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SkS Analogy 5 - Linear, Non-linear, and Coastal Flooding

May 23, 2017 - 11:37am
Tag Line

We age linearly and earn non-linearly.
In a warming world, coastal flooding occurs non-linearly … or faster!

Elevator Statement

Linear means a straight line, non-linear means a line that is not straight, and is often a simple, curved line. Consider the following examples from our everyday lives that illustrate linear and non-linear behavior.

  • Our age increases linearly, because our age increases at a constant rate, 1 year per year.
  • Our income increases non-linearly, because our income increases at a varying rate, x% per year.

When the change of your salary is related to your salary, you get a non-linear response. To illustrate, suppose you got a 3.5% raise each year.

  • Year 1: Start with a $30,000/year salary.
  • Year 2: 3.5% more than $30,000. New salary is $30,000 + 0.035*30,000 = 31,050.
  • Year 3: 3.5% more than $31,050. New salary is $31,050 + 0.035*31,050 = 32,137.
  • ...

Suppose a person is born in the year 2000. If we do the simple thing and plot their age on the “Y” axis and the year on the “X” axis, we get a straight line, as follows. We call this a linear relationship. If they start working at age 16, for $30,000/year, and if they get a pay raise of 3.5%/year until they retire at age 65, then we get the non-linear growth of income.

Climate Science

Researchers like James Hansen regularly talk about the doubling time for ice melt, especially in his recent paper “Ice melt, sea level rise and superstorms: evidence from paleoclimate data, climate modeling, and modern observations that 2°C warming could be dangerous,” published by Hansen and 18 co-authors. What do they mean when they say “doubling time?” In their paper they talk about 10-, 20-, or 40-year doubling times that could yield multi-meter sea level rise in 50, 100, or 200 years. What does all of this mean? In a nut-shell, doubling times are techno-speak for non-linear relationships. We can break down doubling times in terms of annual percentage increases as follows, similar to the annual 3.5% salary increase of our young worker.

Annual Increase [%] Doubling Time [years] 1.8 40 2.3 30 (within the IPCC 5th-assessment projections) 3.5 20 5.0 14 7.0 10

Let’s work out what all of this means for our young worker who has their first job, and in the not too distant future may be considering buying property on the East Coast of the USA.

Sea level is currently rising at about 3 mm/year. Starting with this rate, we work out how fast sea level rises for the following annual rates of increase: 0, 2.3, 3.5, 5.0, and 7.0%. Note that a 0% annual increase implies a linear rate of increase of sea level: sea level will be assumed to rise at a constant rate of 3 mm/yr into the future. The non-zero rates imply non-linear rates of increase as shown in the following plot.

Note that making sea-level predictions is much more complicated that using this simple plot, because sea-level responds not only to melting ice, but also to the warming oceans (causing the water to expand, much like in an old-fashioned mercury thermometer) and to local changes in land elevation due to other natural processes. What this plot allows one to do, however, is to convert from techno-speak of ??-year doubling times to what that means in terms of sea-level rise over a specific time period.

So what does all of this mean for someone who buys a house near the East Coast of the USA, and is concerned about the future of their property? Because some East-coast states have been reluctant to embrace even the conservative IPCC forecasts, much less the more current results from researchers like James Hansen and others, our coastal homeowner to-be does their own research and uses the above plot to determine a “safe” place to buy a house, consistent with their risk tolerance. The 14-year doubling time is included because Hansen et al. note that “Recent ice melt doubling times are near the lower end of the 10-40 year range”, and a 14-year doubling time works out to an annual rate of increase of 5%, which is a nice, round number. So whereas 10-yr. doubling times can be viewed as a worst-case scenario, the 14-yr. doubling time is one for which there is some basis from current observations, although the data set from which Hansen et al. draw their conclusions is too short to be definitive. However, considering that we buy insurance to cover improbable events, when current research suggests a probable event such as coastal flooding, it is only prudent to plan accordingly. The scenario we accept from this graph depends on how averse we are to risk. Perhaps the important question to ask is not what risk scenarios our individual home owners are selecting for themselves, but rather, what risk scenarios are East-coast legislators imposing on their constituents?

Because coastal real-estate is valuable, by definition, near the coast we develop every scrap of land possible, meaning that any amount of sea-level rise will affect someone: there is no such thing as inconsequential sea-level rise. It is just a question of how rapidly we will flood coastal property, how many people will be affected and at what rate, and how fast the cost will rise for tax payers who subsidize government-backed flood insurance.

On top of these smooth processes there may also be lurking hard-to-predict, abrupt events. If you have ever seen an unbroken ice-cycle sitting in a snow-bank in front of your house, you have clear evidence that glacier calving from the roof of your house does not always occur predictably and slowly: at some point melting ice-cycles break off and fall. Sometimes ice sheets let lose all at once, causing a sudden increase in ice flow. Such scenarios are not included in IPCC forecasts because they are difficult to predict. But there is plenty of evidence from the paleo record of rapid accelerations of ice loss … at a time when the climate was being forced only a fraction as fast as we are pushing it today.

The good news is that future sea-level rise will make the cheap property sitting back from the coast much more valuable, beach-front property.

2017 SkS Weekly Climate Change & Global Warming News Roundup #20

May 20, 2017 - 1:41pm
  • A chronological listing of news articles posted on the Skeptical Science Facebook page during the past week. Articles of high signifigance are highlighted in the Editor's Picks' section.
Editor's Picks

Receding forest on a mountainside in West Kalimantan province in Borneo


Receding forest on a mountainside in West Kalimantan province in Borneo. ROMEO GACAD/AFP/GETTY IMAGES

Palm oil is the second-most important oil in the modern consumer society, after petroleum. Producing it is a $50-billion-a-year business. It’s in a multitude of the household products in North America, Europe, and Australia: margarine, toothpaste, shampoo, lipstick, cookies, Nutella, you name it. Doritos are saturated with palm oil. It’s what gives chocolate bars their appetizing sheen – otherwise, they would look like mud. Palm oil has replaced artery-clogging ghee as India’s main cooking oil. India is now the major consumer of this clear, tasteless oil squeezed from the nuts of the oil-palm tree, Elais guyanensis,originally from West Africa, but now grown pantropically, mainly within ten degrees north and south of the Equator.

