one with major implications for us all in this major environmental issue. In Earth’s atmosphere exists gases which are chemically capable of “trapping” heat in the lower atmosphere, heating the surface. The three most significant “greenhouse gases” are carbon dioxide, water vapor, and methane. These gases in higher concentrations are most effective in reflecting infrared (heat) radiation originally emitted by Earth’s surface back to the surface as opposed to allowing it to be lost to space. If it wasn’t for this greenhouse effect, Earth would be literally completely glaciated over and very cold.

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Example graphic showing the “radiation budget” and how the greenhouse effect impacts how much radiation is retained by Earth’s atmosphere. (By Wikipedia user ZooFari)

Methane is very potent, but short-lived without constant replacement as direct sunlight breaks the molecules apart. Water vapor varies seasonally with some balance because of the water cycle. Therefore carbon dioxide or CO2 ends up being the most important changing variable for warming/cooling the climate. Such changes, along with other variable cycles, have influenced previous periods of ice ages. But human “eruption” of CO2 since the 2nd half of the 19th century has led to clear changes in Earth’s atmosphere and climate.

This YouTube video shows 131 yrs of global warming (1880-2011). The “anomalous temperature” is relative to the average planetary temperature of 1880-1910. The average temperature of Earth has continued to warm above this average to record levels since 2011. The planet is known to have warmed by ~1 degree C (nearly 2 F) since the late 19th century. The most dramatic warming (as can be seen in the video) began to ramp up significantly since 1980. Depending on the scenario, human-induced warming of Earth may reach 1.5-2 degrees C (2.7-3.6 F) above pre-industrial levels by 2050 and (depending on human efforts to decrease CO2 pollution) the warming may hit 2-4+ degrees C (3.6-7.2+ F) by 2100.

3. The importance the rate of warming

Such rapid rates of warming are what alarms climatologists and those who understand the importance of climate stability for life and society on Earth. Remember the last time you saw a wholly mammoth, saber-toothed cat, wholly rhino, or an indigenous North American horse? Never because they all went extinct from the “rapid” climate change of the final end of the ice age glaciation 11,000 yrs ago. What’s “rapid”? Temperatures warmed more than 2.5 degrees C over the course of 1500 years. We may accomplish that in 150-200 yrs! Incredible. But yet the “rapid” natural changes were not non-consequential. Many more species than listed which couldn’t adapt died out over hundreds to a couple thousand years. And minor variations in global climate by 0.5 degrees C or less – or even significant regional variations which barely showed up on the global signature – have led to major losses in agriculture and economics producing stresses on some nations (poverty, famines, wars) and in some cases, isolated civilizations simply died out. Having such rapid, unprecedented warming is a cause for concern because too many species (and many socio-economic or geographically vulnerable peoples) may face significant harm in the face of an inability to adapt to transforming climate regimes.

In Part 2, later this week, I’ll discuss the effect climate change has on regional climates and likely impacts being faced by humans and wildlife as the climate continues to heat up extremely quickly.

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Heat wave hits Pacific NW this week; A look at Climate Change Impacts on Extreme Heat

If you live in Western Washington and like roasting near 100 degree temperatures, you are and will be getting your wish the next 72 hrs. As powerful upper-atmospheric ridge of high pressure is establishing itself over the West Coast of the US, the combination of clear skies and subsiding (downward moving as opposed to upward rising) air under this high pressure system – subsiding air warms as it sinks – is leading to incredible heat over the interior areas of Western WA/OR and Northern CA.

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Forecast surface temperatures at 5 pm PDT Thursday. Upper-90s near Seattle around 100 in Southwest WA, mid-100s in the Willamette Valley and and Medford, OR area. Eastern WA also hit hard with high heat. (Global Forecast System 11 am PDT Tuesday model run).
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Forecast upper-air map showing the atmospheric wave pattern on the 500 millibar pressure surface (approximately 18,000-18,500 ft over the US) on 11 am Thursday. I added text to show the locations of the ridge relative to its influence on the “extreme heat” (where it is producing 20-25 degree above normal temperatures) over the Pacific Northwest. (Global Forecast System computer 11 am Tuesday model run).

Extreme heat warnings have been issued for virtually ALL OF Washington State, Western Oregon, and much of Northern California.

Shown below are the average high temperatures for today (August 1st) for selected cities in Western WA/OR followed by forecast highs for today-Thurs or Fri. The forecast highs in red are highs which would break the record high for that day.

Seattle, WA-

Tues, August 1st Average High Temperature: 77

Forecast Highs (Tues-Fri): 87, 94, 98, 95

Olympia, WA (state capitol)-

Tues, August 1st Average High Temperature: 79

Forecast Highs (Tues-Fri): 92, 98, 103, 95

Portland, OR-

Tues, August 1st Average High Temperature: 82

Forecast High (Tues-Thurs): 99, 105, 105 (All-time record high is 107 from 1965/1981)

Salem, OR (state Capitol)-

Tues, August 1st Average High Temperature: 84

Forecast High (Tues-Thurs): 99, 106, 105 (All-time record high is 108 from ’27, ’41, ’81)

According to the 5 pm PDT observation, Salem has reached 100 degrees, exceeding their forecast temp and tying the daily record of 100 degrees for today.

Eugene, OR-

Tues, August 1st Average High Temperature: 84

Forecast High (Tues-Thurs): 99, 106, 103 (All-time record high is 108 from ’81)

Medford, OR- (edited at 10:40 pm CDT Tuesday to add this city)

Tues, August 1st Average High Temperature: 93

Forecast High (Tues-Thurs): 108, 114, 111 (All-time record high is 115 from ’46)

It’s very possible that for a portion of the Willamette Valley, especially the Central Willamette Valley, Wednesday could be one of the most intense heat days on record!

The worst of the heat for Western WA and Western OR is expected to end after Friday more seasonable to reasonable above normal temperatures this weekend.


One of the most significant impacts of human-induced Global Climate Change are the impact on heat waves. As the average temperature of Earth warms, many local temperature patterns are shifting toward temperatures which are “hot” to “extremely hot” relative to average temperatures in the mid-20th century (typically defined by their standard deviation from the mean temperature for the local area).

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These charts, based on data by NASA climate scientist James Hansen shows the strong deviation in in the bell curve for 2005-2015 local Northern Hemisphere temperatures relative to the same distribution of temperatures in 1951-1980. The trend has been to many more “extremely hot” temperatures and “hot” temperatures have become the new normal in the Northern Hemisphere on average. See full NY Times story HERE

This shift has had implications for impacts on everything from drought to human health such as heat-related illness and vector-borne illnesses. It will continue to do so as carbon dioxide levels continue to climb. The levels of carbon dioxide in the atmosphere reached a record in observed human history of ~410 parts per million in May of this year, the highest level in at least several million years (and humanity is pumping it into the atmosphere at a rate unseen in the past 65 million years).

At this time, global warming has reached approximately 1 degree C (nearly 2 degrees F) since the early modern Industrial Era (the 1880s). It is statistically known that heat waves, droughts and also heavy precipitation events (because of additional moisture added to a warmer atmosphere) are being impacted directly by climate change.