Indonesia and Malaysia chose palm oil as their main economic engine after independence in the 1960s, and they together account for 85 percent of world production, which is expected to double by 2050. As oils go, palm oil gives you the best bang for your buck. Soy fields yield far less than rows of oil-palm trees and have to be replanted annually, while the palms keep bearing huge clusters of oil-rich nuts for 20 years, and can then be replaced. In 2015 17 million hectares of oil palm yielded a total of 62 million tons of oil, while the 120 million hectares planted in soy yielded 48 million tons. Palm oil doesn’t lose its properties when it’s heated, or become rancid at room temperature, and it has multiple industrial uses. It is the edible vegetable oil of choice and is not going away.

Borneo is ground zero for oil-palm devastation. Nowhere has more native rain forest been wiped out.  The world’s third-largest island, Borneo’s lower 73 percent is in Indonesia— the territory of Kalimantan— and its upper portion consists of two states in Malaysia, Sarawak and Sabah, separated by the small, oil-rich sultanate of Brunei. Fifty percent of the lowland Borneo rain forest, which once covered all of the island up to 10,000 feet, is gone, but it’s still the third-largest in the world, after the Amazon and Equatorial Africa’s. It is part of the most ancient rain forest— forest, period— on earth: 130 million years old, more than twice as old as the Amazon’s, and has the greatest density of higher plant species, an estimated 15,000 flowering species. Each new botanical or entomological expedition comes back with new species. Some 20,000 insect species have been found in Sarawak’s Gunung Mulu National Park alone. 

Vanishing Borneo: Saving One of the World’s Last Great Places by Alex Shoumatoff, Yale Environmnet 360, May 18, 2017 

Climate change could slash staple crops: Study

Photo - Oxfam International/flickr 

Climate change, and its impacts on extreme weather and temperature swings, is projected to reduce global production of corn, wheat, rice and soybeans by 23 percent in the 2050s, according to a new analysis.

The study, which examined price and production of those four major crops from 1961 to 2013, also warns that by the 2030s output could be cut by 9 percent. 

The findings come as researchers and world leaders continue to warn that food security will become an increasingly difficult problem to tackle in the face of rising temperatures and weather extremes, combining with increasing populations, and volatile food prices. 

The negative impacts of climate change to farming were pretty much across the board in the new analysis. There were small production gains projected for Russia, Turkey and Ukraine in the 2030s, but by the 2050s, the models “are negative and more pronounced for all countries,” the researchers wrote in the study published this month in the journal Economics of Disasters and Climate Change.  

Climate change could slash staple crops: Study by Brian Bienkowski, The Daily Climate, May 19, 2017

Trump Budget Would Wallop EPA's Climate and Environment Programs

The White House budget is only the first step in a long process. Congress members are already raising concerns. Credit: Jim Watson/AFP/Getty Images

Details of President Donald Trump's 2018 budget proposal, leaked this week, reveal that the administration appears determined to wallop environmental programs, including many that tackle climate change. It would cut Environmental Protection Agency funding by nearly one-third, slash spending on renewable energy innovation, and eliminate the Greenhouse Gas Reporting program, among other programs.

The White House only has the first move in the long budget process; once the proposal is unveiled officially next week, it will be Congress' turn to weigh in on spending priorities. With Trump embroiled in scandal, and many popular programs targeted for elimination, it's not at all clear that lawmakers will follow the president's lead.

The president's so-called "skinny" budget, released in March, also called for slashing EPA funding by 31 percent but was light on detail.

This second version of the budget proposal, leaked late this week, reveals that the administration intends to follow through on its commitment to reduce EPA to the size it was in the 1970s, when climate change wasn't on its radar screen.

Research on air and energy would be slashed by 67 percent, and clean air regulatory programs—which include climate change—would be cut 47 percent. 

Trump Budget Would Wallop EPA's Climate and Environment Programs by Georgina Gustin & Marianne Lavelle, Inside Climate News, May 20, 2017

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Study: inspiring action on climate change is more complex than you might think

May 19, 2017 - 1:23am

We know humans are causing climate change. That is a fact that has been known for well over 100 years. We also know that there will be significant social and economic costs from the effects. In fact, the effects are already appearing in the form of more extreme weather, rising sea levels, ocean acidification, and so on.

So why haven’t humans done much about the problem? Answering that question may be more challenging than the basic science of a changing climate. Fortunately, a new review just out in Science helps us with this question. Lead author, Dr. Elise Amel, a colleague of mine, completed the review with colleagues Drs. Christie ManningBritain Scott, and Susan Koger. Rather than focusing solely on the problems with communicating the science of climate change, this work takes a wider view on the hurdles that get in the way of meaningful action.

The review points out that since the 1970s, extensive efforts to educate people have not lead to significant shifts in behavior. They also acknowledge that using fear or guilt has not been effective in getting people to act. So, what can help? 

Well, first we must understand that it is not just internal forces (emotions, beliefs, attitudes, etc.) that affect human behavior, but external influences as well. External factors, like social networks, societal roles, cultural worldviews, habits, infrastructure, investments, etc, are often severely underestimated in the extent to which they steer behavior. One fault of prior messaging is an almost exclusive focus of the first (internal) set of factors and a near-complete neglect of the latter (externals). The authors write:

Change is hard. Human beings are reticent to change their behavior even under the most compelling of circumstances, and environmental dangers do not tend to arouse the kind of urgency that motivates individuals to act. Mass transformation of unsustainable systems will be even more difficult than shifting individual behaviors, for unlike ants and bees, humans are not well equipped to coordinate behavior for common benefit.

Here is really the center of the problem, the social dilemma wherein it is in the collective’s interest to act in one way but individuals may benefit personally if they act in another way.

This struggle for humans to manage our impact on climate is made more complex by the unique issue of climate change; it is a long-term problem that has no apparent immediate and personal threats. Simply put, we need to take actions now to avoid problems later on even though we personally may not experience these consequences.

To counter this disconnect, climate change discussions need to be framed as matters related to current impacts at the local level. It is great that we want to save polar bears, but what really will motivate people are the risks to them right now. Fortunately or unfortunately, depending on your viewpoint, it is becoming easier and easier to make these connections. Examples abound for instance terrible flooding in the central USA, the record drought in Californiarecent heat waves in central Asia, or in Australia, as just some examples.

The authors identify a variety of strategies for moving forward with human limitations in mind. Since they acknowledge humans tend not to protect those things they either don’t know or don’t value, ingraining a sense of value in the natural world may be critical. In fact, there is a strong relationship between an individual’s connection to nature and their ecological behavior. In today’s world of growing industrialization and severing of the nature/human connection, the challenge may be to find and create new connection opportunities.

More immediately, the authors encourage efforts to change the social norms surrounding environmentally sound behavior - making it cool again.

Click here to read the rest

SkS Analogy 4 - Ocean Time Lag

May 18, 2017 - 3:02pm
Tag Line

Greenhouse gases (GHG) determine amount of warming, but oceans delay the warming.

Elevator Statement

To see how the oceans delay warming of the atmosphere, try the following thought experiment.

  • Imagine a pot that holds about 8 liters/quarts.
  • Hang a thermometer from the center of the lid so that it hangs in the middle of the pot.
  • Put the pot on the stove with no water, just air.
  • Turn the burner on your stove on very low heat.
  • Measure the time it takes for the thermometer to reach 60°C (about 140°F).
  • Remove the pot from the stove, let it cool, fill with water, and place it on the stove on very low heat.
  • How much longer does it take to reach 60°C (about 140°F) with water instead of air in the pot? A lot longer!
  • If you wanted to heat the water to 90°C (about 195°F) in the same amount of time, you would need to start this experiment with the burner on higher heat.

The longer time it takes to heat the pot of water than a pot of air explains why there is a delay between GHG emissions and a rise in temperature of the atmosphere: the oceans absorb a lot of heat, requiring a long time to heat up. This is why scientists such as James Hansen refer to global warming as an inter-generational issue, because the heating due to our emissions are only fully felt by the next generation, due to the time lag created by the oceans.

Climate Science

The earth is covered mostly in water. The large heat capacity of the oceans mean they soak up a lot of energy and slow down the heating of the atmosphere. Just how long is the delay between the time we inject CO2 and other GHG's into the atmosphere and when the effect is felt? The CO2 concentration is like the burner setting in the above example: more CO2 is like a higher burner temperature. However, even though turning up the heat creates hotter water, it takes a while for the water to heat up.

We can estimate the final temperature the atmosphere will reach for a given CO2 concentration by using the average IPCC estimate of 3°C warming for doubling CO2 concentration (this is called the “climate sensitivity”). Using the estimate of pre-industrial CO2 concentration of 280 ppm (parts per million), a climate sensitivity of 3°C implies that CO2 concentrations of 350, 440, and 560 ppm yield 1, 2, and 3°C warming, respectively. Using this estimate of climate sensitivity together with measurements of CO2 from 1970 to today, we can estimate the warming that has been locked in due to recent CO2 emissions. That is, knowing the burner setting, we can estimate the final temperature of the pot of water, even though we will have to wait some time for it to heat up.

We also use the GISS (Goddard Institute for Space Studies) data to plot measured global mean temperature above preindustrial to estimate the time lag between the temperature anomaly suggested by a particular CO2 concentration and the time when that temperature is observed. This is shown in the following figure.

This figure therefore shows the temperature anomaly starting in 1970, the year when the temperature increase due to greenhouse gases began to emerge from the background noise. This figure indicates 3 things: (1) the time lag between emitting greenhouse gases and when we see the principle effect is about 30 years, due mostly to the time required to heat the oceans, (2) the rate of temperature increase predicted by a climate sensitivity of 3°C tracks well with the observed rate of temperature increase, and (3) we have already locked in more than 1.5°C warming. As of 2017 we have reached 406 ppm CO2. At the current increase of 2 ppm CO2/yr., this implies that we will reach 440 ppm and lock in 2°C warming by 2035 … if we don’t act now.

So whereas the experiment at home with a pot of water on low heat yields a time lag of something like 10’s of minutes to heat the water, to heat an Earth-sized pot of water the time lag is about 30 years.

What this figure does not show, however, is that as other complex feedback mechanisms kick in, the rate of warming may begin to exceed the IPCC average climate sensitivity. Therefore, for future trends, this plot likely represents the minimum temperature increase that we can expect for a given CO2 concentration.

NY Times’ Stephens can’t see the elephant in the room on climate change

May 16, 2017 - 1:31am

There was tremendous outcry when the New York Times hired opinion columnist Bret Stephens, who has a long history of making misinformed comments about climate change. Stephens didn’t assuage those fears when he devoted his first column to punching hippies, absurdly suggesting that our lack of progress on climate policy is a result of greens being too mean to climate deniers.

Stephens lamentably stayed on the subject of climate change in his second and third Times columns as well. In those pieces, he used corn-based ethanol subsidies as an example of where climate policy has gone wrong:

So let’s talk about ethanol and other biofuels, a subject some climate-change activists might prefer to forget. In 2007, George W. Bush used his State of the Union speech to call for huge increases in the production of renewable and alternative fuels such as ethanol. Democrats were firmly on board, and President Barack Obama pursued a largely similar course in his first years in office.

This is a clear case of cherry picking. There are hundreds of examples of climate policies with varying degrees of effectiveness; why focus on just one? Many environmental groups and “climate-change activists” have long opposed corn-based ethanol subsidies, as Stephens himself noted. Politicians of both political parties supported those subsidies because they were popular in corn-growing Midwestern states. It had little if anything to do with climate efficacy. So why blame “climate-change activists” for these politically-motivated subsidies?

For his next misleading argument, Stephens shifted to German electricity costs:

The country is producing record levels of energy from wind and solar power, but emissions are almost exactly what they were in 2009. Meanwhile, German households pay nearly the highest electricity bills in Europe, all for what amounts to an illusion of ecological virtue.

Stephens’ comparison to 2009 is another example of blatant cherry picking. German carbon emissions that year were particularly low, due in part to the global recession. The long-term trend is unmistakable.

It’s also odd that Stephens criticized Germany for its electricity bills, given that the report he referenced shows they’re a bit lower than what Americans pay. The difference is that while German electricity rates are 3.3 times higher than Americans’, their electricity consumption is 3.4 times lower. In other words, German policies have been successful in cutting the nation’s carbon pollution while still keeping their electricity bills a bit lower than Americans’. 

The country is far from perfect – they still rely on coal for a significant amount of that electricity generation – but from a climate policy perspective, Germany is mostly a success story. America’s per-person carbon pollution is nearly twice as high as Germany’s.

Although his columns are riddled with these sorts of misleading cherry picks, worse yet is that Stephens’ arguments are red herrings, distracting from the elephant in the room.

On American climate policy, the GOP is the problem

Stephens’ columns worry that America will jump on the bandwagon of any feel-good climate policy. If only we lived in a world where that were a legitimate concern. In reality, the Trump administration is taking every possible step to undo all American climate policies. They’re considering withdrawing from the Paris climate agreement because they believe it won’t allow America to increase its carbon pollution.

The administration has effectively declared war on the Earth’s climate and our future well-being. Noam Chomsky has called the Republican Party the most dangerous organization in human history because of its climate denial and policy obstruction.

Stephens’ focus on corn-based ethanol is like a cancer patient worrying about a hangnail. Certainly, all parties should debate the best and most effective policies to address climate change. We’ve been pleading with Republicans for years to engage in that debate. Democrats have proposed all sorts of different policy solutions - government regulations, free market cap and trade systems (a Republican invention), small government revenue-neutral carbon taxes - you name it. They’re not the problem.

There are a few GOP climate leaders

Fortunately, some prominent Republicans have stepped up to engage in the climate policy debate. Senators John McCain and Lindsey Graham authored past climate legislation. 19 House Republicans have joined the Climate Solutions Caucus, 12 of whom just introduced The Climate Solutions Commission Act that would establish a commission to recommend economically viable climate policies. And a group of Republican elder statesmen on the Climate Leadership Council met with the White House to recommend support for a revenue-neutral carbon tax.

However, while deserving of great praise and encouragement for their efforts, these climate realist Republican Party leaders are in the minority.

Click here to read the rest

2017 SkS Weekly Climate Change & Global Warming News Roundup #19

May 13, 2017 - 12:22pm

A chronological listing of news articles posted on the Skeptical Science Facebook page during the past week. 

Editor's Pick

Global Climate Policy in an Uncertain State of Flux


What would happen if the US leaves the Paris agreement? It would be a big blow to global cooperation, especially since the US is the top emitter after China, and is also by far a bigger emitter per capita than China and most other countries. Credit: Bigstock. 

It was thus heartening that US citizens are protesting against their government’s climate change policies.

It is also important for people and governments in the rest of the world to strengthen their resolve to fight climate change, rather than to relax now that the US leadership is refusing to do its part.

The best solution would be for the US to remain in the Paris agreement, and go along with other countries to meet and improve on their pledges and enable international cooperation to thrive.

That is not going to happen. So we may have to wait at least four years before another US administration rejoins the rest of the world to tackle climate change.  Let’s hope it will not be really too late by then to save the world. 

Global Climate Policy in an Uncertain State of Flux by Martin Khor, Inter Press Service (IPS), May 8, 2017

Links posted on Facebook

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More errors identified in contrarian climate scientists' temperature estimates

May 11, 2017 - 1:46am

Human emission of heat-trapping gases is causing the Earth to warm. We’ve known that for many decades. In fact, there are no reputable scientists that dispute this fact. There are, however, a few scientists who don’t think the warming will be very much or that we should worry about it. These contrarians have been shown to be wrong over and over again, like in the movie Groundhog Day. And, a new study just out shows they may have another error. But, despite being wrong, they continue to claim Earth’s warming isn’t something to be concerned about.

Perhaps the darlings of the denialist community are two researchers out of Alabama (John Christy and Roy Spencer). They rose to public attention in the mid-1990s when they reportedly showed that the atmosphere was not warming and was actually cooling. It turns out they had made some pretty significant errors and when other researchers identified those errors, the new results showed a warming.

To provide perspective, we know the Earth is warming because we can measure it. Most of the heat (93%) goes into the oceans and we have sensors measuring ocean temperatures that show this. We also know about warming because we have thermometers and other sensors all over the planet measuring the temperature at the surface or in the first few meters of air at the surface. Those temperatures are rising too. We are also seeing ice melting and sea level rising around the planet. 

So, the evidence is clear. What Christy and Spencer focus on is the temperatures measured far above the Earth’s surface in the troposphere and the stratosphere. Generally, over the past few decades these two scientists have claimed the troposphere temperatures are not rising very rapidly. This argument has been picked up to deny the reality of human caused climate change – but it has been found to be wrong.

What kinds of errors have been made? Well first, let’s understand how these two researchers measure atmospheric temperatures. They are not using thermometers, rather they are using microwave signals from the atmosphere to deduce temperatures. The microwave sensors are on satellites which rapidly circle the planet. 

Some of the problems they have struggled with relate to satellite altitudes (they slowly fall over their lifetimes, and this orbital decay biases the readings); satellite drift (their orbits shift east-west a small amount causing an error); they errantly include stratosphere temperatures in their lower atmosphere readings; and they have incorrect temperature calibration on the satellites. It’s pretty deep stuff, but I have written about the errors multiple times here, and here for people who want a deeper dive into the details.

It’s important to recognize that there are four other groups that make similar measurement estimates, so it’s possible to compare the temperatures of one group against another. The new paper, completed by Eric Swanson and published by the American Meteorological Society compares the results from three different groups. He focused on measurements made over the Arctic region. His comparison found two main differences amongst the three groups that suggests the errors.

To better appreciate the issues, the satellites have instruments called Microwave Sounding Units (MSUs) or more recently, Advanced Microwave Soundings Units (AMSUs). These instruments allow reconstruction of the lower troposphere (TLT), the mid-troposphere temperature (TMT), and the lower stratosphere temperature (TLS). But the measurements are not at a specific location (like a thermometer) - they are smeared out over large spaces. As a consequence, it’s possible to have one layer of the atmosphere contaminate the results of another layer. You wouldn’t for instance, want your measurement of the troposphere (lower atmosphere) to include part of the stratosphere (above the troposphere).

Among the key differences among the research teams are their methods to ensure this contamination is minimized. According to the recent paper, which was published in January 2017:

Click here to read the rest

SkS Analogy 3 - Greenhouse Effect is a Cloudy Night

May 9, 2017 - 4:09pm
Tag Line

The greenhouse effect is like a warm, cloudy night.

Elevator Statement
  • At night clouds trap infrared radiation emitted from the ground, similar to greenhouse gases, and re-emit some of the absorbed radiation back to the ground.
  • More nighttime cloud cover means more trapped heat, and warmer temperatures near the ground, just as more CO2 in the atmosphere means more trapped heat, and warmer temperatures.
  • Because clouds are big and thick, their radiation-trapping effect is felt immediately, within a single night.
  • Because CO2 is diffuse, its effect is felt slowly, over many decades.
  • Increasing the concentration of CO2 in the atmosphere is like increasing the cloud cover at night: both warm the Earth by trapping infrared radiation.
Climate Science

The greenhouse effect describes the trapping of energy by Earth’s atmosphere: infrared radiation from the ground is absorbed by gases in the atmosphere such as CO2, H2O, CH4, and others. Although the greenhouse effect is active 24/7, it is most apparent at night. This is because with no background solar radiation, nighttime warmth occurs mostly by greenhouse gases and clouds grabbing and storing some of the infrared radiation emitted from the ground that is trying to make it to outer space. This is partly why nighttime temperatures have been steadily increasing as greenhouse gases increase: more greenhouse gases implies more heating.

Everything radiates infrared radiation, but the amount emitted depends on its temperature. Because outer space is at a background temperature of about -270ºC (i.e., 3ºC above absolute 0), it emits essentially no radiation. The upper atmosphere is also much colder than the ground, so infrared energy absorbed high in the atmosphere is only weakly re-radiated back to the ground. On a clear night, therefore, the ground emits radiation to space and the upper atmosphere, but receives very little in return. The greenhouse gases in the atmosphere absorb more infrared radiation than they re-radiate back to the ground.

To see for yourself how this works, if you have a car parked outside with one side facing a house, and the other side facing an open field, and if the air temperature is about 2-3ºC (such as on a cool, Spring night), you will observe the following on a calm night with no clouds. If there is nothing covering the windshield of your car, it will become frosted, because as it radiates energy upward to outer space, it cools. Because it radiates more energy upward than it receives back from either outer space or the upper atmosphere, the windshield actually gets colder than the surrounding air. The same happens for the windows facing the big open field, because if the trees and buildings on the other side of the open field are short enough, then the side windows also effectively “look” at outer space on the other side of the field. However, the windows facing the house will not frost over, because although they transmit radiation to the house, the house is warm and radiates a lot of energy back to the window, keeping it warm.

On a cloudy night all of this changes, because the clouds radiate a lot of energy back to the ground, so that any windows that are looking up or to the side at the sky essentially just exchange energy with the relatively warm clouds. This prevents the windows from cooling to below the ambient temperature, keeping them unfrosted.

This object lesson with the windows of a car illustrates the kind of radiation transfer that is occurring between the ground, outer space, and the upper atmosphere, and allows you to see a clear example of how the greenhouse effect works: on a night when the air temperature is about 2-3ºC, with no clouds the windshield on your car becomes frosted, on a cloudy night it stays unfrosted.

Whereas clouds are like a transient, visible blanket, CO2 and other greenhouse gases are like a permanent, invisible cloak. Increasing greenhouse-gas concentrations increases the warmth of this invisible cloak, trapping more infrared radiation trying to make it out to space, keeping us warmer than we may prefer.

NOTE: if you have a very clean windshield, supercooled water may form on your windshield instead of frost. That is, clean water can cool to below 0ºC without freezing. But if you turn on your windshield wipers, the supercooled water will instantly freeze, demonstrating that the windshield is below 0ºC, even though there may be liquid water instead of frost.

2017 SkS Weekly Climate Change & Global Warming News Roundup #18

May 6, 2017 - 3:23pm

A chronological listing of news articles posted on the Skeptical Science Facebook page during the past week. Articles of high signifigance are highlighted in the Editor's Picks' section.

Editor's Picks

No country on Earth is taking the 2 degree climate target seriously

 (Oil Change International)

One of the morbidly fascinating aspects of climate change is how much cognitive dissonance it generates, in individuals and nations alike.

The more you understand the brutal logic of climate change — what it could mean, the effort necessary to forestall it — the more the intensity of the situation seems out of whack with the workaday routines of day-to-day life. It’s a species-level emergency, but almost no one is acting like it is. And it’s very, very difficult to be the only one acting like there’s an emergency, especially when the emergency is abstract and science-derived, grasped primarily by the intellect.

This psychological schism is true for individuals, and it’s true for nations. Take the Paris climate agreement.

In Paris, in 2015, the countries of the world agreed (again) on the moral imperative to hold the rise in global average temperature to under 2 degrees Celsius, and to pursue "efforts to limit the temperature increase to 1.5 degrees." To date, 62 countries, including the United States, China, and India, have ratified the agreement.

Are any of the countries that signed the Paris agreement taking the actions necessary to achieve that target? 

No country on Earth is taking the 2 degree climate target seriously by David Roberts, Energy & Environment, Vox, Apr 29, 2017 

It can’t just be a march. It has to be a movement.’ What’s next for climate activists?

Mike Theiler / Reuters

“Okay, so what’s next?” said Gene Karpinski, president of the League of Conservation Voters, on Sunday morning as he looked out at the nearly 100 women gathered inside a meeting room at Union Station.

Less than 24 hours earlier, they had joined tens of thousands of demonstrators on a sweltering day in the nation’s capital for the latest mass protest of the Trump era. The Peoples Climate March had been a chance to push for action on climate change and to oppose what activists see as an unprecedented assault on environmental protections during President Trump’s first 100 days. Protesters had chanted and sung, carried clever signs, Snapchatted and tweeted their way down Pennsylvania Avenue to the White House.

Now, the streets of Washington were quiet. The crowds had mostly gone home. Trump was still in the White House. Republicans still controlled Congress. And the entire climate movement, which had seen the Obama era as a time of progress in combating global warming and prioritizing environmental safeguards, faced the question Karpinski had posed: What’s next?

‘It can’t just be a march. It has to be a movement.’ What’s next for climate activists? by Brady Dennis, Energy & Environment, Washington Post, May 1, 2017

Global warming scientists learn lessons from the pause that never was


‘Despite all the other indicators of global warming showing business as usual, a fixation on the average temperature of the globe stuck firm.’ Photograph: Philippe Huguen/AFP/Getty Images

People don’t talk about how global warming has stopped, paused or slowed down all that much any more – three consecutive hottest years on record will tend to do that to a flaky meme.

But there was a time a few years ago when you couldn’t open your news feed without being told global warming had stopped by some conservative columnist, climate science denier or one of those people who spend their waking hours writing comments on stories like this.

The issue at hand was one of the multiple measurements used by scientists to monitor the state of the planet – the globally averaged temperature.

Depending on which particular set of data you looked at, and how you calculated trends, there was an argument that temperature rises had slowed over a period of about 15 years. 

Global warming scientists learn lessons from the pause that never was by Graham Readfearn, Planet Oz, Guardian, May 3, 2017

Negative emissions tech: can more trees, carbon capture or biochar solve our CO2 problem?

Reforestation is the least controversial negative emissions technology - but a substantial amount of good quality land is needed. Photograph: Jenny Bonner/Getty Images 

In the 2015 Paris climate agreement, 195 nations committed to limit global warming to two degrees above pre-industrial levels. But some, like Eelco Rohling, professor of ocean and climate change at the Australian National University’s research school of earth sciences, now argue that this target cannot be achieved unless ways to remove huge amounts of carbon dioxide from the atmosphere are found, and emissions are slashed.

This is where negative emissions technologies come in. The term covers everything from reforestation projects to seeding the stratosphere with sulphates or fertilising the ocean with iron fillings.

It’s controversial – not least because of the chequered history of geoengineering-type projects, but also because of concerns it will grant governments and industry a licence to continue with business as usual. But many argue we no longer have a choice.

“Most things are not applied yet on larger scales but we have a pretty good feeling of things that will work and we can quantify roughly how much carbon we should be able to remove from the atmosphere with them,” says Rohling. 

Negative emissions tech: can more trees, carbon capture or biochar solve our CO2 problem? by Bianca Nogrady, Innovations in Renewables, Guardian, May 4, 2017

The Glaciers are Going 

 The Waggonwaybreen glacier in Svalbard. Photo: Andreas Weith 

As can be seen above, the Waggonwaybreen glacier in Svalbard, Norway, has retreated substantially since 1900. Svalbard’s glaciers are not only retreating, they are also losing about two feet of their thickness each year. Glaciers around the world have retreated at unprecedented rates and some have disappeared altogether. The melting of glaciers will affect people around the world, their drinking water supplies, water needed to grow food and supply energy, as well as global sea levels.

The Intergovernmental Panel on Climate Change estimates that around the world glaciers (excluding the Greenland and Antarctic ice sheets) will decrease in volume between 15 to 55 percent by 2100 even if we are able to limit global warming to under 2˚C; they could shrink up to 85 percent if warming increases much more.

In Earth’s history, there have been at least five major ice ages, when long-term cooling of the planet resulted in the expansion of ice sheets and glaciers. Past ice ages have been naturally set off by a numerous factors, most importantly, changes in the Earth’s orbit around the sun (Milankovitch cycles) and shifting tectonic plate movements that affect wind and ocean currents. The mixture of gases in the atmosphere (such as carbon dioxide and methane) as well as solar and volcanic activity are also contributing factors. Today we are in a warm interval—an interglacial—between ice ages. 

The Glaciers are Going by Renee Cho, State of the Planet, Earth Institute, Columbia University, May 5, 2017

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Medical scientists report on the impact climate change is having on health

May 5, 2017 - 1:48am

As a climate scientist, I spend time and energy studying how fast the Earth is warming and what is causing the warming. This knowledge helps us predict what the future will look like. But, what most people are interested in is, “how will it affect me?” 

Some impacts we are pretty clear about, like the impacts related to sea level rise, increased storms and heavy precipitation, and increased drought and heat waves – particularly the impacts these events have on the economy. But climate change will affect us personally as well (by personally, I mean our physical person). 

In fact, climate change is already affecting personal human health around the world. This subject was the focus of a summary report just published by the Medical Society Consortium. What I really liked about this report is that it breaks down some of the key impacts by region. Unfortunately, the report is limited in scope to the USA. However, the general conclusions and trends can be illuminating for people outside the USA as well.

What was also welcome is that this report was prepared by physicians (not climate scientists) of major medical societies and the conclusions are based on the best available and current information of both the climate and health fields.

So what did they find? Perhaps most importantly they find that climate change is already affecting our health. This isn’t a future problem for the next generation. It is a problem that is present and growing. They also report that some populations are more susceptible to climate change effects. Among the most vulnerable groups are children, student athletes, pregnant women, elderly, people with chronic health conditions, and the impoverished. A third key takeaway is that the problems will get much worse as climate change continues.

The study reports that if you live on the West Coast, wildfires, extreme temperatures, poorer air quality, extreme weather events, and agricultural risks are occurring. On the East Coast, you can add vector-borne diseases as a risk area. The central USA region is also similarly being affected.

As you dig deeper into the report, you learn about how these various climate-related features are affecting health. Each factor is dealt with by three questions: 1) What is happening? 2) How does it harm our health? 3) Who is being harmed?

For instance, with respect to extreme weather, the report correctly notes that the frequency and severity of some weather events such as heavy downpours, floods, droughts, and major storms are increasing. This harms our health because these events can cause direct injury and death as well as displacement. Extreme weather can also harm vital infrastructure like communication systems, homes, and reduce the availability of clean water and food. Finally, extreme weather can lead to acute outbreaks of infectious disease while at the same time reducing access to health care.

Click here to read the rest

SkS Team - Marching for Science around the globe

May 1, 2017 - 4:07am

Many articles have already been written about the recent March for Science - Dana's Guardian post "March against madness" being a case in point. So, this one will not have a lot of words and will let the collages put together from the marches where members from our Skeptical Science team participated in speak for themselves. Where available, you'll also find links to the respective march's homepage. Enjoy!

Sou marched in Melbourne (and has a blog post on HotWhopper about it):

Baerbel joined the rally in Stuttgart (organiser's Flickr album) and the march in Tübingen (video from the event) in southern Germany:

Ian joined the march in London (more of Ian's pictures in his album on Facebook):

Ken marched in Edinburgh (more pictures on the organisers' Facebook page):

John set his sights on creative signs at the march in Washington D.C. (and recorded several comments for episode 9 of Evidence Squared while there):

Sarah lucked out with the weather in Houghton, Michigan:

David marched in St. Louis (the organisers posted many pictures on their Facebook page)

Doug was taking a shower in Seattle:

Here is to a likewise successful March for Climate on April 29!

NY Times hired a hippie puncher to give climate obstructionists cover

April 29, 2017 - 8:50pm

Yesterday, New York Times subscribers were treated to an email alert announcing the first opinion column from Bret Stephens, who they hired away from the Wall Street Journal. Like all Journal opinion columnists who write about climate change, Stephens has said a lot of things on the subject that could charitably be described as ignorant and wrong. Thus many Times subscribers voiced bewilderment and concern about his hiring, to which the paper’s public editor issued a rather offensive response.

Justifying the critics, here’s how the paper announced Stephens’ first opinion column in an email alert (usually reserved for important breaking news):


In his debut as a Times Op-Ed columnist, Bret Stephens says reasonable people can be skeptical about the dangers of climate change

Stephens gets his few facts wrong

In his column, Stephens pooh-poohed climate change as a “modest (0.85 degrees Celsius) warming of the Northern Hemisphere since 1880,” citing the 2014 IPCC report. However, Stephens packed three big mistakes into that single sentence. Here’s what the IPCC said (emphasis added):

The globally averaged combined land and ocean surface temperature data as calculated by a linear trend show a warming of 0.85 [0.65 to 1.06] °C over the period 1880 to 2012

The northern hemisphere warms faster than the global average because it has more land and less ocean than the southern hemisphere (water warms slowly), so this is an important mistake that underestimates the global temperature rise. On top of that, since 2012 we’ve seen the three hottest years on record (2014, 2015, and 2016), so even the 0.85°C warming figure is outdated (it’s now right around 1°C).

Stephens doesn’t understand the rapid pace or urgency of the problem

Most importantly, the global warming we’ve experience is in no way “modest.” We’re already causing a rate of warming faster than when the Earth transitions out of an ice age, and within a few decades we could be causing the fastest climate change Earth has seen in 50 million years. The last ice age transition saw about 4°C global warming over 10,000 years; humans are on pace to cause that much warming between 1900 and 2100 – a period of just 200 years, with most of that warming happening since 1975.

Of course, how much global warming we see in the coming decades depends on how much carbon pollution we dump into the atmosphere. If we take serious immediate action to cut those emissions, as the international community pledged to do under the Paris agreement, we can limit global warming to perhaps 2°C, and the climate consequences that come along with it.

But this is where Stephens’ opinions are particularly unhelpful:

Demanding abrupt and expensive changes in public policy raises fair questions about ideological intentions. Censoriously asserting one’s moral superiority and treating skeptics as imbeciles and deplorables wins few converts … Perhaps if there were less certitude about our climate future, more Americans would be interested in having a reasoned conversation about it.

In other words, the people obstructing climate policies are justified because climate “advocates” are too mean to them, and claim too much certainty about the future.

This is of course nonsense. There is uncertainty about how much global warming and climate change we’ll see in the coming decades (climate scientists are crystal clear about this), but the biggest factor contributing to that uncertainty is human behavior – how much carbon pollution we end up dumping into the atmosphere. This is apparent from looking at the IPCC global temperature projections:

Global average surface temperature projections. Illustration: Intergovernmental Panel on Climate Change Fifth Assessment Report.

In the red ‘burn lots of fossil fuels’ (RCP8.5) scenario, we’ll see a further 3.0–5.5°C warming between now and 2100. In the blue ‘take immediate serious climate action’ (RCP2.6) scenario, we’ll see a further 0.5–1.5°C global warming by 2100. Those ranges represent uncertainties in the climate modeling, but the difference between them – which is based on how much carbon pollution we release – is bigger than the uncertainty in each scenario.

Stephens needs a lesson in risk management

Smoking provides an apt analogy. Each time we smoke, we increase the odds of developing cancer a little bit more. The future outcome is uncertain – we don’t know exactly if or when the disaster of cancer will hit – but we know we’re making it more likely every time we smoke, and the smart move is to mitigate that risk by cutting down on the cigarettes as quickly as possible. With climate change, each time we add more carbon pollution to the atmosphere, we increase the odds of a climate catastrophe a little bit more. The smart move is to mitigate that risk by cutting down on our burning of fossil fuels as quickly as possible.

Stephens’ piece is akin to criticizing doctors and anti-smoking groups for being too mean to the tobacco industry, and for not focusing on the uncertainty about exactly when the chain-smoking patient will develop cancer.

So far, climate change may be humanity’s greatest-ever risk management failure. The Paris climate agreement was a major step to remedy that failure, but now the Trump administration is debating whether to withdraw from it, or simply refuse to honor America’s pledges. 

There have been bipartisan bills in Congress to implement market-based solutionsto the problem, but each has been blocked by the Republican Party at the behest of its fossil fuel donors. Democrats have even proposed small government, revenue-neutral solutions that would benefit the economy, but while some Republican elder statesmen support the policy, Republicans in Congress have refused to even vote on it.

Stephens punches the hippies

In short, on climate science and policy it’s clear where the problem lies, and it’s not with the advocates. Not only does Stephens get basic facts wrong and gloss over the tremendous risks posed by climate change, but he blames partisan policy obstruction on the people who are desperately trying every possible avenue to solve the problem. The New York Times is publishing and promoting textbook hippie punching, and its readers are rightly appalled. 

Click here to read the rest

2017 SkS Weekly Climate Change & Global Warming News Roundup #17

April 29, 2017 - 1:57pm

A chronological listing of news articles posted on the Skeptical Science Facebook page during the past week. Articles of signifigance as determined by the editor are highlighted in the Editor's Picks' section.

Editor's Picks

Tens of thousands marched for science. Now what?


Just hours after the Washington March for Science dispersed, organizers sent an email to demonstrators with the subject line, “What's next?”

“Our movement is just starting,” the message read. It went on to urge marchers to take part in a “week of action,” a set of coordinated activities that range from signing an environmental voting pledge to participating in a citizen science project. They will provide postcards for participants to send to their political leaders and a calendar of events recommended by the march's partner groups.

The march website was also overhauled Saturday night to include a new page on the organization's vision for the future. The details are not fully fleshed out (and the page still included a few typos Sunday afternoon), but organizers say they aim to build a new science advocacy network and establish programs to better engage the public with science.

“We intend to symbolically keep marching,” said national co-chair Valerie Aquino. “I would love for the March for Science to continue growing into a global movement.”

That goal will require a sea change in how scientists think about outreach. But after the success of the march, which turned out tens of thousands of demonstrators in more than 600 cities, organizers think it could happen.

Tens of thousands marched for science. Now what? by Sarah Kaplan, Speaking of Science, Washington Post, Apr 23, 2107 

China, India Become Climate Leaders as West Falters

Less than two years after world leaders signed off on a historic United Nations climate treaty in Paris in late 2015, and following three years of record-setting heat worldwide, climate policies are advancing in developing countries but stalling or regressing in richer ones.

In the Western hemisphere, where centuries of polluting fossil fuel use have created comfortable lifestyles, the fight against warming has faltered largely due to the rise of far-right political groups and nationalist movements. As numerous rich countries have foundered, India and China have emerged as global leaders in tackling global warming.

Nowhere is backtracking more apparent than in the U.S., where President Trump is moving swiftly to dismantle environmental protections and reverse President Obama’s push for domestic and global solutions to global warming.

The U.S. isn’t alone in its regression. European lawmakers are balking at far-reaching measures to tackle climate change. Australian climate policy is in tatters. International efforts to slow deforestation in tropical countries are failing.

China, India Become Climate Leaders as West Falters by John Upton, Climate Central, Apr 24, 2017 


 April 1970 through March 2017 temperature trend from Berkeley Earth.

With the first quarter of 2017 now past, the year is shaping up to be one of climate extremes: high temperatures, low sea ice, and coral bleaching. 

Global surface temperatures continue to increase in-line with climate model predictions, and the world has now experienced an increased global temperature of about 0.8 degrees C (1.5 degrees F) since 1970. Temperatures for the first three months of the year were actually warmer than the 2016 average, and there is a reasonable chance that 2017 for a fourth consecutive year will be the warmest on record.

Global sea ice extent is near historic lows in the Arctic and Antarctic, and Arctic sea ice volume has also been decreasing as it ages and thins, with less new ice to replace it. The Great Barrier Reef experienced an unprecedented second consecutive year of coral bleaching, the only major coral bleaching on record to have occurred other than in an El Niño year.

Worrisome first quarter of 2017 climate trends by Zeke Hausfather, Yale Climate Connections, Apr 27, 2017

An Ice-Free Summer in the Arctic Ocean Would Be Deadly for the Northern Hemisphere


Arctic sea ice near the coast of Greenland in September of 2015 at the peak of the melt season. (Photo: Bob Berwyn)

Climate scientists don’t like to get pinned down on making date-specific projections about the effects of global warming. But after months of watching Arctic sea ice languish at a record low, the big question has surfaced once again: When will we see the Arctic’s first ice-free summer?

According to University of Exeter climate researcher James Screen, the latest modeling suggests that, unless heat-trapping greenhouse gas emissions stop soon, an ice-free Arctic summer will happen as soon as 2046.

“That’s our best estimate, give or take 20 years,” Screen said during an April 24th press conference at the European Geosciences Union conference in Vienna. The ice decline is clearly linked with rising global temperatures, and the chances that the Arctic will be ice-free increase dramatically when the average global temperature rises between 1.7 and 2.1 degrees Celsius, Screen said. 

Worrisome first quarter of 2017 climate trends by Zeke Hausfather, Yale Climate Connections, Apr 28, 2017 

The kids suing Donald Trump are marching to the White House


"The state of the planet is unraveling all around us because of our addiction to fossil fuels," Xiuhtezcatl Martinez said at the steps of the US Supreme Court this week. "For the last several decades, we have been neglecting the fact that this is the only planet that we have and that the main stakeholders in this issue (of climate change) are the younger generation. Not only are the youth going to be inheriting every problem that we see in the world today — after our politicians have been long gone — but our voices have been neglected from the conversation. "Our politicians are no longer representing our voices." So, what's a voiceless kid to do? How about sue President Donald Trump and his administration — and then march to the White House?

The kids suing Donald Trump are marching to the White House by John Sutter, CNN, Apr 29, 2017 

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